APRS Digipeater & KISS Modem Personality Board

The first option board created to use the expansion port in the URC is a KISS modem and APRS digipeater based upon the VP-Digi Blue Pill module. This module connects to an attached transceiver and the URC seral port to provide true modem capabilities for packet radio.

There’s a video of the URC & modem in action in my Facebook page here https://fb.watch/od0tSxN1Fg/

Add-in modules will typically come with a replacement front panel. The expansion port also brings the signals needed to the front pane to allow switching of the serial port between CAT, HT programming and the board so you no longer need to move internal jumpers to adjust the function of the serial port.

The replacement front panel for that comes with the VP-Digi module has a serial port function switch and the enable/disable switch and status indicator for the VP-Digi module

I discussed with Piotr SQ8L, the creator of VP-Digi, about the inclusion and distribution of the VP-Digi and he has been very supportive.

VP-Digi offers 8 configurable beacons and an APRS digipeater, which is capable of handling 4 type n-N aliases (e. g. WIDEn-N, NYn-N) and 4 simple aliases (e. g. CITY, AREA). Moreover, the digipeater incorporates the viscous delay function know from aprx, which can reduce unnecessary traffic. There is also a posibility to filter packets by sender callsign, either in blacklist or whitelist mode. The digipeater can be freely configured, e. g. to work as regional (Wn) or fill-in (W1) digi.

The device also uses the serial port to work in KISS TNC, frame monitor or configuration mode. The configuration is done by simple commands using any terminal program and is stored in the embedded flash memory.

VP-Digi comes with four selectable modems: 1200 Bd Bell 202 (VHF standard), 9600 Bd G3RUH (UHF standard), 300 Bd Bell 103 (HF standard) and 1200 Bd V.23 (alternative VHF standard).

FX.25 protocol support is included, which enables error correction for better reliability. The FX.25 protocol is fully compatible with existing AX.25 protocol.

The modem daughterboard required minimal additional components to interface with the URC, mainly handling audio level and PTT control logic. Front panel controls also provide an internally mounted monitor switch (in place of the SMD mounted on on the base unit) and a power on/off switch for the VP-Digi module.

Making the upgrade

Personality boards will typically arrive as a set with a front panel and the module board. In the existing V2.2 URC, the current front panel will have a solder connection to the underside of the main board for the front panel speaker connection to be removed.

The speaker may need to be transferred to the new board, and the ‘thermoplastic’ led diffusers re-made.

The personality bord will have the 12-pn header connector to plug in to the URC main board.

I’ve added a how-to page for the installation here: https://g1lro.uk/?p=276

Where to get the APRS Digipeater & KISS Modem Personality Board

There will be a early-release batch of boards available for beta testers. There are a couple of known mods needed for the prototype board to function properly but this only entails removing an SMD resistor and applying a wire link. Obviously a URC v2.2 will be required to plug the board in to.

If you are purchasing a URC and wish to have the modem board to help test, then please contact me. You may need to source your own Blue Pill although I do have a small batch on order to be able to provide a fully populated board.

When the board is fully tested and debugged, it’ll be available as a purchasable option in my store.