[aprssig] POCSAG Paging on APRS (new subject)

Nagi Punyamurthula n0agi at n0agi.com
Thu Jul 23 22:03:46 CDT 2015


I have not seen such a large mod/deployment effort that I know of at least here.  I know there was a group in Germany and a Dutch group together have done some work and deployed a modest POCSAG network  using Arduino and RASPi.  But, not sure how Ham modded their set up is.  I believe the German team designed a standalone POCSAG endcoder that behaves like a KISS TNC.  I don’t have the details of these two teams.  But, I think the gentleman that pinged me some time back was, “Ronald PE2KMV” who was at the time involved in a similar deployment of POCSAG network w/I ham communities in Germany / Dutch.

When you say, convert them to Ham, what are we talking here? Perhaps we can explore a pilot program w/ 4 groups representing East/Central/mountain/West and experiment at a low budget ?  If we had 4 groups, each putting out a POCSAG capable encoder/transmission station, we could quickly setup an ALTNET to experiment.

Just an idea






From: aprssig [mailto:aprssig-bounces at tapr.org] On Behalf Of Robert Bruninga via aprssig
Sent: Thursday, July 23, 2015 5:18 PM
To: TAPR APRS Mailing List <aprssig at tapr.org>
Subject: Re: [aprssig] POCSAG Paging on APRS (new subject)

I have a few KPC9612’s but have never experimented with paging.

Mainly because, unless every ham can convert a pager easy, then it does not seem like the idea will catch on and so I did not think it was worth the effort.

But I always thought it was a GOOD IDEA…  Its just that until someone buys 1000 pagers and converts them to HAM and then makes them available cheaply, I don’t think people will do it that much.

Have you ever seen such bulk availability?  If they are available in large quantities and you think this is a good idea, I can contribute some $ upfront if it will help.

Bob

From: Nagi Punyamurthula [mailto:n0agi at n0agi.com<mailto:n0agi at n0agi.com>]
To: Robert Bruninga; TAPR APRS Mailing List
A couple of facts:

1.       POCSAG protocol (FLEX is another) transmission and reception gear are based on FSK modulation and operate in the 512/1200/2400 speeds.

2.       Receiving pagers exist for VHF and UHF bands (900MHz).

a.       Each country/region has a pre-allocated range of vhf/uhf band plans for POCSAG operations.

                                                               i.      Frequencies can be found in the Phil Anderson W0XI documents from links below

3.       There are Two broad methods of “baking in” the frequency at which receiving pagers operate in:

a.       Synthesized (software programmable w/I a pre-defined range of frequencies) or

b.      or Crystallized (crystal based pre-set frequency; non-s/w programmable).

c.       Synthesized pagers are cheaper cost-to-own and easier to reprogram to a different frequency so long as they’re, w/I a pre-destined h/w range.

d.      While Crystalized ones are more expensive to program, to operate on a frequency and require a hardware install of a pre-configured crystal.

4.       TWO Types of pagers available in market today.

a.       Numeric (predominantly 1 line readout pagers).

b.      Alpha-numeric (range btwn 1 to 4 line readouts).

c.       Manufacturers include Motorola Gold Advisor, Apollo and some not so well known Chinese/Taiwanese manufacturers.

d.      Typical Costs

                                                               i.      Synthesized : range from $10 (used, 1-2 liners, a few years old) to $60 (new, 4 liners)

1.       Programmable using proprietary programming h/w cradle and software (Motorola as an example)

                                                             ii.      Crystalized : typically from $10 (used, 1-2 liners from few years old).

1.       Programming is not possible.  Very expensive to custom fit w/ a new crystal typically $20+ more)

5.       HAM gear for Encoding/Transmission

a.       One could purchase a POCSAG encoder/transmitter for ~$110 - ~$140 from Taiwanese companies.

b.      One could also use Kantronics 9612+.  The KPC 9612+ has a built in POCSAG shell in it and works really well.  You will need a TRx radio and a PC to program the KPC setup to transmit

6.       Resources:

a.       I have collated a few POCSAG publicly available documents;  can be downloaded for reference here: http://1drv.ms/1DzwmTL

b.      Of course, there’s the Wiki page: https://en.wikipedia.org/wiki/POCSAG

Nagi

From: Nagi Punyamurthula [mailto:n0agi at n0agi.com<mailto:n0agi at n0agi.com>]
Sent: Thursday, July 23, 2015 12:16 PM

Bob, et al;
Wanted to run this idea by you all;
Over the last couple of months, I have been playing w/ building a prototype for POCSAG pager service to ride on top of APRS backbone.  A short video can be found here (early stages)
https://www.youtube.com/watch?v=BLQyw_SbzMU

the prototype’s objectives:

1.       Station A can send an APRS message of type POCSAG over the air on the network.  The message would obviously include the standard APRS message structure, except include the POCSAG “type ID” as part of the message.

2.       Stations identifying themselves as POCSAG capable (that is stations equipped w/ a POCSAG Tx/Encoder, that know how to parse and send an encoded POCSAG message), will react to this APRS message type, parse out the message and send an encoded POCSAG message thru its own POCSAG infrastructure and gate the packet to APRS-IS and mark it as “processed”

a.       Details are yet TB defined of course

3.       If Stations hearing these type of packets are NOT POCSAG capable, will hopefully digipeat so to move the message forward.

As you can tell, NOT all details have been fleshed out yet.  I am still noodling this idea and would love to include others of similar interest in expanding the APRS web if you will.

Would this be a good candidate for a satellite type digipeating ? may be, may be not

Just brainstorming as an idea, that’s all

Thanks

Nagi
http://N0AGI.com/


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