TO: ALL WOOD COUNTY ARES MEMBERS (OFFICIAL)
ALL ARES AND NON-ARES AMATEURS ANYWHERE (INFORMATION)
FROM: KEN HARRIS WA8LLM ARRL DISTRICT 3
EMERGENCY COORDINATOR WOOD COUNTY EMERGENCY COMMUNICATIONS INC.
WOOD COUNTY ARES BULLETIN NR 19.29 DATE: July 21, 2019
SUBJECT: WHAT IS A SIMPLEX REPEATER?
A Simplex Repeater is a voice radio repeating system that operates on one frequency as opposed to a Duplex Repeater which receives voice signals on one frequency and re-transmits them on another. Both Duplex and Simplex Repeaters have their pros and cons, but they both do the same job, they extend the range of communications of mobile and handheld radios over a larger area.
The Simplex Repeater records any signals that it hears on the frequency and re-transmits them back out on the same frequency. One disadvantage of a Simplex Repeater is the time that it takes to do the job. It takes the same length of time to re-transmit the signal as it took to record it, which only stands to reason. The Simplex Repeater only uses one frequency, instead of two, to do its job, which means it doesn't take up additional radio frequencies that can be used for something else.
If two operators are within hearing range of each other the simplex repeater is not needed, but there may be no way to turn it off, so it will record each conversation and then repeat it. This will cause a delay of the two operators talking to each other. However, since the simplex repeater is recording the conversations, it is repeating the same information which might sometimes help, especially if one of the operators has missed the information the first time. He can just listen for the repeated information without having to ask for a re-transmission.
It takes a little training to use a Simplex Repeater. If the two people who are communicating with each other are within hearing range of each other, they will tend to want to answer, or respond right after the other person quits talking. There is a problem which comes right after the last person talked. The Simplex Repeater will start re-transmitting what it just heard and may, or may not, cover up the person who is trying to answer. The person who is getting ready to respond to the last person who transmitted needs to wait for the Simplex Repeater to quit transmitting, before they respond or answer.
Ken Harris WA8LLM
Wood County WV