US3593147A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Equal gain diversity receiving system with squelch
Assignee: TDK Micronas GmbH
•
Filing: 1969-03-04
•
Granted: 1971-07-13
•
Expires: 1989-03-04
Abstract
Abstract A pair of RF diversity signals are routed to separate channels and heterodyned to two IF signals having the same IF frequency. The IF signals are combined to provide a common IF signal for demodulation. An automatic gain control signal is generated from the common IF signal and is used to control the gain of each IF signal prior to combining to assure a constant amplitude, common IF signal. The common IF signal is also used as a reference signal for a phase comparator in each channel. Each phase comparator compares the phase of its associated IF signal to the reference signal and adjusts its associated IF signal for inphase combining thereof. A squelch diode is included in each channel prior to combining under control of a squelch circuit which responds to the automatic gain control signal and the relative carrier ratios of the two IF signals. The squelch diodes supply no attenuation when the relative carrier ratios are less than a predetermined value and the squelch diode associated with the weaker IF signal supplies substantial attenuation when one of the relative carrier ratios is equal to or greater than the predetermined value. An alarm/normal arrangement is driven by the squelch circuit to indicate critical signal levels for the IF signals.
Inventors
- 👤 Richard J Gurak
- 👤 Milton D Reicher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:48
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/02; H04B7/04; H04B7/08; H04B7/0837; H04B7/084
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
476 words
A diversity receiving system of the predetection combining type comprising: a pair of sources of signals, the signals of each of said sources having random phase relation with respect to each other; first means having a phase control terminal, first and second outputs, a first input coupled to one of said sources and a second input coupled to the other of said sources to provide at said first output a first intermediate frequency signal and at said second output a second intermediate frequency signal, said first and second intermediate frequency signals each having the same frequency; first gain control means having a gain control terminal, an input coupled to said first output of said first means and an output for said first intermediate frequency signal; second gain control means having a gain control terminal, an input coupled to said second input of said first means and an output for said second intermediate frequency signal; first variable attenuation means having an input coupled to the output of said first control means and an output for said first intermediate frequency signal; second variable attenuation means having an input coupled to the output of said second control means and an output for said second intermediate frequency signal; second means having an output, a first input coupled to the output of said first attenuation means and a second input coupled to the output of said second attenuation means to combine said first and second intermediate frequency signals; third means having input means coupled to thE output of said second means and the output of said first and second control means and output means coupled to the phase control terminal of said first means to vary the phase relation of said first and second intermediate frequency signals for inphase combining in said second means; fourth means having an output and an input coupled to the output of said second means to produce a control signal at the output of said fourth means for coupling to the gain control terminal of both said first and second control means to control the amplitude of each of said first and second intermediate frequency signals to produce a constant amplitude signal at the output of said second means; and fifth means having input means coupled to the output of said fourth means, the output of said first and second control means, and the output of both said first and second attenuation means and an output means coupled to the input of both said first and second attenuation means to control said first and second attenuation means for squelching the weaker of said first and second intermediate frequency signals when the relative carrier ratio thereof is equal to or exceeds a predetermined value and for permitting the combining of said first and second intermediate frequencies when the relative carrier ratio is less than said predetermined value.
Claim 2
Dependent Claim
476 words
A diversity receiving system of the predetection combining type comprising: a pair of sources of signals, the signals of each of said sources having random phase relation with respect to each other; first means having a phase control terminal, first and second outputs, a first input coupled to one of said sources and a second input coupled to the other of said sources to provide at said first output a first intermediate frequency signal and at said second output a second intermediate frequency signal, said first and second intermediate frequency signals each having the same frequency; first gain control means having a gain control terminal, an input coupled to said first output of said first means and an output for said first intermediate frequency signal; second gain control means having a gain control terminal, an input coupled to said second input of said first means and an output for said second intermediate frequency signal; first variable attenuation means having an input coupled to the output of said first control means and an output for said first intermediate frequency signal; second variable attenuation means having an input coupled to the output of said second control means and an output for said second intermediate frequency signal; second means having an output, a first input coupled to the output of said first attenuation means and a second input coupled to the output of said second attenuation means to combine said first and second intermediate frequency signals; third means having input means coupled to thE output of said second means and the output of said first and second control means and output means coupled to the phase control terminal of said first means to vary the phase relation of said first and second intermediate frequency signals for inphase combining in said second means; fourth means having an output and an input coupled to the output of said second means to produce a control signal at the output of said fourth means for coupling to the gain control terminal of both said first and second control means to control the amplitude of each of said first and second intermediate frequency signals to produce a constant amplitude signal at the output of said second means; and fifth means having input means coupled to the output of said fourth means, the output of said first and second control means, and the output of both said first and second attenuation means and an output means coupled to the input of both said first and second attenuation means to control said first and second attenuation means for squelching the weaker of said first and second intermediate frequency signals when the relative carrier ratio thereof is equal to or exceeds a predetermined value and for permitting the combining of said first and second intermediate frequencies when the relative carrier ratio is less than said predetermined value.
