Apparatus and method for adjusting an input gain and comparator threshold value within an access identifier interval on a telephone line medium

• US 6,438,184 B1
• Filed: 01/12/1999
• Issued: 08/20/2002
• Est. Priority Date: 01/12/1999
• Status: Expired due to Term

• Current Assignee: Advanced Micro Devices, Inc.
• Original Assignee: Sunnyvale Micro Devices Incorporated
• Inventors: Nayler, Colin
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Fan, Chieh M.
• Application Number:
  US09/228,979
• Time in Patent Office: 1,316 Days
• Field of Search: 375/219, 375/220, 375/222, 375/287, 375/288, 375/345, 375/377, 455/232.1, 455/234.1, 455/245.1, 455/73, 370/241, 370/464, 370/466
• US Class Current: 375/345
• CPC Class Codes: H04L 25/062 Setting decision thresholds using feedforward techniques only
• CPC Class Codes: H04L 25/12 Compensating for variations in line impedance

Abstract

A physical layer transceiver of a home network station connected to a telephone medium has an architecture enabling adaptation of detection circuitry based on received network signals to enable reliable recovery of data signals. The physical layer transceiver includes an input amplifier that amplifies network signals according to one of three gain settings set by a receiver gain control signal. A signal conditioning circuit includes an envelope detector configured for outputting an envelope of the amplified received signal, and an energy detector configured for outputting an energy signal of the amplified received signals. The envelope signal and the energy signal are supplied to slicer threshold circuits, configured for outputting noise, peak, data event and energy event signals based on noise threshold, peak threshold, data transition threshold, and energy threshold signals, respectively. A digital controller controls the input amplifier gain and the threshold values, and adjusts the gain and threshold values based on the noise event signal and the peak event signal within an access ID (AID) interval. In particular, the digital controller adjusts the input amplifier gain during a first part of the AID interval, and adjusts the peak threshold and the data transition threshold during a second part of the AID interval by using the slicer threshold circuits for ternary searching of the peak of the detected envelope signal.

Claims

1. A network station configured for receiving network signals from another network station via a telephone line medium, the network station comprising:

an input amplifier for selectively amplifying a received network signal according to a selected one of a plurality of gain settings and outputting an amplified network signal;

an envelope detector configured for outputting an envelope signal in response to the amplified network signal;

first and second comparator circuits configured for outputting first and second comparison signals indicating whether the envelope signal exceeds first and second threshold values, respectively; and

a digital controller configured for setting the selected one gain setting and the first and second threshold values within a prescribed access identifier interval specified by a prescribed number of the received network signals from the telephone line medium, the digital controller determining the selected one gain setting during a first portion of the prescribed access identifier interval, and a peak threshold value and data threshold value for the respective first and second threshold values during a second portion of the prescribed access identifier interval, the peak threshold value substantially corresponding to a detected peak of the envelope signal.

2. The network station of claim 1, wherein the digital controller initially sets the input amplifier to a maximum gain setting, the digital controller successively setting a corresponding significant bit of the maximum gain setting to an adjusted gain setting based on successive detection of a saturated envelope signal generated in response to amplifying the received network signal according to the adjusted gain setting.

3. The network station of claim 2, wherein the digital controller sets the selected one gain setting based on successively setting a prescribed number of significant bits for the adjusted gain setting.

4. The network station of claim 3, wherein the digital controller sets the selected one gain setting based on three envelope signal pulses as corresponding to the prescribed number of significant bits and the first portion.

5. The network station of claim 1, wherein the digital controller sets the first and second threshold values to first and second detection range threshold values during the second portion of the prescribed access identifier interval, the first and second detection range threshold values defining a group of primary detection regions for detecting the peak of the envelope signal within a dynamic range of the first and second comparator circuits.

6. The network station of claim 5, wherein the digital controller selectively adjusts the first and second threshold values to third and fourth detection range threshold values based on a comparison by the first and second comparator circuits of a first envelope signal output in the second portion and relative to the first and second detection range threshold values, the third and fourth detection range threshold values defining a group of secondary detection regions for detecting the peak of the envelope signal within an identified one of the primary detection regions.

7. The network station of claim 6, wherein the digital controller determines the peak threshold value based on a comparison by the first and second comparator circuits of a second envelope signal successively following the first envelope signal in the second portion and relative to the third and fourth detection range threshold values, the digital controller identifying one of the secondary detection regions as having the peak of the envelope signal.

8. The network station of claim 7, wherein the second portion includes five successive envelope pulses initiated by the first and second envelope signals, the one secondary detection region identified in response to the second successive envelope pulse.

9. The network station of claim 8, wherein the digital controller determines the first threshold value by executing binary search within the one secondary detection region using a remaining portion of the five successive envelope pulses, the digital controller setting the second threshold to within a prescribed range during the remaining portion.

10. The network station of claim 1, wherein the prescribed access identifier interval is specified by eight successive envelope signals, the digital controller setting the first portion to up to three successive envelope pulses and the second portion to at least five successive envelope pulses.

11. The network station of claim 10, wherein the digital controller determines a detection region for the detected peak of the envelope signal based on at least the first two of the five successive envelope pulses.

12. The network station of claim 11, wherein the digital controller determines the first and second threshold values based on a binary search in the detection region using the last three of the five successive envelope pulses.

13. The network station of claim 11, wherein the digital controller determines the detection region from one of nine detection regions within a dynamic range of the first and second comparator circuits.

14. The network station of claim 1, further comprising a digital to analog converter for outputting first and second comparison signals to the first and second comparator circuits in response to the first and second threshold values, respectively.

15. A method of configuring a network station transceiver for reception, from a telephone line medium, of network data signals contiguously following a prescribed number of network access identifier signal pulses defining an access identifier interval, the method comprising:

determining a gain setting for an input amplifier, configured for outputting an amplified network signal to an envelope detector, within a first portion of the access identifier interval; and

determining a data threshold value and a peak threshold value for first and second comparator circuits, configured for identifying whether an envelope signal generated based on the amplified network signal exceeds threshold values supplied to the first and second comparator circuits, within a second portion of the access identifier interval.

16. The method of claim 15, wherein the step of determining a gain setting includes:

setting the input amplifier to an initial maximum gain setting; and

successively adjusting corresponding significant bits of the maximum gain setting based on successive detection of a saturated envelope signal output by the envelope detector, the significant bits corresponding to a first number of the network access identifier signal pulses in the first portion.

17. The method of claim 16, wherein the step of determining a data threshold value and a peak threshold value includes determining a peak detection region from a plurality of detection regions within a dynamic range of the comparator circuits, the peak detection region corresponding to a number of significant bits for the peak threshold value, using a first number of the network access identifier signal pulses in the second portion and less than the number of significant bits.

18. The method of claim 17, wherein the step of determining a data threshold value and a peak threshold value further comprises executing a binary search within the peak detection region for the detected peak using a second number of the network access identifier signal pulses in the second portion.

19. The method of claim 18, wherein the step of determining a data threshold value and a peak value further comprises setting the data threshold value to within a prescribed range during the binary search.