kopia lustrzana https://github.com/F5OEO/rpitx
Include Pifmrds for easy integration - see PifmRDS for reference of the Author Christophe Jacquet: https://github.com/ChristopheJacquet/PiFmRds
F5OEO
rodzic
35d04dcc62
commit
79b0099667
14
src/Makefile
14
src/Makefile
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|
@ -1,4 +1,4 @@
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|||
all: ../pisstv ../piopera ../pifsq ../pichirp ../sendiq ../tune ../freedv ../dvbrf ../pocsag ../spectrumpaint
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||||
all: ../pisstv ../piopera ../pifsq ../pichirp ../sendiq ../tune ../freedv ../dvbrf ../pocsag ../spectrumpaint ../pifmrds
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||||
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||||
CFLAGS = -Wall -g -O2 -Wno-unused-variable
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||||
LDFLAGS = librpitx/src/librpitx.a -lm -lrt -lpthread
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||||
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@ -49,6 +49,16 @@ LDFLAGS_Pissb = librpitx/src/librpitx.a -lm -lrt -lpthread -lsndfile -lliquid
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../spectrumpaint: spectrumpaint/spectrum.cpp librpitx/src/librpitx.a
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$(CCP) $(CFLAGS) -o ../spectrumpaint spectrumpaint/spectrum.cpp $(LDFLAGS)
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../pifmrds: pifmrds/rds.c pifmrds/waveforms.c pifmrds/pi_fm_rds.cpp pifmrds/fm_mpx.c pifmrds/control_pipe.c librpitx/src/librpitx.a
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$(CC) $(CFLAGS) -c -o pifmrds/rds.o pifmrds/rds.c
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$(CC) $(CFLAGS) -c -o pifmrds/control_pipe.o pifmrds/control_pipe.c
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$(CC) $(CFLAGS) -c -o pifmrds/waveforms.o pifmrds/waveforms.c
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||||
$(CC) $(CFLAGS) -c -o pifmrds/rds_wav.o pifmrds/rds_wav.c
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$(CC) $(CFLAGS) -c -o pifmrds/fm_mpx.o pifmrds/fm_mpx.c
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$(CC) -o pifmrds/rds_wav pifmrds/rds_wav.o pifmrds/rds.o pifmrds/waveforms.o pifmrds/fm_mpx.o -lm -lsndfile
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$(CCP) $(CFLAGS) -Wno-write-strings -o ../pifmrds pifmrds/rds.o pifmrds/waveforms.o pifmrds/pi_fm_rds.cpp pifmrds/fm_mpx.o pifmrds/control_pipe.o librpitx/src/librpitx.a -lm -lsndfile -lrt -lpthread
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CFLAGS_Pifm = -Wall -g -O2 -Wno-unused-variable
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LDFLAGS_Pifm = librpitx/src/librpitx.a -lm -lrt -lpthread -lsndfile
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../pifm : ../fm/pifm.c
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@ -65,7 +75,7 @@ LDFLAGS_Pidcf77 = librpitx/src/librpitx.a -lm -lrt -lpthread
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$(CC) $(CFLAGS_Piam) -o ../pidcf77 ../dcf77/pidcf77.c $(LDFLAGS_Piam)
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clean:
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rm -f ../dvbrf ../sendiq ../pissb ../pisstv ../pifsq ../pifm ../piam ../pidcf77 ../pichirp ../tune ../freedv ../piopera ../spectrumpaint ../pocsag
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rm -f ../dvbrf ../sendiq ../pissb ../pisstv ../pifsq ../pifm ../piam ../pidcf77 ../pichirp ../tune ../freedv ../piopera ../spectrumpaint ../pocsag ../pifmrds
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||||
install: all
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@ -0,0 +1,674 @@
|
|||
GNU GENERAL PUBLIC LICENSE
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Version 3, 29 June 2007
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Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
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||||
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|
||||
author attributions in that material or in the Appropriate Legal
|
||||
Notices displayed by works containing it; or
|
||||
|
||||
c) Prohibiting misrepresentation of the origin of that material, or
|
||||
requiring that modified versions of such material be marked in
|
||||
reasonable ways as different from the original version; or
|
||||
|
||||
d) Limiting the use for publicity purposes of names of licensors or
|
||||
authors of the material; or
|
||||
|
||||
e) Declining to grant rights under trademark law for use of some
|
||||
trade names, trademarks, or service marks; or
|
||||
|
||||
f) Requiring indemnification of licensors and authors of that
|
||||
material by anyone who conveys the material (or modified versions of
|
||||
it) with contractual assumptions of liability to the recipient, for
|
||||
any liability that these contractual assumptions directly impose on
|
||||
those licensors and authors.
|
||||
|
||||
All other non-permissive additional terms are considered "further
|
||||
restrictions" within the meaning of section 10. If the Program as you
|
||||
received it, or any part of it, contains a notice stating that it is
|
||||
governed by this License along with a term that is a further
|
||||
restriction, you may remove that term. If a license document contains
|
||||
a further restriction but permits relicensing or conveying under this
|
||||
License, you may add to a covered work material governed by the terms
|
||||
of that license document, provided that the further restriction does
|
||||
not survive such relicensing or conveying.
|
||||
|
||||
If you add terms to a covered work in accord with this section, you
|
||||
must place, in the relevant source files, a statement of the
|
||||
additional terms that apply to those files, or a notice indicating
|
||||
where to find the applicable terms.
|
||||
|
||||
Additional terms, permissive or non-permissive, may be stated in the
|
||||
form of a separately written license, or stated as exceptions;
|
||||
the above requirements apply either way.
|
||||
|
||||
8. Termination.
|
||||
|
||||
You may not propagate or modify a covered work except as expressly
|
||||
provided under this License. Any attempt otherwise to propagate or
|
||||
modify it is void, and will automatically terminate your rights under
|
||||
this License (including any patent licenses granted under the third
|
||||
paragraph of section 11).
|
||||
|
||||
However, if you cease all violation of this License, then your
|
||||
license from a particular copyright holder is reinstated (a)
|
||||
provisionally, unless and until the copyright holder explicitly and
|
||||
finally terminates your license, and (b) permanently, if the copyright
|
||||
holder fails to notify you of the violation by some reasonable means
|
||||
prior to 60 days after the cessation.
|
||||
|
||||
Moreover, your license from a particular copyright holder is
|
||||
reinstated permanently if the copyright holder notifies you of the
|
||||
violation by some reasonable means, this is the first time you have
|
||||
received notice of violation of this License (for any work) from that
|
||||
copyright holder, and you cure the violation prior to 30 days after
|
||||
your receipt of the notice.
|
||||
|
||||
Termination of your rights under this section does not terminate the
|
||||
licenses of parties who have received copies or rights from you under
|
||||
this License. If your rights have been terminated and not permanently
|
||||
reinstated, you do not qualify to receive new licenses for the same
|
||||
material under section 10.
|
||||
|
||||
9. Acceptance Not Required for Having Copies.
|
||||
|
||||
You are not required to accept this License in order to receive or
|
||||
run a copy of the Program. Ancillary propagation of a covered work
|
||||
occurring solely as a consequence of using peer-to-peer transmission
|
||||
to receive a copy likewise does not require acceptance. However,
|
||||
nothing other than this License grants you permission to propagate or
|
||||
modify any covered work. These actions infringe copyright if you do
|
||||
not accept this License. Therefore, by modifying or propagating a
|
||||
covered work, you indicate your acceptance of this License to do so.
|
||||
|
||||
10. Automatic Licensing of Downstream Recipients.
|
||||
|
||||
Each time you convey a covered work, the recipient automatically
|
||||
receives a license from the original licensors, to run, modify and
|
||||
propagate that work, subject to this License. You are not responsible
|
||||
for enforcing compliance by third parties with this License.
|
||||
|
||||
An "entity transaction" is a transaction transferring control of an
|
||||
organization, or substantially all assets of one, or subdividing an
|
||||
organization, or merging organizations. If propagation of a covered
|
||||
work results from an entity transaction, each party to that
|
||||
transaction who receives a copy of the work also receives whatever
|
||||
licenses to the work the party's predecessor in interest had or could
|
||||
give under the previous paragraph, plus a right to possession of the
|
||||
Corresponding Source of the work from the predecessor in interest, if
|
||||
the predecessor has it or can get it with reasonable efforts.
|
||||
|
||||
You may not impose any further restrictions on the exercise of the
|
||||
rights granted or affirmed under this License. For example, you may
|
||||
not impose a license fee, royalty, or other charge for exercise of
|
||||
rights granted under this License, and you may not initiate litigation
|
||||
(including a cross-claim or counterclaim in a lawsuit) alleging that
|
||||
any patent claim is infringed by making, using, selling, offering for
|
||||
sale, or importing the Program or any portion of it.
|
||||
|
||||
11. Patents.
|
||||
|
||||
A "contributor" is a copyright holder who authorizes use under this
|
||||
License of the Program or a work on which the Program is based. The
|
||||
work thus licensed is called the contributor's "contributor version".
|
||||
|
||||
A contributor's "essential patent claims" are all patent claims
|
||||
owned or controlled by the contributor, whether already acquired or
|
||||
hereafter acquired, that would be infringed by some manner, permitted
|
||||
by this License, of making, using, or selling its contributor version,
|
||||
but do not include claims that would be infringed only as a
|
||||
consequence of further modification of the contributor version. For
|
||||
purposes of this definition, "control" includes the right to grant
|
||||
patent sublicenses in a manner consistent with the requirements of
|
||||
this License.
|
||||
|
||||
Each contributor grants you a non-exclusive, worldwide, royalty-free
|
||||
patent license under the contributor's essential patent claims, to
|
||||
make, use, sell, offer for sale, import and otherwise run, modify and
|
||||
propagate the contents of its contributor version.
|
||||
|
||||
In the following three paragraphs, a "patent license" is any express
|
||||
agreement or commitment, however denominated, not to enforce a patent
|
||||
(such as an express permission to practice a patent or covenant not to
|
||||
sue for patent infringement). To "grant" such a patent license to a
|
||||
party means to make such an agreement or commitment not to enforce a
|
||||
patent against the party.
|
||||
|
||||
If you convey a covered work, knowingly relying on a patent license,
|
||||
and the Corresponding Source of the work is not available for anyone
|
||||
to copy, free of charge and under the terms of this License, through a
|
||||
publicly available network server or other readily accessible means,
|
||||
then you must either (1) cause the Corresponding Source to be so
|
||||
available, or (2) arrange to deprive yourself of the benefit of the
|
||||
patent license for this particular work, or (3) arrange, in a manner
|
||||
consistent with the requirements of this License, to extend the patent
|
||||
license to downstream recipients. "Knowingly relying" means you have
|
||||
actual knowledge that, but for the patent license, your conveying the
|
||||
covered work in a country, or your recipient's use of the covered work
|
||||
in a country, would infringe one or more identifiable patents in that
|
||||
country that you have reason to believe are valid.
|
||||
|
||||
If, pursuant to or in connection with a single transaction or
|
||||
arrangement, you convey, or propagate by procuring conveyance of, a
|
||||
covered work, and grant a patent license to some of the parties
|
||||
receiving the covered work authorizing them to use, propagate, modify
|
||||
or convey a specific copy of the covered work, then the patent license
|
||||
you grant is automatically extended to all recipients of the covered
|
||||
work and works based on it.
