EP0245037A2
Expired / Lapsed
EP
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Signal identification
Assignee: Central Research Laboratories Ltd
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Filing: 1987-04-30
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Granted: —
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Expires: 2007-04-30
Abstract
Abstract Equipment for labelling audio signals with identification information has an encoder which inserts the binary information into two very narrow notches of centre frequencies 2883 and 3417 Hz, between semi-tones in the tonic scale to minimise music breakthrough into the decoding circuits, and to ensure that no fundamental frequencies in the tonic scale will be excluded in the reproduction. The notches are derived from a 3-stage biquad filter, and are approximately 50 dB deep and 150 Hz wide at the top. The encoder includes a wide bandpass circuit consisting of a 1 KHz highpass filter 10 and a 6 KHz lowpass filter 11 introduced to ensure that the code insertion level is not determined by frequencies, either high or low, which do not adequately mask the code frequencies. The code amplitude is kept a fixed level below the programme, initially adjustable by a suitable control. The code sequence has an addressing pre-amble consisting of a simultaneous burst of both the lower and higher frequencies for a period of 8 digits, followed by a message portion of 40 bits formed of an appropriate stream of the two frequencies.
Inventors
- 👤 Stuart John Best
- 👤 Reginald Alfred Willard
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 16:44
CPC Classifications
H; H04; H04H; H04H20/00; H04H20/28; H04H20/30; H04H20/31
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
89 words
Apparatus for the labelling of signals, the equipment comprising means to produce a code sequence incorporating a sequence-identification portion and a message portion, the message portion formed of a plurality of bits, one value of bit being represented by a burst of one predetermined frequency and the other value of bit being represented by a burst of another predetermined frequency different from the first predetermined frequency, the sequence-identification portion of the code sequence incorporating a burst of both frequencies, and means to insert the code sequence into a signal.
Claim 2
Dependent Claim
89 words
Apparatus for the labelling of signals, the equipment comprising means to produce a code sequence incorporating a sequence-identification portion and a message portion, the message portion formed of a plurality of bits, one value of bit being represented by a burst of one predetermined frequency and the other value of bit being represented by a burst of another predetermined frequency different from the first predetermined frequency, the sequence-identification portion of the code sequence incorporating a burst of both frequencies, and means to insert the code sequence into a signal.
Claim 3
Dependent Claim
40 words
Apparatus according to Claim 1, comprising means to monitor the frequency range and/or the amplitude of the signal for labelling, and means to inhibit insertion of the code sequence when the monitoring means indicates a value below a specified level.
Claim 4
Dependent Claim
28 words
Apparatus according to Claim 2, wherein the inhibit means is operable to prevent insertion when the signal substantially consists of frequencies below 1 KHz and/or above 6 KHz.
Claim 5
Dependent Claim
49 words
Apparatus according to any one of Claims 1 to 3, comprising means to locate one section of the code sequence in a channel of a multiple-channel signal and another section, following on from the said one section, of the code sequence in a different channel of the multiple-channel signal.
Claim 6
Dependent Claim
89 words
Decoder apparatus for signals incorporating labelling, the equipment including means for monitoring a signal for a sequence-identification portion of a code sequence, and means to extract a message portion from the code sequence, the message portion formed of a plurality of bits, one value of bit being represented by a burst of one predetermined frequency and the other value of bit being represented by a burst of another predetermined frequency different from the first predetermined frequency, the sequence-identification portion of the code sequence incorporating a burst of both frequencies.
Claim 7
Dependent Claim
89 words
Decoder apparatus for signals incorporating labelling, the equipment including means for monitoring a signal for a sequence-identification portion of a code sequence, and means to extract a message portion from the code sequence, the message portion formed of a plurality of bits, one value of bit being represented by a burst of one predetermined frequency and the other value of bit being represented by a burst of another predetermined frequency different from the first predetermined frequency, the sequence-identification portion of the code sequence incorporating a burst of both frequencies.
Claim 8
Dependent Claim
24 words
Decoder apparatus according to Claim 5, comprising means to assemble successive portions of the code sequence located in different channels of a multiple-channel signal.
Claim 9
Dependent Claim
77 words
A recording of a signal, the recording having at least one code sequence incorporating a sequence-identification portion and a message portion, the message portion formed of a plurality of bits, one value of bit being represented by a burst of one predetermined frequency and the other value of bit being represented by a burst of another predetermined frequency different from the first predetermined frequency, the sequence-identification portion of the code sequence incorporating a burst of both frequencies.
Claim 10
Dependent Claim
77 words
A recording of a signal, the recording having at least one code sequence incorporating a sequence-identification portion and a message portion, the message portion formed of a plurality of bits, one value of bit being represented by a burst of one predetermined frequency and the other value of bit being represented by a burst of another predetermined frequency different from the first predetermined frequency, the sequence-identification portion of the code sequence incorporating a burst of both frequencies.
Claim 11
Dependent Claim
49 words
A recording according to Claim 7, wherein one section of the code sequence is located in a channel of a multiple-channel signal and another section of the channel, following on from the said one section, of the code sequence is located in a different channel of the multi-channel signal.
References Cited (Backward Citations)
No citation records indexed.
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