Automatic Position Reporting System or APRS is a digital communication protocol between a large number of amateur radio stations that covers a wide area. APRS can be used to send several tactical information, such as weather, location, messages, and several special events or emergencies in real time. APRS system is made by Bob Bruniga (WB4APR) from over 25 years ago, but this system is still actively used by many amateur radio stations
Like other amateur radio stations which still exists until now, APRS is already integrated through the internet. You can oversee many kinds of tactical information through APRS. One example of a website which shows APRS data is APRS.fi. In Picture 1, you’ll see many weather stations located in Tucson, Arizona, USA. One of the traditions for amateur radio stations in the United States is to provide public services, one of which is weather observation. Amateur radio station operators who owned weather stations use APRS to distribute the collected data
Although it’s called Position Reporting System, APRS itself isn’t intended as a GPS Tracker system. The development of APRS is triggered by GPS development back then, but APRS is actually a two-way communication system for real-time tactical communication
Picture 1. Screenshot of Amateur Radio Stations’ activities in Tucson, Arizona, USA
APRS Radio Network
After knowing about APRS systems and one of its applications, let’s talk about the components of an APRS system. In APRS systems, you may hear several terminologies such as:
- Terminal Node Controller
- Digipeater
- APRS-IS iGate
Terminal Node Controller is the digital radio modem used in APRS. It’s usually based on Bell 202 Modem or Audio Frequency Shift Keying modem with baudrate of 1200 baud.
Digipeater is a digital repeater capable of resending data package which then allows many other stations could receive the information. Digipeater normally has a high power and placed on tall buildings to have a wide coverage area
APRS-IS iGate is an APRS connected to the internet so it can relay messages received through RF waveforms and entered them into APRS-IS server. From APRS-IS server, you can see the packages through several APRS websites or software
To enter the world of APRS, you have to own an amateur radio callsign. In Indonesia, you can register through “SDPPI Postel Kemkominfo”. You will have to enter a national exam for Amateur Radio (Ujian Nasional Amatir Radio) and if you passed, you will receive a certificate for that. Then, make sure you have the Permit to own an Amateur Radio Station (Izin Penguasaan Perangkat Radio Amatir). If you don’t want to do any transmission, tapping into APRS transmissions is allowed by anyone who has TNC and HT Radio
And that’s a small piece of information regarding APRS. I’ll add in more details on a different occasion
Sources:
Josef Matondang 