From 217909fe02482ac304f8959d3d5681d5543ecefa Mon Sep 17 00:00:00 2001
From: Mark Jessop <vk5qi@rfhead.net>
Date: Sat, 24 Jul 2021 14:25:00 +0930
Subject: [PATCH] Add APRS callsign generation support for M20 sondes, matching
 dxlAPRS's weird-ass formatting.

---
 auto_rx/autorx/aprs.py      |  3 ++-
 auto_rx/autorx/decode.py    |  1 +
 auto_rx/autorx/utils.py     | 10 ++++++++++
 auto_rx/station.cfg.example |  2 +-
 4 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/auto_rx/autorx/aprs.py b/auto_rx/autorx/aprs.py
index f23a915..a5c0b2f 100644
--- a/auto_rx/autorx/aprs.py
+++ b/auto_rx/autorx/aprs.py
@@ -13,6 +13,7 @@ import traceback
 import socket
 from threading import Thread, Lock
 from . import __version__ as auto_rx_version
+from .utils import strip_sonde_serial
 
 try:
     # Python 2
@@ -74,7 +75,7 @@ def telemetry_to_aprs_position(
     # Generate the comment field.
     _aprs_comment = aprs_comment
     _aprs_comment = _aprs_comment.replace("<freq>", _freq)
-    _aprs_comment = _aprs_comment.replace("<id>", sonde_data["id"])
+    _aprs_comment = _aprs_comment.replace("<id>", strip_sonde_serial(sonde_data["id"]))
     _aprs_comment = _aprs_comment.replace("<temp>", "%.1fC" % sonde_data["temp"])
     _aprs_comment = _aprs_comment.replace(
         "<pressure>", "%.1fhPa" % sonde_data["pressure"]
diff --git a/auto_rx/autorx/decode.py b/auto_rx/autorx/decode.py
index a64b605..668420d 100644
--- a/auto_rx/autorx/decode.py
+++ b/auto_rx/autorx/decode.py
@@ -535,6 +535,7 @@ class SondeDecoder(object):
             # - Have dropped the low-leakage FIR filter (-F9) to save a bit of CPU
             # Have scaled back sample rate to 220 kHz to again save CPU.
             # mk2mod runs at ~90% CPU on a RPi 3, with rtl_fm using ~50% of another core.
+            # Update 2021-07-24: Updated version with speedups now taking 240 kHz BW and only using 50% of a core.
 
             decode_cmd = "%s %s-p %d -d %s %s-M raw -s 240k -f %d 2>/dev/null |" % (
                 self.sdr_fm,
diff --git a/auto_rx/autorx/utils.py b/auto_rx/autorx/utils.py
index 390943b..7994441 100644
--- a/auto_rx/autorx/utils.py
+++ b/auto_rx/autorx/utils.py
@@ -7,6 +7,7 @@
 #
 
 from __future__ import division, print_function
+import codecs
 import fcntl
 import logging
 import os
@@ -255,6 +256,15 @@ def generate_aprs_id(sonde_data):
             # Use the generated id same as dxlAPRS
             _object_name = sonde_data["aprsid"]
 
+        elif "M20" in sonde_data["type"]:
+            # Generate the M20 ID based on the first two hex digits of the
+            # raw hexadecimal id, followed by the last decimal section.
+            # Why we do this and not just use the three hex bytes, nobody knows...
+            if 'rawid' in sonde_data:
+                _object_name = "ME" + sonde_data['rawid'].split('_')[1][:2] + sonde_data["id"].split("-")[-1]
+            else:
+                _object_name = None
+
         elif "IMET" in sonde_data["type"]:
             # Use the last 5 characters of the unique ID we have generated.
             _object_name = "IMET" + sonde_data["id"][-5:]
diff --git a/auto_rx/station.cfg.example b/auto_rx/station.cfg.example
index c2aa301..bd0bc84 100644
--- a/auto_rx/station.cfg.example
+++ b/auto_rx/station.cfg.example
@@ -249,7 +249,7 @@ aprs_position_report = False
 # <batt> - Battery Voltage (e.g. 3.1V)
 # The default comment (below) is compatible with radiosondy.info's parsers, and should only be modified
 # if absolutely necessary.
-aprs_custom_comment = Clb=<vel_v> t=<temp> h=<humidity> p=<pressure> <freq> Type=<type> Radiosonde
+aprs_custom_comment = Clb=<vel_v> t=<temp> h=<humidity> p=<pressure> <freq> Type=<type> ser=<id> Radiosonde
 
 
 ###########################