|
||||
|
||||
A patent license is "discriminatory" if it does not include within
|
||||
the scope of its coverage, prohibits the exercise of, or is
|
||||
conditioned on the non-exercise of one or more of the rights that are
|
||||
specifically granted under this License. You may not convey a covered
|
||||
work if you are a party to an arrangement with a third party that is
|
||||
in the business of distributing software, under which you make payment
|
||||
to the third party based on the extent of your activity of conveying
|
||||
the work, and under which the third party grants, to any of the
|
||||
parties who would receive the covered work from you, a discriminatory
|
||||
patent license (a) in connection with copies of the covered work
|
||||
conveyed by you (or copies made from those copies), or (b) primarily
|
||||
for and in connection with specific products or compilations that
|
||||
contain the covered work, unless you entered into that arrangement,
|
||||
or that patent license was granted, prior to 28 March 2007.
|
||||
|
||||
Nothing in this License shall be construed as excluding or limiting
|
||||
any implied license or other defenses to infringement that may
|
||||
otherwise be available to you under applicable patent law.
|
||||
|
||||
12. No Surrender of Others' Freedom.
|
||||
|
||||
If conditions are imposed on you (whether by court order, agreement or
|
||||
otherwise) that contradict the conditions of this License, they do not
|
||||
excuse you from the conditions of this License. If you cannot convey a
|
||||
covered work so as to satisfy simultaneously your obligations under this
|
||||
License and any other pertinent obligations, then as a consequence you may
|
||||
not convey it at all. For example, if you agree to terms that obligate you
|
||||
to collect a royalty for further conveying from those to whom you convey
|
||||
the Program, the only way you could satisfy both those terms and this
|
||||
License would be to refrain entirely from conveying the Program.
|
||||
|
||||
13. Use with the GNU Affero General Public License.
|
||||
|
||||
Notwithstanding any other provision of this License, you have
|
||||
permission to link or combine any covered work with a work licensed
|
||||
under version 3 of the GNU Affero General Public License into a single
|
||||
combined work, and to convey the resulting work. The terms of this
|
||||
License will continue to apply to the part which is the covered work,
|
||||
but the special requirements of the GNU Affero General Public License,
|
||||
section 13, concerning interaction through a network will apply to the
|
||||
combination as such.
|
||||
|
||||
14. Revised Versions of this License.
|
||||
|
||||
The Free Software Foundation may publish revised and/or new versions of
|
||||
the GNU General Public License from time to time. Such new versions will
|
||||
be similar in spirit to the present version, but may differ in detail to
|
||||
address new problems or concerns.
|
||||
|
||||
Each version is given a distinguishing version number. If the
|
||||
Program specifies that a certain numbered version of the GNU General
|
||||
Public License "or any later version" applies to it, you have the
|
||||
option of following the terms and conditions either of that numbered
|
||||
version or of any later version published by the Free Software
|
||||
Foundation. If the Program does not specify a version number of the
|
||||
GNU General Public License, you may choose any version ever published
|
||||
by the Free Software Foundation.
|
||||
|
||||
If the Program specifies that a proxy can decide which future
|
||||
versions of the GNU General Public License can be used, that proxy's
|
||||
public statement of acceptance of a version permanently authorizes you
|
||||
to choose that version for the Program.
|
||||
|
||||
Later license versions may give you additional or different
|
||||
permissions. However, no additional obligations are imposed on any
|
||||
author or copyright holder as a result of your choosing to follow a
|
||||
later version.
|
||||
|
||||
15. Disclaimer of Warranty.
|
||||
|
||||
THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
|
||||
APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
|
||||
HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
|
||||
OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
|
||||
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
||||
PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
|
||||
IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
|
||||
ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
|
||||
|
||||
16. Limitation of Liability.
|
||||
|
||||
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
|
||||
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
|
||||
THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
|
||||
GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
|
||||
USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
|
||||
DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
|
||||
PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
|
||||
EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
|
||||
SUCH DAMAGES.
|
||||
|
||||
17. Interpretation of Sections 15 and 16.
|
||||
|
||||
If the disclaimer of warranty and limitation of liability provided
|
||||
above cannot be given local legal effect according to their terms,
|
||||
reviewing courts shall apply local law that most closely approximates
|
||||
an absolute waiver of all civil liability in connection with the
|
||||
Program, unless a warranty or assumption of liability accompanies a
|
||||
copy of the Program in return for a fee.
|
||||
|
||||
END OF TERMS AND CONDITIONS
|
||||
|
||||
How to Apply These Terms to Your New Programs
|
||||
|
||||
If you develop a new program, and you want it to be of the greatest
|
||||
possible use to the public, the best way to achieve this is to make it
|
||||
free software which everyone can redistribute and change under these terms.
|
||||
|
||||
To do so, attach the following notices to the program. It is safest
|
||||
to attach them to the start of each source file to most effectively
|
||||
state the exclusion of warranty; and each file should have at least
|
||||
the "copyright" line and a pointer to where the full notice is found.
|
||||
|
||||
{one line to give the program's name and a brief idea of what it does.}
|
||||
Copyright (C) {year} {name of author}
|
||||
|
||||
This program is free software: you can redistribute it and/or modify
|
||||
it under the terms of the GNU General Public License as published by
|
||||
the Free Software Foundation, either version 3 of the License, or
|
||||
(at your option) any later version.
|
||||
|
||||
This program is distributed in the hope that it will be useful,
|
||||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
GNU General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
|
||||
Also add information on how to contact you by electronic and paper mail.
|
||||
|
||||
If the program does terminal interaction, make it output a short
|
||||
notice like this when it starts in an interactive mode:
|
||||
|
||||
{project} Copyright (C) {year} {fullname}
|
||||
This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
|
||||
This is free software, and you are welcome to redistribute it
|
||||
under certain conditions; type `show c' for details.
|
||||
|
||||
The hypothetical commands `show w' and `show c' should show the appropriate
|
||||
parts of the General Public License. Of course, your program's commands
|
||||
might be different; for a GUI interface, you would use an "about box".
|
||||
|
||||
You should also get your employer (if you work as a programmer) or school,
|
||||
if any, to sign a "copyright disclaimer" for the program, if necessary.
|
||||
For more information on this, and how to apply and follow the GNU GPL, see
|
||||
<http://www.gnu.org/licenses/>.
|
||||
|
||||
The GNU General Public License does not permit incorporating your program
|
||||
into proprietary programs. If your program is a subroutine library, you
|
||||
may consider it more useful to permit linking proprietary applications with
|
||||
the library. If this is what you want to do, use the GNU Lesser General
|
||||
Public License instead of this License. But first, please read
|
||||
<http://www.gnu.org/philosophy/why-not-lgpl.html>.
|
||||
|
|
@ -0,0 +1,213 @@
|
|||
Pi-FM-RDS
|
||||
=========
|
||||
|
||||
|
||||
## FM-RDS transmitter using the Raspberry Pi
|
||||
|
||||
This program generates an FM modulation, with RDS (Radio Data System) data generated in real time. It can include monophonic or stereophonic audio.
|
||||
|
||||
This version modulates the PLL instead of the clock divider for superior signal purity. The harmonics are unaffected, so the [legal warning](#warning-and-disclaimer) still applies.
|
||||
|
||||
|
||||
|
||||
TODO list
|
||||
*watchdog for PLL settings to prevent radio interference
|
||||
*measure PLL loop filter response
|
||||
|
||||
It is based on the FM transmitter created by [Oliver Mattos and Oskar Weigl](http://www.icrobotics.co.uk/wiki/index.php/Turning_the_Raspberry_Pi_Into_an_FM_Transmitter), and later adapted to using DMA by [Richard Hirst](https://github.com/richardghirst). Christophe Jacquet adapted it and added the RDS data generator and modulator. The transmitter uses the Raspberry Pi's clock divider to produce VHF signals.
|
||||
|
||||
It is compatible with both the Raspberry Pi 1 (the original one) and the Raspberry Pi 2 and 3. Users of Raspberry Pi 3 should add gpu_freq=250 to /boot/config.txt . The Pi 3 has very sensitive low voltage detection. When low voltage is detected, clocks are reduced to safe values in an attempt to prevent crashes. This program changes clocks to generate the desired radio frequency without the knowledge of the power management system. While it would be possible to detect and undo changes, this would cause radio interference each time it happens. Setting gpu_freq=250 appears to prevent undesired clock changes because the normal value and safe value are the same.
|
||||
|
||||
|
||||
|
||||
PiFmRds has been developed for experimentation only. It is not a media center, it is not intended to broadcast music to your stereo system. See the [legal warning](#warning-and-disclaimer).
|
||||
|
||||
## How to use it?
|
||||
|
||||
Pi-FM-RDS, depends on the `sndfile` library. To install this library on Debian-like distributions, for instance Raspbian, run `sudo apt-get install libsndfile1-dev`.
|
||||
|
||||
Pi-FM-RDS also depends on the Linux `rpi-mailbox` driver, so you need a recent Linux kernel. The Raspbian releases from August 2015 have this.
|
||||
|
||||
**Important.** The binaries compiled for the Raspberry Pi 1 are not compatible with the Raspberry Pi 2/3, and conversely. Always re-compile when switching models, so do not skip the `make clean` step in the instructions below!
|
||||
|
||||
Clone the source repository and run `make` in the `src` directory:
|
||||
|
||||
```bash
|
||||
git clone https://github.com/F5OEO/PiFmRds.git
|
||||
cd PiFmRds/src
|
||||
git clone https://github.com/F5OEO/librpitx.git
|
||||
cd librpitx/src
|
||||
make
|
||||
cd ../../
|
||||
make clean
|
||||
make
|
||||
```
|
||||
|
||||
Then you can just run:
|
||||
|
||||
```
|
||||
sudo ./pi_fm_rds
|
||||
```
|
||||
|
||||
This will generate an FM transmission on 107.9 MHz, with default station name (PS), radiotext (RT) and PI-code, without audio. The radiofrequency signal is emitted on GPIO 4 (pin 7 on header P1).
|
||||
|
||||
|
||||
You can add monophonic or stereophonic audio by referencing an audio file as follows:
|
||||
|
||||
```
|
||||
sudo ./pi_fm_rds -audio sound.wav
|
||||
```
|
||||
|
||||
To test stereophonic audio, you can try the file `stereo_44100.wav` provided.
|
||||
|
||||
The more general syntax for running Pi-FM-RDS is as follows:
|
||||
|
||||
```
|
||||
pi_fm_rds [-freq freq] [-audio file] [-ppm ppm_error] [-pi pi_code] [-ps ps_text] [-rt rt_text]
|
||||
```
|
||||
|
||||
All arguments are optional:
|
||||
|
||||
* `-freq` specifies the carrier frequency (in MHz). Example: `-freq 107.9`.
|
||||
* `-audio` specifies an audio file to play as audio. The sample rate does not matter: Pi-FM-RDS will resample and filter it. If a stereo file is provided, Pi-FM-RDS will produce an FM-Stereo signal. Example: `-audio sound.wav`. The supported formats depend on `libsndfile`. This includes WAV and Ogg/Vorbis (among others) but not MP3. Specify `-` as the file name to read audio data on standard input (useful for piping audio into Pi-FM-RDS, see below).
