Method of, and receiver for, estimating the bit rate of data
First Claim
1. A method of detecting the presence of a data signal having one of at least two alternative bit rates, the method comprising differentially decoding the digitally modulated signals into oversampled complex signals, forming a running sum of successive groups of samples, determining if the running sum represents a signal as opposed to interference, if the running sum represents a signal, determining the sign of the running sum, assigning one of two binary values dependent on whether the sign is positive or negative, storing successive binary values in a shift register, comparing the content of the shift register with a threshold value related to one of the at least two alternative bit rates, and if the threshold value is exceeded concluding that the data signal is at said one bit rate, but if not repeating the method with the threshold value being related to the other or another of the bit rates.
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Accused Products
Abstract
A bit rate detector for detecting the speed of transmission of a data signal having one of at least two alternative bit rates, comprises a differential decoder (28) for differentially decoding received digitally modulated signals into oversampled complex signals, a summing stage (38, 40 and 42) for forming a running sum of successive groups of samples, and a bit rate detector (58). The bit rate detector (58) having a stage (62, 66 (FIG. 5)) for determining if the running sum represents a signal as opposed to interference, and if the running sum represents a signal, determining the sign of the running sum, a stage (74 (FIG. 5)) for assigning one of two binary values dependent on whether the sign is positive or negative, a shift register (82 (FIG. 5)) for storing successive binary values, a comparator (88 (FIG. 5)) for comparing the content of the shift register with a threshold value related to one of the at least two alternative bit rates, and if the threshold value is exceeded concluding that the data signal is at said one bit rate, but if not repeating the method with the threshold value being related to the other or another of the bit rates.
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Citations
11 Claims
- 1. A method of detecting the presence of a data signal having one of at least two alternative bit rates, the method comprising differentially decoding the digitally modulated signals into oversampled complex signals, forming a running sum of successive groups of samples, determining if the running sum represents a signal as opposed to interference, if the running sum represents a signal, determining the sign of the running sum, assigning one of two binary values dependent on whether the sign is positive or negative, storing successive binary values in a shift register, comparing the content of the shift register with a threshold value related to one of the at least two alternative bit rates, and if the threshold value is exceeded concluding that the data signal is at said one bit rate, but if not repeating the method with the threshold value being related to the other or another of the bit rates.
- 6. A receiver comprising means for receiving a data signal, means for forming the data signal into oversampled differentially decoded complex signals, means for forming a running sum of successive groups of samples, means for determining if the running sum represents a signal as opposed to interference, and, in response to determining that the running sum represents a signal, for determining the sign of the running sum, means for assigning one of two binary values dependent on whether the sign is positive or negative, a shift register for storing successive binary values, and comparing means for comparing the content of the shift register with a threshold value related to one of the at least two alternative bit rates, the comparing means having an output for a signal representing the bit rate has been detected.
Specification