udp rx/tx linkage docs/examples

op25/gr-op25_repeater/apps/900.tsv

@@ -0,0 +1,2 @@
+"Sysname"	"Control Channel List"	"Offset"	"NAC"	"Modulation"	"TGID Tags File"	"Whitelist"	"Blacklist"	"Center Frequency"
+"Fake"	"925.0"	"0"	"0x293"	"FSK4"	""	""	""	"924.95"

op25/gr-op25_repeater/apps/README-example-udp

@@ -0,0 +1,38 @@
+
+Linking OP25 TX and RX                                December 2020
+===================================================================
+
+The OP25 TX application can be configured to transmit one or more
+channels directly to one of the RX apps (rx.py or multi_rx.py) in
+each case by specifying a device args string of the form
+     udp:host:port
+where host and port are the IP address and UDP port number,
+respectively.  Typically, the TX is started first followed by
+the RX, but they can be started in any order.  UDP port 25252 is
+used in the examples.
+
+The sample RX script is in runudp.sh, and the sample TX json config
+is in cfg-900.json .
+
+To start the TX
+      cd .../op25/op25-gr_repeater/apps/tx
+      ./multi_tx.py -c ../cfg-900.json
+
+The RX is started with
+      cd .../op25/op25-gr_repeater/apps
+      ./runudp.sh
+
+There is a 120KHz sized block of spectrum transmitted (SR=120000)
+which is treated as complex baseband with each side pretending that
+the spectrum is converted to/from the 900 MHz band.  On the RX side
+any frequency-change requests are ignored; instead, a "center 
+frequency" is defined.  There are two channels (P25 trunk control
+channel and P25 voice channel) spaced at 50 KHz separation.
+
+The TX reads two data files that must be created beforehand.  To 
+create the trunk control channel data symbol file, refer to
+    tx/README-fakecc.txt
+An audio file (PCM/ rate 8000 / mono / signed int16) must also be
+created - this file will be real-time encoded with the voice codec
+and sent on the P25 voice channel.  These two files must be defined 
+in the cfg-900.json file (channel "source" keyword).

op25/gr-op25_repeater/apps/cfg-900.json

@@ -5,9 +5,9 @@
             "destination": "udp://127.0.0.1:56120", 
             "excess_bw": 0.2, 
             "filter_type": "rc", 
-            "frequency": 925000000, 
+            "frequency": 924975000, 
             "if_rate": 24000, 
-            "name": "p25 cc", 
+            "name": "p25 control channel", 
             "plot": "datascope", 
             "source": "symbols:sym-cc925.dat",
             "symbol_rate": 4800
@@ -17,9 +17,9 @@
             "destination": "udp://127.0.0.1:56124", 
             "excess_bw": 0.2, 
             "filter_type": "rc", 
-            "frequency": 924900000, 
+            "frequency": 924925000, 
             "if_rate": 24000, 
-            "name": "p25 vc", 
+            "name": "p25 voice channel", 
             "plot": "datascope", 
             "source": "/home/mhp/rand4.raw",
             "symbol_rate": 4800
@@ -33,7 +33,7 @@
             "name": "udp", 
             "offset": 0, 
             "ppm": 0, 
-            "rate": 480000, 
+            "rate": 120000, 
             "tunable": false
         }
     ]

op25/gr-op25_repeater/apps/runudp.sh

@@ -0,0 +1,7 @@
+#! /bin/sh
+
+t="-T 900.tsv"
+sr="-S 120000"
+v="-v 255"
+
+python3 rx.py --args "udp:127.0.0.1:25252" -f 924975000 $sr -q 0 -D fsk4 -P "datascope" -V -w -v 255 $t $v 2> stderr.2

op25/gr-op25_repeater/apps/tx/multi_tx.py

@@ -212,7 +212,7 @@ class tx_block(gr.top_block):
                 continue
             cfg = chan.config
             dev = chan.device
-            modulator_rate = 48000	## FIXME
+            modulator_rate = 24000	## FIXME
             bt = _def_bt
             if 'bt' in cfg.keys():
                 bt = cfg['bt']