A liitle about the repeater

Both repeaters are located HERE, on the roof of Bath University overlooking the historic city of Bath

GB3UB is the 70cm 433mhz voice repeater and operates on 433.100/434.700mhz, ctcss 118.8hz. It uses a converted Storno base station using G8CUL logic running 10w to two Jaybeam folded dipoles. It provides hand-held coverage around the city of Bath, out towards Chippenham, down towards Midsomer Norton and across towards Westbury. It is internet linked via Echolink (node no. 201135 )
MB7UB is the APRS data digipeater.

You can find out what I do in my day job HERE.

For further information you can email me

17 August 2008

What is a repeater?

Sounds a bit obvious but for all those new to the hobby found this excellent information on a Canadian user group.

What is a Repeater and Why is it Needed, and How Does It Work?

What: It's a two-way radio system that receives on one frequency, then re-transmits what it hears on another frequency; at exactly the same time. It's nothing more than a "dumb machine" with some smart people behind it.

Why it's needed: Your mobile or handleld transceiver, has a limited range due to it's antenna height with respect to the radio horizon and rf attenuating surroundings. Repeater systems are used to "transfer" your transmitted and received signals to much higher elevations electronically using large, very efficient antennas, low loss feed lines and a transmitter and receiver that is rated for heavy or continuous duty. A repeater "gets out" your signal and receives the station you are talking to with a far
greater range and coverage area! You take advantage of the repeater's higher elevation to increase your effective transmitting and receiving coverage versus your mobile or hand held transceiver!


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 open. If the repeater is in use, wait for a pause in the conversation (watch your S meter and wait for it to drop indicating the repeater is “listening”) 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 say BREAKER! The word BREAKER or BRAKE, BRAKE on Ham radio is commonly used only in EMERGENCIES! Remember....you're an Amateur Radio Operator....NOT A CB'ER!

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.

Don't call CQ to initiate a conversation on a repeater. Just simply listen to make certain the repeater is not in use and then key your mic and say your call sign.
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. 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 control operator of the repeater may have to shut down the repeater until the problem is corrected.)

When a ham is talking and releases the push-to-talk 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. This is referred to as the "tail". The length of the tail will vary from repeater to repeater but the average is about 2 or 3 seconds.
You don't HAVE to wait for the "tail to drop" before keying up again, but make sure that you hear the courtesy tone before going ahead.
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; 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 it the air. e.g. "VE??? to take it, this is VE???", then unkey; or.......

"Do you have any comments Fred?, this is VE2???"; un key.
You could also say "OK...that's all I have.....back to you Fred"... (un 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. This is the nature of FM. The strongest signal wins.

Signal Reports on a Repeater
Lots of new hams don't understand that the S meter on their radio is only reporting the relative strength of the repeater system and NOT the signal strength of the station they are talking to.

When the repeater is transmitting, it may have an output greatly exceding that of the station IT is listening to. Remember the station it hears on the input frequency of it's receiver may be on a hand held radio and only a few blocks from the "machine" or it could be a mobile radio in a vehicle out on the fringes of the repeater coverage area or a base station running a high gain antenna and 100 watts from the next county or in some cases, the
next state.

To a third party, (another ham), listening to the machine on the repeater output, all of these stations would have the same S meter reading on his
S meter!

As long as the repeater can detect the signals and is working properly
as it is setup, then all stations, (to the third ham), will "appear" to have
the same signal strength on the S meter. Remember, the S meter is only reporting the relative strength of the repeater and not the individual stations!

So all that being said, how do you give an accurate signal report to the station you are talking to?
JUST USE PLAIN ENGLISH!
Listen to the background sounds of his AUDIO coming from your speaker in between words and sentences. Don't even look at your S meter. (Assuming the repeater has a good strong signal into your location)

If there is no noise other than room background, road, passenger or other sounds that could be picked up by his microphone, then he would be said to have a FULL QUIETING signal into the repeater.....receiver. NOT 50 OVER S9, S9, OR ANY COMBINATION on your S meter.

If his audio is perfectly understandable with 100 % copy and there is NO "noise" in the background other than the above, then an accurate report
for him would be, "You're full quieting and 100 % copy.

Anything less than the above is usually given in various ways using an exact as possible description of his signal. "Audio" reports are a matter of interpretation by individual ears. We as hams are in the "business" of communications, not HI FI broadcast FM! We can only sound as good as the FCC/CRTC will allow!

If you are having extreme difficulty copying him, he may also be having
the same problem with you, but remember he is hearing the repeater
signal, not yours direct and so are you. Try to get him to go "simplex"
if he is coming closer to you in a few minutes. See hint below.

If the transmissions get so ruff that neither can copy the other, then just give your call sign and clear off the repeater for others to use while he
gets closer or higher or changes his transmitting setup. Not all conversations are completed to the end under adverse conditions or operating situations....be patient.
HINT....If the station is in and out of range of the repeater you and he were using and is coming in your direction...try him on a simplex frequency! He may be loud and clear direct on simplex and only a few miles away and getting stronger all the time!

Another situation that can happen during a new contact is that you and he did not exchange locations at the first of the contact. Both you and he are using a repeater 50 miles away. Then after several minutes you discover in your conversation with the other station that he is in the same town as you and only a couple of miles away! Time for simplex! Don't hog the repeater.

15 August 2008

Carrier

Evening,

There seems to be a carrier on the input of UB. I can hear it on a handi out at Peasdown so would be useful to have some other reports to try and identify the source. The box is working but the echolink is not strong enough to overcome the carrier.I am off sick at present so will be unable to make a site visit (if needed) until Sunday at the earliest.