TO: ALL WOOD COUNTY EMERGENCY COMMUNICATIONS AMATEURS
ALL NON-WOOD COUNTY EMERGENCY COMMUNICATIONS AMATEURS
FROM: KEN HARRIS WA8LLM
WOOD COUNTY EMERGENCY COMMUNICATIONS INCORPORATED
WOOD COUNTY BULLETIN NR 15.34 DATE: August 23, 2015
SUBJECT: HOW A SIMPLEX NETWORK COULD WORK
What is a Simplex Network? A Simplex Network would be a system where everyone is using one frequency for both transmit and receive. For example the National Two Meter Emergency and Calling frequency is 146.52 MHz Simplex. Everyone should be able to monitor that frequency for Amateurs traveling through the area, and wanting to talk, or needing assistance. It doesn't happen, but it should. Unless you live on a mountaintop or hilltop, chances are you wouldn't hear most Amateurs traveling through. How could that be fixed?
One way to allow everyone to hear the National Calling Frequency is to place a transceiver operating on 146.52 MHz on a hilltop or mountaintop, and tie it to a UHF frequency that would re-transmit the signals to anyone monitoring the UHF frequency. To monitor the UHF frequency could be done with a scanner or a cheap hand held radio set on the UHF frequency. If you hear someone calling for assistance on the UHF, then you could switch to the National Calling Frequency to see if you can hear the station direct, or switch to a better UHF radio and answer their call.
Another way to monitor the National Calling frequency is about the same as the first, except use the UHF frequency and tie it to another Two Meter frequency such as 146.49 and/or 146.58 and/or other simplex frequencies located in several different locations. By using several different locations using the Two Meter/UHF combinations, each on their own Two Meter frequency, a Simplex Network could be used as a wide area communications system. Only one UHF simplex frequency is needed for the network.
There are a couple of drawbacks. One is to make sure no two or more Two Meter frequencies, are on the same frequency, unless they are far enough apart so they don't hear each other. The other drawback is the UHF transceivers must be able to hear all of the other UHF transceivers on the system. There are plenty of Two Meter Simplex frequencies available.
Ken Harris WA8LLM
WCEC
Wood County WV