HOW TO USE THE REPEATER

YOU MAY KNOW MOST OF THIS ALREADY BUT THIS MAY COME IN HANDY FOR THOSE OF US NOT USED TO USING REPEATERS!

19 Jun 2010

WHY DO REPEATERS USE AN OFFSET?
Courtesy of the website of G3PRC (January 2007) and updated/amended to suit.
Without having an offset between the transmit signal and the receive signal frequency, the repeater would simply hear itself
when it was transmitting on the same frequency it was listening on! Therefore, to use a repeater a user must use a different
transmit frequency than receive frequency. Your actual transmit frequency is the exact same one that the repeater receiver is listening on. This is a form of duplex, or two frequency operation. It is known as half-duplex as you do not receive and transmit at the same time but normally use the push-to-talk button on your microphone to switch between the two. Cellphones use “full” duplex so each party can hear the other while the other is talking. Even with the offset, the two frequencies are close enough that some isolation is required. Again, this isolation is done by the cavities. So you can see why some repeater components interact with each other and without the basic system components....nothing would work.
What are all those “tones” about? What is a CTCSS Tone? Continuous Tone Coded Squelch System, or CTCSS is used to prevent a repeater from responding to unwanted signals or interference. Tone Squelch is an electronic means of allowing a repeater to respond only to stations that encode or send the proper tone. In other words, if a repeater is set up to operate only when the correct CTCSS is heard by it's receiver, then it will allow the transmitting station access. If your station, (your mobile, base or handheld) does not transmit the tone when you key up, then the receiver of the repeater “does not hear” you and will not be usable by your station until you set the tone in your radio. Any station may be set up to transmit this unique low frequency tone that allows the repeater to operate Some repeaters may be “opened” by using a 1750Hz “tone burst” but GB3GJ will solely work with CTCSS.
UK CTCSS TONES (in Hz) for GB3GJ:
B = 71.9
What Happens When You Key Your mic? Let's "key up" a repeater and see what sequence of events are created within the repeater equipment when someone makes a transmission:
You set your transceiver controls for the 145.6375MHz repeater, for instance the new GB3GJ repeater located at Queens Road, St. Helier, first listen to see if it is in use..., nothing heard. You key your microphone and give out your callsign...."This is MJ3ABC listening ". Then you release the microphone key.
Assuming your station is within range of the repeater....The repeater antenna picked up your signal with it's antenna on 145.0375 (your transmit frequency set to the standard offset and the repeater's receive frequency) and sent it down the feedline to the cavity filter. From there it was sent to the repeater receiver and converted to an audio signal (just like the sounds coming from your speaker)....sent to the controller (the brains of the repeater), then sent to the repeater transmitter and turned back into a much greater amplified radio signal on 145.6375MHz (the output of the repeater)....sent to the cavities.... then through the feedline to the antenna and out over the air. A mobile or base station that happened to be within range and monitoring the GB3GJ repeater heard your transmission on 145.6375MHz (the repeater output frequency). Since radio waves travel at about the speed of light....at the split second that you first keyed your mic, the above events took place and the repeater was receiving your signal on one frequency and re-transmitting your signal on a different frequency at the same time!
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The mobile station that was listening on the output frequency of the repeater heard your callsign....keyed his microphone and came back to you starting the process all over again! A simple way of demonstrating what is going on with a repeater is to set a scanner or a second receiver tuned to the input frequency of a LOCAL active repeater...in the case above...145.0375MHz and you can monitor it's input (and the stations using it if they are local). Then with your transceiver, monitor the output on 145.6375MHz! You should be able to hear both the input signals and the output of the repeater as all this takes place on the air.
How do you make a call on an Amateur Repeater?
