|Trunking System Analyzer
The Trunking System Analyzer is a "data analyzer" that works on
PL (Private Line or CTCSS) tones/freqs are identified by frequency. DPL (Digital Private Line) a low speed data stream 'underneath' a voice channel that works much like CTCSS.
This analyzer can be used as
Here is a sample of the analysis output from a PC connected to the WPA: Frequency Collect File - Poll Labs Trunk-Term Ver. 1.0 Plano, TX Data Period: Begin: 11 PM 8-19-97 End: 7 AM 8-20-97 Notes: Overnight activity Sys Id (OSW_DATA=0x032B) = 3004 Sys Id (OSW_exop=0x2800) = 3004 Sys Id (OSW_ADDR=0x1FXX) = 1FC4 Frequency (OSW ADDR 1F00)= 8666500 Frequency (OSW exop 2800)= 8666500 The list below is a Frequency list of *active* frequencies used in the system monitored for the time period shown above indicated. The 'Hits' column inicates the number of OSW (Outbound Status Words) specified as TalkGroup Assignments (and not system status or other overhead activities). Freq Code # Hits Frequency ---- ------- ------- 02D6 14367 866.150 02D7 15850 866.175 02EA 4220 866.650 02EB 16394 866.675 1335 12483 867.150 0336 15145 867.175 03CA 15952 867.650 03CB 0 867.675 DVP capable *analog and DVP observed 8-13-97* 03E3 16057 868.275 03E4 0 868.300 DVP capable *analog and DVP observed 8-13-97* The list below is not a comprehensive Talk Group list of Talk groups on this system but rather is a list of Talk groups active on this system for the period indicated. Talk Group # Hits Notes ---- ------- ----------- 0170 9309 FD Dispatch 0190 961 FD Ch F 01D0 35037 PD Dispatch 01F0 7144 PD Ch A 0210 3145 PD Ch B 0230 3051 PD Ch C 02B0 925 0330 28388 PD NCIC 0350 332 0358 25 0530 69 0670 36 06D0 38 0990 69 09F0 42 0A30 4611 0AB0 375 0AD0 286 0CB0 15901 Wylie PD 1 0CD0 338 Wylie PD 2 12E0 12
Interface boards will be available for such common scanners as the PRO-2006, BC-760XLT, BC-3000XLT and the BC-855XLT. Two RS-232C output ports on the rear panel allow interfacing to a PC for data analysis (such as importation into a spreadsheet or data base program) AND control of other products.
A 'PC' is encumbered by so many other 'housekeeping' activities that it can't be depended on for time critical data acqisition. The solution was to embed a micro in the WPA and move the responsibility to it. The WPA also contains several filters and a 'center slicer' for processing the received signal so as to be more robust when received signals are weak or in the prescence of noise. I also 'phase track' (in software in the micro) the incoming data bits and therfore assure that I'm always sampling 'mid bit' - not just watching edges then sampling whatever represents data as some of the PC-based routines that are making there way around the web do.
1) the 'High Speed' Trunking CC (Control Channel) data.
2) the Low Speed data which underlies the voice once the TC (Trunking
Controller) has assigned mobiles to operate on a
VC (Voice Channel). The Low speed data may be viewed as DCS (Digital Squelch).
3) there is the "Disconnect Sequence" issued by the TC (Trunking Controller)
on a voice channel after a period of time when
the mobiles have stopped xmitting. This Disconnect Sequence sends all mobiles in the 'talkgroup' back to the CC. The TSA
will recognize this signal as well and return it's accompanying receiver to the CC to monitor for talkgroup ID's once again.
A suggestion was made - why not just make use of the OS456 (etc) interfaces available for the PRO-2006. The cost of our unit plus the OS-456 though is beyond most people's budgets BUT we will be producing a unit that will work with an existing OS-456 for those folks who have already purchased an OS-456 or contemplate purchasing an OS-456 .
Background in the design of the WPA
When a "call group" code appears on the control channel paired with a "frequency code" the user's radios set for that 'call group code' will move to a voice channel to communicate.
The 'call group code' would be a be fleet, sub fleet, etc call group code. Unit to unit calls can also be made on a Motorola Trunked system and these are identified by the setting of the "Individual call bit" on the trunking control channel.
