Programmable low pass digital filter of analog signal

Claim 2

A programmable low pass digital filter of an analog signal, comprising: means receiving an input analog signal of a frequency F A for generating a binary digital signal of a frequency F A therefrom; counting means coupled to said receiving means for counting the number of cycles N A of said binary digital signal during a preset sample time T S ; comparator means coupled to said counting means for determining when said number of pulses N A is equal to a preset high N H number of pulses; programming means coupled to said comparator means for setting in said comparator means said preset high N H number of pulses that defines the minimum number of pulses that exceeds the upper limit of a preset passable low band; first memory means responsively coupled to said comparator means for generating as the alternative output signals, an output True signal or an output False signal indicating that said counting means has counted a number of pulses N A of said binary digital signal that is within or without, respectively, said preset passable low band; first gating means; means coupling said binary digital signal as a first input to said first gating means; means coupling said first memory means to said first gating means for alternatively coupling said True output signal or said False output signal as a second input to said first gating means, said True output signal or said False output signal enabling or disabling said first gating means to provide or not to provide, respectively, as an output signal therefrom said binary digital signal.

Claim 3

The digital filter of claim 1 further including: second memory means responsively coupled to said comparator means for alternatively coupling to said first memory means a True or a False state indicating that said comparator means has determined that said number of pulses N A is within or without said preset passable low band, respectively.

Claim 4

The digital filter of claim 2 further including: time base generator means for generating a continuous time base signal comprising a series of timing pulses, one pulse every sample time T S ; and, second gating means responsively coupled to said time base generator means and coupled to said first memory means for gating said True or said False state of said second memory means into said first memory means during a given one of said sample times T S .

Claim 5

The digital filter of claim 2 further including: edge detector means coupled to said receiving means for generating an edge pulse for every cycle of said binary digital signal and coupling one of said edge pulses to said binary counter for every one of the pulses of said binary digital signal.

Claim 6

A programmable low pass digital filter of an analog signal, comprising: means for receiving an input analog signal of a frequency F A for generating a binary digital signal of a frequency F A therefrom; counting means coupled to said receiving means for counting the number of pulses N A thereof during a preset sample time T S ; comparator means coupled to said counting means for determining when said number of pulses N A is equal to a preset high N H number of pulses and generating a first binary signal; programming means coupled to said comparator means for setting in said comparator means said preset high N H number of pulses and defining a preset passable low band N A <N H ; first memory means for generating as the alternative output signals an output True signal or an output False signal indicating that said counting means has counted a number of pulses N A of said binary digital signal that is within or without, respectively, said preset passable low band; second memory means responsively coupled to said comparator means for alternatively coupling to said first memory means a True or a False state as determined by said first binary signal; first gating means; means coupling said binary digital signal as a first input to said first gating means; means coupling said first memory means to said first gating means for alternatively coupling said True output signal or said False output signal as a second input to said first gating means, said True output signal or said False output signal enabling or disabling said first gating means to provide or not provide, respectively, as an output signal therefrom said binary digital signal; time base generator means for generating a continuous time base signal comprising a series of timing pulses, one pulse every sample time T S ; second gating means responsively coupled to said time base generator means and coupled to said first memory means for gating the True or the False state of said second memory means into said first memory means during a given one of said sample times T S and coupling corresponding True or False output signals from said first memory means as a second input to said first gating means during the first next following one of said sample times T S .

Claim 7

A programmable low pass digital filter of an analog signal, comprising: means for receiving an input analog signal of a frequency F A for generating a binary digital signal of a frequency F A therefrom; counting means coupled to said receiving means for counting the number of pulses N A thereof during a preset sample time T S ; comparator means coupled to said counting means for determining when said number of pulses N A is equal to a preset high N H number of pulses and generating a first binary signal; programming means coupled to said comparator means for setting in said comparator means said preset high N H number of pulses and defining a preset passable low band N A <N H ; first memory means for generating as the alternative output signals an output True signal or an output False signal indicating that said counting means has counted a number of pulses N A of said binary digital signal that is within or without, respectively, said preset passable low band; second memory means responsively coupled to said comparator means for alternatively coupling to said first memory means a True or a False state as determined by said first binary signal; first gating means; means coupling said binary digital signal as a first input to said first gating means; means coupling said first memory means to said first gating means for alternatively coupling said True output signal or said False output signal as a second input to said first gating means, said True output signal or said False output signal enabling or disabling said first gating means to provide or not provide, respectively, as an output signal therefrom said binary digital signal; time base generator means for generating a continuous time base signal comprising a series of timing pulses, one pulse every sample time T S ; second gating means responsively coupled to said time base generator means and coupled to said first memory means for gating the True or the False state of said second memory means into said first memory means during a given one of said sample times T S and coupling corresponding True or False output signals from said first memory means as a second input to said first gating means during the first next following one of said sample times T S .

Claim 8

A programmable low pass digital filter receiving an input signal of a frequency F A including: counting means for counting the number of pulses N A of said input signal during a given one of successive sample times T S and then generating during the next subsequent sample time T S a first signal if the counted number of pulses N A is less than a high number of pulses N H and then generating during said next subsequent sample time T S a second signal if the counted number of pulses N A is equal to or greater than said high number of pulses N H and thereby defining a passable low band, N A <N H ; gating means responsively coupled to said input signal and said first and second signals for passing the input signal received during said next subsequent sample time to user equipment only if the input signal was determined to be within said passable low band; said counting means including programmable means for programmably varying the higher N H number of pulses of said passable low band for programmably varying the higher F H frequency limit of said passable low band.

Claim 9

A programmable low pass digital filter receiving an input signal of a frequency F A including: counting means for counting the number of pulses N A of said input signal during a given one of successive sample times T S and then generating during the next subsequent sample time T S a first signal if the counted number of pulses N A is less than a high number of pulses N H and then generating during said next subsequent sample time T S a second signal if the counted number of pulses N A is equal to or greater than said high number of pulses N H and thereby defining a passable low band, N A <N H ; gating means responsively coupled to said input signal and said first and second signals for passing the input signal received during said next subsequent sample time to user equipment only if the input signal was determined to be within said passable low band; said counting means including programmable means for programmably varying the higher N H number of pulses of said passable low band for programmably varying the higher F H frequency limit of said passable low band.