US5644606A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Receiver with two synchronization loops
Assignee: US Philips Corp
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Filing: 1995-08-24
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Granted: 1997-07-01
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Expires: 2015-08-24
Abstract
Abstract Digital transmission system (10) for digitally modulated signals, comprising a receiving device (14) which includes a demodulator (110), processing apparatus (120) and carrier synchronizing apparatus (16) for estimating and compensating for synchronization errors. The synchronizing apparatus includes a first loop (1) for phase/frequency correction and a second loop (2) for phase correction, the operation of these loops being controlled by a mode detector (130) depending on whether the receiving device is seeking to unlock or lock. The second loop (2) transforms a phase error signal into a phase correction signal which is mixed in mixer (246) with the signal coming from the demodulator. Preferably, the signals are modulated via a coded modulation.
Inventors
- 👤 Georges Martinez
- 👤 Jean-Michel Guillaud
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 19:15
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/085; H03L7/087; H04; H04L; H04L27/00; H04L27/32; H04L27/34; H04L27/38; H04L27/3818; H04L27/3827
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
263 words
A signal transmission system comprising a receiving device which includes carrier synchronizing means for estimating and compensating for synchronization errors between a local carrier and a modulated input signal, while the device further includes input signal demodulation means which produce a demodulated signal, and processing means for recovering estimated symbols from the demodulated signal, the synchronizing means comprising a first correction loop which includes, on the one hand, phase/frequency detection means for producing a first error signal, first low-pass filter means which have a first passband for filtering the first error signal, which filtered first error signal corrects the synchronization errors in an unlocked mode, and, on the other hand, means for generating the local carrier, and a second correction loop which includes phase detection means which produce a second error signal which corrects the synchronization errors in a locked mode, and means for controlling the loops and for putting the synchronizing means either in the unlocked mode or in the locked mode, wherein the second loop includes second low-pass filter means for filtering the second error signal, which second low-pass filter means have a passband which is wider than the first passband to provide that the synchronization is robust to phase noise, transforming means for transforming the second error signal, after it has been filtered by the second filter means, into a phase correction signal, while the the phase detection means is connected to the output of the processing means, and mixing means connected between the demodulation means and the processing means, for mixing the demodulated signal with the phase correction signal.
Claim 2
Dependent Claim
263 words
A signal transmission system comprising a receiving device which includes carrier synchronizing means for estimating and compensating for synchronization errors between a local carrier and a modulated input signal, while the device further includes input signal demodulation means which produce a demodulated signal, and processing means for recovering estimated symbols from the demodulated signal, the synchronizing means comprising a first correction loop which includes, on the one hand, phase/frequency detection means for producing a first error signal, first low-pass filter means which have a first passband for filtering the first error signal, which filtered first error signal corrects the synchronization errors in an unlocked mode, and, on the other hand, means for generating the local carrier, and a second correction loop which includes phase detection means which produce a second error signal which corrects the synchronization errors in a locked mode, and means for controlling the loops and for putting the synchronizing means either in the unlocked mode or in the locked mode, wherein the second loop includes second low-pass filter means for filtering the second error signal, which second low-pass filter means have a passband which is wider than the first passband to provide that the synchronization is robust to phase noise, transforming means for transforming the second error signal, after it has been filtered by the second filter means, into a phase correction signal, while the the phase detection means is connected to the output of the processing means, and mixing means connected between the demodulation means and the processing means, for mixing the demodulated signal with the phase correction signal.
Claim 3
Dependent Claim
106 words
The system as claimed in claim 1, wherein the first filter and the second filter are digital filters and the second filter includes: a first adder which has a first input for receiving the second error signal, an output producing an output signal, a second input which is coupled to the output across a loop circuit, while the loop circuit comprises in a series combination a delay means and weighting means that applies a leakage factor to a delayed output signal, and a second adder which adds together the second error signal and the output signal of the first adder and produces a filtered error signal.
Claim 4
Dependent Claim
53 words
The system as claimed in claim 1, wherein the means for transforming the second error signal into a phase correction signal includes converting means which convert the filtered error signal into a phase signal and means for generating two sine/cosine components of the signal having phase, which components form the phase correction signal.
