Amateur Radio Repeater
An amateur radio repeater is an electronic device that receives a weak or low-level amateur radio signal and retransmits it at a higher level or higher power, so that the signal can cover longer distances without degradation. Many repeaters are located on hilltops or on tall buildings as the higher location increases their coverage area, sometimes referred to as the radio horizon, or “footprint”. Amateur radio repeaters are similar in concept to those in use by public safety (police, fire, etc.), government, military, and more. Amateur radio repeaters may even use commercially-packaged repeater systems tuned into an amateur radio frequency allocation, but more usually amateur repeaters are assembled from various sources for receivers, transmitters, controllers, power supplies, antennas, and other components.
In amateur radio, repeaters are typically maintained by individual hobbyists or local groups of amateur radio operators. Many repeaters are provided openly to other amateur radio operators and typically not used as a remote base station by a single user or group. In some areas multiple repeaters are linked together to form a wide-coverage network, such as the linked system provided by the Independent Repeater Association which covers most part of the country.
In many communities, a repeater has become a major on-the-air gathering spot for the local amateur radio community, especially during “drive time” (the morning or afternoon commuting time). In the evenings local public service nets may be heard on these systems and many repeaters are used by weather spotters. In an emergency or a disaster a repeater can sometimes help to provide needed communications between areas that could not otherwise communicate. Until cellular telephones became popular, it was common for community repeaters to have “drive time” monitoring stations so that mobile amateurs could call in traffic accidents via the repeater to the monitoring station who could relay it to the local police agencies via telephone.
Repeaters may be linked together in order to form what is known as a linked repeater system or linked repeater network. In such a system, when one repeater is keyed-up by receiving a signal, all the other repeaters in the network are also activated and will transmit the same signal. The connections between the repeaters are made via radio (usually on a different frequency from the published transmitting frequency) for maximum reliability. Such a system allows coverage over a wide area, enabling communication between amateurs often hundreds of miles (several hundred km) apart. All the user has to know is which frequency to use in which area.
Repeaters may also be connected to over the Internet using voice over IP (VoIP) techniques. VoIP links are a convenient way to connecting distant repeaters that would otherwise be unreachable by VHF/UHF radio propagation. Popular VoIP amateur radio network protocols include D- STAR, Echolink, IRLP, WIRES and eQSO.
Having two repeaters operate on the same radio frequency is problematic, as they can interfere with each other, even with selective calling methods enabled. To help minimize this issue, regional repeater coordination organizations have been created. In some jurisdictions, coordination may be required by law or regulation. In others, coordination is done on a voluntary basis, but with a regulatory preference for coordinated repeaters.
The most basic repeater consists of an FM receiver on one frequency and an FM transmitter on another frequency usually in the same radio band, connected together so that when the receiver picks up a signal, the transmitter is keyed and rebroadcasts whatever is heard.
Ham repeaters are found mainly in the VHF six meters (50-54 MHz), two meter (144 – 148 MHz), 220 MHz band (222-224 MHz) and the UHF 70 centimeter (420 – 450 MHz) bands, but can be used on almost any frequency pair above 28 MHz. Note that different countries have different rules; for example, In India the two meter band is 144-146 MHz. while in the United States 144-148 MHz and most of Europe it’s 144-146 MHz.
Repeater frequency sets are known as “repeater pairs,” and in the ham radio community most follow adhoc standards for the difference between the two frequencies, commonly called the offset. The standard offset is 600 kHz (0.6 MHz). The actual frequency pair used is assigned by a local frequency coordinating council.
Repeaters typically have a timer to cut off retransmission of a signal that goes too long. Repeaters operated by groups with an emphasis on emergency communications often limit each transmission to 30 seconds, while others may allow three minutes or even longer. The timer restarts after a short pause following each transmission, and many systems feature a beep or chirp tone to signal that the timeout timer has reset.
Timing Out is a term used to describe the situation where a person talks too long and the repeater timer shuts off the repeater transmitter.
Kerchunking is a term used in ham radio that refers to the act of transmitting a momentary signal to check a repeater without identifying. In many countries, such an act violates amateur radio regulations. The term “Kerchunk” can also apply to the sound a large Amplitude Modulation Transmitter makes when the operator switches it off and on.
Some Repeater Terms. :
Simplex repeater, Same-band repeater, Cross-band repeater
Digipeater, SSTV repeater, Amateur television repeater, Transponder.
FOR THE REPEATERS TO DO THEIR VERY BEST, PLEASE DO FOLLOW THESE FEW SIMPLE STEPS WHILE USING THE REPEATERS.
1. Always identify
Correct operating procedure is a distinct characteristic of Amateur Radio. It’s important that you convey to the public and to new hams the image that Amateur Radio operators really know what they are doing. A friendly style is great, but take pains to operate professionally. Don’t become sloppy. Amateur Radio regulations are largely self-enforced and we all need to work together towards these goals. You never know who may be listening. Even late at night, there are generally people listening to the repeater, including non-hams. This is important to understand for several reasons. The Our repeaters serve many purposes. One of the most important is the exposure it gives the hobby to the community. Any scanner can be used to listen to our repeaters. That’s good – It’s actually the most visible aspect of our club. It’s one of our most effective forms of publicity. We want non-hams to know that Amateur Radio is an interesting hobby and a good group of people to get to know – something clean and educational – something they would want their kids to get involved in. Kids may or may not listen late at night, but their parents do. Don’t let our activities on the air become a weapon in the hands of people who want to discredit us. Let’s all do our part to give Amateur Radio a positive image. We want any ham that listens to us to think of us as good operators. Any time we talk on the repeater, we are ambassadors for the hobby. Have you ever noticed how you like to listen to some repeaters, but sometimes you find a repeater that makes you roll your eyes and twist the knob? We may lose good people because of what they hear on our repeaters. Please keep in mind : absolutely no obscene, indecent or profane language at any time.
2. Avoid lengthy QSOs.
Please limit QSOs shorts. Other hams probably want to use the repeater but might not be interested in the subject your group is discussing. Conversations on the repeaters should be friendly ones.
3. Do not routinely circumvent the timeout timer.
The purpose of repeater’s timeout timer is to satisfy requiring us to limit repeater transmissions to a maximum of three minutes under automatic control. Most of the repeaters use the timeout timer as a way to encourage users to limit the length of individual transmissions. This gives everyone a chance to speak. Learn to speak concisely and limit the length of your individual transmissions. To use the repeaters you must follow general principles to become a good operator.