Add DC block stage into sdr wrappers (thanks @rs1729!)

auto_rx/autorx/__init__.py

@@ -12,7 +12,7 @@ from queue import Queue
 # MINOR - New sonde type support, other fairly big changes that may result in telemetry or config file incompatability issus.
 # PATCH - Small changes, or minor feature additions.
 
-__version__ = "1.6.0-beta23"
+__version__ = "1.6.0-beta24"
 
 
 # Global Variables

auto_rx/autorx/sdr_wrappers.py

@@ -221,6 +221,13 @@ def get_sdr_iq_cmd(
 
     """
 
+    # DC removal commmand, using rs1729's IQ_dec utility.
+    # This helps remove the residual DC offset in the 16-bit outputs from
+    # both rtl_fm and ss_iq. 
+    # We currently only use this on narrowband sondes.
+    _dc_remove = f"./iq_dec --bo 16 - {int(sample_rate)} 16 2>/dev/null |"
+    _dc_remove_limit = 80000
+
     if sdr_type == "RTLSDR":
         _gain = ""
         if gain:
@@ -239,6 +246,9 @@ def get_sdr_iq_cmd(
             f"- 2>/dev/null | "
         )
 
+        if sample_rate < _dc_remove_limit:
+            _cmd += _dc_remove
+
         return _cmd
 
     if sdr_type == "SpyServer":
@@ -249,6 +259,9 @@ def get_sdr_iq_cmd(
             f"-r {sdr_hostname} -q {sdr_port} - 2>/dev/null|"
         )
 
+        if sample_rate < _dc_remove_limit:
+            _cmd += _dc_remove
+
         return _cmd
 
     else:

auto_rx/autorx/utils.py

@@ -41,7 +41,8 @@ REQUIRED_RS_UTILS = [
     "mp3h1mod",
     "m20mod",
     "imet4iq",
-    "mts01mod"
+    "mts01mod",
+    "iq_dec"
 ]
 
 

auto_rx/build.sh

@@ -37,5 +37,6 @@ mv ../demod/mod/meisei100mod .
 mv ../demod/mod/imet54mod .
 mv ../demod/mod/mp3h1mod .
 mv ../demod/mod/mts01mod .
+mv ../demod/mod/iq_dec .
 
 echo "Done!"

auto_rx/clean.sh

@@ -24,6 +24,7 @@ rm meisei100mod
 rm mp3h1mod
 rm imet54mod
 rm mts01mod
+rm iq_dec
 
 
 echo "Done!"

demod/mod/Makefile

@@ -1,6 +1,6 @@
 LDLIBS = -lm
 
-PROGRAMS := rs41mod dfm09mod rs92mod lms6mod lms6Xmod meisei100mod m10mod m20mod imet54mod mp3h1mod mts01mod
+PROGRAMS := rs41mod dfm09mod rs92mod lms6mod lms6Xmod meisei100mod m10mod m20mod imet54mod mp3h1mod mts01mod iq_dec
 
 all: $(PROGRAMS)
 
@@ -31,5 +31,8 @@ bch_ecc_mod.o: bch_ecc_mod.h
 demod_mod.o: CFLAGS += -Ofast
 demod_mod.o: demod_mod.h
 
+iq_dec: CFLAGS += -Ofast
+iq_dec: iq_dec.o
+
 clean:
 	$(RM) $(PROGRAMS) $(PROGRAMS:=.o) demod_mod.o bch_ecc_mod.o