GitHub/sdrtrunk
1
0
Fork 0
mirror of https://github.com/DSheirer/sdrtrunk.git synced 2026-11-13 09:07:27 -05:00
Code Issues Packages Projects Releases 2 Wiki Activity

Updated APCO25_V0.3.0 (markdown)

Denny Sheirer
2019-11-24 06:05:07 -05:00
parent 11d98b176a
commit 4717aa3cee
1 changed files with 35 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

62
v0.3/APCO25_V0.3.0.md

@@ -10,26 +10,25 @@ Decodes FDMA Common Air Interface (CAI) C4FM modulation and Linear Simulcast
Modulation (LSM).
## P-25 Phase II
Phase II TDMA decoding is not currently supported.
Phase II TDMA (2 timeslot) traffic channel decoding.
## P-25 Hybrid (Phase I/II)
P25 hybrid systems use both Phase 1 control channels and Phase I and Phase II
## P-25 Phase I/II
P25 Phase II systems use both a Phase 1 control channel and Phase I and Phase II
traffic channels, providing transition support for users with a combination of
Phase I and Phase II radios.
TDMA configuration messages that are broadcast on Phase I control channels are
decoded. Currently these include the TDMA timing synchronization and TDMA
channel identifier messages.
## Audio Vocoders
### IMBE ###
APCO-25 Phase I audio calls use the multi-band excitation model vocoder to
compress the digitized audio. SDRTrunk supports the JMBE library for decoding
APCO-25 Phase I audio calls use the IMBE vocoder for digital audio.
### AMBE ###
APCO-25 Phase II audio calls use the AMBE vocoder for digital audio.
SDRTrunk supports the JMBE library for decoding both IMBE and AMBE digital
audio, but DOES NOT include the jmbe library in the normal application download.
You must download and compile the library and place the jmbe-x.x.x.jar file in
the same directory from where you launch the sdrtrunk application. On startup,
sdrtrunk will attempt to discover the library and can then decode imbe audio.
You must download and compile the library and use the **View >> Preferences** menu
to specify the location of the compiled JMBE library (jmbe-x.x.x.jar).
[JMBE library](https://github.com/DSheirer/jmbe)
@@ -46,9 +45,11 @@ decoder configuration when setting up the channel for decoding.
## Talkgroups and Addresses ##
All talkgroups and radio addresses are listed in hexadecimal (base-16) notation
and use the digits 0 - 9 and the letters A - F. Talkgroups are four characters
in length and radio addresses are six characters in length.
All talkgroups and radio addresses are presented in decimal or hexadecimal
(base-16) notation (see Preferences).
### **Talkgroups**: 1 - 65,535
### **Individual Radio Identifiers**: 65,636 - 16,777,211
Packet data IP Version 4 addresses will normally show in the from column of the
events window and the Logical Link ID (radio address) will show in the from
@@ -61,18 +62,17 @@ will be appended to the IP address.
You can create an Alias List and attach it to your P25 decoder in the channel
configuration window.
When aliasing talkgroups and radio addresses, ensure you include the full 4 or 6
character talkgroup or address with leading zeros.
When aliasing talkgroups and radio addresses, you can use either a single talkgroup decimal value, or you can enter a range of talkgroup decimal values.
Add these trunking system unit ID values to your alias list:
Optionally, add these trunking system unit ID values to your alias list:
**FFFFFD** = (Trunking) System Controller.
**FFFFFE** = Registration Controller
**FFFFFF** = All Call
16,777,212 = (Trunking) System Controller.
16,777,213 = Registration Controller
16,777,215 = All Call
## Modulation ##
Choose either C4FM or LSM Simulcast (CQPSK) modulation in the channel configuration
Choose either C4FM or LSM Simulcast (CQPSK) modulation for Phase 1 channels in the channel configuration
decoder tab. When you select the P25 Decoder from the drop-down list, the
modulation selector list will appear.
@@ -88,7 +88,12 @@ traffic channel frequencies used by the system because the control channel will
tell the sdrtrunk application every thing that it needs to know in order to
setup a temporary decoding channel.
### Traffic Channel Pool ###
**Note**: Phase 2 capable trunked systems will use a Phase 1 control channel
with Phase 2 traffic channels. You only have to setup one channel configuation
for the Phase 1 control channel. The Phase 2 traffic channels will be
automatically created by sdrtrunk as each call occurs.
### Traffic Channel Pool Size ###
When configuring the P25 control channel decode configuration, use the Traffic
Channel Pool setting to set the maximum number of temporary traffic channels
@@ -97,10 +102,13 @@ channel configurations up to this maximum number and reuse the channel
configurations for subsequent calls.
The default value of 4 traffic channels in the pool is suitable for a modern
powerful processor. You may have to reduce this pool size if you are using a
lower powered CPU. Monitor the computer's CPU and memory consumption and adjust
this value as needed. Note: you'll have to stop and restart the decoding after
you change the traffic channel pool size value and save it.
powerful processor. You can increase this value to match the number of traffic
channel frequencies for the system your are monitoring, provided your computer
is capable of running that many channels at the same time. You may have to reduce
this pool size if you are using a lower powered CPU. Monitor the computer's CPU
and memory consumption and adjust this value as needed. Note: you'll have to
stop and restart the decoding after you change the traffic channel pool size
value and save it.
## P25 Decoding Example ##