Reference to raw data format

[sbates]

Hi all,

I have a system that attaches to a RIB or RIM and monitors the OSW data coming out of them. I am interested in building a black box to attach to a scanner that will contain a center slicer and a microcontroller to decode the raw format and produce a 1200 baud output similar to the RIB or RIM. I have been searching around on this site and others for a couple of hours and have found LOTS of info on how to build center slicers and LOTS of info on what to do with the OSW messages, but none on the raw 3600 baud data itself. Would some kind person point me in the right direction?

(of course phase II is to handle other formats as well, EDACS, LTR ,etc. and the 9600 baud versions, then tackle digital audio...)

Any input will be greatly appreciated,

Steve

 

[WayneH]

Your biggest issue is getting your microcontroller to output the format for the RIM. There's actually communication (acks, etc) from the RIM to RF Modem so you'll have a project on your hands. I'd start analyzing the datatream coming from the RF Modem.

The 3600 protocol info is out there. Here's C source for the original Trunker decoder along with patent references: http://www.thebriarpatch.org/treport/files/TRUNKER.C

-Wayne

 

[SCPD]

Hello Steve;

Wayne's reply will set you in the right direction. Is there any particular reason for wanting to build a "black box"? Let me guess, a PIC microcontroller, right?

If the output from the box is being fed into a PC, why not do the decoding there? You can use a sound input or a slicer.

On the system that monitors the OSW stream, what does it do with the data?

Regards,
Rick

 

[WayneH]

It sounds like he wants to run System Watch II or SIMS via a scanner as a source for data.

This is what I wrote Treport for, minus the statistical info.

-Wayne

 

[sbates]

I have a recording and statistics software package that currently runs off a RIM, RIB or ATIA. I don't talk to the system, just listen to it. I'd like to replace the dependence on that equipment with an AVR (would have been PIC but I want to try out my new AVR development kit) and center-slicer that I can mount inside a scanner (or outside as necessary). I might then move to a USB or network interface. I'll also be looking at grabbing other control channels and eventually the digital audio. But as a first step I'll be satisfied with the Motorola CC and simply replacing the RIB and RIM with a customized scanner.

Thanks for the reference to the trunker code. I had wanted to "roll my own" rather than just copy someone else's code. I'll try to learn from the code example and then after sleeping on it a few days, write my own. Then refer back to the code example to help debug my code.

Thanks again,

Steve

 

[WayneH]

Yeah, that code is definitely reference material only. It could use a lot of help.

What I meant about two-way comms with the RIM was I believe the RIM has to communicate with the RF modem. It's been a while so I really don't remember. Not the software to interface link.

The route Rick is going using a soundcard for decoding is your best bet.

-Wayne