Method of and apparatus for echo detection in voice channel signals
AssigneeNorthern Telecom Limited
InventorsFouad Daaboul, Tiu Le Van, Kit-Chung Fung
Life of this patent
Estimating the term…
Abstract
To detect echoes on a transmit path of signals on a receive path, an echo detector stores averages of the signals on the receive path each for a period equal to or just greater than the maximum end delay for received signals to reach the transmit path, and determines the greatest magnitude of the stored signals. This greatest magnitude, reduced by the worst case echo return loss, is compared with the current signal average on the transmit path, and an echo decision is produced in dependence upon this comparison and a detection of speed signals on each of the transmit and receive paths. The echo detector is particularly useful in a digital speech interpolation transmission system.
Claims7
An echo detector for detecting the presence on a first path of echoes of a sampled voice channel signal on a second path, comprising:
- means responsive to speech signals for producing a first signal when speech signals are present on the first path;
- means responsive to speech signals for producing a second signal when speech signals are present on the second path;
- means for storing the n most recent signals which have occurred on the second path, where n is a plural integer equal to the number of signals which occur on the second path during a first predetermined period;
- means for determining the greatest magnitude of the stored signals;
- means for producing a third signal in dependence upon the magnitude of the signal on the first path relative to the determined greatest magnitude;
- and
- means responsive to the first, second, and third signals for producing an echo decision for the signal on the first path.
A method of detecting the presence on a first path of echoes of a sampled voice channel signal on a second path, comprising the steps of:
- detecting speech signals on each of said paths;
- storing the n most recent signals which have occurred on the second path, n being a plural integer;
- determining the greatest magnitude of the stored signals;
- comparing the signal on the first path with the determined greatest magnitude;
- and
- producing an echo decision in response to the detection of speech signals and the comparison.
Dependencies are inferred from the claim text.