US4373205A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Radio subscriber system with efficient use of radio frequency carrier waves
Assignee: NEC Corp
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Filing: 1980-06-09
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Granted: 1983-02-08
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Expires: 2000-06-09
Abstract
Abstract A radio subscriber system switches between a plurality of radio link channels and seizes one responsive to an idle tone appearing thereon. A control circuit uses a microprocessor to select transmit and receive carrier frequencies for the seized channel. This selection is made by storing the channel identification in a random access memory while interrogating a read-only memory for channel frequency assignments. The control circuit identifies the seized circuit by channel signals which are demodulated when the seizure occurs.
Inventors
- 👤 Yasuhiro Mizota
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:10
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/38; H04B1/40; H04B1/403; H04B1/405
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
276 words
A channel-switching system comprising: a plurality of channels, each of which transmits and receives over individually associated a transmission and reception carrier waves with a frequency interval between said transmission and reception carrier waves, at least one of said frequency intervals on one of said channels being different from the other frequency intervals on other of said channels; means for receiving the plurality of reception carrier waves; means for transmitting the plurality of transmission carrier waves; first mixer means coupled to said receiving means for frequency-mixing the output of said receiving means with an oscillation signal; means coupled to said first mixer means for demodulating the output of said first mixer means; means for generating a reference frequency signal; modulation means responsive to a first control signal for converting said reference frequency signal into one of a plurality of carrier waves respectively corresponding to said plurality of transmission carrier waves and for modulating the converted signal with a signal which is to be transmitted; second mixer means coupled to said modulation means for frequency-mixing the output of said modulation means and said local oscillation signal and for supplying the frequency-mixed signal to said transmitting means as one of said plurality of transmission carrier waves; frequency-synthesizing means responsive to a second control signal for frequency-synthesizing said reference frequency signal to provide said local oscillation signal and for supplying it to said first and second mixer means; means responsive to the output of said demodulation means for detecting a signal designating a channel number; and means responsive to the detected signal for supplying said first and second control signals to said modulation means and said frequency-synthesizer means, respectively.
Claim 2
Dependent Claim
276 words
A channel-switching system comprising: a plurality of channels, each of which transmits and receives over individually associated a transmission and reception carrier waves with a frequency interval between said transmission and reception carrier waves, at least one of said frequency intervals on one of said channels being different from the other frequency intervals on other of said channels; means for receiving the plurality of reception carrier waves; means for transmitting the plurality of transmission carrier waves; first mixer means coupled to said receiving means for frequency-mixing the output of said receiving means with an oscillation signal; means coupled to said first mixer means for demodulating the output of said first mixer means; means for generating a reference frequency signal; modulation means responsive to a first control signal for converting said reference frequency signal into one of a plurality of carrier waves respectively corresponding to said plurality of transmission carrier waves and for modulating the converted signal with a signal which is to be transmitted; second mixer means coupled to said modulation means for frequency-mixing the output of said modulation means and said local oscillation signal and for supplying the frequency-mixed signal to said transmitting means as one of said plurality of transmission carrier waves; frequency-synthesizing means responsive to a second control signal for frequency-synthesizing said reference frequency signal to provide said local oscillation signal and for supplying it to said first and second mixer means; means responsive to the output of said demodulation means for detecting a signal designating a channel number; and means responsive to the detected signal for supplying said first and second control signals to said modulation means and said frequency-synthesizer means, respectively.
Claim 3
Dependent Claim
104 words
A channel-switching system as set forth in claim 1, wherein said modulation means comprises a voltage-controlled oscillator means for varying its oscillation frequency in response to a third control signal and said signal which is to be transmitted; means for frequency-dividing the output of said voltage-controlled oscillator means in response to said first control signal; means for phase-comparing said reference frequency signal and the output of said frequency-dividing means; and means for extracting a low-frequency component in the output of said phase comparator means; and means for supplying the output of said extracting means as said third control signal to said voltage-controlled oscillator means.
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) | 1986-02-07 | 1986-08-09 | 1987-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-07 | 1990-08-09 | 1991-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-07 | 1994-08-09 | 1995-02-08 | $7700.00 | Window Closed / Lapsed |