Adaptive equalizer training circuit, modem apparatus and communication apparatus

• US 20010048717A1
• Filed: 05/22/2001
• Published: 12/06/2001
• Est. Priority Date: 05/24/2000
• Status: Active Grant

• Current Assignee: Panasonic Communications Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Graphic Communication Systems, Inc. (Panasonic Holdings Corporation)
• Inventors: Noma, Nobuhiko, Mizutani, Mikio, Ougi, Toshiyuki
• Granted Patent: US 6,928,110 B2
• Time in Patent Office: Days
• US Class Current: 375/231
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03471 Tapped delay lines H04L2025/03464 takes precedence
• CPC Class Codes: H04L 2025/03617 Time recursive algorithms H04L2025/03643 takes precedence
• CPC Class Codes: H04L 25/03012 operating in the time domain H04L25/03165, H04L25/03178 take precedence

Abstract

A training circuit for training a tap coefficient of an adaptive equalizer that performs error calculations in a training process and updating of the tap coefficient in a time area and thereby makes the tap coefficient converge stably in a short time.

Claims

1. An adaptive equalizer training circuit comprising:

a training signal generation section that generates a same training signal as that of a transmitter;

a correction section that corrects a time difference between a training signal received in the training starting stage and a self-produced training signal;

a target signal response updating section that calculates a target signal by carrying out a convolutional calculation of a variable tap coefficient updated by an error signal with the self-produced training signal; and

a tap coefficient updating section that carries out a convolutional calculation of the tap coefficient updated by said error signal with the received training signal, and calculates a difference between the convolutional calculation result and said target signal in a time area and generates said error signal, wherein training is repeated until the tap coefficient of said tap coefficient updating section reaches a convergence condition.

2. The adaptive equalizer training circuit according to

claim 1

, wherein said correction section comprising:

an initial impulse response calculation section that calculates an impulse response of the training signal received via the transmission path;

an initial impulse response time window section that detects a maximum power area of the calculated impulse response and detects a time difference between the training signal received based on said detection position and a self-produced training signal; and

a time-axis shift section that shifts the time-axis of the training signal received based on the detected amount of the difference.

3. The adaptive equalizer training circuit according to

claim 2

, wherein the signal waveform of the maximum power area of the impulse response calculated by said initial impulse response calculation section is given to said target signal response updating section as an initial value of the tap coefficient.

4. The adaptive equalizer training circuit according to

claim 1

that further comprises an averaging section that carries out averaging on the training signal received via the transmission path and uses an averaged signal as the received training signal to update the tap coefficient.

5. A modem apparatus that transmits/receives a signal according to a frequency multiplexing system, comprising:

an adaptive equalizer that adaptively equalizes the transmission path by training a tap coefficient; and

the adaptive equalizer training circuit according to

claim 1

that trains the tap coefficient of said adaptive equalizer.

6. An ADSL terminal side apparatus equipped with the modem apparatus according to

claim 5

.

7. An ADSL station side apparatus equipped with the modem apparatus according to

claim 5

.

8. A communication apparatus equipped with the modem apparatus according to

claim 5

.

9. An adaptive equalizer training method comprising the step of performing error calculations in a training process of the adaptive equalizer and updating of a tap coefficient in a time area.

10. An adaptive equalizer training method comprising the steps of:

generating a same training signal as that of a transmitter;

correcting a time difference between a training signal received in the training starting stage and a self-produced training signal;

calculating a target signal by carrying out a convolutional calculation of a variable tap coefficient updated by an error signal with the self-produced training signal;

carrying out a convolutional calculation of the tap coefficient updated by said error signal with the received training signal, calculating a difference between the convolutional calculation result and said target signal in a time area and generating said error signal; and

repeating training until the tap coefficient of said tap coefficient updating section reaches a convergence condition.

11. The adaptive equalizer training method according to

claim 10

, further comprising the steps of:

calculating an impulse response of the training signal received via the transmission path;

detecting a maximum power area of the calculated impulse response and detecting a time difference between the training signal received based on said detection position and the self-produced training signal; and

shifting the time-axis of the training signal received based on the detected amount of the difference.

12. The adaptive equalizer training method according to

claim 11

, wherein the signal waveform of the maximum power area of the calculated impulse response is used as an initial value of the tap coefficient.

13. The adaptive equalizer training method according to

claim 10

that carries out averaging on the training signal received via the transmission path and uses the averaged signal as the training signal received to update the tap coefficient.