US3925614A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Receiver for the reception of pulse signals transmitted by means of frequency shift modulation
Assignee: US Philips Corp
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Filing: 1974-09-30
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Granted: 1975-12-09
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Expires: 1994-09-30
Abstract
Abstract In a receiver for frequency shift modulation an accurate demodulation of the received signal and a low sensitivity to noise and interference is obtained by using a frequency discriminator in which a number of parallel channels are incorporated between a common frequency generator and a phase comparator and in which each channel includes a frequency divider provided with a phase adjusting circuit, while the different frequency dividers are cyclically adjusted in phase as a function of the zero crossings in the received signal and the demodulated signal is derived from a lowpass filter connected to the phase comparator.
Inventors
- 👤 Michel Antony Marie Jo Bousmar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:17
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/10; H04L27/14; H04L27/156; H04L27/1563
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
185 words
A receiver for the reception of pulse signals transmitted by means of frequency shift modulation in which the received modulated pulse signals are applied to a frequency discriminator from which the demodulated pulse signals are derived, the frequency discriminator comprising a plurality of parallel channels whose inputs are coupled to a common generator having a fixed frequency and whose outputs are coupled to a plase comparator, each channel including a frequency divider provided with a phase adjusting circuit, said divider having output means for providing output signals at a frequency which is equal for all channels and which is higher than the highest frequency of the received modulated pulse signals, said frequency discriminator furthermore including a zero crossing detector for generating set pulses as a function of the zero crossings in the received modulated pulse signals, said set pulses being cyclically applied to the phase adjusting circuits of the different frequency dividers, the output signals of two channels being compared in phase in the phase comparator and the demodulated pulse signals being derived from a lowpass filter coupled to the output of the phase comparator.
Claim 2
Dependent Claim
185 words
A receiver for the reception of pulse signals transmitted by means of frequency shift modulation in which the received modulated pulse signals are applied to a frequency discriminator from which the demodulated pulse signals are derived, the frequency discriminator comprising a plurality of parallel channels whose inputs are coupled to a common generator having a fixed frequency and whose outputs are coupled to a plase comparator, each channel including a frequency divider provided with a phase adjusting circuit, said divider having output means for providing output signals at a frequency which is equal for all channels and which is higher than the highest frequency of the received modulated pulse signals, said frequency discriminator furthermore including a zero crossing detector for generating set pulses as a function of the zero crossings in the received modulated pulse signals, said set pulses being cyclically applied to the phase adjusting circuits of the different frequency dividers, the output signals of two channels being compared in phase in the phase comparator and the demodulated pulse signals being derived from a lowpass filter coupled to the output of the phase comparator.
Claim 3
Dependent Claim
69 words
A receiver as claimed in claim 1, wherein the frequency discriminator includes two parallel channels each being provided with a frequency divider having a number of stages, said phase adjusting circuit comprising a reset circuit coupled to all stages of the frequency divider, said reset circuit resetting all stages of the frequency divider simultaneously to their initial state when a set pulse of the zero crossing detector is applied.
Claim 4
Dependent Claim
39 words
A receiver as claimed in claim 2, wherein the zero crossing detector includes a slicer whose output is coupled to the reset circuits through a differentiating network and a half-wave rectifier of opposite polarity for the two reset circuits.
Claim 5
Dependent Claim
20 words
A receiver as claimed in claim 3, wherein a two-to-one divider is incorporated between the slicer and the differentiating network.
Claim 6
Dependent Claim
114 words
A receiver as claimed in claim 1, wherein the frequency discriminator includes three parallel channels each being provided with a frequency divider in the form of a shift register whose clock input is coupled to the common generator and whose output is coupled to the input through a logical selection gate whose output is coupled to the phase comparator, said logical selection gate also comprising the phase adjusting circuit of the frequency divider, said set pulses of the zero crossing detector blocking always one of the three logical gates in a cyclic sequence for obtaining a constant output signal of the relevant channel and for resetting the relevant shift register to its initial state.
Claim 7
Dependent Claim
39 words
A receiver as claimed in claim 5, wherein the zero crossing detector iNcludes a slicer whose output is coupled to a three-to-one divider which has three outputs for deriving the set pulses therefrom for the three logical selection gates.
Claim 8
Dependent Claim
25 words
A receiver as claimed in claim 6, wherein a differentiating network followed by a full-wave rectifier is incorporated between the slicer and the three-to-one divider.
References Cited (Backward Citations)
US3778727A
Cited
US3796942A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-08 | 1979-06-09 | 1979-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-08 | 1983-06-09 | 1983-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-08 | 1987-06-09 | 1987-12-09 | $7700.00 | Window Closed / Lapsed |