Digital communications systems
AssigneeShaye Communications Limited
InventorDavid J. McCabe
Life of this patent
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Abstract
Corruption in digital data communications systems is detected, at the receiving end, by taking a number of samples of the received signal within each bit period. Flip flops (4, 7 and 8) are used to take samples from the digitized received signal as follows: flip flop (4), a mid bit sample indicative of the value of the center of the bit; flip flop (7), a pre-mid sample taken within the bit period before the mid-bit sample; and flip flop (8), a post-mid sample taken within the bit period after the mid-bit sample. Gating circuitry (23, 24, 25) is used to analyse the three samples and give a "good" or "bad" output signal to register 11 as a result of the analysis. Corruption is judged to be present if any one of the samples has a different value to the others.
Claims12
A method of detecting data corruption in digital communications systems, said method comprising taking samples of the received signal and utilizing a function of the value of such samples to determine whether excessive jitter is occurring, the existence of such jitter being used as an indication of possible data corruption, said method being characterized in that, for each bit of the received signal, three samples are taken as follows:
- 1) a mid-bit sample indicating the value at the approximate mid position of the bit;
- and
- 2) two further samples taken within the bit period, one before and one after the mid-bit sample;
- said method further comprising comparing the values of all three samples with one another to determine whether jitter is present, and wherein jitter is assumed to be present if the value of one sample is different from that of the other two samples.
An apparatus for detecting data corruption in digital communications systems, said apparatus comprising, at the receiving end of such system, a means for taking samples of the received signal and utilizing a function of the value of such samples to determine whether excessive jitter is occurring, the existence of such jitter being used as an indication of possible data corruption, said apparatus being characterized in the sample taking means includes first means for taking a mid-bit sample indicating the value at the approximate mid position of the bit, a second means for taking a further sample within the bit period at a time before the mid bit sample, and a third means for taking a still further sample within the bit period at a time after the mid bit sample and a means for comparing the values of all three samples with one another to determine whether jitter is present, wherein jitter is assumed to be present if the value of one sample is different from that of the other two samples.
Dependencies are inferred from the claim text.