RF22 and POCSAG (paging)

[Kristoff Bonne]

Hi,



As some people of the radioclub of a little bit further down the coast
are looking into POCSAG (paging) we had a little discussion about it in
our local group too.
We did receive a couple of pagers on the "ham-pocsag" frequency
(439.9875) to play around with.

I looked into the specification of it. Based on the wikipedia, it is
standard FSK modulation, 512, 1024 and 2048 bps with 4.5 or 2.5 Khz
frequency-deviation.


Every frame has a preamble which is just a "01010" sequence.
Hmm. Why does this look like something a RF22 could also do if you use
the "disable packet handler" option of the si4432 ???


I did tune the si4332 device to these modulation-parameters and the si
did seams to accept it.

Anybody any experience with this?
Ideas? Any do's or don'ts?



Cheerio!
Kr. Bonne (ON1ARF)

[Kristoff Bonne]

Hi all,


Just for info. It works.

I just managed to send a message from my si4432 trx to a beeper.


The bits where inverted and the message was completely wrong
(apparently, you cannot send numeric messages to alphanumeric beepers
:-( ), but ... the RF part seams to work! :-)


Really looks interesting.
Not only does this open possibilities for a cheap pocsag transmitter for
local usage, if we manage to get the si4332 to also receive POCsac
messages, it would open up the possibility for a cheap and completely
open-source pager (si4432 + arduino + small LCD display ...).


What would also be interesting to see if we cannot combine this with
mesh technology and/or APRS-like technology:
If we encapsulate a POCSAG messages inside an RF22-arduino mesh network
message, the pagers will probably pick it up and react to it, and -at
the same time- have the RF22/si4332 network nodes automatically
distribute it further down the mesh.



Cheerio!
Kr. Bonne