Abstract: A low-power sleep mode of operation for a frequency hopping radio receiver is presented. Digital circuits within the receiver operate based upon a high frequency clock source. During sleep mode, the circuits are clocked with a low-frequency clock source, which is typically less accurate in frequency. Periodically, the receiver awakens. The hop sequence channel tuned by the receiver is determined by a mapping based upon the channel upon which the receiver expects to receive communications. The mapping can be changed as necessary to improve tolerance to timing error. Furthermore, once communications are received after a sleep period, the frequency error of the low-frequency clock source can be determined, and compensated for after awakening from subsequent sleep periods.

Abstract: A technique for controlling the frequency allocation in the hop sequence of a frequency hopping digital communications system is presented. The hop sequence is initially formed such that consecutive channels are likely to differ substantially in frequency. Therefore, channel substitution commands can be transmitted twice on consecutive hops without acknowledgement, inasmuch as the likelihood of a broadband noise source blocking consecutive channels is reduced. The number of channels identified as requiring substitution in the hop sequence is monitored, such that a hop sequence repair operation or communications link termination can be implemented if channel substitution data traffic becomes too great.

Abstract: A low-power sleep mode of operation for a frequency hopping radio receiver is presented. Digital circuits within the receiver operate based upon a high frequency clock source. During sleep mode, the circuits are clocked with a low-frequency clock source, which is typically less accurate in frequency. Periodically, the receiver awakens. The hop sequence channel tuned by the receiver is determined by a mapping based upon the channel upon which the receiver expects to receive communications. The mapping can be changed as necessary to improve tolerance to timing error. Furthermore, once communications are received after a sleep period, the frequency error of the low-frequency clock source can be determined, and compensated for after awakening from subsequent sleep periods.

Abstract: A technique for controlling the frequency allocation in the hop sequence of a frequency hopping digital communications system is presented. The hop sequence is initially formed such that consecutive channels are likely to differ substantially in frequency. Therefore, channel substitution commands can be transmitted twice on consecutive hops without acknowledgement, inasmuch as the likelihood of a broadband noise source blocking consecutive channels is reduced. The number of channels identified as requiring substitution in the hop sequence is monitored, such that a hop sequence repair operation or communications link termination can be implemented if channel substitution data traffic becomes too great.