Narrow band paging or control radio system
First Claim
1. A narrow-band paging or control radio communication system comprising, in combination, a plurality of remote radio receivers, a central radio transmitter station, and an existing local radio broadcast station which transmits synchronizing reference signals to the central transmitting station and to the remote radio receivers;
- said receivers each comprising;
(A) first receiving antenna means for detecting the radio frequency carrier of the broadcast station,(B) first tuned amplifier-limiter means connected to the output of the first receiving antenna means and tuned to the radio frequency carrier of the broadcast station so as to detect and produce hourly time beep output signals, and to remove amplitude modulation from said carrier and produce an output signal that is an amplitude-limited replica of the broadcast station radio frequency carrier,(C) first frequency synthesizer means connected to output of the amplifier-limiter means to produce a synchronizing clock signal coherent with hourly beep signals at its first output and to phase-lock to the radio frequency carrier of the broadcast station to synthesize therefrom and provide at its second output a second radio carrier of predetermined frequency fi, which frequency fi may be different for each remote radio receiver and is different from but phase-locked to the radio frequency carrier of the broadcast station,(D) second receiving antenna means for detecting radio signals from the central transmitter station at radio frequency fi,(E) tuned amplifier means having an input connected to the output of the second antenna means to amplify the received carrier fi,(F) synchronous mixer means having a first input connected to the second output of the frequency synthesizer means, and a second input connected to output of tuned amplifier means to thereby produce a demodulated signal at its output,(G) low pass filter means having an input connected to the output of mixer means and providing output signals essentially identical to narrow-band paging or control signals sent by central transmitter,(H) paging or control signal detector means having a first input connected to output of low pass filter means and a second input connected to first output of first frequency synthesizer means for amplifying and synchronously detecting identification codes and signals and displaying, annunciating and outputting said narrow-band paging or control signals to cooperating external apparatus.
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Accused Products
Abstract
The inventor discloses an ultra narrow band relatively ultra stable radio apparatus for communicting paging or control signals from a central transmitter to a multiplicity of remotely located receivers, which receivers may be carried on the person of individuals or may be fixed to other devices which they control, such as city traffic control lights, programmable signs, machines, or the like, wherein the central transmitting device and the remote receiving device are both phase locked to a local broadcast station RF carrier so as to provide a means to precisely synchronize the transmitting device with the receiving device and thereby achieve very high signal-to-noise ratio transmissions. The apparatus is capable of transmitting a digital identification code or a digital message and the receiving devices may output a simple on-off signal indicating the presence of a call, or digital message may be output to control an apparatus attached to said receiver. An alternative bidirectional remote device that can both receive and transmit is also disclosed. A novel frequency synthesizer, and means for real time synchronization of both the transmitter and the receiver, are also disclosed.
112 Citations
13 Claims
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1. A narrow-band paging or control radio communication system comprising, in combination, a plurality of remote radio receivers, a central radio transmitter station, and an existing local radio broadcast station which transmits synchronizing reference signals to the central transmitting station and to the remote radio receivers;
- said receivers each comprising;
(A) first receiving antenna means for detecting the radio frequency carrier of the broadcast station, (B) first tuned amplifier-limiter means connected to the output of the first receiving antenna means and tuned to the radio frequency carrier of the broadcast station so as to detect and produce hourly time beep output signals, and to remove amplitude modulation from said carrier and produce an output signal that is an amplitude-limited replica of the broadcast station radio frequency carrier, (C) first frequency synthesizer means connected to output of the amplifier-limiter means to produce a synchronizing clock signal coherent with hourly beep signals at its first output and to phase-lock to the radio frequency carrier of the broadcast station to synthesize therefrom and provide at its second output a second radio carrier of predetermined frequency fi, which frequency fi may be different for each remote radio receiver and is different from but phase-locked to the radio frequency carrier of the broadcast station, (D) second receiving antenna means for detecting radio signals from the central transmitter station at radio frequency fi, (E) tuned amplifier means having an input connected to the output of the second antenna means to amplify the received carrier fi, (F) synchronous mixer means having a first input connected to the second output of the frequency synthesizer means, and a second input connected to output of tuned amplifier means to thereby produce a demodulated signal at its output, (G) low pass filter means having an input connected to the output of mixer means and providing output signals essentially identical to narrow-band paging or control signals sent by central transmitter, (H) paging or control signal detector means having a first input connected to output of low pass filter means and a second input connected to first output of first frequency synthesizer means for amplifying and synchronously detecting identification codes and signals and displaying, annunciating and outputting said narrow-band paging or control signals to cooperating external apparatus. - View Dependent Claims (2, 3, 4, 5, 6)
