US5068899A
Expired / Lapsed
US
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Transmission of wideband speech signals
Assignee: Nortel Networks Ltd
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Filing: 1985-04-08
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Granted: 1991-11-26
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Expires: 2005-04-08
Abstract
Abstract Speech signal components in a high band of frequencies between 4 and 8 kHz are transmitted via a digital transmission channel, which carries speech signal samples at frequencies below 4 kHz and sampled at a rate of 8 kHz, by replacing the least significant bit of the samples with bits of information derived from the high band by linear predictive coding. These information bits are transmitted in frames, each frame comprising a synchronizing bit and bits representing the power of and a set of filter coefficients for the high band signal components occurring in a period corresponding to the frame duration. Each such bit is transmitted redundantly three or six times in view of bit stealing techniques already used for signalling on digital transmission links. The resulting wideband speech signal transmission is compatible with existing limited bandwidth voice channel transmission arrangements.
Inventors
- 👤 John G. Ellis
- 👤 Bruce L. Townsend
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 04:56
CPC Classifications
G; G10; G10L; G10L19/00; G10L19/04; G10L19/06; H; H04; H04B; H04B1/00; H04B1/66; H04B1/667; H04J; H04J3/00; H04J3/16; H04J3/1682; H04J3/1688
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
88 words
A method of transmitting components of a signal in a high band of frequencies, above a predetermined frequency, on a digital transmission channel which carries components of the signal in a low band of frequencies, below the predetermined frequency, in the form of signal samples sampled at a rate of twice the predetermined frequency, comprising the steps of: deriving from the signal bits of information relating to the high band signal components; and transmitting said bits of information in place of the least significant bit of the samples.
Claim 2
Independent Claim
88 words
A method of transmitting components of a signal in a high band of frequencies, above a predetermined frequency, on a digital transmission channel which carries components of the signal in a low band of frequencies, below the predetermined frequency, in the form of signal samples sampled at a rate of twice the predetermined frequency, comprising the steps of: deriving from the signal bits of information relating to the high band signal components; and transmitting said bits of information in place of the least significant bit of the samples.
Claim 3
Dependent Claim
28 words
A method as claimed in claim 1 wherein each of said bits is transmitted redundantly in place of the least significant bit of a plurality of consecutive samples.
Claim 4
Dependent Claim
26 words
A method as claimed in claim 1 wherein each of said bits is transmitted redundantly in place of the least significant bit of three consecutive samples.
Claim 5
Dependent Claim
26 words
A method as claimed in claim 1 wherein each of said bits is transmitted redundantly in place of the least significant bit of six consecutive samples.
Claim 6
Dependent Claim
73 words
A method as claimed in claim 1 wherein said bits of information relating to the high band signal components are transmitted in frames of the replaced least significant bits of the samples, each frame comprising a frame synchronizing bit and a plurality of information bits, each frame having a predetermined duration, and the information bits in each frame relating to high band components which occur during a period corresponding to said predetermined duration.
Claim 7
Dependent Claim
24 words
A method as claimed in claim 5 wherein the plurality of information bits in each frame include bits representing a plurality of filter coefficients.
Claim 8
Dependent Claim
29 words
A method as claimed in claim 6 wherein the plurality of information bits in each frame further include bits representing a power level of the high band signal components.
Claim 9
Dependent Claim
28 words
A method as claimed in claim 6 wherein the bits representing the plurality of filter coefficients are produced by linear predictive coding of the high band signal components.
Claim 10
Dependent Claim
34 words
A method as claimed in claim 5 wherein the frame synchronizing and information bits are each transmitted redundantly in each frame in place of the least significant bit of a plurality of consecutive samples.
Claim 11
Dependent Claim
29 words
A method as claimed in claim 5 wherein the frame synchronizing and information bits are each transmitted redundantly in place of the least significant bit of three consecutive samples.
Claim 12
Dependent Claim
29 words
A method as claimed in claim 9 wherein the frame synchronizing and information bits are each transmitted redundantly in place of the least significant bit of six consecutive samples.
Claim 13
Dependent Claim
26 words
A method as claimed in claim 10 wherein the predetermined frequency is 4 kHz and the digital transmission channel has a bit rate of 64 kbit/s.
Claim 14
Dependent Claim
26 words
A method as claimed in claim 11 wherein the predetermined frequency is 4 kHz and the digital transmission channel has a bit rate of 64 kbit/s.
Claim 15
Independent Claim
65 words
A method of transmitting components, at frequencies above 4 kHz, of a speech signal on a digital transmission channel via which eight-bit samples of the speech signal at a sampling rate of 8 kHz are transmitted, comprising the step of replacing an eighth least significant bit of each sample with a bit of information derived from the speech signal components at frequencies above 4 kHz.
Claim 16
Independent Claim
65 words
A method of transmitting components, at frequencies above 4 kHz, of a speech signal on a digital transmission channel via which eight-bit samples of the speech signal at a sampling rate of 8 kHz are transmitted, comprising the step of replacing an eighth least significant bit of each sample with a bit of information derived from the speech signal components at frequencies above 4 kHz.
Claim 17
Dependent Claim
102 words
Apparatus for transmitting signal components of a speech signal in high and low bands of frequencies respectively above and below a predetermined frequency, comprising: means for producing digital samples of speech signal components in the low band at a sampling rate of twice the predetermined frequency for transmission, each sample comprising eight bits including a least significant bit; means for producing, from the speech signal, bits of information relating to speech signal components in the high band; and means for replacing the least significant bit of each sample with a bit of information relating to speech signal components in the high band.
Claim 18
Dependent Claim
102 words
Apparatus for transmitting signal components of a speech signal in high and low bands of frequencies respectively above and below a predetermined frequency, comprising: means for producing digital samples of speech signal components in the low band at a sampling rate of twice the predetermined frequency for transmission, each sample comprising eight bits including a least significant bit; means for producing, from the speech signal, bits of information relating to speech signal components in the high band; and means for replacing the least significant bit of each sample with a bit of information relating to speech signal components in the high band.
Claim 19
Dependent Claim
28 words
Apparatus as claimed in claim 15 wherein the means for producing bits of information relating to speech signal components in the high band comprises linear predictive coding means.
Claim 20
Dependent Claim
63 words
Apparatus as claimed in claim 15 wherein the means for replacing the least significant bit of each sample with a bit of information relating to speech signal components in the high band comprises means for replacing the least significant bit of each of a plurality of consecutive samples with the same bit of information relating to speech signal components in the high band.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-11-25 | 1995-05-27 | 1995-11-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-11-25 | 1999-05-27 | 1999-11-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-11-25 | 2003-05-27 | 2003-11-26 | $7700.00 | Window Closed / Lapsed |