What is FHSS license free digital two way radio?
As you may know, Retevis 900MHZ FHSS walkie-talkies will be available soon. It is a digital license-free radio, using FHSS technology, compared with standard analog radio, can achieve more reliable and more private communication, ultra-thin body, with display and half keyboard settings, card sleeve type rotating back clip Design, etc., suitable for the retail industry, restaurants and other scenarios. So do you know what FHSS is?
FHSS definition
Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly changing the carrier frequency among many distinct frequencies occupying a large spectral band. The changes are controlled by a code known to both transmitter and receiver. FHSS is used to avoid interference, to prevent eavesdropping, and to enable code-division multiple access (CDMA) communications.
FHSS main advantages over a fixed-frequency transmission
- FHSS signals are highly resistant to narrowband interference because the signal hops to a different frequency band.
- Signals are difficult to intercept if the frequency-hopping pattern is not known.
- FHSS transmissions can share a frequency band with many types of conventional transmissions with minimal mutual interference. FHSS signals add minimal interference to narrowband communications, and vice versa.
The meaning of FHSS
In the existing DS/CDMA system, the near-far effect is a big problem. Since the high-power signal only produces near-far effects on a certain frequency, it will not be affected when the carrier frequency jumps to another frequency. Therefore, the frequency hopping system has no obvious near-far effects, which makes it easy to be applied and applied in mobile communications. development of. In a digital cellular mobile communication system, if mutually orthogonal frequency hopping patterns are used for synchronous frequency hopping between links, or a low cross-correlation frequency hopping pattern is used for asynchronous frequency hopping, the interference between links can be completely eliminated or basically eliminated. It is of great significance to increase the capacity of the system. In addition, frequency hopping is an instantaneous narrowband system, and its frequency allocation has great flexibility. This is of great significance under the condition that the existing frequency resources are very crowded.
What is the difference between 9000MHZ FHSS license free radio and ordinary FRS license free radio?
1.900Mhz frequency, when there are many obstacles, the penetration power will be better than FRS
2. North America, South America and the entire Americas are license free.
3.900Mhz is a digital license free frequency, FRS is an analog license free frequency.
