What factors need to be considered in the early stage of the relay system construction?
B. Equipment selection
C. Antenna position selection
D. Repeater and antenna distance
How to choose the frequency for your replay system?
First the repeater is not a personal device. Before use, you need to report to the local radio committee. When reporting, the radio committee will give you a small range of frequencies from which you can select one or several frequency points to use the relay station legally.
Note that the assigned frequency provided by the Radio Committee is generally at both ends of the UHF and is an unusual frequency. This is to avoid affecting the use of popular frequency points.
For example, in various regions of the USA, the FCC provides a selectable frequency segment between 440 and 450 mHz in the U.H.F range.
Therefore, before customizing the repeater station, you must first consult and report to the local radio committee.
If you want to establish a GMRS repeater, the GMRS repeater frequency is fixed, as shown in below figure.
The center frequency of the relay system should be:
Lower frequency(simplex / repeater output, MHz): 462.625 MHz
Upper frequency (repeater input, MHz): 467.625 MHz
This frequency point is the center value of the 8 channels of the GMRS. Each repeater station is allowed to float 1 mHz above and below its center frequency, and 462.625 MHz and 467.625 MHz are used as the center value of the relay station, and any of 8 channels can be used also.
What equipment is the best for relay system? (The right one is the best)
There are many brands of relay stations: Motorola, Icom, Retevis. The relay station can be divided into: digital relay and analog relay. There are also many latitude classification methods. Which is the best? People here often enter a misunderstanding. That is, when buying, pay too much attention to performance parameters, and inspirational to get a best repeater.
But buying a repeater doesn’t just need to consider the performance of the repeater.
What should be considered is what effect do I want to achieve? What functions can realize these effects ? As long as the purchased repeater has these functions, it can be used as an alternative target.
There are also a lot of walkie-talkies, there are a lot of features, but not every feature you need, Just choose what is most suitable for you is ok.
The purchase price is also an important indicator of our selection. Within the target price range, if the performance of the relay is enough good, the quality is very good, the lower the price, the better it will save money.
For example, the Retevis RT97 radio repeater is a portable repeater. The center frequency can be customized. You can also purchase the stock frequency written by retevis. UHF or VHF is optional. The frequency difference is 5~10mhz. It supports CTCSS: 50, DCS: 104 pairs, channel adjustable in display directly, compact size: 310 × 283 × 170mm, weight 2700g, support 220v power, DC12V ~ 24V mobile power, vehicle power.
Retevis RT97 analog repeater is suitable for: concerts, outdoor hiking, small factories, farms, companies and other scenes.
These scenarios are not very demanding on big or very high cost relays. The use of the Retevis RT97 is fully capable of doing the job, and the price of the Retevis RT97 is very affordable.
Antenna position selection for relay system:
Based on your building and surroundings, the higher position Antenna erected, the better the effect will be. But make sure you set some lightning protection measures.
What is the good distance between the repeater and the antenna?
The repeater should not be too far from the antenna. The relay station and the antenna are connected by a feeder cable. The radio signal has a certain loss when it is transmitted in the feeder. The longer the antenna, the greater the loss. Therefore, the relay station installed to a position that is convenient for maintenance and as close as possible to the antenna will be good.
Any questions, please feel free to discuss here.