![]() Repeater frequency sets are known as "repeater pairs", and in the ham radio community most follow ad hoc standards for the difference between the two frequencies, commonly called the offset. Note that different countries have different rules for example, in the United States, the two meter band is 144–148 MHz, while in the United Kingdom (and most of Europe) it is 144–146 MHz. In some areas, 33 centimeters (902–928 MHz) and 23 centimeters (1.24–1.3 GHz) are also used for repeaters. Repeaters are found mainly in the VHF 6 meter (50–54 MHz), 2 meter (144–148 MHz), 1.25-meter band (1 1⁄ 4 meters) (220–225 MHz) and the UHF 70 centimeter (420–450 MHz) bands, but can be used on almost any frequency pair above 28 MHz. 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 of western Michigan, or the Western Intertie Network System ("WINsystem") that now covers a great deal of California, and is in 17 other states, including Hawaii, along with parts of four other countries, Australia, Canada, Great Britain and Japan. 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. Use a radio with good sensitivity for this project.In amateur radio, repeaters are typically maintained by individual hobbyists or local groups of amateur radio operators. Distance between node and repeater is 150 meter is an assumption it could be greater or less depending on environment and antenna length. NOTE: Here the node represents one set of transmitter and receiver. The transmission frequency, repeating frequency and receiving frequency must be well determined before communication just to avoid confusion.For example: 90MHz at TX1 and this frequency should not be used anywhere in the repeater circuit. All the frequencies used in repeater must not be used more than once.Then the receiving frequency at SET ‘B’ must be 92MHz. Let the repeating frequency at TX1 be 92MHz. Then the receiving frequency at repeater must be 90MHz (RX1). Let, SET ‘A’s transmission frequency be 90MHz.Let’s assume some factors and simulate the situation: When the repeater comes in between the transmission and reception, the whole system gets slightly complicated. We can use same transmitter circuit as shown above. Here we need two FM transmitters and two receivers ( FM radio) for 2 channel design. The radio repeaters in real world consist of several numbers of channels. A channel consists of one transmitting and one receiving frequency here we have two such sets. The given radio repeater circuit is a two channel design. The repeater must be within the range of the transmitting node, only then the repeater may be able to re-broadcast the signal to multiple nodes. The repeater station is place on top of hills, so that it can receive maximum signal from a node and re-transmit to single or multiple nodes with less distorted signal. In other words a repeater extends the range of the signal being transmitted. A radio repeater repeats the transmitted signal to wider range, even over several 100 KM, which ensures that the receiving party will receive a clear signal. To avoid this kind of issues we go for a radio repeater. These obstacles could potentially reduce the range of the propagated signals, thus the person at the receiving end may hear broken signals. ![]() For example: Person ‘A’ can talks through walky-talky to person ‘B’, but person ’B’ can’t reply simultaneously and vice versa.ĭuring propagation of modulated signal from walky-talky ‘A’ to walky-talky ‘B’, there could be obstacles between them, such as mountain, buildings, trees, etc. A walky-talky is a half-duplex communication device, which means the communication takes place in one direction at an instant. Here we are taking walky-talky as an example. NOTE: Follow the strict rules and regulation implemented by your local and country government before proceeding with this project. This may be used for short distance communication when you are on a camp or use as an intercom or some similar applications. In the end you would be able to build a micro repeater station for the proposed full duplex communicator design in this article. In this article we are going to see what radio repeater is, how it works and how to build one in a hobby lab.
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