US5467394A
Expired / Lapsed
US
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Method of improving sidetone attenuation in electroacoustic systems
Assignee: Alcatel Lucent NV
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Filing: 1994-02-16
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Granted: 1995-11-14
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Expires: 2014-02-16
Abstract
Abstract To improve the anti-sidetone of electro-acoustic installations, particularly to improve the intercom characteristics of a telecommunication terminal, with compander control by an echo evaluation circuit (52) assigned to the compander (4), the latter has an echo compensator (40) located upstream, and/or a voice-controlled balance (51) is located downstream of the compander (4), which are controlled by the echo evaluation circuit (52) of the compander (4). To control the echo compensator (40) and/or the voice-controlled balance (51), the usual control circuitry required for their operation can be omitted. The result is a particularly effective, economical method with very good intercom characteristics.
Inventors
- 👤 Michael Walker
- 👤 Peter Heitkamper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:35
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/08; H04M9/10; H04M9/082
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
208 words
A method of improving the transmission properties, in particular the anti-sidetone (induction) of an electro-acoustic installation equipped with adaptive dynamic (range) control, which contains a transmitting branch with at least one microphone and a transmitting amplifier, and a receiving branch with a receiving amplifier and at least one loudspeaker, and a compander with an echo evaluation circuit for the adaptive dynamic control, whose compression and expansion starting points can be changed as a function of transmission, reception, echo and noise signals, whereby these signals are determined and control signals are produced in accordance with their level, and are used to control the compander by changing and displacing the compander curves, particularly to improve the intercom characteristics of a telecommunication terminal, characterized in that, to increase the anti-sidetone, the compander (4) is preceded by an echo compensator (40), with the input side located at the receiving branch (26) and the output side at the transmitting branch (2), controlled by the incoming signal (U12; x(k)) and by the transmitted signal (U1; y(k)), and a voice-controlled balance (51), which is connected between the receiving branch (26) and the transmitting branch (2), is located downstream of the compander and is further controlled by the echo evaluation circuit (52) of the compander (4).
Claim 2
Independent Claim
208 words
A method of improving the transmission properties, in particular the anti-sidetone (induction) of an electro-acoustic installation equipped with adaptive dynamic (range) control, which contains a transmitting branch with at least one microphone and a transmitting amplifier, and a receiving branch with a receiving amplifier and at least one loudspeaker, and a compander with an echo evaluation circuit for the adaptive dynamic control, whose compression and expansion starting points can be changed as a function of transmission, reception, echo and noise signals, whereby these signals are determined and control signals are produced in accordance with their level, and are used to control the compander by changing and displacing the compander curves, particularly to improve the intercom characteristics of a telecommunication terminal, characterized in that, to increase the anti-sidetone, the compander (4) is preceded by an echo compensator (40), with the input side located at the receiving branch (26) and the output side at the transmitting branch (2), controlled by the incoming signal (U12; x(k)) and by the transmitted signal (U1; y(k)), and a voice-controlled balance (51), which is connected between the receiving branch (26) and the transmitting branch (2), is located downstream of the compander and is further controlled by the echo evaluation circuit (52) of the compander (4).
Claim 3
Dependent Claim
66 words
A method according to claim 1, characterized in that an adaptive filter (41), particularly a digital adaptive filter, is used as echo compensator (40), whose step width (α) is controlled as a function of the incoming signal (U12; x(k)) in such a way, that it is large with a large incoming signal (U12; x(k)), and small or zero with a nonexisting or very small incoming signal.
Claim 4
Dependent Claim
56 words
A method according to claim 2, characterized in that on the one hand, the step width (α) is controlled by a signal level (U1; U2; y(k); y 2 (k)) derived from the transmitting branch (2), and on the other by a signal level (U x ; y o max) derived from the echo evaluation circuit (52).
Claim 5
Dependent Claim
32 words
A method according to claim 3, characterized in that the step width (α) is switched in one or several steps from a large (maximum) value to a small value or to zero.