|
||||
* `-pi` specifies the PI-code of the RDS broadcast. 4 hexadecimal digits. Example: `-pi FFFF`.
|
||||
* `-ps` specifies the station name (Program Service name, PS) of the RDS broadcast. Limit: 8 characters. Example: `-ps RASP-PI`.
|
||||
* `-rt` specifies the radiotext (RT) to be transmitted. Limit: 64 characters. Example: `-rt 'Hello, world!'`.
|
||||
* `-ctl` specifies a named pipe (FIFO) to use as a control channel to change PS and RT at run-time (see below).
|
||||
* `-ppm` specifies your Raspberry Pi's oscillator error in parts per million (ppm), see below.
|
||||
|
||||
By default the PS changes back and forth between `Pi-FmRds` and a sequence number, starting at `00000000`. The PS changes around one time per second.
|
||||
|
||||
|
||||
### Clock calibration (only if experiencing difficulties)
|
||||
|
||||
The RDS standards states that the error for the 57 kHz subcarrier must be less than ± 6 Hz, i.e. less than 105 ppm (parts per million). The Raspberry Pi's oscillator error may be above this figure. That is where the `-ppm` parameter comes into play: you specify your Pi's error and Pi-FM-RDS adjusts the clock dividers accordingly.
|
||||
|
||||
In practice, I found that Pi-FM-RDS works okay even without using the `-ppm` parameter. I suppose the receivers are more tolerant than stated in the RDS spec.
|
||||
|
||||
One way to measure the ppm error is to play the `pulses.wav` file: it will play a pulse for precisely 1 second, then play a 1-second silence, and so on. Record the audio output from a radio with a good audio card. Say you sample at 44.1 kHz. Measure 10 intervals. Using [Audacity](http://audacity.sourceforge.net/) for example determine the number of samples of these 10 intervals: in the absence of clock error, it should be 441,000 samples. With my Pi, I found 441,132 samples. Therefore, my ppm error is (441132-441000)/441000 * 1e6 = 299 ppm, **assuming that my sampling device (audio card) has no clock error...**
|
||||
|
||||
|
||||
### Piping audio into Pi-FM-RDS
|
||||
|
||||
If you use the argument `-audio -`, Pi-FM-RDS reads audio data on standard input. This allows you to pipe the output of a program into Pi-FM-RDS. For instance, this can be used to read MP3 files using Sox:
|
||||
|
||||
```
|
||||
sox -t mp3 http://www.linuxvoice.com/episodes/lv_s02e01.mp3 -t wav - | sudo ./pi_fm_rds -audio -
|
||||
```
|
||||
|
||||
Or to pipe the AUX input of a sound card into Pi-FM-RDS:
|
||||
|
||||
```
|
||||
sudo arecord -fS16_LE -r 44100 -Dplughw:1,0 -c 2 - | sudo ./pi_fm_rds -audio -
|
||||
```
|
||||
|
||||
|
||||
### Changing PS, RT and TA at run-time
|
||||
|
||||
You can control PS, RT and TA (Traffic Announcement flag) at run-time using a named pipe (FIFO). For this run Pi-FM-RDS with the `-ctl` argument.
|
||||
|
||||
Example:
|
||||
|
||||
```
|
||||
mkfifo rds_ctl
|
||||
sudo ./pi_fm_rds -ctl rds_ctl
|
||||
```
|
||||
|
||||
Then you can send “commands” to change PS, RT and TA:
|
||||
|
||||
```
|
||||
cat >rds_ctl
|
||||
PS MyText
|
||||
RT A text to be sent as radiotext
|
||||
TA ON
|
||||
PS OtherTxt
|
||||
TA OFF
|
||||
...
|
||||
```
|
||||
|
||||
Every line must start with either `PS`, `RT` or `TA`, followed by one space character, and the desired value. Any other line format is silently ignored. `TA ON` switches the Traffic Announcement flag to *on*, any other value switches it to *off*.
|
||||
|
||||
|
||||
## Warning and Disclaimer
|
||||
|
||||
PiFmRds is an **experimental** program, designed **only for experimentation**. It is in no way intended to become a personal *media center* or a tool to operate a *radio station*, or even broadcast sound to one's own stereo system.
|
||||
|
||||
In most countries, transmitting radio waves without a state-issued licence specific to the transmission modalities (frequency, power, bandwidth, etc.) is **illegal**.
|
||||
|
||||
Therefore, always connect a shielded transmission line from the RaspberryPi directly
|
||||
to a radio receiver, so as **not** to emit radio waves. Never use an antenna.
|
||||
|
||||
Even if you are a licensed amateur radio operator, using PiFmRds to transmit radio waves on ham frequencies without any filtering between the RaspberryPi and an antenna is most probably illegal because the square-wave carrier is very rich in harmonics, so the bandwidth requirements are likely not met.
|
||||
|
||||
I could not be held liable for any misuse of your own Raspberry Pi. Any experiment is made under your own responsibility.
|
||||
|
||||
|
||||
## Tests
|
||||
|
||||
Pi-FM-RDS was successfully tested with all my RDS-able devices, namely:
|
||||
|
||||
* a Sony ICF-C20RDS alarm clock from 1995,
|
||||
* a Sangean PR-D1 portable receiver from 1998, and an ATS-305 from 1999,
|
||||
* a Samsung Galaxy S2 mobile phone from 2011,
|
||||
* a Philips MBD7020 hifi system from 2012,
|
||||
* a Silicon Labs [USBFMRADIO-RD](http://www.silabs.com/products/mcu/Pages/USBFMRadioRD.aspx) USB stick, employing an Si4701 chip, and using my [RDS Surveyor](http://rds-surveyor.sourceforge.net/) program,
|
||||
* a “PCear Fm Radio”, a Chinese clone of the above, again using RDS Surveyor.
|
||||
|
||||
Reception works perfectly with all the devices above. RDS Surveyor reports no group errors.
|
||||
|
||||
|
||||
|
||||
|
||||
### CPU Usage
|
||||
|
||||
CPU usage on a Raspberry Pi 1 is as follows:
|
||||
|
||||
* without audio: 9%
|
||||
* with mono audio: 33%
|
||||
* with stereo audio: 40%
|
||||
|
||||
CPU usage increases dramatically when adding audio because the program has to upsample the (unspecified) sample rate of the input audio file to 228 kHz, its internal operating sample rate. Doing so, it has to apply an FIR filter, which is costly.
|
||||
|
||||
## Design
|
||||
|
||||
The RDS data generator lies in the `rds.c` file.
|
||||
|
||||
The RDS data generator generates cyclically four 0A groups (for transmitting PS), and one 2A group (for transmitting RT). In addition, every minute, it inserts a 4A group (for transmitting CT, clock time). `get_rds_group` generates one group, and uses `crc` for computing the CRC.
|
||||
|
||||
To get samples of RDS data, call `get_rds_samples`. It calls `get_rds_group`, differentially encodes the signal and generates a shaped biphase symbol. Successive biphase symbols overlap: the samples are added so that the result is equivalent to applying the shaping filter (a [root-raised-cosine (RRC) filter ](http://en.wikipedia.org/wiki/Root-raised-cosine_filter) specified in the RDS standard) to a sequence of Manchester-encoded pulses.
|
||||
|
||||
The shaped biphase symbol is generated once and for all by a Python program called `generate_waveforms.py` that uses [Pydemod](https://github.com/ChristopheJacquet/Pydemod), one of my other software radio projects. This Python program generates an array called `waveform_biphase` that results from the application of the RRC filter to a positive-negative impulse pair. *Note that the output of `generate_waveforms.py`, two files named `waveforms.c` and `waveforms.h`, are included in the Git repository, so you don't need to run the Python script yourself to compile Pi-FM-RDS.*
|
||||
|
||||
Internally, the program samples all signals at 228 kHz, four times the RDS subcarrier's 57 kHz.
|
||||
|
||||
The FM multiplex signal (baseband signal) is generated by `fm_mpx.c`. This file handles the upsampling of the input audio file to 228 kHz, and the generation of the multiplex: unmodulated left+right signal (limited to 15 kHz), possibly the stereo pilot at 19 kHz, possibly the left-right signal, amplitude-modulated on 38 kHz (suppressed carrier) and RDS signal from `rds.c`. Upsampling is performed using a polyphase filter bank of 32 filters, each with 32 coefficients. To help understand the polyphase filter bank, consider upsampling the input signal by zero stuffing. Then, apply a low pass filter with the cutoff at the original Nyquist frequency. Finally, collect some of the filtered samples at the new sampling rate. The polyphase filter bank does the same thing mathematically, but avoids computing output samples that will not be used. It also avoids processing all of the suffed zeros. The low pass part of the filter is a sampled sinc. The filter is also used to provide pre-emphasis. The low pass filter coefficients are convolved with the pre-emphasis filter, providing pre-emphasis at no additional cost. The combined filter is windowed by a Hamming window. The filter coefficients are generated at startup so that the filter cuts frequencies above the minimum of:
|
||||
* the Nyquist frequency of the input audio file (half the sample rate) to avoid aliasing (this is the typical case for resampling),
|
||||
* 15 kHz, the bandpass of the left+right and left-right channels, as per the FM broadcasting standards.
|
||||
|
||||
An Octave script to compute the frequency response of the filter is provided in the doc folder.
|
||||
|
||||
The samples are played by `pi_fm_rds.c` that is adapted from Richard Hirst's [PiFmDma](https://github.com/richardghirst/PiBits/tree/master/PiFmDma). The program was changed to support a sample rate of precisely 228 kHz.
|
||||
|
||||
|
||||
### References
|
||||
|
||||
* [EN 50067, Specification of the radio data system (RDS) for VHF/FM sound broadcasting in the frequency range 87.5 to 108.0 MHz](http://www.interactive-radio-system.com/docs/EN50067_RDS_Standard.pdf)
|
||||
|
||||
|
||||
## History
|
||||
* 2018-11-01: Integrate in rpitx project. Hope not to hurt the author , copying readme and licence.
|
||||
* 2018-03-19: Use librpitx for easy integration
|
||||
* 2015-09-05: support for the Raspberry Pi 2
|
||||
* 2014-11-01: support for toggling the Traffic Announcement (TA) flag at run-time
|
||||
* 2014-10-19: bugfix (cleanly stop the DMA engine when the specified file does not exist, or it's not possible to read from stdin)
|
||||
* 2014-08-04: bugfix (ppm now uses floats)
|
||||
* 2014-06-22: generate CT (clock time) signals, bugfixes
|
||||
* 2014-05-04: possibility to change PS and RT at run-time
|
||||
* 2014-04-28: support piping audio file data to Pi-FM-RDS' standard input
|
||||
* 2014-04-14: new release that supports any sample rate for the audio input, and that can generate a proper FM-Stereo signal if a stereophonic input file is provided
|
||||
* 2014-04-06: initial release, which only supported 228 kHz monophonic audio input files
|
||||
|
||||
--------
|
||||
|
||||
© [Christophe Jacquet](http://www.jacquet80.eu/) (F8FTK), 2014-2015. Released under the GNU GPL v3.
