Granted Patent B1

US 7,109,906 · App. 11/118,211 · Granted Sep 19, 2006

Abstract

Claims (31)

1. A NICAM encoder comprising:

a NICAM processor; and

a front-end section coupled to the NICAM processor, wherein the front-end section synchronizes the front-end section and the NICAM processor with timing derived from integer divisions of a single system clock, wherein the front-end section comprises a front-end input section and a front-end output section, the front-end input section coupled to an input of the NICAM processor and the front-end output section coupled to an output of the NICAM processor, wherein the front-end input section comprises one of:

(a) an interpolator by factor N, a first decimator by factor M, a pre-emphasis filter, and a second decimator by factor P, wherein the interpolator couples to the first decimator, the first decimator couples to the pre-emphasis filter, and the pre-emphasis filter couples to the second decimator, or

(b) a dual-channel analog-to-digital converter (ADC), an interpolator by factor N, a first decimator by factor M, a pre-emphasis filter, and a second decimator by factor P, wherein the ADC couples to the interpolator, the interpolator couples to the first decimator, the first decimator couples to the pre-emphasis filter, and the pre-emphasis filter couples to the second decimator.

2. The NICAM encoder of claim 1 , wherein the NICAM processor operates at a sampling frequency of 728 kHz or 364 kHz, and wherein the front-end section comprises a front-end input section that has an output at a sampling frequency of 32 kHz and a front-end output section that has an output at a sampling frequency of one of 24 MHz or 27 MHz.

3. The NICAM encoder of claim 1 , further wherein the quantity (N/(M*P)) is equal to a ratio of 32 kHz to the system clock.

4. The NICAM encoder of claim 1 , further wherein the dual-channel ADC includes an initial resolution of better than 14 bits and provides an output of the front-end input section with a resolution of 14 bits.

5. The NICAM encoder of claim 1 , further wherein the pre-emphasis filter is operated at a frequency greater than 32 kHz.

6. The NICAM encoder of claim 1 , further wherein the NICAM processor and the front-end section comprise a single integrated circuit chip implementation.

7. The NICAM encoder of claim 1 , further wherein the NICAM processor and the front-end section are embedded in an audio/video integrated circuit.

8. The NICAM encoder of claim 1 , further comprising:

a first analog filter coupled to an input of the front-end section, wherein the first analog filter comprises an anti-aliasing filter; and

a second analog filter coupled to an output of the front-end section, wherein the second analog filter comprises a reconstruction filter.

9. A NICAM encoder comprising:

a NICAM processor; and

a front-end section coupled to the NICAM processor, wherein the front-end section synchronizes the front-end section and the NICAM processor with timing derived from integer divisions of a single system clock, wherein the front-end section comprises a front-end input section and a front-end output section, the front-end input section coupled to an input of the NICAM processor and the front-end output section coupled to an output of the NICAM processor wherein the front-end output section comprises a digital square-root raised-cosine (SRRC) filter with interpolation factor K, a variable interpolator with variable interpolation factor L, a digital mixer, a digital-to-analog converter (DAC), and a sine & cosine generator, wherein the SRRC filter couples to the variable interpolator, the variable interpolator couples to the mixer, and the mixer couples to the DAC and to the sine & cosine generator.

10. The NICAM encoder of claim 9 , further comprising an interpolator timing circuit, wherein the interpolator timing circuit couples to the SRRC filter, the variable interpolator, and the NICAM processor, further wherein the interpolator timing circuit provides strobes to the NICAM processor, the SRRC filter, and the variable interpolator.

11. The NICAM encoder of claim 10 , further wherein the interpolator timing circuit generates a first strobe signal for the NICAM processor and the SRRC filter and generates a second strobe signal for the SRRC filter and the interpolator.

12. The NICAM encoder of claim 11 , wherein the interpolator timing circuit includes an N-bit adder that comprises full adders, wherein N is a prescribed number of bits.

13. The NICAM encoder of claim 12 , further wherein the N-bit adder includes a 24 bit adder of full adders (FA 0 , FA 1 , . . . , FA 20 , FA 21 , FA 22 , and FA 23 ).

14. The NICAM encoder of claim 13 , further wherein the first strobe signal corresponds to a MSB Full-adder carry-out (CO 23 ) and the second strobe signal corresponds to a MSB-2 Full-adder carry-out (CO 21 ).

15. The NICAM encoder of claim 10 , further wherein the strobe to the NICAM processor approximates one of a 728 kHz or 364 kHz clock derived from the system clock.

16. The NICAM encoder of claim 10 , further wherein the interpolator timing circuit provides a strobe to synchronize the NICAM processor with the front-end output section by resetting an interpolator timing circuit register of the interpolator timing circuit at regular intervals.

17. The NICAM encoder of claim 9 , wherein the SRRC filter with interpolation factor K comprises a pulse shaping filter portion configured to perform pulse-shaping and an interpolator portion for interpolating by a factor K, further wherein the pulse shaping filter portion and the interpolator portion comprise separate individual blocks or a single combined block.

18. A NICAM encoder comprising:

a front-end input section, wherein the front-end input section comprises one of:

(a) an interpolator by factor N, a first decimator by factor M, a pre-emphasis filter, and a second decimator by factor P, wherein the interpolator couples to the first decimator, the first decimator couples to the pre-emphasis filter, and the pre-emphasis filter couples to the second decimator, or

(b) a dual-channel analog-to-digital converter (ADC), an interpolator by factor N, a first decimator by factor M, a pre-emphasis filter, and a second decimator by factor P, wherein the ADC couples to the interpolator, the interpolator couples to the first decimator, the first decimator couples to the pre-emphasis filter, and the pre-emphasis filter couples to the second decimator;

a NICAM processor, the front-end input section being coupled to an input of the NICAM processor; and

a front-end output section, wherein the front-end output section comprises a digital square-root raised-cosine (SRRC) filter with interpolation factor K, a variable interpolator with variable interpolation factor L, a digital mixer, a digital-to-analog converter (DAC), and a sine & cosine generator, wherein the SRRC filter couples to the variable interpolator, the variable interpolator couples to the mixer, and the mixer couples to the DAC and to the sine & cosine generator, the NICAM processor being coupled to an input of the front-end output section, wherein the front-end output section provides a synchronization strobe to the NICAM processor with timing derived from integer divisions of a single system clock.

Assignments (17)