GB1593835A - Reduction of adjacent channel interference in stereo receivers - Google Patents
Reduction of adjacent channel interference in stereo receivers Download PDFInfo
- Publication number
- GB1593835A GB1593835A GB17759/80A GB1775980A GB1593835A GB 1593835 A GB1593835 A GB 1593835A GB 17759/80 A GB17759/80 A GB 17759/80A GB 1775980 A GB1775980 A GB 1775980A GB 1593835 A GB1593835 A GB 1593835A
- Authority
- GB
- United Kingdom
- Prior art keywords
- stereo
- signal
- phase
- sum
- develop
- 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
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
- H04H20/44—Arrangements characterised by circuits or components specially adapted for broadcast
- H04H20/46—Arrangements characterised by circuits or components specially adapted for broadcast specially adapted for broadcast systems covered by groups H04H20/53-H04H20/95
- H04H20/47—Arrangements characterised by circuits or components specially adapted for broadcast specially adapted for broadcast systems covered by groups H04H20/53-H04H20/95 specially adapted for stereophonic broadcast systems
- H04H20/49—Arrangements characterised by circuits or components specially adapted for broadcast specially adapted for broadcast systems covered by groups H04H20/53-H04H20/95 specially adapted for stereophonic broadcast systems for AM stereophonic broadcast systems
-
- 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
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/1646—Circuits adapted for the reception of stereophonic signals
- H04B1/1661—Reduction of noise by manipulation of the baseband composite stereophonic signal or the decoded left and right channels
Description
PATENT SPECIFICATION
( 11) 1 593 835 21) Application No 17759/80 ( 22) Filed 18 Jan 1978 ( 19) 52) Divided out of No 1 593 834 // 1) Convention Application No 764476 ( 32) Filed 31 Jan 1977 in x 3) United States of America (US)
$ 4) Complete Specification published 22 July 1981
51) INT CL 3 H 04 H 5/00 2) Index at acceptance H 4 R ST ( 54) REDUCTION OF ADJACENT CHANNEL INTERFERENCE IN STEREO RECEIVERS ( 71) I, LEONARD RICHARD KAHN, a citizen of the United States of America, of 137 East 36th Street, New York City, State of New York, United States of America, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:-
This invention relates to the reduction of adjacent channel interference in the phase shift type of independent sideband AM stereo signal receivers.
This application is divided out from parent Patent Application No 1919/78 (Serial No 1593834) The parent application discloses and claims a method of reducing adjacent channel interference in the reception of an independent type sideband type AM stereo signal, comprising:
(a) obtaining a measure of the level of the received adjacent channel interference in the demodulated upper sideband of said sereo signal; (b) obtaining a measure of the level of the received adjacent channel interference in the demodulated lower sideband of said stereo signal; and (c) in response to said measures, automatically reducing the audio frequency response of the stereo channel having the greater level of adjacent channel interference whenever said level exceeds a predetermined level.
The parent Application also discloses and claims a receiver.
In accordance with the present invention there is provided a phase shift type of stereo receiver for reception of an independent RF sideband AM stereo signal having a stereo difference signal component which has an effective upper stereo frequency limit, said receiving comprising:
(a) means for receiving a said signal and for converting the received signal to an intermediate frequency (IF) signal; (b) means responsive to said IF signal, for demodulating said signal to develop a stereo sum and a stereo difference signal; (c) means for shifting the relative phase of said stereo sum and difference signals to develop a pair of phase-shifted stereo sum and difference signals having a substantially quadrature phase relationship for audio frequencies lying within a predetermined frequency band extending above said upper stereo frequency limit; and (d) means responsive to said phaseshifted stereo sum and difference signals for combining said signals to develop a pair of output stereo signals suitable for application to separate stereo audio frequency amplifying and reproducing apparatus, whereby the adverse effects of adjacent channel interference will be reduced by the "cocktail party effect".
The "cocktail party effect" is that effect that allows a binaural listener to separate speech arriving from two different talkers and pay more attention to one of the talkers.
This invention is especially useful for reception of the type of stereo signal in which the carrier is amplitude modulated by the stereo summation, L +R, intelligence and simultaneously phase modulated with the stereo difference, L-R, intelligence.
Such a stereo wave is described in detail in U S Patents Nos 3,218,393 and 3,908,090 (British Patents Nos 970,051 and 1,509,212) for example.
In a preferred embodiment of the present invention a receiver for such a stereo wave is designed to accentuate the cocktail party effect This is accomplished by providing selected characteristics for the phase shift sideband separation device which operates at the intermediate frequency and is fed by a super-heterodyne type circuit The phase shift separation device, unlike a normal stereo receiver, would provide substantial separation for adjacent channel interference signal components falling above 5 kilohertz which is normally the acceptable high frequency range of stereo separated components BY connecting the output of the phase shift sideband separation device to means for separately amplifying the audio outputs of the sideband separation device, 00 e:
m:
( 2 ( 3 ( 2 ( 4 (S ( 5 1,593,835 the interference components for one sideband can be caused to fall at one stereo loudspeaker, whereas the adjacent channel interference associated with the other sideband would fall at the second stereo speaker.