First, LISTEN AND LISTEN SOME MORE...... to make sure that the repeater is not already in use. When you are satisfied that the repeater is not in use, set your transmitter power to the minimum and increase only as needed to make contact with the repeater, begin with the callsign of the station you are trying to contact followed by your callsign. e.g. " MJ0XYZ this is MJ3ABC” (The MJ3ABC is your callsign). If you don't establish contact with the station you are looking for, wait a minute or two and repeat your call. If you are just announcing your presence on the repeater it is helpful to others that may be listening if you identify the repeater you are using AND your callsign. e.g. " This is MJ3ABC listening on the GJ repeater”. This allows people that are listening on radios that scan several repeaters to identify which repeater you are using. If the repeater you are using is a busy repeater you may consider moving to a simplex frequency (transmit and receive on the same frequency..... see more below), once you have made contact with the station you were calling. Repeaters are designed to enhance communications between stations that normally wouldn't be able to communicate because of terrain or power limitations. If you can maintain your conversation without using the repeater, going "simplex" (both stations on same frequency in a different part of the band) will leave the repeater free for other stations to use!
Repeater Etiquette.
The first and most important rule before using a repeater is to LISTEN FIRST. Nothing is more annoying than someone that "keys up" or DOUBLES in the middle of another conversation without first checking to make sure the repeater is free. If the repeater is in use, wait for a pause in the conversation and simply announce your callsign and wait for one of the other stations to acknowledge your call. This is not CB, Don't use CB lingo such as 10-4,.....don't just say BREAKER, it’s OK to say “Break, MJ3ABC”, that way the stations using the repeater will know who you are and that you want to join them or use the repeater. If you are mobile, that is “MJ3ABC mobile” then one of the stations using the repeater will usually let you use the repeater immediately. This is in case you go out of range of the repeater or into a dip in the road which masks the repeater from you. Use plain language on a repeater. If you want to know someone's location, say "Where are you? or what's your location?" If you want to know whether someone you're talking with is using a mobile rig or a hand-held radio, just ask: "What kind of radio are you using?" You get the idea. (You will hear Q codes used, OK as long as everyone understands)
If you want to you can call CQ to initiate a conversation on a repeater. Alternatively just simply listen to make certain the repeater is not in use and then key your mic and say “MJ3ABC accessing GB3GJ (or which ever repeater) and listening”. If someone happens to be listening and they want to talk to you they will respond.
When you are using the repeater leave a couple of seconds between exchanges to allow other stations to join in or make a quick call. Most repeaters have a "Courtesy Tone" (a short...beep or series of beeps) that will help in determining how long to pause (PLEASE NOTE - with the current setup GB3GJ will close at the end of each over and only re-open to a user with CTCSS). The courtesy tone serves two purposes. Repeaters have a time out function that will shut down the transmitter if the repeater is held on for a preset length of time (normally three or four minutes). This ensures that if someone's transmitter is stuck on for any reason, it won't hold the repeater's transmitter on indefinitely. (Don't laugh, many microphones get lodged in the fold of car seats and keep a repeater busy until it times out. Of course if it is not noticed soon by the mobile operator.....the repeater keeper may have to shut down the repeater until the problem is corrected.)
When a radio amateur is talking and releases the push-to-talk (PTT) switch on their radio, the controller in the repeater detects the loss of carrier and resets the time-out timer. When the timer is reset, the repeater sends out the courtesy tone. If you wait until you hear this beep (normally a couple of seconds), before you respond, you can be sure that you are pausing a suitable length of time. After you hear the beep, the repeater's transmitter will stay on for a few more seconds before turning off. Make sure that you hear the courtesy tone before going ahead, but don’t wait too long after the tone or the repeater will shut down. Note: If you don't wait for the beep, the time-out timer may not reset. If you time-out the repeater,
YOUR conversation AFTER the time-out will not be heard. The repeater time-out function does not care if you are still talking or not; it will shut down, and the station on the other end may rib you about hogging the machine and you will have wasted all those words!
What is Doubling?
When two stations try to talk at the same time on the same repeater, the signals mix in the repeater's receiver and results in a buzzing sound, squeal, distorted sound or severely jumbled and broken words. When you are involved in a roundtable discussion with several other stations it is always best to pass off the repeater to a specific person (station) rather than leave it up in the air. e.g. "MJ0XYZ to take it, this is MJ3ABC” then de key; or.......
"Do you have any comments Fred?, this is MJ3ABC”, de key. You could also say "OK...that's all I have.....back to you Fred"... (de key)....
Failing to use this or other techniques is an invitation to total confusion.
As a point of interest, a repeater will usually lock into the strongest of two FM signals.
Thats all for now, happy repeater use everyone, hear you on GB3GJ hopefully!