FHSS

Hello,

Frequency Hopping Spread Spectrum (FHSS) is a method used to rapidly switch transmitting radio signals among several frequency channels.

The FCC has certain regulations in place with which RFID readers must comply in order to transmit 1 W of output power. The FCC allows high output power if the system:

• Uses FHSS

• Supports hopping across 50 channels (500 kHz wide) between the operating frequencies of 902 - 928 MHz

• Transmits no longer than 0.4 seconds per channel

Frequency hopping is a technique mainly used to keep two or more RFID readers from interfering with each other while reading RFID tags in the same area. Each reader initiates its operating program, and, once it receives a frequency hop trigger signal, a frequency hopping sequence is then selected from the available operating frequencies. The reader then prompts the RF module to switch to a frequency channel described in the hopping sequence and stays there for 0.4 seconds. Once completed, the reader will stop transmitting and store the channel it was using. The reader will then continue to use the same sequence if a new trigger signal arrives in less than 30 seconds. Because of this rapid hopping among  various frequencies, multiple readers and tags are allowed to communicate with one another with minimal, if any, reader collision.

The nature of this technique allows for very minimal interference since the probability of two readers transmitting at the exact same frequency is very low. This comes in handy when using multiple readers that have overlapping read zones. 

Thanks

What Are the Advantages and Disadvantages of FHSS and DSSS?

The direct sequence spread spectrum (DSSS) technology has advantages in high-reliability applications, whereas the frequency hopping spread spectrum (FHSS) technology has advantages in low-cost applications. Generally, DSSS fast transmits data in full-band mode, and allows for a higher transmission frequency in the future. The DSSS technology applies to a fixed environment or applications requiring high transmission quality. Therefore, DSSS wireless products are usually used in wireless plants, wireless hospitals, network communities, and campus networking. The FHSS technology applies to the endpoints requiring fast mobility. Because the FHSS transmission range is small, more FHSS devices than DSSS devices are required in the same transmission environment, which requires a high cost.

Hi friend!

https://support.huawei.com/enterprise/en/doc/EDOC1000060368/a9c74ad5/what-are-the-advantages-and-disadvantages-of-fhss-and-dsss

Thanks!

Thanks you for your information

great!