Radio at Makerspace – POCSAG Paging MB7PNE

MB7PNE is a Paging transmitter using the industry sstandaard POCSAG protocol

  • Call Sign: MB7PNE
  • Location: Newcastle and Gateshead
  • Mode: POCSAG ( Post Office Code Standardisation Advisory Group )
  • Band: 70CM
  • Output Frequency: 439.9875 MHz
  • Output Power: 3.7 dbW (2.3 W)
  • Network: DAPNET



Pager technology, once the bane of anyone on call, has been reinvented by the amateur community in a distributed system which can be used to push alerts and other useful messages in the form of DAPNET (Decentralised Amateur Paging Network).

Hardware

MB7PNE is largely the same as the transmitter described on the DAPNET wiki here. The notable differences being the use of a Motorola GM900 instead of a GM1200, the addition of hardware to remotely disable the radio and a very over-engineered software/infrastructure deployment.

Full details of just how over-engineered this transmitter is are available here.

Pagers

This page on the DAPNET wiki has a good overview of compatible pagers that will work with DAPNET. SDR based options and the protocol spec are also easy to find for homebrew solutions.

The wiki also details how to program Skyper and non-Skyper pagers to receive pages both directed to you and containing rubric news.

Fof those who cant find suitable second hand pager harware and/or are wincing at the cost of an Alphapoc there is an alternative using a Lora board. The one I had to hand is a TTGO T3 V1.6 which is an ESP32 based device but boards based on AVR should work just as well provided you add the correct mods.

The LoRa chip cant demodulate POCSAG pager protocol directly so you need to add a couple of jumpers from the raw I/O pins on the LoRa module to a suitable pair of inputs on the microcontroller, fortunately on this board the LoRa pins are brought out on the main board so a simple pair of jumpers will suffice from Lora1 -> IO35 and Lora2 -> IO34:

If you want to add an audible alert you will need to connect a passive sounder or small speaker between IO14 and GND (note that the version i used looks very similar to an active beeper so be careful with your selection unless you want to alter the code so it outputs DC rather than PWM)

You will now need some firmware, the one I used came from:

https://github.com/ManoDaSilva/ESP32-Pocsag-Pager

I updated my ric and callsign in config.h (line 33 or thereabouts) and left everything else alone since the frequency was already correct @ 439.9875 MHz however if you use a different microcontroller you will need to adjust perip.h.

ric[RICNUMBER]={

        {[your ric], “[your callsign”,2,0,0}

};

Now test it out, and print a neat little box (i used this one from Printables):

Thats it for now. If i get a chance id like to extend the firmware to store say the last 10 messages and scroll through them.

Data

MB7PNE is in the uk-en-northeast and uk-all transmitter groups on DAPNET, so anything targeting those groups will be transmitted.

MB7PNE is built and managed by Maker Space members.