The invention discloses a system (100) for a fast frequency hopping radio, and comprises a transmit part (110) and a receive part (120). Each of the receive (110) and transmit (120) parts comprise a unit (115, 125) for random frequency generation, the random frequency generating unit of both parts being similar. The random frequency generator (115, 125) of each of said parts comprises a pseudo random number generator, a PRN-generator, the PRN-generator being based on a FIR-algorithm, and said PRN-generator uses a clock signal which has been generated externally to the system as input. The external clock signal which is used is suitably a clock signal from the GPS-system.