There are all kinds of funky noises out there in radio land; here's a sampler of the more common things you will hear on your scanner. There's also some software here that you can use to (legally) decode some of these things.
Motorola
Motorola Analog or Mixed-Mode Trunking - Motorola trunking control channels using 3600 baud unencrypted ASCII.
Motorola Digital Trunking - Fully digital Motorola Project 25-compliant trunking control channels using 9600 baud unencrypted ASCII.
Motorola MDT - Motorola Mobile Data Terminals (Also called KDT, for Keyboard Data Terminal) commonly used by public safety agencies utilize 4800 baud unencrypted ASCII.
Motorola DES - Motorola Digital Encryption Standard (This is a digitally encrypted analog voice signal).
Motorola ASTRO - Motorola ASTRO Digital Modulation. Note that digital modulation does NOT mean encryption, although encryption can be used on a digital transmission.
Motorola RD-LAP Motorola RD-LAP digital data protocol. I found this one 11/21/1997 on 856.8625 MHz, which is licensed to Federal Express.
Trunker - A link to the latest version of a program originally written and posted to the Internet by an anonymous author, this highly useful program will read the data on a Motorola 3600 baud trunking control channel and show the system activity. It will also allow the user to annotate each talkgroup designator with an alias (talkgroup name) and so on. This version incorporates the capability to "trunk control" radios such as the AR-8000, the Optoscan-equipped Pro-2005/6 or Pro-2035/42 and the BC895, allowing the user to monitor desired talkgroups, just as with the Bearcat Trunktracker. It will also allow the use of any comm port; previous versions recognized only Com1.
Ericsson/GE
EDACS/EDACS ProVoice - MA/Com EDACS and EDACS ProVoice digital trunked systems use 9600 baud unencrypted ASCII on the control channel.
Mobitex - An Ericsson ASCII data system.
E-Trunk - A link to the latest version of ETrunk. Similar to the Motorola Trunker program, this program will allow one to read the data on an Ericsson/GE trunking control channel and show the system activity. Like the Motorola version, it allows the user to annotate each talkgroup designator and unit ID with an alias (talkgroup name) and so on, and allows "trunk control" of radios such as the AR-8000, the Optoscan-equipped Pro-2005/6 or Pro-2035/42 and the BC895, allowing the user to monitor desired talkgroups.
Mobitex decoder - Yet another program written and posted anonymously to the Internet, this program will decode transmissions using the Ericsson Mobitex format. These conventional (non-trunked) systems operated by RAM Mobile Data are used by businesses. Check the following frequencies for activity in your area:
East/Northeast Ohio:
935.7625 935.7750 935.7875 935.8000 935.8125 935.8250 935.8375 935.8500 935.8625 935.8750
Central/West/Southwest Ohio:
936.2625 936.2750 936.2875 936.3000 936.3125 936.3250 936.3375 936.3500 936.3625 936.3750
West/Northwest Ohio:
937.0125 937.0250 937.0375 937.0500 937.0625 937.0750 937.0875 937.1000 937.1125 937.1250 937.1250
Other Modes
Motorola FLEX - An alphanumeric paging format.
POCSAG - Another alphanumeric paging format.
1200 Baud AX.25 packet - Used by ham radio operators (please excuse the 60 Hz AC hum; I have NO idea where it came from all of a sudden).
Packet Monitor - This program will allow monitoring of 1200 baud AX.25 packet signals. Check the following frequencies for packet activity:
144.910 144.930 144.950 144.970 144.990 145.010 145.030 145.050 145.070 145.090
All of the above programs use a very simple interface to the computer (shown below), and all (except Packet Monitor) require a connection to the discriminator of the scanner in order to get the cleanest audio possible. The circuit shows an LM741 op-amp, but for better results you can use a TL081 op-amp and change R1 to something around 3.3k (experiment with the value for best results).
Slicer - A highly useful DOS utility for tweaking your slicer interface for best performance.
Note:
There are some other freeware and shareware programs out there that use the same interface and allow decoding of alphanumeric pager transmissions; however, decoding of these modes is prohibited by Federal law. Given Congressional and Justice Department attention to misuse of scanners and decoding software, I've decided that I'm not going to be the one who provides the rope for someone to hang themselves with. The pager programs are available at several other locations on the 'Web, so if you choose to go get them and attempt decoding the pager modes, good luck and keep it to yourself.
Created: 11/18/1997
Last Updated: 02/15/2005
© 1997/2005, T.R. Swisher, Jr, WA8PYR