US4034160A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for the transmission of speech signals
Assignee: US Philips Corp
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Filing: 1976-03-05
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Granted: 1977-07-05
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Expires: 1996-03-05
Abstract
Abstract A speech bandwidth compression system uses a first set of filters to separate the speech signal into baseband (300-800 hz) and highband (800-3200 hz) signals. The baseband (first formant or fundamental pitch frequency) is transmitted directly, and is also rectified to form harmonics which are mixed with the highband signals in a second set of (paired digital) filters which form sine and cosine forms (amplitude and phase information) of the harmonic components, which are then multiplexed for transmission to a receiver which provides the corresponding bandwidth expansion system to reconstruct the original speech signal.
Inventors
- 👤 Petrus Josephus van Gerwen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:13
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/66; H04B1/667
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
189 words
A speech transmission system comprising a band compressor including a baseband channel means for transmitting a baseband of speech signals located in a lower speech frequency range, a plurality of parallel band compressor channel means for band compression of successive sub-bands of speech signals above said lower range, means having an input coupled to said base-band channel and an output coupled to said band compressor channels for generating components in said sub-bands of said speech frequency range, a plurality of parallel reference channel means for generating reference frequency components in the same sub-bands as said compressor sub-bands, at least one of said plurality of channels comprising a frequency analyzer coupled to said component generator and having for each sub-band first and second sub-bandpass filters with the same amplitude frequency characteristics and differing phase-frequency characteristics, each of said band compressor channels including a comparator having a first input means for receiving a constant amplitude signal from said component generating means, a second input coupled to the respective reference channel to receive said reference signal components and an output means for providing phase and amplitude data characteristics of the respective sub-bands.
Claim 2
Dependent Claim
189 words
A speech transmission system comprising a band compressor including a baseband channel means for transmitting a baseband of speech signals located in a lower speech frequency range, a plurality of parallel band compressor channel means for band compression of successive sub-bands of speech signals above said lower range, means having an input coupled to said base-band channel and an output coupled to said band compressor channels for generating components in said sub-bands of said speech frequency range, a plurality of parallel reference channel means for generating reference frequency components in the same sub-bands as said compressor sub-bands, at least one of said plurality of channels comprising a frequency analyzer coupled to said component generator and having for each sub-band first and second sub-bandpass filters with the same amplitude frequency characteristics and differing phase-frequency characteristics, each of said band compressor channels including a comparator having a first input means for receiving a constant amplitude signal from said component generating means, a second input coupled to the respective reference channel to receive said reference signal components and an output means for providing phase and amplitude data characteristics of the respective sub-bands.
Claim 3
Dependent Claim
74 words
A transmission system as claimed in claim 1, wherein the frequency analyser having for each sub-band a first and a second sub-bandpass filter with the same amplitude-frequency characteristics having a relative phase difference comprises a delay circuit and a plurality of weighting networks, one end of each of these weighting networks being connected to a point of a respective delay time in the delay circuit, and a summing circuit coupled to the remaining ends.
Claim 4
Dependent Claim
33 words
A transmission system as claimed in claim 2, wherein the first and second sub-bandpass filters for the same sub-band in the frequency analyser have phase-frequency characteristics having a relative phase difference of π/2.
Claim 5
Dependent Claim
74 words
A transmission system as claimed in claim 1, wherein the comparator in the band compressor comprises a first and a second modulator, said modulators being controlled by the frequency components of constant amplitude from the component generator and by the frequency components in the relevant sub-band of the original speech signal, a pair of low pass filter means coupled to said modulators respectively for providing the phase and amplitude data of the relevant sub-band.
Claim 6
Dependent Claim
68 words
A transmission system as claimed in claim 1, wherein the band compressor further comprises a consonant detector fed by the speech signals to be transmitted, a noise generator, an electronic switch means controlled by the consonant detector for connecting the component generator in response to a vowel and for connecting said noise generator in response to a consonant to the input of the plurality of band compressor channels.
Claim 7
Dependent Claim
47 words
A transmission system as claimed in claim 1, wherein the base-band channel in the band compressor and a baseband channel in a receiver band expander together comprise a synchronization circuit for the mutual synchronization of the component generators in the band compressor and in the band expander.
Claim 8
Dependent Claim
28 words
A transmission system as claimed in claim 1, wherein the remaining plurality of channels further comprises an additional frequency analyser having only one sub-bandpass filter for each sub-band.
Claim 9
Dependent Claim
38 words
A transmission system as claimed in claim 1, further comprising a limiter circuit means for obtaining the constant amplitude value of the frequency components including separate limiters which are connected to the sub-bandpass filters of the frequency analyser.
Claim 10
Dependent Claim
36 words
A transmission system as claimed in claim 8, wherein the baseband signal comprises the first formant frequency range, and the component generator connected to the baseband channel comprises a frequency distorter which includes a non-linear circuit.
