Using the PCR-1000 with Trunker

From The RadioReference Wiki

Over the Christmas holiday I decided to do something useful for once. After that thought passed I just went ahead and played with my radios. More and more radios in my area seemed to be going to trunked systems, and while I LOVE my PCR-1000 I was thinking I might also pick up an Optocom to followed the trunked systems. While doing research on trunked systems I came across the program called Trunker. Trunker is a public domain program that allows you to follow Trunked systems. It uses 2 radios. One radio needs its discriminator port connected to a "Hamcomm" data slicer (more about this later). This radio is tuned to the digital control channed of the trunked system. The control channel tells the radios what frequencys to change to. It also transmits various information about each transmission and information about the trunked system itself. Decoding this data allows Trunker to display information about the system and each transmission. Since this data allows trunker to know each frequency a converstaion is on, it also allows it to tune a computer controlled scanner to the correct frequency to follow a conversation, this is the second radio. The latest version of Trunker (v371) supports the PCR1000 as the scanning radio. Yea! The PCR1000 could also be used as the data channel radio using its discriminator port. I have done it both ways and it actually works!

I began by building the Hamcomm interface and connecting it to the PCRs discriminator port. To my amazement it worked. I was also able to find quite a number of Trunked systems in my area (6 systems so far) by scanning for data channels and letting Trunker decode information about the system. It worked great. Next I took apart my BC3000 and tapped into the discriminator point. This allowed me to use the BC3000 to decode the data channel and the use the PCR as the audio scanner. The whole thing works and it only ended up costing about $10 worth of parts from Rat shack.

I figured I would type up how it was done so that if anyone else wanted to do it they would have everything in one place. This is a great first project if you have never build anything before and the Hamcomm interface you build is supported by many other digital mode decoders.

First, download the Trunker software and read the instructions. Read the instructions! They are well written and explain everything about the program. You can find the latest versions on the Trunker article.

Next, build the HamComm "data slicer" interface. There are several designs that can be found on the Data Slicers article. I also chose to modify this plan slightly by tying the CTS pin (pin 8 on a 9 pin connector) to DSR (pin 6 on a 9 pin connector). This is because some programs want to see the data on CTS, while some want to see it on DSR. If you look at the black and white plan on the previous web page you will see it shows pin 6 of the 741 going to either CTS or DSR. The color plans shows pin 6 of the 741 going to DSR. I chose to make it go the both CTS and DSR. Trunker has an environment variable that allows you to choose, some other programs do not.

Next locate a Trunked systems control channel. Information on trunked systems frequenys and group IDs in your area can be found on the RR database. The link is in the 'quicklinks' on the left frame. You can find control frequencys by plugging in all the frequencies of a system and then checking them for a digital signal. Once the scanner is locked on to the control channel start trunker. I use the following environment variables in my trackenv.txt:

In my example, I have my data slicer circuit connected to COM1 and the PCR1000 on COM4. You must add the TRACKSCANBAUD=9600 line to the example trackenv.txt that comes with Trunker or the PCR1000 will not work. It only seems to work at 9600.

Trunker should start and begin adding frequencys to the list. The field labled "SysId" should fill itself out immediatly. The field "Flavor" also should be filled out, and you should see some value in the "Acc" field. Acc stands for accuracy of decoding the data channel. On the strongest system in my area trunker will decode with 98% accuracy over 24 hours. Not bad. The worst accuracy is a system some distance away, with that I get around 60%, Trunker still tracks the calls, but the voices themselves have some static in them. Trunker considers anything over 80% high quality. You should also start hearing conversations and seeing talk groups appear on the screen. Just follow the instructions that come with Trunker and you will be able to edit the talk groups so the Trunker will show you who is calling who. Try it and you will like it.

Other digital mode decoding programs use the Hamcomm interface. You can find many of the popular programs in the HF Digital Decoding article. You can find decoders for WeFAX, SSTV, Packet and more. There are also a few websites listed there that have audio samples of many different modes. Trunker and programs for EDACS and other trunked systems can be found in the Trunked Radio Decoders article. I have used them and the do work. Best of all many are free. Good luck and enjoy!

Mike Curtis