Digital Amateur POCSAG Paging
Send out digital numeric and/or alphanumeric pages for: Automatic weather
alerts for Skywarn use; LiTZ / emergency alerts when linked to repeater
controllers; club (function) meeting reminders; paging your friend to get
on the radio; computer status messages useful in conjunction with packet
radio gateways; and so on. Carefull reading of Part 97 [sections
97.3(a)(10), 97.111(b)(2), 97.305(c), and 97.307(f)(5)] makes it clear
that digital paging is allowed for VHF and UHF operations.
It can be setup so hams could send the pages a number of different ways.
An DTMF interface to repeater controllers;
Where a traditional user number is assigned to everyone with a pager.
First enter the user number, then the numeric message which gets passed to
the paging transmitter.
A packet interface;
Either a web cgi, telnet prompt, or separate email address to accept
numeric and alpha numeric messages which get passed to the paging
A phone interface;
An incoming line that would first: prompt you for a numeric password
for protection, then a user number and finally the traditional numeric
A VHF or UHF radio
It must be capable of transmitting +/- 4.5 KHz FSK data. The transmitter
must have a low audio response, around 20 to 50 hertz. You will need a
direct (varactor or varacap) drive to transmit pages, and a discriminator
output to monitor pages. Most 9600 baud "data ready" radios will work.
The following radios are capable of being FSK'ed real hard:
- Alinco DR-1200 Data Radio
- GE Mastr Executive II, VHF and UHF
- GE Custom MVP, VHF and UHF
- Icom IC series: 25, 38, 228, 271, 290, 471
- Kenwood TM series: 211, 212, 221, 231, 431
- Kenwood TS series: 700, 770
- Motorola Mitrek, Maxar
- MFJ Model 8621 VHF Data Radio
- Standard C58, C140
- Yaesu FT series: 212, 221, 230
A Pager Encoder
Here are two known options:
The Kantronics KPC-9612 TNC (Capable of sending POCSAG)
Or you can encode using a software computer program:
PE Clive Cooper's (G8UKN) POCSAG encoder for DOS - (local copy)
You had two options here. Kantronics has discontinued selling their refurbished pagers. (They were about $100 a piece all set to go on the 2m
or 70cm freqs.)
Now you have to have commercial pagers modified locally. If you decide to try
it yourself and have access to programmers and test equipment, look for these
types of pagers:
Motorola Bravo Plus, Motorola Bravo Classic, Motorola Renegade Motorola
Lifestyle Plus, OI Electric Pocketbell, NEC
Your best bet is to stick with the Motorola Bravo Series.
Make sure they are using the POCSAG protocol, not GOLAY or FLEX. Make sure
they are 100 MHz or 400 MHz depending on which type of transmitter you are
going to use. Try to get 512 baud in case your setup has trouble at faster
speeds, also try to get the capcode and any
programming passwords, you should be able to find these used pagers for
Local Copy of Misc Related Files:
PE-PAGER.GIF - Interface schematic for PE program
PD-205.ZIP - Shareware POCSAG decoder for DOS
PD-PAGER.GIF - Interface schematic for PD program
POCSAG.TXT - Explanation of the POCSAG protocol
DISCRIM.TXT - Where to make a discriminator tap in your model scanner (list) & more
all other files
- Before investing a lot of money recrystaling VHF hi-band, and UHF pagers to amateur frequencies send test pages into a dummy load on their existing frequencies.
- Use an oscilloscope to check that your square waves are clean. Check output level by monitoring the discriminator tap of a receiver.
- Try to send and decode pages that you send using PE and PD. Use 512bps speed rates to avoid any errors that will occur if your transmitter can't handle being FSK'ed that fast.
"Pager Handbook for the Radio Amateur" By: Philip N. Anderson, W0XI
"The Book of the CCIR Radiopaging Code No. 1" (CCIR-1) Radio Design Group, OR
QTH.net POCSAG mailing list/archive http://mailman.qth.net/archive/pocsag/pocsag.html
Kantronics new line of paging products http://www.kantronics.com/paging.htm
PE Clive Cooper's (G8UKN) POCSAG encoder for DOS http://www.cooperware.com/pe
PD Pete Baston's (GW0PJA) POCSAG decoder for DOS http://www.bearnet.demon.co.uk/pocsag
Henry Carl Ott's (N2RVQ) PIC/AVR based POCSAG encoders http://users.rcn.com/carlott/projects.html
Oliver Durm's (DL3SDW) Ham Pager Site - SAM http://home.t-online.de/home/dl3sdw/pag100.htm
Stefan Petersen's (SM0PHK) C-program for encoding POCSAG http://www.stacken.kth.se/~spe/projects/pocsag.html
Philips Pager Data Sheets http://www.semiconductors.philips.com/handbook/chapter_215.html