On-line channel quality monitor for a communication channel
AssigneeDigital Communications Corporation
InventorsRobert L. Richmond, Paul F. Wyar
Life of this patent
Estimating the term…
Abstract
An on-line channel monitor, for measuring E.sub.b /N.sub.O, measures the quality of a communication channel while the channel is in use. The channel monitor employs a soft-decision demodulator so as to compare analog signal levels of an AGC compensated signal in a demodulator with the desired signal level. Deviations, termed pseudo-errors, are counted and the number of counts integrated. The result is employed to drive a meter calibrated in terms of E.sub.b /N.sub.O.
Claims20
A communication channel monitor for monitoring channel quality for channels of the type transmitting analog samples of data and which channel includes a demodulator for providing an information bearing analog signal and a symbol clock, said communication channel monitor comprising:
- soft-decision demodulation means responsive to said analog signal and to said symbol clock for providing a multi-bit digital output at the rate of said symbol clock,
- logic means responsive to said multi-bit digital output for providing a specified logic output each time said multi-bit digital output corresponds to one of a selected number of predetermined bit patterns, and
- integrating means responsive to said logic output for providing a representation of average number of specific logic outputs per unit time.
A digital communication channel monitor for monitoring channel quality in which said channel includes a soft-decision demodulator producing a multi-bit output repeating at a rate of received symbols, each said multi-bit output representing an analog signal magnitude;
- in which said monitor comprises:
- logic means responsive to said multi-bit output for providing a specific logic output for each multi-bit output representing an analog signal magnitude outside a predetermined magnitude range, and
- integrating means responsive to said specific logic output for providing a representation of average number of logic outputs per unit time.
A channel quality monitor for a four-phase PSK digital communication channel providing E.sub.b /N.sub.O information, where E.sub.b is energy per bit and N.sub.O is noise, in a digital demodulator which provides an information bearing analog signal and a symbol clock, in which said monitor comprises:
- soft-decision demodulator means producing I and Q multi-bit outputs at the rate of said clock, each output representing I or Q analog signal magnitude,
- logic means responsive to said I and Q multi-bit outputs for providing a specific logic output for multi-bit outputs representing an analog signal magnitude deviating from a predetermined analog signal magnitude range, and
- averaging means for averaging logic outputs per unit time.
An on-line channel monitor for a digital demodulator including an information bearing baseband analog signal and a symbol clock, in which said monitor comprises:
- pseudo-error measuring means responsive to said information bearing baseband analog signal for producing a pseudo-error signal, and
- averaging means responsive to said pseudo-error signal for providing a time averaged sum of said pseudo-errors,
- wherein the improvement comprises pseudo-error measuring means including means for producing a pseudo-error signal when said baseband analog signal magnitude, at the time of a symbol clock, is outside of a predetermined magnitude range.
Dependencies are inferred from the claim text.