Claim 6
Dependent Claim
38 words
A method according to claim 3, characterized in that the step width (α) is controlled in such a way, that it increases superproportionally with an increasing incoming signal (U12; x(k)), and decreases superproportionally with a decreasing incoming signal.
Claim 7
Dependent Claim
28 words
A method according to claim 5, characterized in that the step width control signals (xα; yα) are supplied to the filter (41) via a signal averager (49.1; 49.2).
Claim 8
Dependent Claim
81 words
A method according to claim 2, characterized in that a constant or essentially constant signal level is used as a step width control signal (xα), which is so dimensioned that it corresponds to a curve control value (U x , y o max) of the compander (4) curve (5) specified by the entire circuit, which is located between a value that determines a starting point (p1) of the expansion, and a value that determines the starting point (p2) of the compression.
Claim 9
Dependent Claim
56 words
A method according to claim 6, characterized in that step width control only takes place when the step width control signal (xα) containing the information of the incoming signal (U12; x(k)) is equal to, or larger than the step width control signal (yα) containing the information of the transmitted signal (U1; U2; y(k), y s (k)).
Claim 10
Dependent Claim
75 words
A method according to claim 8, characterized in that a compander (4) is used, containing a peak value detector (MAX; 62), which is controlled by the transmitting branch input signal (U1; y(k)) and the transmitting branch output signal (U2; U6), and by the echo evaluation circuit (52), and the step width (α) of the filter (41) is controlled by the output signal U x ; y o max) of the maximum value detector (MAX; 62).
Claim 11
Dependent Claim
36 words
A method according to claim 9, characterized in that the downstream voice-controlled balance (51 ) control range is adjusted as a function of the output signal (d2; U x ) of the echo evaluation circuit (52).
Claim 12
Dependent Claim
32 words
A method according to claim 2, characterized in that the step width (α) is switched in one or several steps from a large (maximum) value to a small value or to zero.
Claim 13
Dependent Claim
38 words
A method according to claim 2, characterized in that the step width (α) is controlled in such a way, that it increases superproportionally with an increasing incoming signal (U12; x(k)), and decreases superproportionally with a decreasing incoming signal.
Claim 14
Dependent Claim
28 words
A method according to claim 2, characterized in that the step width control signals (xα; yα) are supplied to the filter (41) via a signal averager (49.1; 49.2).
Claim 15
Dependent Claim
81 words
A method according to claim 1, characterized in that a constant or essentially constant signal level is used as a step width control signal (xα), which is so dimensioned that it corresponds to a curve control value (U x , y o max) of the compander (4) curve (5) specified by the entire circuit, which is located between a value that determines a starting point (p1) of the expansion, and a value that determines the starting point (p2) of the compression.
Claim 16
Dependent Claim
56 words
A method according to claim 2, characterized in that step width control only takes place when the step width control signal (xα) containing the information of the incoming signal (U12; x(k)) is equal to, or larger than the step width control signal (yα) containing the information of the transmitted signal (U1; U2; y(k), y s (k)).
Claim 17
Dependent Claim
75 words
A method according to claim 2, characterized in that a compander (4) is used, containing a peak value detector (MAX; 62), which is controlled by the transmitting branch input signal (U1; y(k)) and the transmitting branch output signal (U2; U6), and by the echo evaluation circuit (52), and the step width (α) of the filter (41) is controlled by the output signal U x ; y o max) of the maximum value detector (MAX; 62).
Claim 18
Dependent Claim
35 words
A method according to claim 1, characterized in that the downstream voice-controlled balance (51) control range is adjusted as a function of the output signal (d2; U x ) of the echo evaluation circuit (52).
Claim 19
Dependent Claim
35 words
A method according to claim 2, characterized in that the downstream voice-controlled balance (51) control range is adjusted as a function of the output signal (d2; U x ) of the echo evaluation circuit (52).
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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) | 1998-11-13 | 1999-05-15 | 1999-11-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-11-13 | 2003-05-15 | 2003-11-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-11-13 | 2007-05-15 | 2007-11-14 | $7700.00 | Window Closed / Lapsed |