Error detector circuit for digital receiver using variable threshold based on signal quality
First Claim
1. An error detector circuit for a receiver operative to receive a discretely-encoded signal at an input thereof, the error detector circuit operative to determine when a sequence of the discretely-encoded signal is comprised of an excessive number of signal portions of erroneous signal values, the error detector circuit comprising:
- a first detector coupled to the input to determine when signal portions of the sequence of the discretely-encoded signal received by the receiver are of erroneous signal values and to generate a first error signal of a value representative of numbers of signal portions determined to be of the erroneous signal values;
a second detector coupled to the input to determine signal quality levels of the sequence of the discretely-encoded signal and to generate a signal-quality signal representative of signal quality levels determined thereat;
a combiner coupled to the first and second detectors to combine the first error signal and the signal-quality signal to form thereby a weighted error signal;
a threshold generator receiving an estimated signal quality signal and generating a variable threshold level as a function of the estimated signal quality signal; and
a signal generator coupled to the threshold generator, the first detector, and to the combiner, to generate a received-signal sequence error when either the weighted error signal is of a value beyond a preselected threshold value or the first error signal is of a value beyond the variable threshold level, wherein generation of a received-signal sequence error signal is indicative of when the sequence of the discretely-encoded signal is comprised of the excessive number of signal portions of the erroneous signal values.
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Accused Products
Abstract
An error detector circuit (300) for a discrete receiver indicates bad frames of binary information signals which contain distorted bits of data in numbers so great as to prevent a convolutional decoder (738) from generating, accurately, a decoded signal. A variable threshold generator (440) generates a variable threshold level according to the signal quality estimate for the received signal. When bit errors are detected in numbers beyond the variable threshold or when a first preselected value of the signal quality of a received signal combined with the detected number of bit errors forms a signal beyond a second preselected value, a bad frame is indicated.
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Citations
20 Claims
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1. An error detector circuit for a receiver operative to receive a discretely-encoded signal at an input thereof, the error detector circuit operative to determine when a sequence of the discretely-encoded signal is comprised of an excessive number of signal portions of erroneous signal values, the error detector circuit comprising:
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a first detector coupled to the input to determine when signal portions of the sequence of the discretely-encoded signal received by the receiver are of erroneous signal values and to generate a first error signal of a value representative of numbers of signal portions determined to be of the erroneous signal values; a second detector coupled to the input to determine signal quality levels of the sequence of the discretely-encoded signal and to generate a signal-quality signal representative of signal quality levels determined thereat; a combiner coupled to the first and second detectors to combine the first error signal and the signal-quality signal to form thereby a weighted error signal; a threshold generator receiving an estimated signal quality signal and generating a variable threshold level as a function of the estimated signal quality signal; and a signal generator coupled to the threshold generator, the first detector, and to the combiner, to generate a received-signal sequence error when either the weighted error signal is of a value beyond a preselected threshold value or the first error signal is of a value beyond the variable threshold level, wherein generation of a received-signal sequence error signal is indicative of when the sequence of the discretely-encoded signal is comprised of the excessive number of signal portions of the erroneous signal values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A bad frame indicator for a digital receiver, comprising:
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a first circuit for generating a first error signal of a value representative of a number of erroneous signal values in a frame input to the digital receiver; a second circuit generating respective estimated signal quality signals representative of signal quality of each of a plurality of segments of the frame input to the digital receiver; a threshold generator coupled to the second circuit to derive a variable threshold as a function of a number of the segments of the frame that are determined to be bad based upon the respective estimated signal quality signal for each segment; and a signal generator coupled to the threshold generator and the first circuit for generating a received-signal sequence error signal when the first error signal is of a value beyond the variable threshold, wherein generation of the received-signal sequence error signal is indicative of when the frame input to the digital receiver is comprised of an excessive number of signal portions of erroneous signal values.
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20. In a radiotelephone transceiver having digital receiver circuitry operative to receive discretely-encoded signals, a combination with the digital receiver circuitry of an error detector circuit for determining when a sequence of the discretely-encoded signals is comprised of an excessive number of signal portions of erroneous signal values, said error detector circuit comprising:
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a first generator generating a first error signal of a value representative of a number of erroneous signal values in the sequence of discretely encoded signals; a generator generating a signal-quality signal representative of signal quality levels of signals input to the digital receiver circuitry; a circuit to combine the first error signal and the signal-quality signal to form a weighted error signal; a signal quality estimate generating circuit to generate an estimate of signal quality level in the signals input to the digital receiver circuitry; an error quality circuit coupled to the signal quality estimate generating circuit to generate a variable threshold as a function of the estimate of signal quality level; and a signal generator coupled to the first generator, to the quality circuit and to the error circuit to generate a received-signal sequence error when either the weighted error signal is of a value beyond a first preselected value or the first error signal is of a value beyond the variable threshold, wherein generation of the received-signal sequence error is indicative of when the sequence of the discretely-encoded signals is comprised of the excessive number of signal portions of erroneous signal values.
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Specification