Claim 5
Dependent Claim
24 words
The system as claimed in claim 3, wherein the means for generating the two sine/cosine components comprise a memory that stores a look-up Table.
Claim 6
Dependent Claim
15 words
A receiving device for use in a digital transmission system as claimed in claim 1.
Claim 7
Dependent Claim
53 words
The system as claimed in claim 2, wherein the means for transforming the second error signal into a phase correction signal includes converting means which convert the filtered error signal into a phase signal and means for generating two sine/cosine components of the signal having phase, which components form the phase correction signal.
Claim 8
Dependent Claim
15 words
A receiving device for use in a digital transmission system as claimed in claim 2.
Claim 9
Dependent Claim
15 words
A receiving device for use in a digital transmission system as claimed in claim 3.
Claim 10
Dependent Claim
15 words
A receiving device for use in a digital transmission system as claimed in claim 4.
Claim 11
Dependent Claim
15 words
A receiving device for use in a digital transmission system as claimed in claim 6.
Claim 12
Dependent Claim
201 words
A signal transmission system comprising: an oscillator for generating a local carrier; a receiving device having a carrier synchronizer for estimating and compensating for synchronization errors between the local carrier and a modulated input signal; an input signal demodulator for producing a demodulated signal; a processor for recovering estimated symbols from the demodulated signal; a phase/frequency detector for producing a first error signal, a first filter for filtering the first error signal which corrects the synchronization errors in an unlocked mode; a phase detector for producing a second error signal which corrects the synchronization errors in a locked mode; a second filter for filtering the second error signal, said second filter having a passband wider than a passband of the first filter; a transformer for transforming the second error signal, after it has been filtered by the second filter, into a phase correction signal while the phase detector is connected to the output of the processor; a mixer connected between the demodulator and the processor for mixing the demodulated signal with the phase correction signal; and a switcher for switching the synchronizer from one of an unlocked mode and a locked mode to the other of an unlocked and locked mode.
Claim 13
Dependent Claim
201 words
A signal transmission system comprising: an oscillator for generating a local carrier; a receiving device having a carrier synchronizer for estimating and compensating for synchronization errors between the local carrier and a modulated input signal; an input signal demodulator for producing a demodulated signal; a processor for recovering estimated symbols from the demodulated signal; a phase/frequency detector for producing a first error signal, a first filter for filtering the first error signal which corrects the synchronization errors in an unlocked mode; a phase detector for producing a second error signal which corrects the synchronization errors in a locked mode; a second filter for filtering the second error signal, said second filter having a passband wider than a passband of the first filter; a transformer for transforming the second error signal, after it has been filtered by the second filter, into a phase correction signal while the phase detector is connected to the output of the processor; a mixer connected between the demodulator and the processor for mixing the demodulated signal with the phase correction signal; and a switcher for switching the synchronizer from one of an unlocked mode and a locked mode to the other of an unlocked and locked mode.
Claim 14
Dependent Claim
86 words
The system as claimed in claim 11, wherein the second filter includes a first adder having a first input for receiving the second error signal, an output producing an output signal, a second input coupled to the output of a loop circuit, said loop circuit including delay means and weighting means that applies a leakage factor to a delayed output signal, and a second adder which adds together the second error signal and the output signal of the first adder and produces a filtered error signal.
Claim 15
Dependent Claim
43 words
The system as claimed in claim 11, wherein the transformer includes a converter for converting the filtered error signal into a phase signal and a generator for generating two sine/cosine components of the signal having phase and which form the phase correction signal.
Claim 16
Dependent Claim
18 words
The system as claimed in claim 13, wherein the generator includes a memory that stores a look-up Table.
Claim 17
Dependent Claim
15 words
A receiving device for use in a digital transmission system as claimed in claim 11.
Claim 18
Dependent Claim
18 words
The system as claimed in claim 11, wherein the first filter and the second filter are digital filters.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-06-30 | 2000-12-30 | 2001-07-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-06-30 | 2004-12-30 | 2005-07-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-06-30 | 2008-12-30 | 2009-07-01 | $7700.00 | Window Closed / Lapsed |