Adaptive blanking apparatus

Claim 2

Blanking apparatus for interrupting a received noise-plussignal waveform when the value of the waveform exceeds its r.m.s. value for a predetermined percentage of time, comprising variable gain means for receiving the noise-plus-signal waveform and producing an output therefrom in which the value of the waveform exceeds the r.m.s. value plus a fixed amount a predetermined percentage of time, said variable gain means including a linear amplifier controlled by an applied voltage, a bipolar comparator connected to said amplifier for producing a rectangular output during periods that the applied voltage exceeds either a positive or a negative preset threshold level, an averager connected to said bipolar comparator for producing an averaged voltage over a predetermined time interval, comparator means connected to said averager for producing a difference voltage when the averaged voltage is different from a preset voltage, said difference voltage being applied to said linear amplifier to produce said output therefrom, and switch means for disconnecting the received noise-plus-signal waveform when the output from said variable gain means exceeds a preset threshold level.

Claim 3

Blanking apparatus as set forth in claim 1 wherein said linear amplifier includes a field effect transistor.

Claim 4

Blanking apparatus as set forth in claim 1, wherein said percentage of time is about seven percent.

Claim 5

Blanking circuit means suitable for interrupting switch means through which a received noise-plus-signal waveform passes when the value of the waveform exceeds its r.m.s. value for a predetermined percentage of time, comprising variable gain means for receiving the noise-plus-signal waveform, first comparison means connected to said variable gain means for producing an output difference by which the output from said variable gain means exceeds a threshold voltage level, averaging means connected to said first comparison means for producing an average output over a selected time interval, said average voltaGe output applied to said variable gain means for controlling the gain thereof so that the r.m.s. output therefrom equals the threshold voltage level of said first comparison means, and to thereby permit the output difference from said first comparison means to occur for a predetermined percentage of the selected time interval, and second comparison means for producing an output when the output from said variable gain means exceeds a threshold voltage level higher than said threshold level of said first comparison means, the output thereof suitable for operating the switch means.

Claim 6

Blanking circuit means suitable for interrupting switch means through which a received noise-plus-signal waveform passes when the value of the waveform exceeds its r.m.s. value for a predetermined percentage of time, comprising variable gain means for receiving the noise-plus-signal waveform, first comparison means connected to said variable gain means for producing an output difference by which the output from said variable gain means exceeds a threshold voltage level, averaging means connected to said first comparison means for producing an average output over a selected time interval, said average voltaGe output applied to said variable gain means for controlling the gain thereof so that the r.m.s. output therefrom equals the threshold voltage level of said first comparison means, and to thereby permit the output difference from said first comparison means to occur for a predetermined percentage of the selected time interval, and second comparison means for producing an output when the output from said variable gain means exceeds a threshold voltage level higher than said threshold level of said first comparison means, the output thereof suitable for operating the switch means.

Claim 7

Adaptive receiver blanking means for establishing automatic gain control to a received signal-plus-noise waveform and interrupting said waveform during periods of high impulse noise, comprising variable gain means connected to receive the input signal-plus-noise waveform and controllable by an applied control voltage for producing a controlled output level, first bipolar, level-comparator means for producing a rectangular pulse during the time the controlled output level exceeds a first fixed voltage level, voltage averaging means connected to receive the rectangular pulses from said first bipolar, level-comparator means for producing an average voltage, said control voltage applied to said variable gain means being a function of said average voltage, second bipolar, level comparator means for producing an output when said controlled level output from said variable gain means exceeds a third fixed voltage level, said third fixed voltage level being higher than said first fixed voltage level, and switching means operably connected for interrupting said received signal-plus-noise waveform when there is an output from said second bipolar, level-comparator means.

Claim 8

Adaptive receiver blanking means for establishing automatic gain control to a received signal-plus-noise waveform and interrupting said waveform during periods of high impulse noise, comprising variable gain means connected to receive the input signal-plus-noise waveform and controllable by an applied control voltage for producing a controlled output level, first bipolar, level-comparator means for producing a rectangular pulse during the time the controlled output level exceeds a first fixed voltage level, voltage averaging means connected to receive the rectangular pulses from said first bipolar, level-comparator means for producing an average voltage, said control voltage applied to said variable gain means being a function of said average voltage, second bipolar, level comparator means for producing an output when said controlled level output from said variable gain means exceeds a third fixed voltage level, said third fixed voltage level being higher than said first fixed voltage level, and switching means operably connected for interrupting said received signal-plus-noise waveform when there is an output from said second bipolar, level-comparator means.

Claim 9

Adaptive receiver blanking means for establishing automatic gain control to a received signal-plus-noise waveform and interrupting said waveform during periods of high impulse noise, comprising variable gain means connected to receive the input signal-plus-noise waveform and controllable by an applied control voltage for producing a controlled output level, first bipolar, level-comparator means for producing a rectangular pulse during the time the controlled output level exceeds a first fixed voltage level, voltage averaging means connected to receive the rectangular pulses from said first bipolar, level-comparator means for producing an average voltage over a fixed duty cycle, voltage comparison means for producing a voltage difference between a second fixed voltage level and the average voltage from said voltage averaging means, said voltage difference being applied as said control voltage to said variable gain means, second bipolar, level-comparator means for producing an output when said controlled level output from said variable gain means exceeds a third fixed voltage level, said third fixed voltage level being higher than said first fixed voltage level, and switching means operably connected for interrupting said received signal-plus-noise waveform when there is an output from said second bipolar, level-comparator means.

Claim 10

Adaptive receiver blanking means for establishing automatic gain control to a received signal-plus-noise waveform and interrupting said waveform during periods of high impulse noise, comprising variable gain means connected to receive the input signal-plus-noise waveform and controllable by an applied control voltage for producing a controlled output level, first bipolar, level-comparator means for producing a rectangular pulse during the time the controlled output level exceeds a first fixed voltage level, voltage averaging means connected to receive the rectangular pulses from said first bipolar, level-comparator means for producing an average voltage over a fixed duty cycle, voltage comparison means for producing a voltage difference between a second fixed voltage level and the average voltage from said voltage averaging means, said voltage difference being applied as said control voltage to said variable gain means, second bipolar, level-comparator means for producing an output when said controlled level output from said variable gain means exceeds a third fixed voltage level, said third fixed voltage level being higher than said first fixed voltage level, and switching means operably connected for interrupting said received signal-plus-noise waveform when there is an output from said second bipolar, level-comparator means.