The desired stereo components would generally range in between the two speakers, as is normal for the stereo illusion.
In the development of the AM stereo system, as described in U S Patents Nos.
3,218,393; 3,908,090; 3,947,749; and 4,018,994 (British Patent No 1,516,433), the phase shift networks utilized in the receiver provided reasonably good separation; i e 20 db or more from 200 hertz to 5,000 herz However, the overall monophonic frequency response of the receiver was somewhat greater, i e.
up to 10 kilohertz The reason circuitry providing separation for the higher frequencies was not provided was that there is little stereo information provided by the high frequency sounds if sufficient information is located in the low and middle range for a listener to identify location.
Therefore, because of economic and othe reaons, the separation was limited to approximately 200 hertz to 5,000 hertz as above mentioned which approximately matched the separation characteristics of the stereo transmitter, that is the transmitted stereo signal had a stereo difference component having an effective upper stereo frequency limit.
In accordance with the present invention, it is desirable to provide relatively good separation for the full high frequency response of the receiver so that full use may be made of the cocktail party effect However, the separation need not be very great for the listener to be able to discriminate against the interference Generally a 10 db separation figure is adequate.
For details of a complete receiver attention is drawn to the parent Patent Application No 1919/78 (Serial No 1593834) and to the U S and British Patents specifically referred to herein For details as to the construction of phase shift networks see "Normalized Design of 900 Phase-Difference Networks" by S D Bedrosian in IRE Transactions of the Professional Group on Circuit Theory" Vol CP-7, No 2, at pages 128-136 (June 1960) and the biographical references therein.
Claims (2)
1 A phase shift type of stereo receiver for reception of an independent RF sideband AM stereo signal having a stereo difference signal component which has an effective upper stereo frequency limit, said receiver comprising:
(a) means for receiving a said signal and for converting the received signal to an intermediate frequency (IF) signal; (b) means responsive to said IF signal, for demodulating said signal to develop a stereo sum and a stereo difference signal; (c) means for shifting the relative phase of said stereo sum and difference signals to develop a pair of phase-shifted stereo sum and difference signals having a substantially quadrature phase relationship for audio frequencies lying within a predetermined frequency band extending above said upper stereo frequency limit; and (d) means responsive to said phase shifted stereo sum and difference signals for combinining said signals to develop a pair of output stereo signals suitable for application to separate stereo audio frequency amplifying and reproducing apparatus, whereby the adverse effects of adjacent channel interference will be reduced by the "cocktail party effect".
2 A phase shift type of stereo receiver as claimed in claim 1 wherein said means for shifting the relative phase of said stereo sum and difference signals operates to develop a pair of phase-shifted stereo sum and difference signals having a substantially quadrature phase relationship for audio frequencies lying within a predetermined frequency band extending up to at least 10 kilohertz.
MICHAEL BURNSIDE & PARTNERS, Chartered Patent Agents, 2 Serjeants' Inn, Fleet Street, London EC 4 Y IHL.
Agents for the Applicants.
Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon), Ltd -1981.
Published at The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US76447677A | 1977-01-31 | 1977-01-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1593835A true GB1593835A (en) | 1981-07-22 |
Family
ID=25070842
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB17759/80A Expired GB1593835A (en) | 1977-01-31 | 1978-01-18 | Reduction of adjacent channel interference in stereo receivers |
| GB1919/78A Expired GB1593834A (en) | 1977-01-31 | 1978-01-18 | Reduction of adjacent channel interference |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1919/78A Expired GB1593834A (en) | 1977-01-31 | 1978-01-18 | Reduction of adjacent channel interference |
Country Status (14)
| Country | Link |
|---|---|
| JP (2) | JPS5396702A (en) |
| AU (1) | AU513310B2 (en) |
| BR (1) | BR7800554A (en) |
| CA (1) | CA1127717A (en) |
| DE (1) | DE2803979A1 (en) |
| FR (1) | FR2379192A1 (en) |
| GB (2) | GB1593835A (en) |
| IL (2) | IL53821A (en) |
| IT (1) | IT1192325B (en) |
| MX (2) | MX150961A (en) |
