If My Beacon Led You Here…
If you’ve reached this page by following a link in an APRS beacon then welcome, and thanks for visiting. I hope you’ll leave a comment with your callsign and any observations (like where and when you heard my station). I’m a relatively new ham and a very new packet radio operator, so any kind of constructive criticism or suggestions about how I can improve my station or operating practices would be welcome and appreciated. If you’d prefer a more private sort of message, I’d also welcome email to dhenke@mythopoeic.org.
My station equipment is:
- Kenwood TM-D710A
- Samlex SEC-1212 10A switching power supply
- homebrew J-pole antenna similar to the KB3KAI design
I am operating at the US nationwide APRS frequency of 144.390MHz, at a power output of 50W. Update: Power reduced to 5W, since I’m getting heard and digipeated just fine at that level. Too much power just creates needless congestion. (In addition to being rude and clueless of me, running at 50W in an urban area with nearby digis violates FCC §97.313(a), which requires that stations use the minimum power necessary to carry out communications.)
What is APRS?
If you’re one of my other visitors and are curious about what all this means:
APRS is the Automatic Packet Reporting System. It’s a specific application of packet radio, which is one of many ways of moving data using amateur (“ham”) radio. Most of the time, when you hear about APRS it’s in the context of position tracking (where a GPS-equipped vehicle is periodically transmitting its position). However, that’s really a very small subset of what APRS can do.
It’s really a general-purpose, flexible way of being aware of stations and conditions near you, in almost real time. Some of the specific things you can use it for are:
- knowing the position and status of nearby stations
- learning additional ways to communicate with those stations (e.g. simplex voice frequencies)
- finding out about area-specific hazards such as traffic congestion
- discovering and making use of wide-area communications resources such as gateways and repeaters
- obtaining weather information
- sending short text messages (including using gateways to/from Internet email)
The core innovations that make APRS uniquely useful, above and beyond packet radio in general, include:
- a flexible but specific message structure which allows complex information to be expressed concisely, and which makes it possible for much of that information to be understood by computer programs
- a clever way of specifying destination which allows efficient use of gateways and repeaters without requiring that individual stations know the network topology (and without that topology having to be static)
If you want to learn more, there are a lot of great resources online:
- For basic information about amateur radio in general, try the ARRL or Wikipedia.
- Bob Bruninga, WB4APR is the originator of APRS, and his aprs.org site is a treasure-trove of information.
- The APRS specification 1.0.1 (3.2MB PDF) from the TAPR APRS Working Group.
- The APRS specification 1.1 addendum and the proposed 1.2 changes.
- There is an APRSWiki.
Space Applications
The ISS has an amateur radio station on board
, and a TM-D700 (the predecessor of the TM-D710A I’m using) is part of that station. (Photo via http://www.marexmg.org/hardware/computers.html.) The control head of the radio is visible just next to the cosmonaut’s right shoulder. The ISS acts as an APRS digipeater (in addition to conducting many other types of amateur radio operations).
Update: The person in the picture is cosmonaut Alexander Y. Kaleri. The picture was taken on 08 December 2003, during the Expedition 8 flight.