Abstract In an improved speech compressor which provides frequency transformation by passing speech signals through an analog shift register and controlling the shift rate of the register with a varying period, the control of the sample period and output blanking is improved by automatically initiating reset as soon as a zero crossing of the signal is detected within the enable blank interval. Thus, discard of information in the line and refilling of the line with the next initial portion of the sample signal will occur as soon as the detected zero crossing within the enable period blanks the output and the effective blanked period will thereby be shortened to the extent that a zero crossing is detected prior to the regular termination point of the ramp controlled voltage.
In a speech compression-expansion system having variable delay line means repetitively varied to provide frequency transformation of signals passing through the line the combination comprising: means for sensing zero crossing points on said signal at the output of said line; enabling means for establishing an interval at the end of each repetitive variation; blanking means responsive to detection of a zero crossing within said interval and if no such zero crossing is detected responsive to the end of said interval for blanking the output of said line; and means responsive to the inititiation of said blanking for resetting said variation to start the next repetitive Variation of said line.
Claim 2
Dependent Claim
109 words
In a speech compression-expansion system having variable delay line means repetitively varied to provide frequency transformation of signals passing through the line the combination comprising: means for sensing zero crossing points on said signal at the output of said line; enabling means for establishing an interval at the end of each repetitive variation; blanking means responsive to detection of a zero crossing within said interval and if no such zero crossing is detected responsive to the end of said interval for blanking the output of said line; and means responsive to the inititiation of said blanking for resetting said variation to start the next repetitive Variation of said line.
Claim 3
Dependent Claim
40 words
Apparatus according to claim 1 in which said delay line means comprises an analog shift register with controlled shift period and said resetting includes initiation of shifting of signal samples into said register at the beginning of said blanking interval.
Claim 4
Dependent Claim
36 words
Apparatus according to claim 2 in which said blanking is maintained after the start of the next repetitive variation of said line at least until the shifting of signal samples into said register fills said register.
Claim 5
Dependent Claim
27 words
Apparatus according to claim 3 in which said blanking is terminated upon the detection of a zero crossing in said signal after said shifting fills said register.