Reducing switching noise
The present solution relates to a method in a first communication node ( 501 ) for suppressing noise in a communication system ( 500 ) utilizing an automatic gain control. The first communication node ( 501 ) receives ( 1301 ) a signal from a second communication node ( 503 ). Then, the first communication node ( 501 ) determines ( 1302 ) if a gain level is changed. The signal gain is changed ( 1303 ). The next step is for the first communication node ( 501 ) to determine ( 1305 ) if an inband interferer is present, and then to suppress ( 1306 ) transient noise in the signal.
1. A method in a first communication node for suppressing noise in a communication system utilizing an automatic gain control, the method comprising:
receiving, at the first communication node, a signal from a second communication node; and
determining if a gain level of the received signal is changed, wherein the step of determining if the gain level is changed comprises: measuring a wideband signal level of the received signal evaluating if the measured wideband signal level is outside a range:
changing the signal gain if the evaluated signal level is outside the range;
determining if an inband interferer is present;
suppressing, using a suppression unit, transient noise in the signal if the inband interferer is present; and
disabling the suppressing.
2. The method according to claim 1 , wherein
the step of changing the signal gain changing the signal gain in an analogue domain; and
the method further comprises the step of: restoring the signal gain to a digital domain.
3. The method according to claim 2 , wherein the step of determining the presence of an inband interferer comprises measuring an inband signal level in the restored signal gain.
4. The method according to claim 3 , wherein the step of suppressing transient noise comprises: comparing the inband signal level with a threshold level.
5. The method according to claim 4 , wherein the comparing is based on bit error rate.
6. The method according to claim 1 , wherein the step of suppressing transient noise comprises: delaying the signal in time, wherein the time is in correspondence with a duration of the suppressed noise.
7. A receiver in a first communication node for suppressing noise in a communication system utilizing an automatic gain control, the receiver comprising:
a receiving unit configured to receive a signal from a second communication node;
a determining unit configured to: determine if a gain level in the received signal is changed; measure a wideband signal level of the received signal; evaluate if the measured wideband signal is outside a range, and determine if an inband interferer is present;
a changing unit configured to change the signal gain if the evaluated signal level is outside the range; and
a suppression unit configured to suppress transient noise in the signal if the inband interferer is present and to disable the suppression.
8. The receiver according to claim 7 , wherein the changing unit is further configured to change the signal gain in an analogue domain; and wherein the receiver further comprises a restoring unit configured to restore the signal gain to a digital domain.
9. The receiver according to claim 8 , wherein the determining unit is further configured to measure an inband signal level in the restored signal gain.
10. The receiver according to claim 9 , wherein the suppression unit is further configured to compare the inband signal level with a threshold level.
11. The receiver according to claim 7 , wherein the suppression unit is further configured to delay the signal in time, wherein the time is in correspondence with the duration of the suppressed noise.