Frequency-hopping digital data link

摘要

Ordinary digital data is reformed and time shifted such that it may be broadcast over a radio link which periodically shifts its frequency. The system of this invention utilizes timing information obtained from a pre-existing frequency-hopping radio link in conjunction with its own buffer and control circuitry to accurately time-position discrete digital data packets within those time bands of the radio transmission wherein the frequency is not changing from one frequency to another. In the drawing, TH1 is a very short duration pulse which commands the AM frequency-hopping system to shift frequencies. The time period necessary for the frequency hop operation to settle down and attain a stable frequency is represented by the interval between TH1 and T1. The actual reception of the uplink message occurs in the interval between T3 and T4; transmission of the downlink signal from the system occurs in the interval between T5 and T6. The interval between T4 and T5 is a necessary pause at the actual station. The intervals between T1 and T3 and T6 and T allow for other delays such as slant range differences between stations, propagation delays, and timing offsets between stations.