- said receivers each comprising;
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7. A bi-directional narrow-band paging or control radio communication system comprising, in combination, a plurality of remote radio transceivers, a central radio transmitter-receiver station to send and receive narrow-band paging or control signals, and an existing local radio broadcast station to provide a radio frequency carrier reference for the remote radio transceivers and the central transmitter-receiver station, the remote radio transceivers each comprising:
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(A) first receiving antenna means for detecting the radio frequency carrier of the broadcast station, (B) tuned amplifier-limiter means connected to the output of the first receiving antenna means and tuned to the radio frequency carrier of the broadcast station so as to remove any amplitude modulation thereon and produce an amplitude limited signal replica of the broadcast station radio frequency carrier at its output, (C) frequency synthesizer means connected to an output of the amplifier-limiter means and thereby phase-locked to the radio frequency carrier of the broadcast station to synthesize therefrom a second radio carrier predetermined frequency fi at its output, which frequency fi may be different for each remote transceiver and is different from but phase-locked to the radio frequency carrier of the broadcast station, (D) second antenna with duplexer means including a receiving terminal and a transmitting terminal for sending and receiving radio signals at frequency fi, (E) tuned amplifier means having an input connected to the receiving terminal of the second antenna means to amplify the received carrier fi, (F) synchronous mixer means having a first input connected to the output of the frequency synthesizer means, and the second input connected to the output of tuned amplifier means, to thereby produce a demodulated signal at its output, (G) low pass filter means having an input connected to the output of mixer means and providing an output signal to external cooperating apparatus which is essentially identical to narrow-band paging or control signals sent by central transmitter, (H) narrow-band paging or control signal source means connected to output of external cooperating apparatus to generate specific identification codes, messages and control signals for transmission to central receiver-transmitter station, (I) modulator means having a first input connected to output of frequency synthesizer means, and a second input connected to output of narrow-band paging or control signal source means to thereby produce modulated carrier fi at its output, (J) power amplifier means with input connected to the modulator means and with output connected to transmitting terminal of second antenna means to thereby radiate paging or control signals to central receiver-transmitter station. - View Dependent Claims (8, 9)
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10. A radio or digital frequency synthesizer for use in communication and control systems comprising, in combination, an existing radio broadcast station modified to transmit periodic hourly time signals and a plurality of remote radio or digital frequency synthesizer means connected to a corresponding plurality of external communication or control apparatus for synchronizing purposes, said synthesizer comprising:
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(A) first receiving antenna means for detecting the radio frequency carrier of the broadcast station, (B) tuned amplifier-limiter means connected to the output of the receiving antenna means and tuned to the radio frequency carrier of the broadcast station so as to detect and produce hourly time beep signals at a first output and to remove amplitude modulation from said carrier and produce an amplitude-limited replica of the broadcast station radio frequency carrier at its second output, (C) frequency divider means connected to second output of limiter-amplifier to thereby divide the frequency of the broadcast station carrier to provide a low frequency output signal on the order of 1 Hz phase-locked to said carrier, (D) time gate generator means connected to output of frequency divider to generate therefrom a time gate whose duration To is precisely controlled by frequency of broadcast station carrier, (E) voltage controlled crystal oscillator means having multiple outputs and a control terminal, the first output being connected to one input of a gated amplifier, the second input to the gated amplifier being connected to the output of the time gate generator to thereby enable flow of signal through gated amplifier only during time gate duration To, and a second oscillator output being connected to external apparatus for radio frequency synchronization purposes, (F) presetable modulo M frequency counter means that is reset to a preselected count prior to each count interval To and having one input connected to output of gated amplifier to thereby sum the number of cycles of crystal oscillator signal during time duration To but overflowing a fixed number of times M to leave a remainder count K at its output, (G) digital-to-analog converter means connected to output of modulo M counter to latch-in remainder count K at end of time gate To and convert K into an analog voltage which is connected to control terminal of voltage controlled crystal oscillator in a closed-loop arrangement whereby oscillator is forced to operate at a precise frequency fi. - View Dependent Claims (11, 12, 13)
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Specification