Method and device for disturbance suppression in a signal

• US 6,522,707 B1
• Filed: 04/30/1999
• Issued: 02/18/2003
• Est. Priority Date: 04/30/1999
• Status: Active Grant

• Current Assignee: Lantiq Beteiligungs-GmbH & Company KG (Intel Corporation)
• Original Assignee: Siemens AG
• Inventors: Brandstetter, Markus, Hanneberg, Armin
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Fan, Chieh M.
• Application Number:
  US09/302,652
• Time in Patent Office: 1,390 Days
• Field of Search: 375/229, 375/232, 375/233, 375/254, 375/285, 375/287, 375/288, 375/289, 375/345, 375/346, 375/348, 375/350, 455/63, 455/296, 455/307, 455/501, 327/551, 333/18, 333/28.R, 708/300, 708/301, 708/319, 708/323, 708/819
• US Class Current: 375/350
• CPC Class Codes: H04B 3/04 Control of transmission; Equalising
• CPC Class Codes: H04L 2025/03547 Switching between time domain structures
• CPC Class Codes: H04L 25/03885 adaptive

Abstract

Disturbances in bipolar signals transmitted on a transmission line are suppressed by adjusting the amplitude of the signals with coarse adjustment steps and with fine adjustment steps. The amplitude adjusted signals are compared to at least a lower reference level and an upper reference level for determining a first percentage of the amplitude adjusted signals violating the lower reference level and a second percentage of the amplitude adjusted signals violating the upper reference level. The coarse adjustment steps and the fine adjustment steps are selected in accordance with an adjustment characteristic which evaluates at least the first percentage and the second percentage. The adjustment characteristic is changed if a tendency of reference level violation of the amplitude adjusted signals is detected and a check is performed if the step of changing the adjustment characteristic improves the disturbance suppression. A device for suppressing disturbances is also provided.

Claims

1. A method for suppressing disturbances in signals transmitted on a transmission line, the method which comprises:

receiving signals having an amplitude;

adjusting the amplitude of the signals with coarse adjustment steps and with fine adjustment steps for a disturbance suppression, including;

performing the coarse adjustment steps with a group delay filter selectively operating with a first filter stage suited for signals received from a transmission line having a first length and operating with a second filter stage suited for signals received from a transmission line having a second length, the second length being greater than the first length; and

performing the fine adjustment steps with a gain control device selectively operating at a plurality of different gains, the fine adjustment steps covering a first amplitude range, when the group delay filter operates with the first filter stage and covering a second amplitude range when the filter operates with the second filter stage, the first amplitude range being greater than the second amplitude range;

subsequently comparing the amplitude adjusted signals to at least a lower reference level and an upper reference level for determining a first percentage of the amplitude adjusted signals violating the lower reference level and a second percentage of the amplitude adjusted signals violating the upper reference level;

selecting the coarse adjustment steps and the fine adjustment steps in accordance with an adjustment characteristic which evaluates at least the first percentage and the second percentage;

changing the adjustment characteristic if a tendency of reference level violation of the amplitude adjusted signals is detected; and

checking if the step of changing the adjustment characteristic improves the disturbance suppression.

2. The method according to claim 1, which comprises changing the adjustment characteristic such that an adjustment range of the fine adjustment steps is increased.

3. The method according to claim 1, which comprises suppressing modulation disturbances with the step of adjusting the amplitude of the signals.

4. The method according to claim 1, which comprises extending the first amplitude range by a range of at least 3 dB beyond a lower boundary and beyond an upper boundary of the second amplitude range.

5. The method according to claim 4, which comprises dividing the range of the at least 3 dB into three fine adjustment steps each having a step width of at least 1 dB.

6. The method according to claim 1, which comprises further changing the adjustment characteristic in dependence of the step of checking if the disturbance suppression has improved.

7. The method according to claim 1, wherein the signals are bipolar signals.

8. A device for suppressing disturbances in signals transmitted on a transmission line, comprising:

an equalizer receiving signals having an amplitude and adjusting the amplitude of the signals;

said equalizer having a gain control device for providing fine adjustment steps and having a group delay filter connected to said gain control device, said filter providing coarse adjustment steps;

said filter having a first filter stage suited for signals received from a transmission line having a first length and haing a second filter stage for signals received from a transmission line having a second length, the second length being greater than the first length;

said fine adjustment steps covering a first amplitude range, upon said filter operating with said first filter stage and covering a second amplitude range upon said filter operating with said second filter stage, said first amplitude range being greater than said second amplitude range;

a level detector connected to said equalizer for comparing the amplitude adjusted signals to at least a lower reference level and an upper reference level;

a control device connected to said equalizer for determining a first percentage of the amplitude adjusted signals violating said lower reference level and a second percentage of the amplitude adjusted signals violating said upper reference level, for detecting a tendency of reference level violation of the amplitude adjusted signals, for controlling said equalizer to perform said coarse adjustment steps and said fine adjustment steps in accordance with an adjustment characteristic evaluating at least said first percentage and said second percentage, and for changing said adjustment characteristic on detection of the tendency of reference level violation of the amplitude adjusted signals.

9. The device according to claim 8, wherein said control device changes said adjustment characteristic by increasing an adjustment range of said fine adjustment steps.