[aprssig] POCSAG Paging on APRS (new subject)

Robert Bruninga bruninga at usna.edu
Thu Jul 23 17:18:11 CDT 2015


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]
*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
<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]
*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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