|
||||
|
|
@ -0,0 +1,102 @@
|
|||
/*
|
||||
PiFmRds - FM/RDS transmitter for the Raspberry Pi
|
||||
Copyright (C) 2014 Christophe Jacquet, F8FTK
|
||||
|
||||
See https://github.com/ChristopheJacquet/PiFmRds
|
||||
|
||||
rds_wav.c is a test program that writes a RDS baseband signal to a WAV
|
||||
file. It requires libsndfile.
|
||||
|
||||
This program is free software: you can redistribute it and/or modify
|
||||
it under the terms of the GNU General Public License as published by
|
||||
the Free Software Foundation, either version 3 of the License, or
|
||||
(at your option) any later version.
|
||||
|
||||
This program is distributed in the hope that it will be useful,
|
||||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
GNU General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
|
||||
control_pipe.c: handles command written to a non-blocking control pipe,
|
||||
in order to change RDS PS and RT at runtime.
|
||||
*/
|
||||
|
||||
|
||||
#include <string.h>
|
||||
#include <fcntl.h>
|
||||
#include <stdio.h>
|
||||
#include <unistd.h>
|
||||
#include <errno.h>
|
||||
|
||||
#include "rds.h"
|
||||
#include "control_pipe.h"
|
||||
|
||||
#define CTL_BUFFER_SIZE 100
|
||||
|
||||
FILE *f_ctl;
|
||||
|
||||
/*
|
||||
* Opens a file (pipe) to be used to control the RDS coder, in non-blocking mode.
|
||||
*/
|
||||
int open_control_pipe(char *filename) {
|
||||
int fd = open(filename, O_RDONLY | O_NONBLOCK);
|
||||
if(fd == -1) return -1;
|
||||
|
||||
int flags;
|
||||
flags = fcntl(fd, F_GETFL, 0);
|
||||
flags |= O_NONBLOCK;
|
||||
if( fcntl(fd, F_SETFL, flags) == -1 ) return -1;
|
||||
|
||||
f_ctl = fdopen(fd, "r");
|
||||
if(f_ctl == NULL) return -1;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* Polls the control file (pipe), non-blockingly, and if a command is received,
|
||||
* processes it and updates the RDS data.
|
||||
*/
|
||||
int poll_control_pipe() {
|
||||
static char buf[CTL_BUFFER_SIZE];
|
||||
|
||||
char *res = fgets(buf, CTL_BUFFER_SIZE, f_ctl);
|
||||
if(res == NULL) return -1;
|
||||
if(strlen(res) > 3 && res[2] == ' ') {
|
||||
char *arg = res+3;
|
||||
if(arg[strlen(arg)-1] == '\n') arg[strlen(arg)-1] = 0;
|
||||
if(res[0] == 'P' && res[1] == 'S') {
|
||||
arg[8] = 0;
|
||||
set_rds_ps(arg);
|
||||
printf("PS set to: \"%s\"\n", arg);
|
||||
return CONTROL_PIPE_PS_SET;
|
||||
}
|
||||
if(res[0] == 'R' && res[1] == 'T') {
|
||||
arg[64] = 0;
|
||||
set_rds_rt(arg);
|
||||
printf("RT set to: \"%s\"\n", arg);
|
||||
return CONTROL_PIPE_RT_SET;
|
||||
}
|
||||
if(res[0] == 'T' && res[1] == 'A') {
|
||||
int ta = ( strcmp(arg, "ON") == 0 );
|
||||
set_rds_ta(ta);
|
||||
printf("Set TA to ");
|
||||
if(ta) printf("ON\n"); else printf("OFF\n");
|
||||
return CONTROL_PIPE_TA_SET;
|
||||
}
|
||||
}
|
||||
|
||||
return -1;
|
||||
}
|
||||
|
||||
/*
|
||||
* Closes the control pipe.
|
||||
*/
|
||||
int close_control_pipe() {
|
||||
if(f_ctl) return fclose(f_ctl);
|
||||
else return 0;
|
||||
}
|
||||
|
|
@ -0,0 +1,31 @@
|
|||
/*
|
||||
PiFmRds - FM/RDS transmitter for the Raspberry Pi
|
||||
Copyright (C) 2014 Christophe Jacquet, F8FTK
|
||||
|
||||
See https://github.com/ChristopheJacquet/PiFmRds
|
||||
|
||||
rds_wav.c is a test program that writes a RDS baseband signal to a WAV
|
||||
file. It requires libsndfile.
|
||||
|
||||
This program is free software: you can redistribute it and/or modify
|
||||
it under the terms of the GNU General Public License as published by
|
||||
the Free Software Foundation, either version 3 of the License, or
|
||||
(at your option) any later version.
|
||||
|
||||
This program is distributed in the hope that it will be useful,
|
||||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
GNU General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
*/
|
||||
|
||||
|
||||
#define CONTROL_PIPE_PS_SET 1
|
||||
#define CONTROL_PIPE_RT_SET 2
|
||||
#define CONTROL_PIPE_TA_SET 3
|
||||
|
||||
extern int open_control_pipe(char *filename);
|
||||
extern int close_control_pipe();
|
||||
extern int poll_control_pipe();
|
||||
|
|
@ -0,0 +1,335 @@
|
|||
/*
|
||||
PiFmRds - FM/RDS transmitter for the Raspberry Pi
|
||||
Copyright (C) 2014 Christophe Jacquet, F8FTK
|
||||
|
||||
See https://github.com/ChristopheJacquet/PiFmRds
|
||||
|
||||
rds_wav.c is a test program that writes a RDS baseband signal to a WAV
|
||||
file. It requires libsndfile.
|
||||
|
||||
This program is free software: you can redistribute it and/or modify
|
||||
it under the terms of the GNU General Public License as published by
|
||||
the Free Software Foundation, either version 3 of the License, or
|
||||
(at your option) any later version.
|
||||
|
||||
This program is distributed in the hope that it will be useful,
|
||||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
GNU General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
|
||||
fm_mpx.c: generates an FM multiplex signal containing RDS plus possibly
|
||||
monaural or stereo audio.
|
||||
*/
|
||||
|
||||
#include <sndfile.h>
|
||||
#include <stdlib.h>
|
||||
#include <strings.h>
|
||||
#include <math.h>
|
||||
|
||||
#include "rds.h"
|
||||
|
||||
|
||||
#define PI 3.141592654
|
||||
|
||||
|
||||
#define FIR_PHASES (32)
|
||||
#define FIR_TAPS (32) // MUST be a power of 2 for the circular buffer
|
||||
|
||||
size_t length;
|
||||
|
||||
// coefficients of the low-pass FIR filter
|
||||
float low_pass_fir[FIR_PHASES][FIR_TAPS];
|
||||
|
||||
|
||||
float carrier_38[] = {0.0, 0.8660254037844386, 0.8660254037844388, 1.2246467991473532e-16, -0.8660254037844384, -0.8660254037844386};
|
||||
|
||||
float carrier_19[] = {0.0, 0.5, 0.8660254037844386, 1.0, 0.8660254037844388, 0.5, 1.2246467991473532e-16, -0.5, -0.8660254037844384, -1.0, -0.8660254037844386, -0.5};
|
||||
|
||||
int phase_38 = 0;
|
||||
int phase_19 = 0;
|
||||
|
||||
|
||||
float downsample_factor;
|
||||
|
||||
|
||||
float *audio_buffer;
|
||||
int audio_index = 0;
|
||||
int audio_len = 0;
|
||||
float audio_pos;
|
||||
|
||||
float fir_buffer_left[FIR_TAPS] = {0};
|
||||
float fir_buffer_right[FIR_TAPS] = {0};
|
||||
int fir_index = 0;
|
||||
int channels;
|
||||
float left_max=1, right_max=1; // start compressor with low gain
|
||||
|
||||
SNDFILE *inf;
|
||||
|
||||
|
||||
|
||||
float *alloc_empty_buffer(size_t length) {
|
||||
float *p =(float *) malloc(length * sizeof(float));
|
||||
if(p == NULL) return NULL;
|
||||
|
||||
bzero(p, length * sizeof(float));
|
||||
|
||||
return p;
|
||||
}
|
||||
|
||||
|
||||
int fm_mpx_open(char *filename, size_t len) {
|
||||
length = len;
|
||||
|
||||
if(filename != NULL) {
|
||||
// Open the input file
|
||||
SF_INFO sfinfo;
|
||||
|
||||
// stdin or file on the filesystem?
|
||||
if(filename[0] == '-') {
|
||||
if(! (inf = sf_open_fd(fileno(stdin), SFM_READ, &sfinfo, 0))) {
|
||||
fprintf(stderr, "Error: could not open stdin for audio input.\n") ;
|
||||
return -1;
|
||||
} else {
|
||||
printf("Using stdin for audio input.\n");
|
||||
}
|
||||
} else {
|
||||
if(! (inf = sf_open(filename, SFM_READ, &sfinfo))) {
|
||||
fprintf(stderr, "Error: could not open input file %s.\n", filename) ;
|
||||
return -1;
|
||||
} else {
|
||||
printf("Using audio file: %s\n", filename);
|
||||
}
|
||||
}
|
||||
|
||||
int in_samplerate = sfinfo.samplerate;
|
||||
downsample_factor = 228000. / in_samplerate;
|
||||
|
||||
printf("Input: %d Hz, upsampling factor: %.2f\n", in_samplerate, downsample_factor);
|
||||
|
||||
channels = sfinfo.channels;
|
||||
if(channels > 1) {
|
||||
printf("%d channels, generating stereo multiplex.\n", channels);
|
||||
} else {
|
||||
printf("1 channel, monophonic operation.\n");
|
||||
}
|
||||
|
||||
// Choose a cutoff frequency for the low-pass FIR filter
|
||||
float cutoff_freq = 15700;
|
||||
//float cutoff_freq = 3000; //For NBFM
|
||||
if(in_samplerate/2 < cutoff_freq) cutoff_freq = in_samplerate/2 * .8;
|
||||
|
||||
|
||||
// Create the low-pass FIR filter, with pre-emphasis
|
||||
double window, firlowpass, firpreemph , sincpos;
|
||||
double gain=FIR_PHASES/25.0; // Why??? Maybe gain adjustment for preemphais
|
||||
|
||||
// IIR pre-emphasis filter
|
||||
// Reference material: http://jontio.zapto.org/hda1/preempiir.pdf
|
||||
double tau=75e-6;
|
||||
double delta=1.96e-6;
|
||||
double taup, deltap, bp, ap, a0, a1, b1;
|
||||
taup=1.0/(2.0*(in_samplerate*FIR_PHASES))/tan( 1.0/(2*tau*(in_samplerate*FIR_PHASES) ));
|
||||
deltap=1.0/(2.0*(in_samplerate*FIR_PHASES))/tan( 1.0/(2*delta*(in_samplerate*FIR_PHASES) ));
|
||||
bp=sqrt( -taup*taup + sqrt(taup*taup*taup*taup + 8.0*taup*taup*deltap*deltap) ) / 2.0 ;
|
||||
ap=sqrt( 2*bp*bp + taup*taup );
|
||||
a0=( 2.0*ap + 1/(in_samplerate*FIR_PHASES) )/(2.0*bp + 1/(in_samplerate*FIR_PHASES) );
|
||||
a1=(-2.0*ap + 1/(in_samplerate*FIR_PHASES) )/(2.0*bp + 1/(in_samplerate*FIR_PHASES) );
|
||||
b1=( 2.0*bp + 1/(in_samplerate*FIR_PHASES) )/(2.0*bp + 1/(in_samplerate*FIR_PHASES) );
|
||||
double x=0,y=0;
|
||||
|
||||
for(int i=0; i<FIR_TAPS; i++) {
|
||||
for(int j=0; j<FIR_PHASES; j++) {
|
||||
int mi=i*FIR_PHASES + j+1;// match indexing of Matlab script
|
||||
sincpos = (mi)-(((FIR_TAPS*FIR_PHASES)+1.0)/2.0); // offset by 0.5 so sincpos!=0 (causes NaN x/0 )
|
||||
//printf("%d=%f \n",mi ,sincpos);
|
||||
firlowpass = sin(2 * PI * cutoff_freq * sincpos / (in_samplerate*FIR_PHASES) ) / (PI * sincpos) ;
|
||||
|
||||
y=a0*firlowpass + a1*x + b1*y ; // Find the combined impulse response
|
||||
x=firlowpass; // of FIR low-pass and IIR pre-emphasis
|
||||
firpreemph=y; // y could be replaced by firpreemph but this
|
||||
// matches the example in the reference material
|
||||
|
||||
window = (.54 - .46 * cos(2*PI * (mi) / (double) FIR_TAPS*FIR_PHASES )) ; // Hamming window
|
||||
low_pass_fir[j][i] = firpreemph * window * gain ;
|
||||
}
|
||||
}
|
||||
|
||||
printf("Created low-pass FIR filter for audio channels, with cutoff at %.1f Hz\n", cutoff_freq);
|
||||
|
||||
if( 0 )
|
||||
{
|
||||
printf("f = [ ");
|
||||
for(int i=0; i<FIR_TAPS; i++) {
|
||||
for(int j=0; j<FIR_PHASES; j++) {
|
||||
printf("%.5f ", low_pass_fir[j][i]);
|
||||
}
|
||||
}
|
||||
printf("]; \n");
|
||||
}
|
||||
|
||||
audio_pos = downsample_factor;
|
||||
audio_buffer = alloc_empty_buffer(length * channels);
|
||||
if(audio_buffer == NULL) return -1;
|
||||
|
||||
} // end if(filename != NULL)
|
||||
else {
|
||||
inf = NULL;
|
||||
// inf == NULL indicates that there is no audio
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
// samples provided by this function are in 0..10: they need to be divided by
|
||||
// 10 after.
