HamIM^(c) on 147.585 MHz

HamIM (Ham Instant Messaging) is a variation of APRS that is customized to be VHF Contest friendly and ARRL Contest Desk approved! Participants use APRS technology, but on 147.585 MHz (the highest 2m simplex frequency in the ARRL band plan) rather than 144.390 MHz (the APRS frequency). The difference is that all operation is simplex (unassisted). This requires only minor setting changes to the APRS software used. When reconfigured, we abandon the label APRS for the new standard: known as HamIM.

How the system works

Rovers equip their stations with high-power 2m FM transceivers, TNC's, laptops and GPS's (just like many mobiles do on APRS). As they move from hilltop to hilltop, their stations will accept GPS readings and periodically transmit their lat/lon on 147.585 MHz. Any station within simplex range will decode these transmissions to a map, placing an icon representing that station at the correct location on the map.

At a glance, all stations within range know that a Rover is there for the contacting! All they need to do is mouse-point to the Rover's icon and send them a HamIM all-RF, all-Amateur Instant Message. When received by the Rover, a pop-up window will appear and the keyboard IM can be completed! This first QSO can go into the log (it's simplex and contest qualified) and arrangements can then be made to QSY to any other bands available.

Why the system works

It is an automatic pipeline to your target. If the rover's icon is on your screen, then they are in-range. There is no need to go band scanning to look for them because they're tuned to 147.585 MHz and CQing at all times!

What makes HamIM contest-friendly

HamIM is all-RF. There is no Internet component. This takes care of the injunction against the use of any non-Amateur communication mechanisms.

HamIM is simplex. There is no repeating, digipeating or 3rd party assistance of any kind.

HamIM resides on 147.585 MHz. For Rovers, that is still not too far away from 144.200 MHz as to assure that there is no self-QRM between HamIM operations and traditional contest operation. This is used to an advantage. Typically, packet TNC's will "hold off" transmitting if they sense that the channel is busy. Self-QRM from SSB operation on 144.200 MHz is usually sufficient to assure that there is never 2 signals on the band at the same time. (note: testing should occur ahead of a contest just to make sure. Otherwise, a PTT relay controlling the power to the TNC may be in order).

For home stations, it is even easier because all fixed-location stations lurk. Home stations do not auto transmit. They simply wait for Rovers to show up on the map and then manually engage them in a HamIM! Of course, there is nothing to keep a home station from periodically sending a HamIM CQ by manually pressing the <F9> key (that's the manual CQ key), and there's nothing wrong with fixed stations sending each other HamIM's either!

Overview of the power of HamIM

When you call a station on voice, you trust that they are there waiting to hear from you. If they are not, the effort is fully wasted. Using HamIM's pop-up messaging, you can send a station a message, even if they aren't right there to read it. When they return, your message will be there for them to see and react to!

A Rover may already be in the middle of running the bands with another station (maybe they're already on 222- or 432-MHz). Send them a popup HamIM to find out where they are on the other bands and join-in as a "coat-tail QSO" to the band-run that they are already in the middle of with someone else!

Since a Rover's location is constantly HamIM updated because of their connected GPS, you can quickly tell if they are still in the same grid as when you worked them earlier, in transit to another grid or just crossing into the next grid (send them a HamIM and get them in the log before they even get setup on their hilltop!).

Important things to remember

This is s-i-m-p-l-e-x and FM-based packet. You won't get the same range on HamIM as you enjoy on SSB or CW. Plan your HamIM station with the idea of using the most amount of RF output that you can muster. There are lots of 50-watt and above amateur FM transceivers on the market at very reasonable prices. Use them. The idea is to be seen and heard by others. It's OK to use a 160-watt amplifier on your HamIM station! Just don't use an H-T and expect to be very successful. Antenna polarization is vertical (and omnidirectional is best).

Rovers will operate from hilltops. Don't expect to be able to track their progress everywhere they drive. The nature of simplex operation is that range is limited. However, you can certainly expect to see any and all HamIM equipped Rovers once they've settled on their regional hilltop, at altitude.

How to participate

Assemble the equipment: High power FM transceiver, KISS-capable packet TNC (or soundcard TNC emulator), Windows-based computer, interconnecting cables.

Download the UI-View software from the UI-View web site (this version is honorware and is fully functional for HamIM purposes), following the excellent help files that will pop-up the first time you use it as a home station. See http://www.ui-view.org/index.shtml#downloads if you need to do a floppy based install or want to go the UI-View32 route. If you are a Rover, lookup the term "GPS" in the help files. Everything you need to know is right there. Note: the HamIM software allows you to create and use custom maps. You will need maps for Rochester (they are not included in the download above). Download these zip files and extract the two files for each map and place them in your folder called MAPS.

USA Northeast - 4 MB

Rochester, New York & 20 surrounding grids - 800 kB

Rochester, New York & 4 surrounding grids - 630 kB

Resources for making your own maps are here.

Power-up on APRS as a test to assure that you can see others on your map, and they can see you. The frequency is 144.390 MHz.

When you're ready, makes [these] final mandatory tweaks before you QSY to the North American HamIM frequency of 147.585 MHz.

QSY to 147.585 Mhz and wait. This is a BRAND NEW strategy. It may take a while to gather enough interest in your area. When it does, you'll be among the first to capitalize on the power of HamIM !

A brand-new HamIM discussion group has been created on Yahoogroups. Join in on the FUN!