| NL (1) | NL187883C (en) |
| NZ (1) | NZ186319A (en) |
| SE (1) | SE420881B (en) |
| SU (1) | SU976864A3 (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3005537A1 (en) * | 1980-02-14 | 1981-08-20 | Wolf, Max, 8103 Oberammergau | Transmission system with line fault rectifying circuit - splits HF into two symmetrical sections supplied to comparator controlling logic |
| US4653095A (en) * | 1986-02-06 | 1987-03-24 | Kahn Leonard R | AM stereo receivers having platform motion protection |
| JPH0232248U (en) * | 1988-08-24 | 1990-02-28 | ||
| US5222255A (en) * | 1991-08-05 | 1993-06-22 | Ford Motor Company | Intermodulation controller for radio receiver |
| US5307515A (en) * | 1991-08-05 | 1994-04-26 | Ford Motor Company | Adjacent channel controller for radio receiver |
| DE4241362C2 (en) * | 1992-12-09 | 1997-06-05 | Blaupunkt Werke Gmbh | Radio receiver |
| DE10116358A1 (en) * | 2001-04-02 | 2002-11-07 | Micronas Gmbh | Device and method for the detection and suppression of faults |
| DE10141394A1 (en) * | 2001-08-23 | 2003-03-13 | Siemens Ag | Method for filtering a radio signal to prepare for an EDGE signal calculates signal-to-noise ratios to detect neighboring channel interference during filtering prior to producing a desired signal. |
| CN100367677C (en) | 2001-08-23 | 2008-02-06 | 西门子公司 | Adaptive filtering method and filter for filtering a radio signal in a mobile radio-communication system |
| JP2004347474A (en) * | 2003-05-22 | 2004-12-09 | Sharp Corp | Mobile navigation system |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3218393A (en) * | 1960-02-11 | 1965-11-16 | Leonard R Kahn | Compatible stereophonic transmission and reception systems, and methods and components characterizing same |
| DE1938838C3 (en) * | 1969-07-28 | 1979-06-13 | Matsushita Electric Industrial Co., Ltd., Kadoma, Osaka (Japan) | Noise reduction system |
| JPS5225681B1 (en) * | 1970-12-11 | 1977-07-09 | ||
| US3944749A (en) * | 1972-05-10 | 1976-03-16 | Kahn Leonard R | Compatible AM stereophonic receivers involving sideband separation at IF frequency |
| US3908090A (en) * | 1972-05-10 | 1975-09-23 | Leonard R Kahn | Compatible AM stereophonic transmission system |
| US3973203A (en) * | 1972-09-13 | 1976-08-03 | Kahn Leonard R | Carrier isolation system |
| US4018994A (en) * | 1974-07-10 | 1977-04-19 | Kahn Leonard R | Compatible AM stereophonic receivers |
| US3947749A (en) * | 1975-01-31 | 1976-03-30 | Hitachi, Ltd. | Apparatus for generating high voltage for cathode-ray tube |
-
1978
- 1978-01-16 IL IL53821A patent/IL53821A/en unknown
- 1978-01-18 GB GB17759/80A patent/GB1593835A/en not_active Expired
- 1978-01-18 GB GB1919/78A patent/GB1593834A/en not_active Expired
- 1978-01-19 CA CA295,324A patent/CA1127717A/en not_active Expired
- 1978-01-20 AU AU32588/78A patent/AU513310B2/en not_active Expired
- 1978-01-25 NZ NZ186319A patent/NZ186319A/en unknown
- 1978-01-27 FR FR7802334A patent/FR2379192A1/en active Granted
- 1978-01-30 IT IT67175/78A patent/IT1192325B/en active
- 1978-01-30 JP JP920678A patent/JPS5396702A/en active Granted
- 1978-01-30 BR BR787800554A patent/BR7800554A/en unknown
- 1978-01-30 SU SU782573752A patent/SU976864A3/en active
- 1978-01-30 SE SE7801100A patent/SE420881B/en not_active IP Right Cessation
- 1978-01-30 DE DE19782803979 patent/DE2803979A1/en active Granted
- 1978-01-31 NL NLAANVRAGE7801097,A patent/NL187883C/en not_active IP Right Cessation
- 1978-01-31 MX MX172262A patent/MX150961A/en unknown
- 1978-01-31 MX MX192948A patent/MX158303A/en unknown
-
1980
- 1980-04-03 IL IL59757A patent/IL59757A0/en unknown
-
1985
- 1985-05-29 JP JP60116341A patent/JPS6121636A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| CA1127717A (en) | 1982-07-13 |
| DE2803979A1 (en) | 1978-08-03 |
| AU513310B2 (en) | 1980-11-27 |
| IL59757A0 (en) | 1980-06-30 |
| IT7867175A0 (en) | 1978-01-30 |
| SE7801100L (en) | 1978-08-01 |
| GB1593834A (en) | 1981-07-22 |
| NL7801097A (en) | 1978-08-02 |
| NZ186319A (en) | 1983-11-18 |
| FR2379192B1 (en) | 1984-02-24 |
| FR2379192A1 (en) | 1978-08-25 |
| JPS6214974B2 (en) | 1987-04-04 |
| JPS6341254B2 (en) | 1988-08-16 |
| JPS6121636A (en) | 1986-01-30 |
| JPS5396702A (en) | 1978-08-24 |
| AU3258878A (en) | 1979-07-26 |
| MX158303A (en) | 1989-01-20 |
| IL53821A (en) | 1980-10-26 |
| DE2803979C2 (en) | 1988-09-15 |
| SU976864A3 (en) | 1982-11-23 |
| BR7800554A (en) | 1979-02-13 |
| IT1192325B (en) | 1988-03-31 |
| NL187883C (en) | 1992-02-03 |
| IL53821A0 (en) | 1978-04-30 |
| SE420881B (en) | 1981-11-02 |
| MX150961A (en) | 1984-08-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed [section 19, patents act 1949] | ||
| PE20 | Patent expired after termination of 20 years |
Effective date: 19980117 |