|
||||
int fm_mpx_get_samples(float *mpx_buffer) {
|
||||
get_rds_samples(mpx_buffer, length);
|
||||
|
||||
if(inf == NULL) return 0; // if there is no audio, stop here
|
||||
|
||||
for(int i=0; i<length; i++) {
|
||||
if(audio_pos >= downsample_factor) {
|
||||
audio_pos -= downsample_factor;
|
||||
|
||||
if(audio_len <= channels ) {
|
||||
for(int j=0; j<2; j++) { // one retry
|
||||
audio_len = sf_read_float(inf, audio_buffer, length);
|
||||
if (audio_len < 0) {
|
||||
fprintf(stderr, "Error reading audio\n");
|
||||
return -1;
|
||||
}
|
||||
if(audio_len == 0) {
|
||||
if( sf_seek(inf, 0, SEEK_SET) < 0 ) {
|
||||
fprintf(stderr, "Could not rewind in audio file, terminating\n");
|
||||
return -1;
|
||||
}
|
||||
} else {
|
||||
break;
|
||||
}
|
||||
}
|
||||
audio_index = 0;
|
||||
} else {
|
||||
audio_index += channels;
|
||||
audio_len -= channels;
|
||||
}
|
||||
|
||||
fir_index++; // fir_index will point to newest valid data soon
|
||||
if(fir_index >= FIR_TAPS) fir_index = 0;
|
||||
// Store the current sample(s) into the FIR filter's ring buffer
|
||||
fir_buffer_left[fir_index] = audio_buffer[audio_index];
|
||||
if(channels > 1) {
|
||||
fir_buffer_right[fir_index] = audio_buffer[audio_index+1];
|
||||
}
|
||||
} // if need new sample
|
||||
|
||||
// Polyphase FIR filter
|
||||
float out_left = 0;
|
||||
float out_right = 0;
|
||||
// Calculate which FIR phase to use
|
||||
//int iphase = FIR_PHASES-1 - ((int) (audio_pos/downsample_factor*FIR_PHASES) );
|
||||
int iphase = ((int) (audio_pos*FIR_PHASES/downsample_factor) );// I think this is correct
|
||||
//int iphase=FIR_PHASES-1; // test override
|
||||
//printf("%d %d \n",fir_index,iphase); // diagnostics
|
||||
// Sanity checks
|
||||
if ( iphase < 0 ) {iphase=0; printf("low\n"); }// Seems to run faster with these checks in place
|
||||
if ( iphase >= FIR_PHASES ) {iphase=FIR_PHASES-2; printf("high\n"); }
|
||||
|
||||
if( channels > 1 )
|
||||
{
|
||||
for(int fi=0; fi<FIR_TAPS; fi++) // fi = Filter Index
|
||||
{ // use bit masking to implement circular buffer
|
||||
out_left+= low_pass_fir[iphase][fi]* fir_buffer_left[(fir_index-fi)&(FIR_TAPS-1)];
|
||||
out_right+=low_pass_fir[iphase][fi]*fir_buffer_right[(fir_index-fi)&(FIR_TAPS-1)];
|
||||
}
|
||||
}
|
||||
else
|
||||
{
|
||||
for(int fi=0; fi<FIR_TAPS; fi++) // fi = Filter Index
|
||||
{ // use bit masking to implement circular buffer
|
||||
out_left+=low_pass_fir[iphase][fi] * fir_buffer_left[(fir_index-fi)&(FIR_TAPS-1)];
|
||||
}
|
||||
}
|
||||
|
||||
// Simple broadcast compressor
|
||||
//
|
||||
// The goal is to get the loudest sounding audio while
|
||||
// keeping the deviation within legal limits, and
|
||||
// without degrading the audio quality significantly.
|
||||
// Don't expect this simple code to match the
|
||||
// performance of commercial broadcast equipment.
|
||||
float left_abs, right_abs;
|
||||
float compressor_decay=0.999995;
|
||||
float compressor_attack=1.0;
|
||||
// Setting attack to anything other than 1.0 could cause overshoot.
|
||||
float compressor_max_gain_recip=0.01;
|
||||
left_abs=fabsf(out_left);
|
||||
if( left_abs>left_max )
|
||||
{
|
||||
left_max+= (left_abs-left_max)*compressor_attack;
|
||||
}
|
||||
else
|
||||
{
|
||||
left_max*=compressor_decay;
|
||||
}
|
||||
|
||||
if( channels > 1 )
|
||||
{
|
||||
right_abs=fabsf(out_right);
|
||||
if( right_abs>right_max )
|
||||
{
|
||||
right_max+= (right_abs-right_max)*compressor_attack;
|
||||
}
|
||||
else
|
||||
{
|
||||
right_max*=compressor_decay;
|
||||
}
|
||||
if( 1 )// Experimental joint compressor mode
|
||||
{
|
||||
if( left_max > right_max )
|
||||
right_max=left_max;
|
||||
else if( left_max < right_max )
|
||||
left_max=right_max;
|
||||
}
|
||||
out_right=out_right/(right_max+compressor_max_gain_recip);
|
||||
}
|
||||
out_left= out_left/(left_max+compressor_max_gain_recip); // Adjust volume with limited maximum gain
|
||||
|
||||
// Generate the stereo mpx
|
||||
if( channels > 1 ) {
|
||||
mpx_buffer[i] += 4.05*(out_left+out_right) + // Stereo sum signal
|
||||
4.05 * carrier_38[phase_38] * (out_left-out_right) + // Stereo difference signal
|
||||
.9*carrier_19[phase_19]; // Stereo pilot tone
|
||||
|
||||
phase_19++;
|
||||
phase_38++;
|
||||
if(phase_19 >= 12) phase_19 = 0;
|
||||
if(phase_38 >= 6) phase_38 = 0;
|
||||
}
|
||||
else
|
||||
{
|
||||
mpx_buffer[i] =
|
||||
mpx_buffer[i] + // RDS data samples are currently in mpx_buffer :to be Remove in NBFM
|
||||
9.0*out_left; // Unmodulated monophonic signal
|
||||
}
|
||||
|
||||
audio_pos++;
|
||||
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
int fm_mpx_close() {
|
||||
if(sf_close(inf) ) {
|
||||
fprintf(stderr, "Error closing audio file");
|
||||
}
|
||||
|
||||
if(audio_buffer != NULL) free(audio_buffer);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
|
@ -0,0 +1,26 @@
|
|||
/*
|
||||
PiFmRds - FM/RDS transmitter for the Raspberry Pi
|
||||
Copyright (C) 2014 Christophe Jacquet, F8FTK
|
||||
|
||||
See https://github.com/ChristopheJacquet/PiFmRds
|
||||
|
||||
rds_wav.c is a test program that writes a RDS baseband signal to a WAV
|
||||
file. It requires libsndfile.
|
||||
|
||||
This program is free software: you can redistribute it and/or modify
|
||||
it under the terms of the GNU General Public License as published by
|
||||
the Free Software Foundation, either version 3 of the License, or
|
||||
(at your option) any later version.
|
||||
|
||||
This program is distributed in the hope that it will be useful,
|
||||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
GNU General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
*/
|
||||
|
||||
extern int fm_mpx_open(char *filename, size_t len);
|
||||
extern int fm_mpx_get_samples(float *mpx_buffer);
|
||||
extern int fm_mpx_close();
|
||||
|
|
@ -0,0 +1,36 @@
|
|||
#!/usr/bin/python
|
||||
|
||||
|
||||
# PiFmRds - FM/RDS transmitter for the Raspberry Pi
|
||||
# Copyright (C) 2014 Christophe Jacquet, F8FTK
|
||||
#
|
||||
# See https://github.com/ChristopheJacquet/PiFmRds
|
||||
#
|
||||
# This program is free software: you can redistribute it and/or modify
|
||||
# it under the terms of the GNU General Public License as published by
|
||||
# the Free Software Foundation, either version 3 of the License, or
|
||||
# (at your option) any later version.
|
||||
#
|
||||
# This program is distributed in the hope that it will be useful,
|
||||
# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
# GNU General Public License for more details.
|
||||
#
|
||||
# You should have received a copy of the GNU General Public License
|
||||
# along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
|
||||
# This program generates a WAV file with a 1-second sine wave at 440 Hz,
|
||||
# followed by a 1-second silence.
|
||||
|
||||
|
||||
import scipy.io.wavfile as wavfile
|
||||
import numpy
|
||||
|
||||
sample_rate = 228000
|
||||
samples = numpy.zeros(2 * sample_rate, dtype=numpy.dtype('>i2'))
|
||||
|
||||
# 1-second tune
|
||||
samples[:sample_rate] = (numpy.sin(2*numpy.pi*440*numpy.arange(sample_rate)/sample_rate)
|
||||
* 20000).astype(numpy.dtype('>i2'))
|
||||
|
||||
wavfile.write("pulses.wav", sample_rate, samples)
|
||||
|
|
@ -0,0 +1,83 @@
|
|||
#!/usr/bin/python
|
||||
|
||||
|
||||
# PiFmRds - FM/RDS transmitter for the Raspberry Pi
|
||||
# Copyright (C) 2014 Christophe Jacquet, F8FTK
|
||||
#
|
||||
# See https://github.com/ChristopheJacquet/PiFmRds
|
||||
#
|
||||
# This program is free software: you can redistribute it and/or modify
|
||||
# it under the terms of the GNU General Public License as published by
|
||||
# the Free Software Foundation, either version 3 of the License, or
|
||||
# (at your option) any later version.
|
||||
#
|
||||
# This program is distributed in the hope that it will be useful,
|
||||
# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
# GNU General Public License for more details.
|
||||
#
|
||||
# You should have received a copy of the GNU General Public License
|
||||
# along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
|
||||
# This program generates the waveform of a single biphase symbol
|
||||
#
|
||||
# This program uses Pydemod, see https://github.com/ChristopheJacquet/Pydemod
|
||||
|
||||
import pydemod.app.rds as rds
|
||||
import numpy
|
||||
import scipy.io.wavfile as wavfile
|
||||
import io
|
||||
import matplotlib.pyplot as plt
|
||||
|
||||
sample_rate = 228000
|
||||
|
||||
outc = io.open("waveforms.c", mode="w", encoding="utf8")
|
||||
outh = io.open("waveforms.h", mode="w", encoding="utf8")
|
||||
|
||||
header = u"""
|
||||
/* This file was automatically generated by "generate_waveforms.py".
