DECOUPLED DATA-AIDED SYMBOL TIMING RECOVERY LOOP

• US 20100283911A1
• Filed: 01/14/2008
• Published: 11/11/2010
• Est. Priority Date: 01/14/2008
• Status: Active Grant

• Current Assignee: InterDigital Madison Patent Holdings (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Belotserkovsky, Maxim
• Granted Patent: US 8,761,311 B2
• Time in Patent Office: Days
• US Class Current: 348/726
• CPC Class Codes: H04L 2027/003 at baseband only
• CPC Class Codes: H04L 2027/0057 quadrature phase
• CPC Class Codes: H04L 27/38 Demodulator circuits; Receiver circuits
• CPC Class Codes: H04L 7/0029 interpolation of received data signal
• CPC Class Codes: H04L 7/027 extracting the synchronising or clock signal from the received signal spectrum, e.g. by using a resonant or bandpass circuit
• CPC Class Codes: H04L 7/065 and superimposed by modulation

Abstract

A receiver is an ATSC (Advanced Television Systems Committee)-receiver and comprises a staggered quadrature amplitude modulator for providing an staggered quadrature amplitude modulated (SQAM) signal from a received signal; a data-aided carrier tracking loop (CTL) and a data-aided symbol timing recovery (STR) loop. The data-aided STR loop operates such that the data-aided STR loop is now insensitive to carrier phase offset.

Claims

1. Apparatus for use in a receiver, the apparatus comprising:

a staggered quadrature amplitude modulator for providing a staggered quadrature amplitude modulated signal from a received signal;

a carrier tracking loop, for tracking a carrier frequency in the staggered quadrature amplitude modulated signal; and

a data-aided symbol timing recovery loop for tracking symbol timing in the staggered quadrature amplitude modulated signal wherein the symbol timing recovery loop includes

a filter for removing a phase response symmetry in a signal derived from the staggered quadrature amplitude modulated signal for providing a filter output signal; and

a timing phase detector responsive to the filter output signal for driving the symbol timing recovery loop.

2. The apparatus of claim 1, wherein the carrier tracking loop is a data-aided carrier tracking loop.

3. The apparatus of claim 1, wherein the data-aided symbol timing recovery loop further comprises:

a multiplier for derotating the staggered quadrature amplitude modulated signal for providing a derotated staggered quadrature amplitude modulated signal;

an interpolator responsive to the derotated staggered quadrature amplitude modulated signal for providing an interpolated signal;

a demodulator for demodulating the interpolated signal for providing a demodulated signal; and

an equalizer for equalizing the demodulated signal for providing an equalized signal and a training signal;

wherein the filter removes a phase response symmetry from the equalized signal.

4. The apparatus of claim 3, wherein the demodulator translates the interpolated signal back to a vestigial sideband modulated signal before providing the demodulated signal.

5. The apparatus of claim 1, wherein the data-aided symbol timing recovery loop further comprises:

a multiplier for derotating the staggered quadrature amplitude modulated signal for providing a derotated staggered quadrature amplitude modulated signal;

an interpolator responsive to the derotated staggered quadrature amplitude modulated signal for providing an interpolated signal;

a demodulator for demodulating the interpolated signal for providing a demodulated signal; and

an equalizer for equalizing the demodulated signal for providing an equalized signal and a training signal;

wherein the filter removes a phase response symmetry from the demodulated signal.

6. The apparatus of claim 5, wherein the demodulator translates the interpolated signal back to a vestigial sideband modulated signal before providing the demodulated signal.

7. The apparatus of claim 1, wherein the received signal is an ATSC (Advanced Television Systems Committee) VSB (Vestigial Sideband) modulated signal.

8. A method for use in a receiver, the method comprising:

staggered quadrature amplitude modulating a received signal for providing a staggered quadrature amplitude modulated signal;

removing a phase response symmetry in a signal derived from the staggered quadrature amplitude modulated signal for providing a filter output signal; and

detecting timing phase differences as a function of the filter output signal for driving a symbol timing recovery loop;

9. The method of claim 8, further comprising:

derotating the staggered quadrature amplitude modulated signal for providing a derotated staggered quadrature amplitude modulated signal;

interpolating the derotated staggered quadrature amplitude modulated signal for providing an interpolated signal;

demodulating the interpolated signal for providing a demodulated signal; and

equalizing the demodulated signal for providing an equalized signal and a training signal;

wherein the removing step removes a phase response symmetry from the equalized signal.

10. The method of claim 9, wherein the demodulating step comprises:

converting the interpolated signal back to a vestigial sideband modulated signal before providing the demodulated signal.

11. The method of claim 8, further comprising:

derotating the staggered quadrature amplitude modulated signal for providing a derotated staggered quadrature amplitude modulated signal;

interpolating the derotated staggered quadrature amplitude modulated signal for providing an interpolated signal;

demodulating the interpolated signal for providing a demodulated signal; and

equalizing the demodulated signal for providing an equalized signal and a training signal;

wherein the removing step removes a phase response symmetry from the demodulated signal.

12. The method of claim 11, wherein the demodulating step comprises:

converting the interpolated signal back to a vestigial sideband modulated signal before providing the demodulated signal.

13. The method of claim 8, wherein the received signal is an ATSC (Advanced Television Systems Committee) VSB (Vestigial Sideband) modulation signal.