Claim 11
Dependent Claim
32 words
A transmission system as claimed in claim 1 further comprising a limiting circuit means for obtaining the constant amplitude value of all frequency components comprising a common limiter in the component generator.
Claim 12
Dependent Claim
18 words
A transmission system as claimed in claim 10, wherein the component generator comprises a fundamental tone pulse generator.
Claim 13
Dependent Claim
42 words
A transmission system as claimed in claim 4, wherein the component generator comprises a fundamental tone pulse generator, the output signal of the fundamental tone pulse generator being supplied direct to the two modulators of the comparator, said modulators comprising switching modulators.
Claim 14
Dependent Claim
42 words
A transmission system as claimed in claim 12, further comprising a delay circuit coupled between the fundamental tone pulse generator and the comparator and having a delay time equal to the delay time of a frequency analyser in a receiver band expander.
Claim 15
Dependent Claim
46 words
A transmission system as claimed in claim 4, further comprising a common limiter disposed in the component generator to obtain a constant amplitude value of all frequency components, the original speech signal being supplied direct to two modulators of the comparator, said modulators comprising product modulators.
Claim 16
Dependent Claim
116 words
A receiver for band compressed speech signals comprising a band expander including a baseband channel, a plurality of a sub-band expander channels, means having an input coupled to said baseband channel and an output coupled to said expander channels for generating components in said subbands, a frequency analyzer coupled to said component generator and having for each sub-band first and second sub-bandpass filters with the same amplitude-frequency characteristics and differing phase frequency characteristics, and a modulator circuit having a first input means for receiving a constant amplitude signal from said component generator, a second input means for receiving reference phase and amplitude data, and an output means for supplying a portion of the original speech signal.
Claim 17
Dependent Claim
116 words
A receiver for band compressed speech signals comprising a band expander including a baseband channel, a plurality of a sub-band expander channels, means having an input coupled to said baseband channel and an output coupled to said expander channels for generating components in said subbands, a frequency analyzer coupled to said component generator and having for each sub-band first and second sub-bandpass filters with the same amplitude-frequency characteristics and differing phase frequency characteristics, and a modulator circuit having a first input means for receiving a constant amplitude signal from said component generator, a second input means for receiving reference phase and amplitude data, and an output means for supplying a portion of the original speech signal.
Claim 18
Dependent Claim
62 words
A receiver as claimed in claim 15 wherein the modulator circuit in the band expander comprises a first and a second modulator, said modulators being controlled by frequency components of constant amplitude from the component generator and by the phase and amplitude data belonging to the relevant sub-band, and a summing circuit means connected to the modulators for providing the recovered sub-band.
Claim 19
Dependent Claim
54 words
A receiver as claimed in claim 15 characterized in that the frequency analyser comprises a delay circuit and a plurality of weighting networks, one end of each of these weighting networks being connected to a point of a respective delay time in the delay circuit, and a summing circuit coupled to the remaining end.
Claim 20
Dependent Claim
32 words
A receiver as claimed in claim 17, wherein the first and second sub-bandpass filters for the same sub-band in the frequency analyzer have phase-frequency characteristics having a relative phase difference of π/2.
Claim 21
Dependent Claim
54 words
A receiver as claimed in claim 15, wherein the band expander includes a noise generator, electronic switch means controlled by the baseband channel for connecting the component generator in response to a vowel and for connecting said noise generator in response to a consonant to the input of the plurality of band expander channels.
Claim 22
Dependent Claim
46 words
A receiver as claimed in claim 15, wherein a base-band channel in a transmitter band compressor and the base-band channel in the band expander together comprise a synchronization circuit for the mutual synchronization of the component generators in the band compressor and in the band expander.
Claim 23
Dependent Claim
37 words
A receiver as claimed in claim 15, further comprising a limiter circuit means for obtaining the constant amplitude value of the frequency components including separate limiters which are connected to the sub-bandpass filters of the frequency analyser.
Claim 24
Dependent Claim
35 words
A receiver as claimed in claim 21, wherein the baseband signal comprises the first formant frequency range, and the component generator connected to the baseband channel comprises a frequency distorter which includes a non-linear circuit.
Claim 25
Dependent Claim
31 words
A receiver as claimed in claim 15, further comprising a limiting circuit means for obtaining the constant amplitude value of all frequency components comprising a common limiter in the component generator.
Claim 26
Dependent Claim
17 words
A receiver as claimed in claim 23, wherein the component generator comprises a fundamental tone pulse generator.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-04 | 1981-01-03 | 1981-07-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-04 | 1985-01-03 | 1985-07-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-04 | 1989-01-03 | 1989-07-05 | $7700.00 | Window Closed / Lapsed |