Device for speech detection independent of amplitude

Claim 3

The method of claim 1 wherein the step of determining comprises: a. generating a reference waveform corresponding to the predetermined sign sequence; and b. comparing said reference waveform to the detected sign sequence.

Claim 4

The method of claim 1 wherein the predetermined sign sequence is one sample of one sign followed by one sample of the other sign.

Claim 5

The method of claim 3 wherein the predetermined period of time is 2 milliseconds.

Claim 6

The method of claim 2 wherein the predetermined sign sequence is 16 signs of one binary value followed by x signs of the other binary value wherein x may vary between 4 and 8.

Claim 7

The method of claim 2 wherein the predetermined sign sequence is x signs of one binary value followed by 16 signs of the other binary value wherein x may vary between 4 and 8.

Claim 8

Apparatus for detecting a speech signal in the presence of noise independent of the amplitude of said speech wherein speech signal is sampled into a plurality of samples each sample having a characteristic sign represented by a binary 1 or a binary 0, comprising: a. means for detecting the sign of each successive sample; b. means, connected to said detecting means, for determining the presence of a predetermined sequence of signs characteristic of said successive samples, said sequence comprising a mixture of the sign represented by a binary 1 and the sign represented by a binary 0; and c. means, connected to said determining means, for generating a pulse indicative of speech when said predetermined sequence of signs is present for a predetermined period of time.

Claim 9

Apparatus for detecting a speech signal in the presence of noise independent of the amplitude of said speech wherein speech signal is sampled into a plurality of samples each sample having a characteristic sign represented by a binary 1 or a binary 0, comprising: a. means for detecting the sign of each successive sample; b. means, connected to said detecting means, for determining the presence of a predetermined sequence of signs characteristic of said successive samples, said sequence comprising a mixture of the sign represented by a binary 1 and the sign represented by a binary 0; and c. means, connected to said determining means, for generating a pulse indicative of speech when said predetermined sequence of signs is present for a predetermined period of time.

Claim 10

The apparatus of claim 7 wherein said means for determining comprises: a. means for generating a reference waveform corresponding to the predetermined sign sequence; and b. means for comparing said reference waveform to the detected sign sequence.

Claim 11

The apparatus of claim 8 wherein the predetermined sign sequence is one sign of one binary value followed by one sign of the other binary value.

Claim 12

The apparatus of claim 9 wherein the predetermined period of time is 2 milliseconds.

Claim 13

The apparatus of claim 8 wherein the predetermined sign sequence is 16 signs of one binary value followed by x signs of the, other binary value, wherein x may vary between 4 and 8.

Claim 14

The apparatus of claim 8 wherein the predetermined sequence of signs is x signs of one binary value followed by 16 signs of the, other binary value wherein x may vary between 4 and 8.

Claim 17

The method of claim 13 wherein the step of generating a pulse comprises. a. generating a response signal each time said first output signal and said reference waveform correspond; b. delaying said response signal to produce a delayed response signal; c. comparing said response signal with said delayed response signal to produce a second output signal until such time as said response signal changes state; and d. detecting the duration of said second output signal.

Claim 18

The method of claim 14 wherein said predetermined minimum period is 2 milliseconds.

Claim 19

The method of claim 14 wherein said predetermined minimum period is 3 milliseconds.

Claim 20

Apparatus for detecting a speech signal in the presence of noise wherein the speech signal is sampled into a plurality of samples and each sample is digitally encoded into a pulse code modulated (PCM) word of n-bit length wherein one bit of the code word represents the sign of the speech sample, comprising: a. means for generating a reference waveform having a predetermined sign sequence; b. means for generating a clock signal phased with the sign bit of each code word; c. means for comparing said clock signal with the sign bit of each code word; d. means for generating a first output signal each time the clock signal is compared with a code word representing the same sign of the sample; e. means for comparing said first output signal and said reference waveform; and f. means for generating a pulse indicative of speech when said reference waveform and said first output signal correspond for a predetermined minimum period.

Claim 21

Apparatus for detecting a speech signal in the presence of noise wherein the speech signal is sampled into a plurality of samples and each sample is digitally encoded into a pulse code modulated (PCM) word of n-bit length wherein one bit of the code word represents the sign of the speech sample, comprising: a. means for generating a reference waveform having a predetermined sign sequence; b. means for generating a clock signal phased with the sign bit of each code word; c. means for comparing said clock signal with the sign bit of each code word; d. means for generating a first output signal each time the clock signal is compared with a code word representing the same sign of the sample; e. means for comparing said first output signal and said reference waveform; and f. means for generating a pulse indicative of speech when said reference waveform and said first output signal correspond for a predetermined minimum period.

Claim 22

The apparatus of claim 17 wherein said means for generating a pulse comprises: a. means for generating a response signal each time said first output signal and said reference signal correspond; b. means for delaying said response signal to produce a delayed response signal; c. means for comparing said response signal to said delayed response signal to produce a second output signal until such time as said response signal changes state; and d. means for detecting the duration of said second output signal.