Add a little script to push RTCMv2 messages transcoded from NTRIP ove…

…r UDP

RTCMv3_decode.py

@@ -16,6 +16,8 @@
 
 from bitstring import BitStream
 
+max_sats = 12
+
 RTCMv3_PREAMBLE = 0xD3
 PRUNIT_GPS = 299792.458
 CLIGHT = 299792458.0
@@ -113,10 +115,11 @@ def decode_1004(pkt):
     smint = pkt.read(3).uint
 
     prs = {}
+    temp_corrs = {}
 
     for n in range(nsat):
         svid = pkt.read(6).uint
-        corr_set[svid] = {}
+        temp_corrs[svid] = {}
 
         code1 = pkt.read(1).uint
         pr1 = pkt.read(24).uint
@@ -133,27 +136,37 @@ def decode_1004(pkt):
         pr1 = pr1 * 0.02 + amb * PRUNIT_GPS
 
         if ppr1 != 0x80000:
-            corr_set[svid]['P1'] = pr1
+            temp_corrs[svid]['P1'] = pr1
             cp1 = adjcp(svid, 0, ppr1 * 0.0005 / lam_carr[0])
-            corr_set[svid]['L1'] = pr1 / lam_carr[0] + cp1
+            temp_corrs[svid]['L1'] = pr1 / lam_carr[0] + cp1
 
-        corr_set[svid]['LLI1'] = lossoflock(svid, 0, lock1)
-        corr_set[svid]['SNR1'] = snratio(cnr1 * 0.25)
-        corr_set[svid]['CODE1'] = 'CODE_P1' if code1 else 'CODE_C1'
+        temp_corrs[svid]['LLI1'] = lossoflock(svid, 0, lock1)
+        temp_corrs[svid]['SNR1'] = snratio(cnr1 * 0.25)
+        temp_corrs[svid]['CODE1'] = 'CODE_P1' if code1 else 'CODE_C1'
 
         if pr21 != 0xE000:
-            corr_set[svid]['P2'] = pr1 + pr21 * 0.02
+            temp_corrs[svid]['P2'] = pr1 + pr21 * 0.02
 
         if ppr2 != 0x80000:
             cp2 = adjcp(svid, 1, ppr2 * 0.0005 / lam_carr[1])
-            corr_set[svid]['L2'] = pr1 / lam_carr[1] + cp2
+            temp_corrs[svid]['L2'] = pr1 / lam_carr[1] + cp2
 
-        corr_set[svid]['LLI2'] = lossoflock(svid, 1, lock2)
-        corr_set[svid]['SNR2'] = snratio(cnr2 * 0.25)
-        corr_set[svid]['CODE2'] = L2codes[code2]
+        temp_corrs[svid]['LLI2'] = lossoflock(svid, 1, lock2)
+        temp_corrs[svid]['SNR2'] = snratio(cnr2 * 0.25)
+        temp_corrs[svid]['CODE2'] = L2codes[code2]
+
+    # Sort the list of sats by SNR, trim to 10 sats
+    quals = sorted([ (s, temp_corrs[s]['SNR1']) for s in temp_corrs], key=lambda x: x[1])
+    if len(quals) > max_sats:
+        print("Drop {} sats for encode".format(len(quals) - max_sats))
+        quals = quals[:max_sats]
+
+    # Copy the kept sats in to the correction set 
+    corr_set = {}
+    for sv, snr in quals:
+        corr_set[sv] = temp_corrs[sv]
+        prs[sv] = temp_corrs[sv]['P1']
 
-        prs[svid] = corr_set[svid]['P1']
-
     itow = tow
 
 
@@ -350,16 +363,16 @@ def parse_rtcmv3(pkt):
 def RTCM_converter_thread(server, port, username, password, mountpoint, rtcm_callback = None):
     import subprocess
 
-    """nt = subprocess.Popen(["./ntripclient",
+    nt = subprocess.Popen(["./ntripclient",
                             "--server", server,
                             "--password", password,
                             "--user", username,
                             "--mountpoint", mountpoint ],
-                            stdout=subprocess.PIPE)"""
-
-    nt = subprocess.Popen(["./ntrip.py", server, str(port), username, password, mountpoint],
                             stdout=subprocess.PIPE)
 
+    """nt = subprocess.Popen(["./ntrip.py", server, str(port), username, password, mountpoint],
+                            stdout=subprocess.PIPE)"""
+
 
     if nt is None or nt.stdout is None:
         indev = sys.stdin

ntrip_to_udp.py

@@ -0,0 +1,42 @@
+#!/usr/bin/env python
+'''
+NTRIP -> RTCMv2 transcode, UDP link
+'''
+
+import time, socket
+import RTCMv3_decode
+
+from optparse import OptionParser
+
+parser = OptionParser("ntrip_to_udp.py [options]")
+
+parser.add_option("--ntrip-server", default='192.104.43.25')
+parser.add_option("--ntrip-port", type='int', default=2101)
+parser.add_option("--ntrip-user")
+parser.add_option("--ntrip-password")
+parser.add_option("--ntrip-mount", default='TID10')
+
+parser.add_option("--udp-port", type='int', default=13320)
+parser.add_option("--udp-addr", default="127.0.0.1")
+
+
+(opts, args) = parser.parse_args()
+
+packet_count = 0
+
+def send_rtcm(msg):
+    global packet_count
+    packet_count += 1
+    msg = msg[:-2] # Trim off \r\n that the RTCM encoder puts there
+    port.sendto(msg,(opts.udp_addr, opts.udp_port))
+    print(len(msg), msg)
+
+RTCMv3_decode.run_RTCM_converter(opts.ntrip_server, opts.ntrip_port, opts.ntrip_user, opts.ntrip_password, opts.ntrip_mount, rtcm_callback=send_rtcm)
+
+port = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+# port.setsockopt...
+
+
+while True:
+	print(packet_count)
+	time.sleep(10)