Method and system for enhancing a digitally sampled voltage input waveform

• US 5,867,058 A
• Filed: 08/01/1997
• Issued: 02/02/1999
• Est. Priority Date: 08/01/1997
• Status: Expired due to Term

• Current Assignee: Zenith Electronics Corporation (LG Corporation)
• Original Assignee: Zenith Electronics Corporation (LG Corporation)
• Inventors: DeCarlo, Robert D. Jr.
• Primary Examiner(s): TON, MY TRANG
• Application Number:
  US08/904,902
• Time in Patent Office: 550 Days
• Field of Search: 327/551, 327/552, 327/553, 327/555-559, 327/352, 327/361, 341/143, 330/305-307, 330/109, 333/173, 333/172
• US Class Current: 327/551
• CPC Class Codes: H03M 1/661 Improving the reconstruction of the analogue output signal beyond the resolution of the digital input signal, e.g. by interpolation, by curve-fitting, by smoothing

Abstract

A method and system for enhancing a digital input signal and producing a modified digital output signal that can either be further digitally processed or that can be converted to an analog signal. A digital input signal passes through a low-pass filter, a high-pass filter and a bandpass filter. A digital signal emitted from a high-pass section of the bandpass filter is delivered to a dynamically-controlled multiplier operating in a digital domain. Digital signals emitted from the low-pass filter, the high-pass filter and the bandpass filter are summed with a signal multiplied by the dynamically-controlled multiplier. A process controller and a contour controller can be used to vary low-frequency boost and high-frequency boost delivered by the modified digital input signal which can then be converted to an analog audio output sample.

Claims

1. A method for enhancing a digitally sampled voltage input waveform, comprising:

(a) passing the digitally sampled voltage input waveform (10) through a high-pass filter (15) and emitting a high-frequency portion (16) of a signal;

(b)) passing the digitally sampled voltage input waveform (10) through a low-pass filter (20) and emitting a low-frequency portion (21) of the signal;

(c) passing the digitally sampled voltage input waveform (10) through a high-pass section (26) of a bandpass filter (25) and emitting a first digital signal (27) at a first frequency above a high-pass frequency of the bandpass filter (25), and passing the first digital signal (27) through a low-pass section (28) of the bandpass filter (25) and emitting a second digital signal (29) at a midrange-frequency between a low-pass frequency and the high-pass frequency of the bandpass filter (25);

(d) passing the first digital signal (27) through a control signal generator (30) and emitting a dynamically-controlled digital signal (31);

(e) summing the low-frequency portion (21) of the signal and the second digital signal (29) producing a first-summed digital signal (35);

(f) summing the first-summed digital signal (35) and the high-frequency portion (16) of the signal producing a second summed digital signal (40);

(g) multiplying the second summed digital signal (40) producing a scaled second summed digital signal (41); and

(h) multiplying the high-frequency portion (16) of the signal producing a multiplied high-frequency digital signal (17) by varying the dynamically-controlled digital signal (31) to control a factor of multiplication of the high-frequency portion (16) of the signal, summing the multiplied high-frequency digital signal (17) and the scaled second summed digital signal (41) producing a third summed digital signal (45), multiplying the low-frequency portion (21) of the signal and a first control input signal (24) producing a multiplied low-frequency digital signal (22), and summing the third summed digital signal (45) and the multiplied low-frequency digital signal (22) producing a fourth summed digital signal (50).

2. A method according to claim 1 wherein an output level of the dynamically-controlled digital signal (31) is saturated at a threshold level of the first digital signal (27).

3. A method according to claim 2 wherein the dynamically-controlled digital signal (31) and a second control input signal (32) are multiplied to produce a boost signal (33).

4. A method according to claim 3 wherein the boost signal (33) controls a factor of multiplication of the high-frequency portion (16) of the digital signal to produce the multiplied high-frequency digital signal (17) that is summed with the scaled second suimmned digital signal (41).

5. A method according to claim 3 wherein at least one of the first control input signal (24) and the second control input signal (32) is variable.

6. A method according to claim 1 wherein a level of multiplication of the low-frequency portion (21) of the signal is variably controlled to produce the multiplied low-frequency digital signal (22) that is summed with the third summed digital signal (45).

7. A method according to claim 1 wherein the high-pass section (26) of the bandpass filter (25) has a high-pass frequency setpoint of about 210 Hz.

8. A method according to claim 1 wherein the low-pass section (28) of the bandpass filter (25) has a low-pass frequency setpoint of about 2.4 kHz.

9. A method according to claim 1 wherein the low-pass filter (20) is a variable pole filter.

10. A method according to claim 1 wherein the high-pass filter (15) has a high-pass frequency setpoint of about 3.8 kHz.

11. A method according to claim 1 wherein the dynamically-controlled digital signal (31) has a decay time of about 200 ms.

12. A method according to claim 1 wherein the dynamically-controlled digital signal (31) has an attack time that is instantaneous.

13. A method for enhancing a digital input signal, wherein the digital input signal is passed through a high-pass filter, a low pass filter and a bandpass filter, the method comprising:

(a) passing the digital input signal (10) through the high-pass filter (15) and emitting a high-frequency portion (16) of a signal;

(b) passing the digital input signal (10) though the low-pass filter (20) and emitting a low-frequency portion (21) of the signal;

(c) passing the digital input signal (10) through a bandpass filter (25) to produce a first digital signal (27) at a first frequency above a high-pass frequency setpoint;

(d) passing the first digital signal (27) to a control signal generator (30) and emitting from the control signal generator (30) a dynamically-controlled digital signal (31);

(e) generating a constant control signal (32) from a process controller;

(f) multiplying the dynamically-controlled digital signal (31) and the constant control signal (32) to produce a boost signal (33);

(g) multiplying the boost signal (33) and the high-frequency portion (16) of the signal to produce a multiplied high-frequency digital signal (17); and

(h) combining the multiplied high-frequency digital signal (17) and a processed of the low-frequency portion (21) of the signal.

14. A method for enhancing a digitally sampled voltage input waveform, comprising:

(a) passing the digitally sampled voltage input waveform (10) through a high-pass filter (15) and emitting a high-frequency portion (16) of a signal;

(b) passing the digitally sampled voltage input waveform (10) through a low-pass filter (20) and emitting a low-frequency portion (21) of the signal and multiplying the low-frequency portion (21) of the signal and a first control input signal (24) producing a multiplied low-frequency digital signal (22);

(c) passing the digitally sampled voltage input waveform (10) through a second high-pass filter (26'"'"') and emitting a first digital signal (27) and passing the first digital signal (27) through a control signal generator (30) and emitting a dynamically-controlled digital signal (31);

(d) passing the digitally sampled voltage input waveform (10) through a bandpass filter (25) and emitting a second digital signal (29);

(e) multiplying the high-frequency portion (16) of the signal, the dynamically-controlled digital signal (31) and a control digital input signal (32) producing a multiplied high-frequency digital signal (17); and

(f) summing the multiplied high-frequency digital signal (17), the multiplied low-frequency digital signal (22) and the second digital signal (29) producing a summed digital signal (50).

15. A method according to claim 14, further comprising summing the high-frequency portion (16) of the signal with the multiplied high-frequency digital signal (17), the multiplied low-frequency digital signal (22) and the second digital signal (29) to produce the summed digital signal (50).

16. A method according to claim 14, wherein a level of multiplication of the low-frequency portion (21) of the signal is variably controlled to produce the multiplied low-frequency digital signal (22).