Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
240 words
In a TDMA satellite communication system of the type wherein multiple earth stations transmit their respective data during transmission bursts which arrive at a satellite transponder at non-overlapping times, a repetitive group of said bursts comprising a TDMA transponder frame, and wherein synchronization is maintained by comparing the time separation between a station''s burst and a frame reference to a known time difference and slightly altering a frame counter that controls the timing of burst transmission to cause it to recycle at an earlier or later count to decrease the difference between said time separation and said known time difference, the improvement being a system for rapidly re-establishing synchronization comprising, a. first means for periodically monitoring the time difference, Delta T, between the detection of said frame reference and some predetermined state of said frame counter, b. second means for periodically calculating and storing the rate of change of Delta T, c. third means for monitoring outages in said earth station equipment and for signaling the beginning and end of an outage, d. calculator means connected to said first, second and third means for calculating the expected time separation of said frame reference and said predetermined state at end of said outage, and e. means for setting a number in said frame counter based on the calculation by said calculator means to provide a time separation, Delta T, equal to said expected time separation, following the termination of said outage.
Claim 2
Dependent Claim
240 words
In a TDMA satellite communication system of the type wherein multiple earth stations transmit their respective data during transmission bursts which arrive at a satellite transponder at non-overlapping times, a repetitive group of said bursts comprising a TDMA transponder frame, and wherein synchronization is maintained by comparing the time separation between a station''s burst and a frame reference to a known time difference and slightly altering a frame counter that controls the timing of burst transmission to cause it to recycle at an earlier or later count to decrease the difference between said time separation and said known time difference, the improvement being a system for rapidly re-establishing synchronization comprising, a. first means for periodically monitoring the time difference, Delta T, between the detection of said frame reference and some predetermined state of said frame counter, b. second means for periodically calculating and storing the rate of change of Delta T, c. third means for monitoring outages in said earth station equipment and for signaling the beginning and end of an outage, d. calculator means connected to said first, second and third means for calculating the expected time separation of said frame reference and said predetermined state at end of said outage, and e. means for setting a number in said frame counter based on the calculation by said calculator means to provide a time separation, Delta T, equal to said expected time separation, following the termination of said outage.
Claim 3
Dependent Claim
125 words
A TDMA system as claimed in claim 1 wherein said calculator means comprises, a. a battery operated source of clock pulses, b. counting means responsive to said third means for accumulating said clock pulses during said outage, c. multiplier means for multiplying the time accumulated by said counting means by the last calculated rate of change in Delta T, d. summation means for algebraically adding the product formed by said multiplying means by the last monitored time difference to form a new predicted time difference Delta T + or - S, and e. means for presetting said frame counter to provide a time difference between the first frame reference following said outage and said predetermined state of said counter which equals said predicted time difference.
Claim 4
Dependent Claim
78 words
A TDMA system as claimed in claim 2 wherein said presetting means comprises, a. means for subtracting said predicted time difference, Delta T + or - S, from N, where N is the number of increments nominally counted by said frame counter each cycle of said frame counter, and b. means responsive to the first occurring frame reference following said outage for presetting the count of (N- ( Delta T + or - S)) into said frame counter.
Claim 5
Dependent Claim
26 words
A TDMA system as claimed in claim 1 wherein the outage is a power transient and said third means is a means for monitoring power transients.
Claim 6
Dependent Claim
26 words
A TDMA system as claimed in claim 2 wherein said outage is a power transient and said third means is a means for monitoring power transients.