A duplexer is an electronic device that allows bi-directional (duplex) communication over a single path. Most radio repeater systems include a duplexer. Duplexers can be based on frequency (often a waveguide filter), polarization (such as an orthomode transducer), or timing (as is typical in radar).
How does a radio repeater work. A radio repeater simultaneously receives a radio signal and re-transmits it at a higher power so it can cover greater distances. Repeaters receive radio waves on one frequency, called the “input†frequency, and then re-transmit the information on its “output†frequency.
A simplex repeater records incoming transmissions and retransmits them at the same frequency. While a traditional repeater typically costs thousands of dollars and might be semi-portable at best, a simplex repeater can be set up with a single handheld radio and is battery operated.
Also called a cellular repeater, RF signal repeaters use a three-part system to capture weak signal, and then amplify, or repeat that signal to strengthen it. RF repeaters are used in many different industries like government buildings, schools, stores, and offices to improve in-building cell signal.
Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction. Some types of repeaters broadcast an identical signal, but alter its method of transmission, for example, on another frequency or baud rate.
For example, if you and a friend are using handheld transceivers (HTs) with a typical output power of 5 watts, you can expect your range to be about 5 miles maximum. If you're using a repeater, however, you should be able to talk much farther.
Repeaters strengthen and sustain both UHF (Ultra High Frequency) and VHF (Very High Frequency) signals, especially in rugged terrain and over water. Most repeaters available for businesses today use UHF frequencies. It receives signals on one frequency and re-broadcasts them on another frequency.
Vehicular repeatersThe low-power radio repeats transmissions from the portable over the vehicle's high power mobile radio, which has a much longer range. In these systems, the hand-held works so long as it is within range of the low power mobile repeater.
Definition(s): A method of communicating on half-duplex communication lines, including two-way radio, using a “walkie-talkie†button to switch from voice reception to transmit mode.
How to listen to repeater contacts
- Use a repeater directory or website to find a repeater in your area.
- Determine the repeater's input and output frequencies.
- Set up your radio to listen on the repeater's output frequency.
- Tune your radio as you do for FM signals.
The 5 watt radio can reach up to 12 miles or more. Some handheld radios have 6 watts which can reach up to 20 miles in the right conditions.
1. Motorola T470 2-Way Radios. The T470 is a powerful option from Motorola; it boasts an up to a 35-mile range, and it has 22 channels and 121 privacy codes to more easily stay in touch with your party. The channels include FRS and GMRS.
Ham radio repeaters are the equivalent of mobile phone towers. They receive a signal from someone nearby and rebroadcast it into the greater network, usually with more power and clarity, so it can travel farther. Repeaters are usually on top of a tall building or hill, with high quality equipment and antennas.
You can realistically get about 2-18 miles of range with a handheld Ham radio unless you have a particularly powerful base station with a large antenna, in which case your range can be hundreds of miles.
You will also typically hear the repeater identify itself with either Morse Code tone patterns or by recorded or electronic voice ID at least every 10 minutes.
Most airband radios are 5 - 8 watts and typically have a range of around 200 miles.
For example, a 25-watt marine radio will roughly have a maximum range of 60 nautical miles (111 km) between antennas mounted on tall ships, but that same radio will only have a range of 5 nautical miles (9 km) between antennas mounted on small boats at sea level.