Claim 3
Dependent Claim
43 words
A system according to claim 1, wherein said first and second control means each include an intermediate frequency amplifier with automatic gain control; and further including a conductor interconnecting each of said amplifiers to compensate for circuit variations therein due to temperature variations.
Claim 4
Dependent Claim
17 words
A system according to claim 1, wherein said first and second attenuation means each include a diode.
Claim 5
Dependent Claim
67 words
A system according to claim 1, wherein said third means includes a first phase comparator coupled to the output of said second means and the output of said first control means, and a second phase comparator coupled to the output of said second means and the output of said second control means, the outputs of said first and second phase comparators being coupled to said first means.
Claim 6
Dependent Claim
159 words
A system according to claim 1, wherein said first means includes a first mixer coupled to one of said sources, a first variable frequency oscillator means having an output signal coupled to said first mixer, the said first mixer mixing the signal of one of said sources and output signal of said first oscillator means to produce said first intermediate frequency signal, a second mixer coupled to the other of said sources, and a second variable frequency oscillator means having an output signal coupled to said second mixer, said second mixer mixing the signal of the other of said sources and the output signal of said second oscillator means to produce said second intermediate frequency signal, said first and second oscillator means being coupled to the phase control terminal of said first means and controlled by said third means to vary the phase relation of said first and second intermediate frequency signals for inphase combining in said second means.
Claim 7
Dependent Claim
134 words
A system according to claim 1, wherein said fifth means includes sixth means coupled to the output of said first and second control means to produce a first voltage equal to the algebraic sum of said first and second intermediate frequency signal and a second voltage equal to the algebraic sum of said second and first intermediate frequency signal; and seventh means coupled to said sixth means, said fourth means and said first and second attenuation means to control said first and second attenuation means to have substantially no attenuation when both said first and second voltages are less than said predetermined value and to control one of said first and second attenuation means to have substantial attenuation when one of said first and second voltages is equal to or exceeds said predetermined value.
Claim 8
Dependent Claim
115 words
A system accoRding to claim 6, further including eighth means coupled to said seventh means to indicate a normal condition for both said first and second intermediate frequency signals when both of said first and second voltages are less than said predetermined value, a normal condition for one of said first and second intermediate frequency signals and an alarm condition for the other of said first and second intermediate frequency signal when one of said first and second voltages is equal to or exceeds said predetermined value, and an alarm condition for both said first and second intermediate frequency signals when both said first and second voltages are equal to or exceeds said predetermined value.
Claim 9
Dependent Claim
377 words
A system according to claim 6, wherein said first attenuation means includes a first diode coupled to said first control means; said second attenuation means includes a second diode coupled to said second control means; said seventh means includes comparator means having a first input, a second input, a third input, a first output and a second output, said third input being coupled to said fourth means, said first output being coupled to said first diode to normally forward bias said first diode, and said second output being coupled to said second diode to normally forward bias said second diode, a third diode, a fourth diode, a first voltage divider to develop a given voltage coupled between said first input and said third diode to normally back bias said third diode by said given voltage, and a second voltage divider to develop said given voltage coupled between said second input and said fourth diode to normally back bias said fourth diode by said given voltage; and said sixth means includes a first positive peak detector coupled to said first control means, a first negative peak detector coupled to said second control means, a first combiner coupled to said first positive peak detector and said first negative peak detector, a first amplifier coupled between said first combiner and said third diode to produce said first voltage, said first amplifier having a gain sufficient to provide an amplitude for said first voltage so that at said predetermined value said given voltage is overcome, said third diode is forward biased, and said comparator produces on its second output sufficient voltage to back bias said second diode, a second positive peak detector coupled to said second control means, a second negative peak detector coupled to said first control means, a second combiner coupled to said second positive peak detector and said second negative peak detector, and a second amplifier coupled between said second combiner and said fourth diode to produce said second voltage, said second amplifier having a gain sufficient to provide an amplitude for said second voltage so that at said predetermined value said given voltage is overcome, said fourth diode is forward biased, and said comparator produces on its first output sufficient voltage to back bias said first diode.
