N1SU APRS Digipeater & TX IGate

N1SU APRS Digipeater & TX IGate

Configuration and setup overview by Jason Buchanan

August 2019

APRS UHF VHF crossband digipeater configuration is in use. A single instance of aprx is used to provide digipeater coverage from UHF to VHF, and vice versa, including full APRS-IS internet gateway service.

The crossband aprx.conf configuration file is availble for online reference. This configuration includes weather and radiation monitoring via geiger counter sent to UHF and VHF every 30 minutes - this configuration provides interesting data to view propagation changes. The weather data is never sent via APRS-IS and this is intentional, as it intended to be received by UHF and VHF gateways.

The basics

Purpose: to provide Global APRS Messaging service in the Seattle area, supporting 2-way APRS messaging on VHF and UHF APRS radios.

N1SU-2 (VHF, 144.390) and N1SU-4 (UHF, 440.800) provide full duplex APRS digipeater and internet gateway services, allowing you to send messages and receive replies using only your radio, no internet or cellular service required.

N1SU APRS Network Configuration
N1SU-2N1SU-4N1SU-13RX/TX gatewayAPRS uplinkWeather stationRadiation monitor
Geiger counter
1200 baud
Kenwood TM-281A
Ham Made cable
9600 baud
Yaesu FT-7800R
6-pin DIN
aprx 2.9.0
weewx 3.9.2
9600 baud TX 440.800
aprx 2.9.0 aprsc 2.1.4 Davis Weather Monitor II
weewx and wmII.py
Aware Electronics
model RM-80

Everything shown above runs on a single Raspberry Pi.

The TNC-Pi and TNC-Pi9K6 are stacked on a single Raspberry Pi 3 Model B+
aprx 2.9.0 is used for digipeater and APRS-IS internet gateway
weewx and wmII.py are used to read the Davis Weather Monitor II
Aware Electronics model RM-80 is used for gathering radiation rate as microRoentgen per hour, mR/hr - also at http://digistar.com/seattle/

N1SU-13 changes symbol to match APRS spec 1.2 for reporting the level of Nuclear Radiation levels, using type X. Quoted from the spec:

RADIATION LEVEL: The field Xxxx has been proposed for reporting the level of Nuclear Radiation levels if available. The X is the type indicator. We chose "X" for radiation. The xxx are like the resistor code. First, two digits of precision and the last digit is the order of magnitude in NANOSEVERTS/Hr. So 123 is 12 * 10^3 nanosieverts/hr or 12 microsieverts/hr. Or 456 is 45 * 10^6 nanosieverts/hr or 45 millisieverts/hr. One bananna generates about .1 uSieverts/hr, a Brazil nut .4 uS/hr. If the radiation is at background levels the /_ weather symbol may be used, when elevated readings occur, the R_ weather symbol with "R" overlay will indicate a Radiation Sensor weather station. When a hazard threshold has been reached, the symbol can change to a RH symbol (Hazard with R overlay).

Getting started with Aprx

I put together a page about the aprx.conf and general aprx configuration. Hopefully it will provide some help to those getting started with aprx.

I created a mailing list for APRS UHF discussion, to possibly coordinate a nationwide UHF frequency for APRS, and general APRS digipeater and internet gateway topics.

Enter your email address in the box below to join the group.

Google Groups Subscribe to aprs-uhf
Browse Archives at groups.google.com

N1SU-3 was QRT 8-Jul-19 and became N1SU-2 (2 meters).

N1SU-4 (440MHz 9600 BAUD UHF APRS) was QRV 8-Jul-19.

N1SU APRS Digipeater & TX IGate overview - Updated: 21-Jul-19
(C) 2019 jsb@digistar.com

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