|
||||
(C) 2014 Christophe Jacquet.
|
||||
Released under the GNU GPL v3 license.
|
||||
*/
|
||||
|
||||
"""
|
||||
|
||||
outc.write(header)
|
||||
outh.write(header)
|
||||
|
||||
def generate_bit(name):
|
||||
offset = 240
|
||||
l = 96
|
||||
count = 2
|
||||
|
||||
|
||||
sample = numpy.zeros(3*l)
|
||||
sample[l] = 1
|
||||
sample[2*l] = -1
|
||||
|
||||
# Apply the data-shaping filter
|
||||
sf = rds.pulse_shaping_filter(96*8, 228000)
|
||||
shapedSamples = numpy.convolve(sample, sf)
|
||||
|
||||
|
||||
out = shapedSamples[528-288:528+288] #[offset:offset+l*count]
|
||||
#plt.plot(sf)
|
||||
#plt.plot(out)
|
||||
#plt.show()
|
||||
|
||||
iout = (out * 20000./max(abs(out)) ).astype(numpy.dtype('>i2'))
|
||||
wavfile.write(u"waveform_{}.wav".format(name), sample_rate, iout)
|
||||
|
||||
outc.write(u"float waveform_{name}[] = {{{values}}};\n\n".format(
|
||||
name = name,
|
||||
values = u", ".join(map(unicode, out/2.5))))
|
||||
# note: need to limit the amplitude so as not to saturate when the biphase
|
||||
# waveforms are summed
|
||||
|
||||
outh.write(u"extern float waveform_{name}[{size}];\n".format(name=name, size=len(out)))
|
||||
|
||||
|
||||
generate_bit("biphase")
|
||||
|
||||
outc.close()
|
||||
outh.close()
|
||||
|
|
@ -0,0 +1,306 @@
|
|||
/*
|
||||
* PiFmRds - FM/RDS transmitter for the Raspberry Pi
|
||||
* Copyright (C) 2018 Evariste Courjaud, F5OEO
|
||||
* Copyright (C) 2014, 2015 Christophe Jacquet, F8FTK
|
||||
* Copyright (C) 2012, 2015 Richard Hirst
|
||||
* Copyright (C) 2012 Oliver Mattos and Oskar Weigl
|
||||
*
|
||||
* See https://github.com/ChristopheJacquet/PiFmRds
|
||||
*
|
||||
* PI-FM-RDS: RaspberryPi FM transmitter, with RDS.
|
||||
*
|
||||
* This file contains the VHF FM modulator. All credit goes to the original
|
||||
* authors, Oliver Mattos and Oskar Weigl for the original idea, and to
|
||||
* Richard Hirst for using the Pi's DMA engine, which reduced CPU usage
|
||||
* dramatically.
|
||||
*
|
||||
* I (Christophe Jacquet) have adapted their idea to transmitting samples
|
||||
* at 228 kHz, allowing to build the 57 kHz subcarrier for RDS BPSK data.
|
||||
*
|
||||
* To make it work on the Raspberry Pi 2, I used a fix by Richard Hirst
|
||||
* (again) to request memory using Broadcom's mailbox interface. This fix
|
||||
* was published for ServoBlaster here:
|
||||
* https://www.raspberrypi.org/forums/viewtopic.php?p=699651#p699651
|
||||
*
|
||||
* Never use this to transmit VHF-FM data through an antenna, as it is
|
||||
* illegal in most countries. This code is for testing purposes only.
|
||||
* Always connect a shielded transmission line from the RaspberryPi directly
|
||||
* to a radio receiver, so as *not* to emit radio waves.
|
||||
*
|
||||
* ---------------------------------------------------------------------------
|
||||
* These are the comments from Richard Hirst's version:
|
||||
*
|
||||
* RaspberryPi based FM transmitter. For the original idea, see:
|
||||
*
|
||||
* http://www.icrobotics.co.uk/wiki/index.php/Turning_the_Raspberry_Pi_Into_an_FM_Transmitter
|
||||
*
|
||||
* All credit to Oliver Mattos and Oskar Weigl for creating the original code.
|
||||
*
|
||||
* I have taken their idea and reworked it to use the Pi DMA engine, so
|
||||
* reducing the CPU overhead for playing a .wav file from 100% to about 1.6%.
|
||||
*
|
||||
* I have implemented this in user space, using an idea I picked up from Joan
|
||||
* on the Raspberry Pi forums - credit to Joan for the DMA from user space
|
||||
* idea.
|
||||
*
|
||||
* The idea of feeding the PWM FIFO in order to pace DMA control blocks comes
|
||||
* from ServoBlaster, and I take credit for that :-)
|
||||
*
|
||||
* This code uses DMA channel 5 and the PWM hardware, with no regard for
|
||||
* whether something else might be trying to use it at the same time (such as
|
||||
* the 3.5mm jack audio driver).
|
||||
*
|
||||
* I know nothing much about sound, subsampling, or FM broadcasting, so it is
|
||||
* quite likely the sound quality produced by this code can be improved by
|
||||
* someone who knows what they are doing. There may be issues realting to
|
||||
* caching, as the user space process just writes to its virtual address space,
|
||||
* and expects the DMA controller to see the data; it seems to work for me
|
||||
* though.
|
||||
*
|
||||
* NOTE: THIS CODE MAY WELL CRASH YOUR PI, TRASH YOUR FILE SYSTEMS, AND
|
||||
* POTENTIALLY EVEN DAMAGE YOUR HARDWARE. THIS IS BECAUSE IT STARTS UP THE DMA
|
||||
* CONTROLLER USING MEMORY OWNED BY A USER PROCESS. IF THAT USER PROCESS EXITS
|
||||
* WITHOUT STOPPING THE DMA CONTROLLER, ALL HELL COULD BREAK LOOSE AS THE
|
||||
* MEMORY GETS REALLOCATED TO OTHER PROCESSES WHILE THE DMA CONTROLLER IS STILL
|
||||
* USING IT. I HAVE ATTEMPTED TO MINIMISE ANY RISK BY CATCHING SIGNALS AND
|
||||
* RESETTING THE DMA CONTROLLER BEFORE EXITING, BUT YOU HAVE BEEN WARNED. I
|
||||
* ACCEPT NO LIABILITY OR RESPONSIBILITY FOR ANYTHING THAT HAPPENS AS A RESULT
|
||||
* OF YOU RUNNING THIS CODE. IF IT BREAKS, YOU GET TO KEEP ALL THE PIECES.
|
||||
*
|
||||
* NOTE ALSO: THIS MAY BE ILLEGAL IN YOUR COUNTRY. HERE ARE SOME COMMENTS
|
||||
* FROM MORE KNOWLEDGEABLE PEOPLE ON THE FORUM:
|
||||
*
|
||||
* "Just be aware that in some countries FM broadcast and especially long
|
||||
* distance FM broadcast could get yourself into trouble with the law, stray FM
|
||||
* broadcasts over Airband aviation is also strictly forbidden."
|
||||
*
|
||||
* "A low pass filter is really really required for this as it has strong
|
||||
* harmonics at the 3rd, 5th 7th and 9th which sit in licensed and rather
|
||||
* essential bands, ie GSM, HAM, emergency services and others. Polluting these
|
||||
* frequencies is immoral and dangerous, whereas "breaking in" on FM bands is
|
||||
* just plain illegal."
|
||||
*
|
||||
* "Don't get caught, this GPIO use has the potential to exceed the legal
|
||||
* limits by about 2000% with a proper aerial."
|
||||
*
|
||||
*
|
||||
* As for the original code, this code is released under the GPL.
|
||||
*
|
||||
* Richard Hirst <richardghirst@gmail.com> December 2012
|
||||
*/
|
||||
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <unistd.h>
|
||||
#include <string.h>
|
||||
#include <errno.h>
|
||||
#include <stdarg.h>
|
||||
#include <stdint.h>
|
||||
#include <math.h>
|
||||
#include <time.h>
|
||||
#include <signal.h>
|
||||
#include <sys/types.h>
|
||||
#include <sys/stat.h>
|
||||
#include <fcntl.h>
|
||||
#include <sys/mman.h>
|
||||
#include <sndfile.h>
|
||||
|
||||
extern "C"
|
||||
{
|
||||
#include "rds.h"
|
||||
#include "fm_mpx.h"
|
||||
#include "control_pipe.h"
|
||||
}
|
||||
|
||||
#include "../librpitx/src/librpitx.h"
|
||||
|
||||
ngfmdmasync *fmmod;
|
||||
// The deviation specifies how wide the signal is.
|
||||
// Use 75kHz for WBFM (broadcast radio)
|
||||
// and about 2.5kHz for NBFM (walkie-talkie style radio)
|
||||
#define DEVIATION 75000
|
||||
//FOR NBFM
|
||||
//#define DEVIATION 2500
|
||||
|
||||
static void
|
||||
terminate(int num)
|
||||
{
|
||||
delete fmmod;
|
||||
fm_mpx_close();
|
||||
close_control_pipe();
|
||||
|
||||
|
||||
exit(num);
|
||||
}
|
||||
|
||||
static void
|
||||
fatal(char *fmt, ...)
|
||||
{
|
||||
va_list ap;
|
||||
|
||||
va_start(ap, fmt);
|
||||
vfprintf(stderr, fmt, ap);
|
||||
va_end(ap);
|
||||
terminate(0);
|
||||
}
|
||||
|
||||
|
||||
|
||||
|
||||
#define SUBSIZE 512
|
||||
#define DATA_SIZE 5000
|
||||
|
||||
|
||||
int tx(uint32_t carrier_freq, char *audio_file, uint16_t pi, char *ps, char *rt, float ppm, char *control_pipe) {
|
||||
// Catch all signals possible - it is vital we kill the DMA engine
|
||||
// on process exit!