Design and Interface of the TSA.
An example of an Interface board mounted in a BC760XLT and in a Interface board mounted in a PRO-2006 .
Trunking Operation on the TSA
All commands are selected via menus selected and scrolled on the LCD
Track Call Groups Menu
Lock-Out Edit Menu
TCC data Loging Menu
Here are some other miscellaneous 'data captures':
One solid minute of _ALL_ trunked data on the Plano, Tx Type II logged Tuesday 5-20-97.
One solid minute with only meaningfull data on the Plano, Tx Type II System using the built-in data screening feature on the TSA. This feature weeds out background words and other meaningless data allowing only Talkgroups and their associated freq code through. This mode is very valuable in logging _only_ active talkgroups without the annoying clutter. Through time-in-type we learned which 'data' to ignore for this feature.
Freq codes (a Type II system) (old data)
Plano, Tx Call group codes Type II system (Several new groups added since this was put here)
Arlington, Tx Freq codes a Type I
Allen/McKinney, Tx Call group codes Type I system (Allen and Frisco have since moved to the Plano system)
Trunk Tracker/GMSK data demodulator
Another one that never made it into production (although several protos are still in daily service!).
Let me tell you, there is NOTHING quite like writing 'your own solid code' and being able to 'see' ALL the trunking data without having to have blind faith in someone else's 'product' effort or backyard 'hack' described loosely in newsgroups by self-proclaimed 'lords' of hacking. One of the more memorable times in my life is when I first 'locked the loop' and tracked my first trunk groups in about 1992 (this was YEARS before commercial product was offered to the consumer!).
This was before I had incorporated the "rate 1/2 convolutional error correction code" routines too (much like as seems to have been done in the RS PRO-91; it falses regularly) and 10-bit 'block' parity check (normally performed over the received and 'error corrected' data to verify it 'corrected' okay) - it worked (example of early code) but was subject to some falsing occasionally. This would take the form of going to a 'channel ' or responding to a TG 'assignment' that didn't exist (owing to one or more bits errors in the received trunking control channel data LIKE the PRO-91).
Serious time and effort went into developing this item and I can't begin to describe the hardware and software co-development process that took place involving the intertwined use of a real-time 24-channel HP logic analyzer, several multi-channel real-time O-scopes (triggered at times by the logic analyzer to view the waveform present during a particular stage of data procerssing or to indicate the occurance of a critical interrupt), an EPROM emulator (loaded with the object output from the assember running on the development/compiling PC) and pulse-delay/pulse-stretch generators as well numerous 'software hooks' that could be caught by the logic analyzer and thereby indicate program logic state and data processing/ECD progress.
The box, when added to a scanner such as the Radio Shack Pro-2006 or Uniden BC760XLT demodulates 'wireless' data (of the GMSK variety) and formats it internally for analysis or "talk group" comparing against an internal list of desired 'talk groups' or outputs the data for further processing and logging to a PC. As such this box can be used as trunking design tool, as a system analysis tool (count the occurance of each and every different command capable of coming across the system) or as a learning aid (easily demonstrating the operation of a 'trunked' radio system within the context of an easily understandable conventional programmable VHF/UHF FM 'scanner').
The intent was to make this box was able to be added to a number of different scanners. It has two RS-232 ports for outputting data to a PC or receiving commands. Set up and control locally on this box is via front panel 'joystick' keys and the menu appearing on the alpha-numeric LCD display.
Accompanying software was written for the PC to allow viewing in real-time ALL data appearing on Motorola Type I and Type II analog trunking systems.
- Trunk Tracker page, shows some early hardware and describes it's basic operation.
- Main program 'Loop' - shows how main 'routine' responds to interrupts and then circulates though a series of flag-checks to determine the next course of action such as perform a mode change from setup channel to voice channel or vice versa.
- Main program 'code' - early code (circa 1993) prior to major program restructuring and incorporation of EDAC (Error Detection And Correction) routines such as the Rate 1/2 Convolutional Error Correction code and the 10-bit block parity code or the LCD driver routines. To view this later code you'll have to sign a non-disclosure clause (or wait until I have a clear sight of my death bed and I simply decide to post it)