Claim 10
Dependent Claim
449 words
A system according to claim 1, wherein said first means includes a first mixer coupled to one of said sources, a first variable frequency oscillator means having an output signal coupled to said first mixer, said first mixer mixing the signal of one of said sources and the output signal of said first oscillator means to produce at its output said first intermediate frequency signal, a second mixer coupled to the other of said sources, and a second variable frequency oscillator means having an output signal coupled to said second mixer, said second mixer mixing the signal of the other of said sources and the output signal of said second oscillator means to produce at its output said second intermediate frequency signal; said first control means includes a first intermediate frequency amplifier with automatic gain control means having an output, an input coupled to the output of said First mixer and a gain control terminal coupled to the output of said fourth means; said second control means includes a second intermediate frequency amplifier with automatic gain control means having an output, an input coupled to the output said second mixer and a gain control terminal coupled to the output of said fourth means; said first attenuation means includes a first diode coupled to the output of said first intermediate frequency amplifier; said second attenuation means includes a second diode coupled to the output of said second intermediate frequency amplifier; said third means includes a first phase comparator coupled to the output of said second means, the output of said first intermediate frequency amplifier, and said first oscillator means, and a second phase comparator coupled to the output of said second means, the output of said second intermediate frequency amplifier, and said second oscillator means; and said fifth means includes sixth means coupled to the output of both said first and second intermediate frequency amplifiers to produce a first voltage equal to the algebraic sum of said first and second intermediate frequency signals and a second voltage equal to the algebraic sum of said second and first intermediate frequency signals, and seventh means coupled to said sixth means, the output of said fourth means and said first and second diodes to control said first and second diodes to have substantially no attenuation when both said first and second voltages are less than said predetermined value and to control one of said first and second diodes to have substantial attenuation when one of said first and second voltages is equal to or exceeds said predetermined value; and further including a conductor interconnecting each of said first and second intermediate frequency amplifiers to compensate for circuit variations therein due to temperature variations.
Claim 11
Dependent Claim
353 words
A system according to claim 9, wherein said seventh means includes comparator means having a first input, a second input, a third input, a first output and a second output, said third input being coupled to said fourth means, said first output being coupled to said first diode to normally forward bias said first diode, and said second output being coupled to said second diode to normally forward bias said second diode, a third diode, a fourth diode, a first voltage divider to develop a given voltage coupled between said first input and said third diode to normally back bias said third diode by said given voltage, and a second voltage divider to develop said given voltage coupled between said second input and said fourth diode to normally back bias said fourth diode by said given voltage; and said sixth means includes a first positive peak detector coupled to said first intermediate frequency amplifier; a first negative peak detector coupled to said second intermediate frequency amplifier, a first combiner coupled to said first positive peak detector and said first negative peak detector, a first amplifier coupled between said first combiner and said third diode to produce said first voltage, said first amplifier having a gain sufficient to provide an amplitude for said first voltage so that at said predetermined value said given voltage is overcome, said third diode is forward biased, and said comparator produces on its second output sufficient voltage to back bias said second diode, a second positive peak detector coupled to said second intermediate frequency amplifier, a second negative peak detector coupled to said first intermediate frequency amplifier, a second combiner coupled to said second positive peak detector and said second negative peak detector, and a second amplifier coupled between said second combiner and said fourth diode to produce said second voltage, said second amplifier having a gain sufficient to provide an amplitude foR said second voltage so that at said predetermined value said given voltage is overcome, said fourth diode is forward biased, and said comparator produces on its first output sufficient voltage to back bias said first diode.
References Cited (Backward Citations)
US3029338A
Cited
US3487309A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-07-12 | 1975-01-11 | 1975-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-07-12 | 1979-01-11 | 1979-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-07-12 | 1983-01-11 | 1983-07-13 | $7700.00 | Window Closed / Lapsed |