# US 5,706,057 A · Phase detector in a carrier recovery network for a vestigial sideband signal

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- Number: US 5,706,057 A
- Document ID: US5706057A
- Status: Granted
- Kind: A
- Application number: 08/704,788
- Filed: 1996-09-05
- Granted: 1998-01-06
- Earliest claimed: 1994-03-21
- Assignees: RCA Thomson Licensing Corporation
- Inventors: Christopher Hugh Strolle; Steven Todd Jaffe
- Web page: https://patentgrep.com/patent/US5706057A

## CPC

- H04N 5/455: Demodulation-circuits
- H04L 25/0305: {using blind adaptation}
- H04L 25/0307: {using blind adaptation}
- H04L 25/061: {providing hard decisions only; arrangements for tracking or suppressing unwanted low frequency components, e.g. removal of DC offset (removal of DC offset in coupling arrangements H04L25/029, H04L25/0296)}
- H04L 25/067: {providing soft decisions, i.e. decisions together with an estimate of reliability (H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178)}
- H04L 27/02: Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation (H04L27/32 takes precedence)
- H04L 27/066: {Carrier recovery circuits (H04L27/2271 takes precedence)}
- H04N 5/211: {Ghost signal cancellation (H04N23/81 takes precedence)}
- H04N 21/4382: {Demodulation or channel decoding, e.g. QPSK demodulation (analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002)}
- H04L 2025/03382: {Single of vestigal sideband}
- H04L 2025/0363: {Feature restoration, e.g. constant modulus}
- H04N 21/426: Internal components of the client {; Characteristics thereof} (H04N5/44 takes precedence)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A television signal receiver for processing an HDTV signal transmitted in a vestigial sideband (VSB) format with a one-dimensional data constellation includes a first carrier recovery network (18), an equalizer (20), and a second carrier recovery network (22, 30, 62). A multiple stage quantizer network (50, 66) exhibiting progressively finer resolution is associated with the operation of the equalizer for providing blind equalization without need of a "training" signal. The second carrier recovery network includes a phase detector (30) wherein a one-symbol delayed (312) input signal and a quantized (310) input signal are multiplied (316), and an unquantized input signal and a quantized (310) one-symbol delayed (314) input signal are multiplied (316), and an unquantized input signal and a quantized (310) one-symbol delayed (314) input signal are multiplied (318). Signals produced by the multiplication are subtractively combined (320) to produce an output signal representing carrier phase error.

## Claims

### Claim 1

In a system for receiving a vestigial sideband (VSB) video signal formatted as a one-dimensional constellation of data symbols representing digital image data and subject to exhibiting a carrier offset, apparatus comprising:
a carrier recovery network (22,30) for shifting said received VSB signal toward baseband; and
a phase detector (32) in said carrier recovery network, including
an input for receiving a near baseband VSB signal;
a quantizer (310) responsive to said input VSB signal for producing a quantized VSB signal;
a symbol delay network (312,314) for delaying said input VSB signal and for delaying said quantized signal;
a first multiplier (316) responsive to said quantized VSB signal and to a symbol delayed signal from said delay network, for producing a first signal;
a second multiplier (314) responsive to said input VSB signal and to a symbol delayed quantized signal from said delay network, for producing a second signal; and
a combiner for subtractively combining said first and second signals to produce a phase error representative signal.

### Claim 2 (depends on 1)

Apparatus according to claim 1, wherein
said input VSB signal exhibits a real component exclusive of an imaginary component.

### Claim 3 (depends on 1)

Apparatus according to claim 1 and further comprising:
a timing recovery network for providing a symbol clock in synchronism with a transmitter clock so that said input signal to said phase detector exhibits timing lock.

### Claim 4 (depends on 1)

Apparatus according to claim 1 and further including:
a signal equalizer (20) having an input for receiving a transmitted VSB signal, an output coupled to said carrier recovery network, and a control input for receiving a control signal that is a function of said error signal.

### Claim 5 (depends on 4)

Apparatus according to claim 4 and further including:
an additional carrier recovery network (18) with an input for receiving a transmitted VSB signal and an output coupled to said equalizer input.

### Claim 6 (depends on 1)

Apparatus according to claim 1, wherein
said input VSB signal is an N-level VSB signal; and
said quantizer exhibits N quantization levels.

### Claim 7 (depends on 1)

Apparatus according to claim 1, wherein:
said delay network exhibits a one symbol delay.