|
||||
for (int i = 0; i < 64; i++) {
|
||||
struct sigaction sa;
|
||||
|
||||
memset(&sa, 0, sizeof(sa));
|
||||
sa.sa_handler = terminate;
|
||||
sigaction(i, &sa, NULL);
|
||||
}
|
||||
|
||||
|
||||
|
||||
// Data structures for baseband data
|
||||
float data[DATA_SIZE];
|
||||
float devfreq[DATA_SIZE];
|
||||
int data_len = 0;
|
||||
int data_index = 0;
|
||||
|
||||
// Initialize the baseband generator
|
||||
if(fm_mpx_open(audio_file, DATA_SIZE) < 0) return 1;
|
||||
|
||||
// Initialize the RDS modulator
|
||||
char myps[9] = {0};
|
||||
set_rds_pi(pi);
|
||||
set_rds_rt(rt);
|
||||
uint16_t count = 0;
|
||||
uint16_t count2 = 0;
|
||||
int varying_ps = 0;
|
||||
|
||||
if(ps) {
|
||||
set_rds_ps(ps);
|
||||
printf("PI: %04X, PS: \"%s\".\n", pi, ps);
|
||||
} else {
|
||||
printf("PI: %04X, PS: <Varying>.\n", pi);
|
||||
varying_ps = 1;
|
||||
}
|
||||
printf("RT: \"%s\"\n", rt);
|
||||
|
||||
// Initialize the control pipe reader
|
||||
if(control_pipe) {
|
||||
if(open_control_pipe(control_pipe) == 0) {
|
||||
printf("Reading control commands on %s.\n", control_pipe);
|
||||
} else {
|
||||
printf("Failed to open control pipe: %s.\n", control_pipe);
|
||||
control_pipe = NULL;
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
printf("Starting to transmit on %3.1f MHz.\n", carrier_freq/1e6);
|
||||
|
||||
|
||||
float deviation_scale_factor;
|
||||
//if( divider ) // PLL modulation
|
||||
{ // note samples are [-10:10]
|
||||
deviation_scale_factor= 0.1 * (DEVIATION ) ; // todo PPM
|
||||
}
|
||||
|
||||
|
||||
|
||||
for (;;)
|
||||
{
|
||||
// Default (varying) PS
|
||||
if(varying_ps) {
|
||||
if(count == 512) {
|
||||
snprintf(myps, 9, "%08d", count2);
|
||||
set_rds_ps(myps);
|
||||
count2++;
|
||||
}
|
||||
if(count == 1024) {
|
||||
set_rds_ps("RPi-Live");
|
||||
count = 0;
|
||||
}
|
||||
count++;
|
||||
}
|
||||
|
||||
if(control_pipe && poll_control_pipe() == CONTROL_PIPE_PS_SET) {
|
||||
varying_ps = 0;
|
||||
}
|
||||
|
||||
if( fm_mpx_get_samples(data) < 0 ) {
|
||||
terminate(0);
|
||||
}
|
||||
data_len = DATA_SIZE;
|
||||
for(int i=0;i< data_len;i++)
|
||||
{
|
||||
|
||||
devfreq[i] = data[i]*deviation_scale_factor;
|
||||
|
||||
|
||||
}
|
||||
fmmod->SetFrequencySamples(devfreq,data_len);
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
int main(int argc, char **argv) {
|
||||
char *audio_file = NULL;
|
||||
char *control_pipe = NULL;
|
||||
uint32_t carrier_freq = 107900000;
|
||||
char *ps = "Librpitx";
|
||||
char *rt = "PiFmRds: live FM-RDS transmission from the RaspberryPi";
|
||||
uint16_t pi = 0x1234;
|
||||
|
||||
float ppm = 0;
|
||||
|
||||
|
||||
// Parse command-line arguments
|
||||
for(int i=1; i<argc; i++) {
|
||||
char *arg = argv[i];
|
||||
char *param = NULL;
|
||||
|
||||
if(arg[0] == '-' && i+1 < argc) param = argv[i+1];
|
||||
|
||||
if((strcmp("-wav", arg)==0 || strcmp("-audio", arg)==0) && param != NULL) {
|
||||
i++;
|
||||
audio_file = param;
|
||||
} else if(strcmp("-freq", arg)==0 && param != NULL) {
|
||||
i++;
|
||||
carrier_freq = 1e6 * atof(param);
|
||||
//if(carrier_freq < 76e6 || carrier_freq > 108e6)
|
||||
// fatal("Incorrect frequency specification. Must be in megahertz, of the form 107.9, between 76 and 108.\n");
|
||||
} else if(strcmp("-pi", arg)==0 && param != NULL) {
|
||||
i++;
|
||||
pi = (uint16_t) strtol(param, NULL, 16);
|
||||
} else if(strcmp("-ps", arg)==0 && param != NULL) {
|
||||
i++;
|
||||
ps = param;
|
||||
} else if(strcmp("-rt", arg)==0 && param != NULL) {
|
||||
i++;
|
||||
rt = param;
|
||||
} else if(strcmp("-ppm", arg)==0 && param != NULL) {
|
||||
i++;
|
||||
ppm = atof(param);
|
||||
} else if(strcmp("-ctl", arg)==0 && param != NULL) {
|
||||
i++;
|
||||
control_pipe = param;
|
||||
}
|
||||
else {
|
||||
fatal("Unrecognised argument: %s.\n"
|
||||
"Syntax: pi_fm_rds [-freq freq] [-audio file] [-ppm ppm_error] [-pi pi_code]\n"
|
||||
" [-ps ps_text] [-rt rt_text] [-ctl control_pipe]\n", arg);
|
||||
}
|
||||
}
|
||||
int FifoSize=DATA_SIZE*2;
|
||||
fmmod=new ngfmdmasync(carrier_freq,228000,14,FifoSize);
|
||||
int errcode = tx(carrier_freq, audio_file, pi, ps, rt, ppm, control_pipe);
|
||||
|
||||
terminate(errcode);
|
||||
}
|
||||
|
|
@ -0,0 +1,255 @@
|
|||
/*
|
||||
PiFmRds - FM/RDS transmitter for the Raspberry Pi
|
||||
Copyright (C) 2014 Christophe Jacquet, F8FTK
|
||||
|
||||
See https://github.com/ChristopheJacquet/PiFmRds
|
||||
|
||||
This program is free software: you can redistribute it and/or modify
|
||||
it under the terms of the GNU General Public License as published by
|
||||
the Free Software Foundation, either version 3 of the License, or
|
||||
(at your option) any later version.
|
||||
|
||||
This program is distributed in the hope that it will be useful,
|
||||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
GNU General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
*/
|
||||
|
||||
#include <stdint.h>
|
||||
#include <string.h>
|
||||
#include <stdio.h>
|
||||
#include <time.h>
|
||||
#include <stdlib.h>
|
||||
#include "waveforms.h"
|
||||
|
||||
#define RT_LENGTH 64
|
||||
#define PS_LENGTH 8
|
||||
#define GROUP_LENGTH 4
|
||||
|
||||
struct {
|
||||
uint16_t pi;
|
||||
int ta;
|
||||
char ps[PS_LENGTH];
|
||||
char rt[RT_LENGTH];
|
||||
} rds_params = { 0 };
|
||||
/* Here, the first member of the struct must be a scalar to avoid a
|
||||
warning on -Wmissing-braces with GCC < 4.8.3
|
||||
(bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53119)
|
||||
*/
|
||||
|
||||
/* The RDS error-detection code generator polynomial is
|
||||
x^10 + x^8 + x^7 + x^5 + x^4 + x^3 + x^0
|
||||
*/
|
||||
#define POLY 0x1B9
|
||||
#define POLY_DEG 10
|
||||
#define MSB_BIT 0x8000
|
||||
#define BLOCK_SIZE 16
|
||||
|
||||
#define BITS_PER_GROUP (GROUP_LENGTH * (BLOCK_SIZE+POLY_DEG))
|
||||
#define SAMPLES_PER_BIT 192
|
||||
#define FILTER_SIZE (sizeof(waveform_biphase)/sizeof(float))
|
||||
#define SAMPLE_BUFFER_SIZE (SAMPLES_PER_BIT + FILTER_SIZE)
|
||||
|
||||
|
||||
uint16_t offset_words[] = {0x0FC, 0x198, 0x168, 0x1B4};
|
||||
// We don't handle offset word C' here for the sake of simplicity
|
||||
|
||||
/* Classical CRC computation */
|
||||
uint16_t crc(uint16_t block) {
|
||||
uint16_t crc = 0;
|
||||
|
||||
for(int j=0; j<BLOCK_SIZE; j++) {
|
||||
int bit = (block & MSB_BIT) != 0;
|
||||
block <<= 1;
|
||||
|
||||
int msb = (crc >> (POLY_DEG-1)) & 1;
|
||||
crc <<= 1;
|
||||
if((msb ^ bit) != 0) {
|
||||
crc = crc ^ POLY;
|
||||
}
|
||||
}
|
||||
|
||||
return crc;
|
||||
}
|
||||
|
||||
/* Possibly generates a CT (clock time) group if the minute has just changed
|
||||
Returns 1 if the CT group was generated, 0 otherwise
|
||||
*/
|
||||
int get_rds_ct_group(uint16_t *blocks) {
|
||||
static int latest_minutes = -1;
|
||||
|
||||
// Check time
|
||||
time_t now;
|
||||
struct tm *utc;
|
||||
|
||||
now = time (NULL);
|
||||
utc = gmtime (&now);
|
||||
|
||||
if(utc->tm_min != latest_minutes) {
|
||||
// Generate CT group
|
||||
latest_minutes = utc->tm_min;
|
||||
|
||||
int l = utc->tm_mon <= 1 ? 1 : 0;
|
||||
int mjd = 14956 + utc->tm_mday +
|
||||
(int)((utc->tm_year - l) * 365.25) +
|
||||
(int)((utc->tm_mon + 2 + l*12) * 30.6001);
|
||||
|
||||
blocks[1] = 0x4400 | (mjd>>15);
|
||||
blocks[2] = (mjd<<1) | (utc->tm_hour>>4);
|
||||
blocks[3] = (utc->tm_hour & 0xF)<<12 | utc->tm_min<<6;
|
||||
|
||||
utc = localtime(&now);
|
||||
|
||||
int offset = utc->tm_gmtoff / (30 * 60);
|
||||
blocks[3] |= abs(offset);
|
||||
if(offset < 0) blocks[3] |= 0x20;
|
||||
|
||||
//printf("Generated CT: %04X %04X %04X\n", blocks[1], blocks[2], blocks[3]);
|
||||
return 1;
|
||||
} else return 0;
|
||||
}
|
||||
|
||||
/* Creates an RDS group. This generates sequences of the form 0A, 0A, 0A, 0A, 2A, etc.
|
||||
The pattern is of length 5, the variable 'state' keeps track of where we are in the
|
||||
pattern. 'ps_state' and 'rt_state' keep track of where we are in the PS (0A) sequence
|
||||
or RT (2A) sequence, respectively.
