In Fast Frequency hopping multiple frequencies or hops are used to transmit one symbol.
The hop rate is higher than symbol rate but chip rate is equal to hop rate
For each symbol several hops takes place. So several frequencies changes for one symbol such that symbol rate Rs< Hop rate Rh
A jammer cannot detect this signal because one symbol is transmitted using more than one carrier frequency.
Advantages :
1. The processing gain is higher
2. More secured transmission as only transmitter and receiver are aware of PN Codes
3. Shorter time for acquisition
4. Robust technology
Disadvantages :
1. Bandwidth requirement is more [GHz]
2. Lower Coverage range due to high SNR requirement at receiver
3. Complex and expensive digital frequency synthesizers are required
4. Data rates are low