updated README and added photo

README.md

@@ -1,13 +1,47 @@
-RPi Pico FT8 Transciever
+# Raspberry Pi Pico FT8 Transciever
 
-Code to run a standalone FT8 transceiver based on the new Raspberry Pi Pico RP2040 microcontroller. Implemented in C, based on Karlis Goba YL3JG's FT8 Library. Uses the RPi Pico C/C++ SDK.
+Run FT8 on the $4 Raspberry Pi Pico microcontroller! This code, based on
+[Karlis Goba's (YL3JG) FT8 Library](https://github.com/kgoba/ft8_lib), runs a
+standalone FT8 amateur radio transciever.
 
-Currently, it is able to decode live audio signals that are input into the ADC, displaying them on the LCD. Uses a ST7789 240x320 LCD display, 4x4 membrane keyboard, Si5351 clock generator.
+![Decoded FT8 Messages](decodedmessages.jpg)
 
-To do list:
--fix snr readings
--add abort option during sending
--add split frequency operation
--find how to use DSP quadrature filter + LPF in software
--sending waterfall
+### It does the following:
+
+- Decodes FT8 signals in real-time.
+- Displays decoded signals and a spectrum waterfall on a ST7789 240x320 LCD display.
+- Controls a Si5351 programmable oscillator used for a direct conversion
+  reciever, and for driving a Class-E amplifier during transmission.
+- Encodes response messages based on recieved messages and user selection.
+- Reads in user selection from a 4x4 membrane keyboard.
+- Offers a startup screen where time is calibrated to the second to ensure
+  proper reception/transmission intervals.
+
+### Technical Notes
+
+- This code implements incremental decoding. The Pico only has around 200kB of
+  RAM. It is not possible to store a 15 second duration of samples, and thus
+  samples are collected in ~1 second intervals, processed with the FFT, and only
+  the FFT data is stored.
+- The Pico has a dual-core processor. This code uses multithreading, using one
+  core to control the functionality of the transciever (display, ADC readings,
+  etc.) and the other core to do signal processing (FFT and error correction
+  codes).
+- This code overclocks the Pico's processor, since running at normal clock
+  frequency, it is unable to keep up with decoding all samples within the 15
+  second transmission interval.
+- The audio-frequency FT8 signals are fed into the built-in ADC on the Pico. The
+  Pico has the ability to sample two analog inputs, but only one is used right
+  now. In the future both can be used for quadrature signals coming out of a
+  direct conversion reciever so the transciever can have sideband rejection. 
+
+### Development
+
+- Set up the Raspberry Pi Pico C/C++ SDK, as described
+[here](https://www.raspberrypi.com/documentation/pico-sdk/).
+- My apologies for the sloppy code quality. I coded this in high school, before
+  I took a proper programming class. I've improved since then.
+- See [Dhiru Kholia's (VU3CER) fork of my
+  code](https://github.com/kholia/pico_ft8_xcvr) for his own transciever
+  project. His project has details on how to implement it in hardware.
 

TODO.txt

@@ -0,0 +1,6 @@
+-fix snr readings
+-add abort option during sending
+-add split frequency operation
+-find how to use DSP quadrature filter + LPF in software
+-sending waterfall
+