|
||||
*/
|
||||
void get_rds_group(int *buffer) {
|
||||
static int state = 0;
|
||||
static int ps_state = 0;
|
||||
static int rt_state = 0;
|
||||
uint16_t blocks[GROUP_LENGTH] = {rds_params.pi, 0, 0, 0};
|
||||
|
||||
// Generate block content
|
||||
if(! get_rds_ct_group(blocks)) { // CT (clock time) has priority on other group types
|
||||
if(state < 4) {
|
||||
blocks[1] = 0x0400 | ps_state;
|
||||
if(rds_params.ta) blocks[1] |= 0x0010;
|
||||
blocks[2] = 0xCDCD; // no AF
|
||||
blocks[3] = rds_params.ps[ps_state*2]<<8 | rds_params.ps[ps_state*2+1];
|
||||
ps_state++;
|
||||
if(ps_state >= 4) ps_state = 0;
|
||||
} else { // state == 5
|
||||
blocks[1] = 0x2400 | rt_state;
|
||||
blocks[2] = rds_params.rt[rt_state*4+0]<<8 | rds_params.rt[rt_state*4+1];
|
||||
blocks[3] = rds_params.rt[rt_state*4+2]<<8 | rds_params.rt[rt_state*4+3];
|
||||
rt_state++;
|
||||
if(rt_state >= 16) rt_state = 0;
|
||||
}
|
||||
|
||||
state++;
|
||||
if(state >= 5) state = 0;
|
||||
}
|
||||
|
||||
// Calculate the checkword for each block and emit the bits
|
||||
for(int i=0; i<GROUP_LENGTH; i++) {
|
||||
uint16_t block = blocks[i];
|
||||
uint16_t check = crc(block) ^ offset_words[i];
|
||||
for(int j=0; j<BLOCK_SIZE; j++) {
|
||||
*buffer++ = ((block & (1<<(BLOCK_SIZE-1))) != 0);
|
||||
block <<= 1;
|
||||
}
|
||||
for(int j=0; j<POLY_DEG; j++) {
|
||||
*buffer++= ((check & (1<<(POLY_DEG-1))) != 0);
|
||||
check <<= 1;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/* Get a number of RDS samples. This generates the envelope of the waveform using
|
||||
pre-generated elementary waveform samples, and then it amplitude-modulates the
|
||||
envelope with a 57 kHz carrier, which is very efficient as 57 kHz is 4 times the
|
||||
sample frequency we are working at (228 kHz).
|
||||
*/
|
||||
void get_rds_samples(float *buffer, int count) {
|
||||
static int bit_buffer[BITS_PER_GROUP];
|
||||
static int bit_pos = BITS_PER_GROUP;
|
||||
static float sample_buffer[SAMPLE_BUFFER_SIZE] = {0};
|
||||
|
||||
static int prev_output = 0;
|
||||
static int cur_output = 0;
|
||||
static int cur_bit = 0;
|
||||
static int sample_count = SAMPLES_PER_BIT;
|
||||
static int inverting = 0;
|
||||
static int phase = 0;
|
||||
|
||||
static int in_sample_index = 0;
|
||||
static int out_sample_index = SAMPLE_BUFFER_SIZE-1;
|
||||
|
||||
for(int i=0; i<count; i++) {
|
||||
if(sample_count >= SAMPLES_PER_BIT) {
|
||||
if(bit_pos >= BITS_PER_GROUP) {
|
||||
get_rds_group(bit_buffer);
|
||||
bit_pos = 0;
|
||||
}
|
||||
|
||||
// do differential encoding
|
||||
cur_bit = bit_buffer[bit_pos];
|
||||
prev_output = cur_output;
|
||||
cur_output = prev_output ^ cur_bit;
|
||||
|
||||
inverting = (cur_output == 1);
|
||||
|
||||
float *src = waveform_biphase;
|
||||
int idx = in_sample_index;
|
||||
|
||||
for(int j=0; j<FILTER_SIZE; j++) {
|
||||
float val = (*src++);
|
||||
if(inverting) val = -val;
|
||||
sample_buffer[idx++] += val;
|
||||
if(idx >= SAMPLE_BUFFER_SIZE) idx = 0;
|
||||
}
|
||||
|
||||
in_sample_index += SAMPLES_PER_BIT;
|
||||
if(in_sample_index >= SAMPLE_BUFFER_SIZE) in_sample_index -= SAMPLE_BUFFER_SIZE;
|
||||
|
||||
bit_pos++;
|
||||
sample_count = 0;
|
||||
}
|
||||
|
||||
float sample = sample_buffer[out_sample_index];
|
||||
sample_buffer[out_sample_index] = 0;
|
||||
out_sample_index++;
|
||||
if(out_sample_index >= SAMPLE_BUFFER_SIZE) out_sample_index = 0;
|
||||
|
||||
|
||||
// modulate at 57 kHz
|
||||
// use phase for this
|
||||
switch(phase) {
|
||||
case 0:
|
||||
case 2: sample = 0; break;
|
||||
case 1: break;
|
||||
case 3: sample = -sample; break;
|
||||
}
|
||||
phase++;
|
||||
if(phase >= 4) phase = 0;
|
||||
|
||||
*buffer++ = sample;
|
||||
sample_count++;
|
||||
}
|
||||
}
|
||||
|
||||
void set_rds_pi(uint16_t pi_code) {
|
||||
rds_params.pi = pi_code;
|
||||
}
|
||||
|
||||
void set_rds_rt(char *rt) {
|
||||
strncpy(rds_params.rt, rt, 64);
|
||||
for(int i=0; i<64; i++) {
|
||||
if(rds_params.rt[i] == 0) rds_params.rt[i] = 32;
|
||||
}
|
||||
}
|
||||
|
||||
void set_rds_ps(char *ps) {
|
||||
strncpy(rds_params.ps, ps, 8);
|
||||
for(int i=0; i<8; i++) {
|
||||
if(rds_params.ps[i] == 0) rds_params.ps[i] = 32;
|
||||
}
|
||||
}
|
||||
|
||||
void set_rds_ta(int ta) {
|
||||
rds_params.ta = ta;
|
||||
}
|
||||
|
|
@ -0,0 +1,34 @@
|
|||
/*
|
||||
PiFmRds - FM/RDS transmitter for the Raspberry Pi
|
||||
Copyright (C) 2014 Christophe Jacquet, F8FTK
|
||||
|
||||
See https://github.com/ChristopheJacquet/PiFmRds
|
||||
|
||||
This program is free software: you can redistribute it and/or modify
|
||||
it under the terms of the GNU General Public License as published by
|
||||
the Free Software Foundation, either version 3 of the License, or
|
||||
(at your option) any later version.
|
||||
|
||||
This program is distributed in the hope that it will be useful,
|
||||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
GNU General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
*/
|
||||
|
||||
#ifndef RDS_H
|
||||
#define RDS_H
|
||||
|
||||
|
||||
#include <stdint.h>
|
||||
|
||||
extern void get_rds_samples(float *buffer, int count);
|
||||
extern void set_rds_pi(uint16_t pi_code);
|
||||
extern void set_rds_rt(char *rt);
|
||||
extern void set_rds_ps(char *ps);
|
||||
extern void set_rds_ta(int ta);
|
||||
|
||||
|
||||
#endif /* RDS_H */
|
||||
|
|
@ -0,0 +1,101 @@
|
|||
/*
|
||||
PiFmRds - FM/RDS transmitter for the Raspberry Pi
|
||||
Copyright (C) 2014 Christophe Jacquet, F8FTK
|
||||
|
||||
See https://github.com/ChristopheJacquet/PiFmRds
|
||||
|
||||
rds_wav.c is a test program that writes a RDS baseband signal to a WAV
|
||||
file. It requires libsndfile.
|
||||
|
||||
This program is free software: you can redistribute it and/or modify
|
||||
it under the terms of the GNU General Public License as published by
|
||||
the Free Software Foundation, either version 3 of the License, or
|
||||
(at your option) any later version.
|
||||
|
||||
This program is distributed in the hope that it will be useful,
|
||||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
GNU General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
*/
|
||||
|
||||
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <math.h>
|
||||
#include <sndfile.h>
|
||||
#include <string.h>
|
||||
|
||||
#include "rds.h"
|
||||
#include "fm_mpx.h"
|
||||
|
||||
|
||||
#define LENGTH 114000
|
||||
|
||||
|
||||
/* Simple test program */
|
||||
int main(int argc, char **argv) {
|
||||
if(argc < 4) {
|
||||
fprintf(stderr, "Error: missing argument.\n");
|
||||
fprintf(stderr, "Syntax: rds_wav <in_audio.wav> <out_mpx.wav> <text>\n");
|
||||
return EXIT_FAILURE;
|
||||
}
|
||||
|
||||
set_rds_pi(0x1234);
|
||||
set_rds_ps(argv[3]);
|
||||
set_rds_rt(argv[3]);
|
||||
|
||||
char *in_file = argv[1];
|
||||
if(strcmp("NONE", argv[1]) == 0) in_file = NULL;
|
||||
|
||||
if(fm_mpx_open(in_file, LENGTH) != 0) {
|
||||
printf("Could not setup FM mulitplex generator.\n");
|
||||
return EXIT_FAILURE;
|
||||
}
|
||||
|
||||
|
||||
|
||||
// Set the format of the output file
|
||||
SNDFILE *outf;
|
||||
SF_INFO sfinfo;
|
||||
|
||||
sfinfo.frames = LENGTH;
|
||||
sfinfo.samplerate = 228000;
|
||||
sfinfo.channels = 1;
|
||||
sfinfo.format = SF_FORMAT_WAV | SF_FORMAT_PCM_16;
|
||||
sfinfo.sections = 1;
|
||||
sfinfo.seekable = 0;
|
||||
|
||||
// Open the output file
|
||||
char *out_file = argv[2];
|
||||
if (! (outf = sf_open(out_file, SFM_WRITE, &sfinfo))) {
|
||||
fprintf(stderr, "Error: could not open output file %s.\n", out_file);
|
||||
return EXIT_FAILURE;
|
||||
}
|
||||
|
||||
float mpx_buffer[LENGTH];
|
||||
|
||||
for(int j=0; j<40; j++) {
|
||||
if( fm_mpx_get_samples(mpx_buffer) < 0 ) break;
|
||||
|
||||
// scale samples
|
||||
for(int i=0; i<LENGTH; i++) {
|
||||
mpx_buffer[i] /= 10.;
|
||||
}
|
||||
|
||||
if(sf_write_float(outf, mpx_buffer, LENGTH) != LENGTH) {
|
||||
fprintf(stderr, "Error: writing to file %s.\n", argv[1]);
|
||||
return EXIT_FAILURE;
|
||||
}
|
||||
}
|
||||
|
||||
if(sf_close(outf) ) {
|
||||
fprintf(stderr, "Error: closing file %s.\n", argv[1]);
|
||||
}
|
||||
|
||||
fm_mpx_close();
|
||||
|
||||
return EXIT_SUCCESS;
|
||||
}
|
||||
Plik binarny nie jest wyświetlany.
File diff suppressed because one or more lines are too long
|
|
@ -0,0 +1,7 @@
|
|||
|
||||
/* This file was automatically generated by "generate_waveforms.py".
|
||||
(C) 2014 Christophe Jacquet.
|
||||
Released under the GNU GPL v3 license.
|
||||
*/
|
||||
|
||||
extern float waveform_biphase[576];
|
||||
|
|
@ -0,0 +1 @@
|
|||
sudo ./pifmrds -freq 434 -audio src/pifmrds/stereo_44100.wav
|
||||
Ładowanie…
Reference in New Issue