GB932556A - Improvements relating to stereophonic sound transmission systems - Google Patents

Improvements relating to stereophonic sound transmission systems

Info

Publication number
GB932556A
GB932556A GB2727558A GB2727558A GB932556A GB 932556 A GB932556 A GB 932556A GB 2727558 A GB2727558 A GB 2727558A GB 2727558 A GB2727558 A GB 2727558A GB 932556 A GB932556 A GB 932556A
Authority
GB
United Kingdom
Prior art keywords
amplifier
filter
elongator
signals
output
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
Application number
GB2727558A
Inventor
William Spencer Percival
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EMI Ltd
Electrical and Musical Industries Ltd
Original Assignee
EMI Ltd
Electrical and Musical Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by EMI Ltd, Electrical and Musical Industries Ltd filed Critical EMI Ltd
Priority to GB2727558A priority Critical patent/GB932556A/en
Publication of GB932556A publication Critical patent/GB932556A/en
Expired legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04SSTEREOPHONIC SYSTEMS 
    • H04S1/00Two-channel systems
    • H04S1/002Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Tone Control, Compression And Expansion, Limiting Amplitude (AREA)

Abstract

932,556. Stereophonic systems. ELECTRIC & MUSICAL INDUSTRIES Ltd. Aug. 21, 1959 [Aug. 26, 1958], No. 27275/58. Class 40 (4). In a system wherein, as in that described in Specification 871,992, there are derived from sound an audio frequency signal representative of the waveshape of the sound and a control signal representative of the direction or position of the source of the sound, left and right signals VL and VR are derived from the sound and components of each of these signals in different frequency bands are individually processed to provide different parts of the control signal. A pair of crossed directional microphones 1, 2 provide the signals VL, VR which pass via preamplifiers and tone and volume control circuits to amplifiers 7, 8 of adjustable gain, the outputs of which are summed in amplifier 9 and differenced in amplifier 10. The sum and difference signals pass through phase shift networks 11 and 12 which produce a relative delay of 90 degrees between components of the respective signals over their full frequency range, the resulting signals being added in amplifier 13 to produce the composite signal VA representative of the waveshape of the sounds picked up by the microphones 1 and 2. Components of the signal VL having frequencies greater than 1,000 c/s. also pass via high-pass filter 14 to five narrow band channels, centred on the frequencies shown in Fig. 1, which are all of similar construction. The first such channel has a filter and amplifier 16 centred on 1,300 c/s., the output of which is rectified at 17. The filter 18 removes audio components from the resulting envelope signal which is then applied by a cathode follower 19 to a filter 20 which emphasizes high-frequency components corresponding to transients in the original sound. The pulses produced by filter 20 are elongated by the elongator 21 having a time constant of the order of 100 ms. The individual envelope signals produced by the five narrow band channels are fed by summing resistors 22 to 26 to an amplifier 27. Components of-VL having frequencies of less than 1,000 c/s. pass via lowpass filter 15 to an amplifier 28 and thence to a suppressed carrier modulator 29 fed by a 5,000 c/s. oscillator 29a, the filter and amplifier 30 selecting the lower-side band from the modulation products. This side-band is applied to six narrow band channels similar to that described above, the outputs of which pass via summing resistors 37 to 42 to the amplifier 27. The output of 27 passes to a further transient-emphasizing filter 43 and an elongator 44 with a time constant of the order of 35 ms., the output of which is applied by way of resistor 45 to an amplifier 46. VL is also applied to an amplifier 47 the output of which is rectified (48), filtered (49) and applied via resistor 50 to the amplifier 46. The proportions in which the envelope of VL and the output of elongator 44 are added is determined by the ratio of resistors 50 and 45, the output of amplifier 46 being the desired processed control signal port V<SP>11</SP>L. The signal VR is processed in like manner to derive V<SP>11</SP>R and V<SP>11</SP>L and V<SP>11</SP>R are fed to an encoding circuit, 51, which may be as described in the above-mentioned Specification, to produce the control signal. Transient emphasizing filter and elongator.- The filter 20 and elongator 21 are shown in Fig. 2. For falling transients the diode 62 conducts and produces substantial attenuation, but for a rising transient a pulse of relatively large amplitude is applied to the elongator, charging the capacitor 67 rapidly to nearly that amplitude. The capacitor 67 discharges slowly, after the impulse ends, by way of resistors 65 and 66.
GB2727558A 1958-08-26 1958-08-26 Improvements relating to stereophonic sound transmission systems Expired GB932556A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2727558A GB932556A (en) 1958-08-26 1958-08-26 Improvements relating to stereophonic sound transmission systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2727558A GB932556A (en) 1958-08-26 1958-08-26 Improvements relating to stereophonic sound transmission systems

Publications (1)

Publication Number Publication Date
GB932556A true GB932556A (en) 1963-07-31

Family

ID=10256926

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2727558A Expired GB932556A (en) 1958-08-26 1958-08-26 Improvements relating to stereophonic sound transmission systems

Country Status (1)

Country Link
GB (1) GB932556A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985003616A1 (en) * 1984-02-01 1985-08-15 Audim S.A. A stereophonic sound system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985003616A1 (en) * 1984-02-01 1985-08-15 Audim S.A. A stereophonic sound system

Similar Documents

Publication Publication Date Title
US4182930A (en) Detection and monitoring device
US2835814A (en) Electrical musical instruments
GB1458663A (en) Microphone circuits
US3057960A (en) Normalized sound control system
GB1384761A (en) Audio frequency apparatus
GB2177576A (en) Multi-channel reproducing system
GB2111807A (en) Noise reduction by integrating frequency-splitted signals with different time constants
US4008641A (en) Device for modulating a musical tone signal to produce a rotating sound effect
US3737783A (en) Signal-to-noise ratio improving device for receiving systems having two wave collectors
US3246081A (en) Extended stereophonic systems
GB946707A (en) Improvements in stereophonic broadcasting system
EP0122663A3 (en) Method and system for improving speaker performance
US3124649A (en) Filter
ES422597A1 (en) Method and apparatus for amplifying signal transmission through transmission lines
ES351041A1 (en) Hybrid transformer
GB932556A (en) Improvements relating to stereophonic sound transmission systems
US4415768A (en) Tuning apparatus and method
US3067287A (en) Stereophonic sound transmission systems
Percival A compressed-bandwidth stereophonic system for radio transmission
US2836662A (en) Electrical sound transmission systems
JPS5642413A (en) Sound-field singla correcting device
EP0052415A3 (en) Frequency characteristic adjusting apparatus
US3059053A (en) Stereophonic sound transmission systems
US4093820A (en) Electronic echo generation equipment
US3911370A (en) Audio frequency amplitude compensator