GB1424133A - Transmission of wide-band sound signals - Google Patents
Transmission of wide-band sound signalsInfo
- Publication number
- GB1424133A GB1424133A GB578073A GB578073A GB1424133A GB 1424133 A GB1424133 A GB 1424133A GB 578073 A GB578073 A GB 578073A GB 578073 A GB578073 A GB 578073A GB 1424133 A GB1424133 A GB 1424133A
- Authority
- GB
- United Kingdom
- Prior art keywords
- amplitude
- signals
- frequency range
- band
- transmitted
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000005540 biological transmission Effects 0.000 title abstract 3
- 230000005236 sound signal Effects 0.000 title abstract 2
- 239000003990 capacitor Substances 0.000 abstract 3
- 230000006835 compression Effects 0.000 abstract 2
- 238000007906 compression Methods 0.000 abstract 2
- 238000000034 method Methods 0.000 abstract 1
- 238000005070 sampling Methods 0.000 abstract 1
Classifications
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
- G10L21/00—Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility
- G10L21/02—Speech enhancement, e.g. noise reduction or echo cancellation
- G10L21/038—Speech enhancement, e.g. noise reduction or echo cancellation using band spreading techniques
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/66—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission for reducing bandwidth of signals; for improving efficiency of transmission
- H04B1/667—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission for reducing bandwidth of signals; for improving efficiency of transmission using a division in frequency subbands
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Computational Linguistics (AREA)
- Quality & Reliability (AREA)
- Health & Medical Sciences (AREA)
- Audiology, Speech & Language Pathology (AREA)
- Human Computer Interaction (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Reduction Or Emphasis Of Bandwidth Of Signals (AREA)
Abstract
1424133 Bandwidth reduction system INTERNATIONAL STANDARD ELECTRIC CORP 22 Feb 1973 [24 Feb 1972 14 April 1972 12 Oct 1972] 5780/73 Heading H4R In a transmission system for sound signals of about 20 to 15,000 Hz a lower frequency range of the signals is transmitted directly together with amplitude information in respect of a number of partial frequency ranges in the remainder of the band to be transmitted, the amplitude information being transmitted as sequential modulation of a subcarrier of frequency above the upper limit of the lower frequency range. At the receiver signals in the higher frequency range are synthesized by modulating equivalent signals, lying approximately at the centres of the partial frequency ranges, with the respective amplitude information signals recovered by demodulation of the subcarrier. As described, Fig. la, the incoming signal at 1 can be passed through an amplitude compressor 2 and split into a low frequency range, by low pass filter 3, and respective partial frequency ranges, by band pass filters 4, 5 and 6. The low frequency range is transmitted direct while the partial ranges, at the outputs of filters 4, 5 and 6, are fed to rectifiers 7, 8 and 9, to derive signals representing the amplitude of the signals in the respective ranges. The amplitude signals are transmitted by a time division sampling technique, using a switch 11. The resulting amplitude modulated pulses are fed via a pre-emphasis circuit 12 to a modulator 13 and filter 18. The modulator can provide either frequency or amplitude modulation of a carrier 14 which is in the frequency range above that transmitted by the filter 3. One pulse position in the time division multiplex cycle is utilized for a synchronizing signal provided by a negative potential source 15, the amplitude of which is also modulated to convey information as to the degree of compression provided by compressor 2. The resulting modulated signal from modulator 13 may then comprise amplitude information for the partial frequency ranges as modulation from 0 to 70%, with synchronizing pulses as modulation above 80% and compression information in the modulation range 80 to 100%. At the receiver, Fig. lb, the low frequency range is selected by filter 23, and the amplitude information carrier by filter 24. The amplitude information carrier is demodulated by demodulator 25, and passed through logarithmic de-emphasis network 26 to switch 27. The synchronizing pulses are detected by an amplitude discriminator 40 to control a clock generator 41 driving the switch 27 so that the amplitude control signals appear on the storage capacitors 28, 29, 30, and the expander control signal on capacitor 39. The amplitude control signals are used to modulate the amplitudes of the frequencies generated by oscillators 34, 35, 36, whose frequencies are set in the middle of the appropriate partial frequency ranges. The resulting signals are added to the low band signal from filter 23 in adder 37, the sum passed through expander 38, controlled by. the signal on capacitor 39, for reproduction at 42. In an alternative system, Figs. 4a and 4b (not shown), a separate sound source is split into only two bands, a low frequency band which is added to the low frequency band of a system as described above and a high frequency band convering the rest of the transmission band. The high frequency band is rectified, sampled, and the samples transmitted in time division multiplex with the partial frequency band amplitude signals. At the receiver the amplitude signal of the single high frequency range is used to modulate the output of a random noise signal, limited to the frequency range of the high frequency band, and reproduced with the low frequency and synthesized partial frequency range signals.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE2208805A DE2208805A1 (en) | 1972-02-24 | 1972-02-24 | METHOD FOR TRANSMISSION OF BROADBAND AUDIO SIGNALS |
DE19722250094 DE2250094A1 (en) | 1972-10-12 | 1972-10-12 | TRANSMISSION SYSTEM FOR TRANSMISSION OF BROADBAND SOUND SIGNALS |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1424133A true GB1424133A (en) | 1976-02-11 |
Family
ID=25762775
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB578073A Expired GB1424133A (en) | 1972-02-24 | 1973-02-22 | Transmission of wide-band sound signals |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB1424133A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1796082A1 (en) * | 2005-12-09 | 2007-06-13 | QNX Software Systems (Wavemakers), Inc. | System for improving speech intelligibility through high frequency compression |
US7813931B2 (en) | 2005-04-20 | 2010-10-12 | QNX Software Systems, Co. | System for improving speech quality and intelligibility with bandwidth compression/expansion |
US8249861B2 (en) | 2005-04-20 | 2012-08-21 | Qnx Software Systems Limited | High frequency compression integration |
-
1973
- 1973-02-22 GB GB578073A patent/GB1424133A/en not_active Expired
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7813931B2 (en) | 2005-04-20 | 2010-10-12 | QNX Software Systems, Co. | System for improving speech quality and intelligibility with bandwidth compression/expansion |
US8086451B2 (en) | 2005-04-20 | 2011-12-27 | Qnx Software Systems Co. | System for improving speech intelligibility through high frequency compression |
US8219389B2 (en) | 2005-04-20 | 2012-07-10 | Qnx Software Systems Limited | System for improving speech intelligibility through high frequency compression |
US8249861B2 (en) | 2005-04-20 | 2012-08-21 | Qnx Software Systems Limited | High frequency compression integration |
EP1796082A1 (en) * | 2005-12-09 | 2007-06-13 | QNX Software Systems (Wavemakers), Inc. | System for improving speech intelligibility through high frequency compression |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed | ||
PCNP | Patent ceased through non-payment of renewal fee |