APRS – Automatic Packet Report System – Tracking without Ma Bell

Most geolocation technologies that industry and consumers use consist of GPS reporting via cell phone data. That means a GPS receiver takes a position and hands it over to a mobile phone modem. The mobile modem in turn will encode the position with an identifier and transmit that information over the mobile network. These units may also permit SMS texting over the same service for two way communication. This technology is great for tracking assets on the move, and it gives the disptach centre an improved situational awareness. This technology, however, depends on cell towers and also Internet connections to get a map, or even the data feed for an inhouse map. What happens if the mobile service is down, or your data feed is disrupted because of the lack of Internet connection? How do you achieve the same situational awareness with your assets and people without the Internet or the mobile network infrastructure?

Automatic Packet Reporting System (APRS)

One way of achieving basic situational awareness without the telecommunications infrastructure is to make use of the Automatic Packet Reporting System (or APRS) from amateur radio. APRS provides a very similar service to that of the commercial solutions, with the exception that the technology makes use of the amateur radio frequencies available, as well as the packet radio (known as AX.25) infrastructure that already exists in many locations. APRS was developed by Bob Bruninga, an amateur radio operator and engineer at the US Naval Academy. APRS makes use of a radio modem, known as a TNC, and like its commercial counterpart, it will take GPS co-ordinates, and the identifier (in this case, a call sign) and transmit the information over FM Radio. APRS, however, have some distinct and unique features that make it very suitable for emergency response.

Telecom Infrastructure Independence

APRS does not depend on the Internet, or on the mobile phone network. That means if you are in an areas that is a communications “dark region”, you can still have geolocation tracking of your people and assets. APRS was built to use the voice channels of standard amateur radios, thus, so long as you have radio contact, you have a geolocation feed. Secondly, APRS is built upon AX.25 – the radio packet technology of amateur radio. AX.25 has routing abilities that allows packets to be sent further along via hopping from radio to radio. Thus, with APRS, if your asset is beyond the range of your reception, but you have a second asset in midpoint to you and your first asset, the middle asset can retransmit the data from the first asset. In amateur radio terms, this is known as digipeating. You can set up your own digipeaters to get the range you require, effectively building your own infrastructure. Third, to render the information on a map does not require the use of Google Maps or any other Internet dependent mapping system. APRS map programs such as UIView, XASTIR, and YAAC, have their own maps cached locally. Thus, when a location transmission comes in, it is plotted on the cached map data and no Internet communication is required.

Open Standard

The APRS protocol is not owned by any one company. It is an open standard that can be implemented by anyone, and as a result, a number of hardware and software solutions have arisen. Radio equipment companies sucha as Kenwood, Yaesu (aka Vertex Standard), and Alinco build radios with built in TNC’s that can handle APRS. Smaller outfits such as Byonics, and Kantronics make specialized units that can mate with existing voice only radios, and sotware such as UIView, XASTIR, and YAAC, provide the mapping function. There also exists software TNCs such as the Linux Soundmodem, or the Windows based AGWPE, so that a computer may send and receive APRS transmissions directly from a radio. APRS information has also been fed into the Internet in the form of the website http://aprs.fi. The open nature of APRS has allowed for various solutions to be developed to be geared towards various applications.

No Recurring Expense

Since APRS does not depend on an Internet service to send or receive geospatial data, there is no cost to use an APRS service. Any costs that are incurred are capital costs with the necessary hardware (computer, TNC, and radio). For organizations under tight budgeting constraints and one time capital funding opportunities, APRS represents a low cost way of building up tracking abilities. The software used is free, and older equipment can be used to reduce the capital cost.

Partnering with Amateur Radio Clubs

Transmitting APRS on the Amateur Band requires that the units have valid callsigns. If you or members of your organization do not have an amateur radio license, but want to make use of APRS for emergency response, you can partner with an Amateur Radio club to help you meet the regulation requirements. Club members can hold valid call signs for you to assign to transmitting units, and club members can assist with the setup and testing of the transmitting units and tracking software.

More Information

Want to know more? Well, you can visit the following sites to help you get a greater understanding of APRS:

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