Communications: electrical – Continuously variable indicating – With meter reading
Patent
1982-02-08
1984-02-14
Yusko, Donald J.
Communications: electrical
Continuously variable indicating
With meter reading
34082563, H04Q 912
Patent
active
044319908
ABSTRACT:
The receiver comprises a processor circuit which receives and processes a modulated carrier wave. The modulation is a code consisting of a single tone or a sequence of tones, followed by intelligence signals. The processor circuit separates the code and the intelligence signals from the carrier wave. The receiver also comprises a decoder circuit responsive to a given code to provide an enabling signal. An audio circuit is rendered operative by the enabling signal so that it can process the ensuing intelligence signals. The receiver has a push-button switch which can be actuated at any time to monitor the channel. Such switch is associated with a timer and an electronic switch.
A first optional connection may be made internally in the receiver, whereby actuations of the push-button switch places the receiver in a monitor mode so that it will be continuously on. Subsequent actuation of the switch will cause the receiver to revert to its tone-squelch mode.
A second optional connection may be made internally in the receiver so that a proper code will unsquelch the receiver for a certain time and thereafter place the receiver in condition to be unsquelched by just the carrier wave. Subsequent actuation of the push-button switch will cause the receiver to revert to its code-squelch mode. The receiver can manually be placed in the carrier-squelch mode by actuating the same switch for at least a certain time.
The receiver further comprises a battery saver circuit which produces a pulsed supply voltage for the processor circuit, the decoder circuit and the audio circuit. While the correct first tone is being received, the battery saver circuit provides a continuous supply voltage to these various circuits, which voltage is maintained during the entirety of the code and for a time thereafter.
When the second optional connection is made, as described above, the rate of the pulsed supply voltage produced after such time has passed will be increased. Alternately, if the push-button switch is operated, the receiver will be manually placed in the carrier-squelch mode, and the rate of the pulsed supply voltage will be increased. Subsequent operation of the push-button switch will reset the receiver to the code-squelch mode and cause the pulsed supply voltage to revert to its usual rate.
A two-tone decoder circuit includes a normally operative channel for the first tone and a normally inoperative channel for the second tone. The first channel includes a frequency discriminator responsive to a first tone of predetermined frequency. The first channel also includes means to convert the first tone into a train of pulses. A delay circuit in the first channel produces a train of modified tone pulses commencing a first predetermined time after the start of detection of the first tone, to render ensuing circuitry nonresponsive to glitches (extraneous pulses such as noise and the like). An envelope detector produces an output pulse when tone pulses are absent for a second predetermined time. A latch is set by the first of the tone pulses and is reset by the output pulse. Accordingly, a tone signal is produced which commences a first predetermined time after the first tone starts and ends a second predetermined time after that tone ends.
The first channel further includes a duration detector which responds to a tone signal of at least a predetermined duration to produce an enabling signal commencing with the termination of the first tone. The enabling signal is coupled to the second channel which has the same basic elements as the first channel, namely a frequency discriminator responsive to the second tone, means to convert the second tone into a train of pulses, a delay circuit, an envelope detector, a latch and a duration detector. The duration detector provides detected signals representative of the duration of such second tone. A control circuit produces one of a plurality of alerting tones having characteristics and durations corresponding to the detected signals. A gate circuit is rendered operative by a control signal from the control circuit to apply the alerting tone to the audio circuit. In the absence of such control signal, the output of the gate floats so as not to load the audio circuit while it is processing the intelligence signals.
The first tone in the two-tone sequence may have one of two durations. A shorter first tone will enable the second channel as just described, while an even longer first tone bypasses the second channel to cause an alerting tone to be applied to the audio circuit. Such longer tone will similarly enable all receivers responsive to that same first tone to call them as a group.
An optional connection may be made in the first channel to cause it to respond to a first tone of longer-than-normal duration to provide an output which also bypasses the second channel. This option enables ready conversion to a single tone receiver.
The decoder further includes an oscillator and a chain of free-running, divide-by-two circuits to produce a plurality of clock frequencies. Each of the circuits described above includes one or more chains of resettable divide-by-two circuits connected to the clock. The timing functions in the receiver are performed by the clock and these resettable divide-ty-two circuits.
REFERENCES:
patent: 3769593 (1973-10-01), Williams
patent: 4069477 (1978-01-01), Maben
patent: 4194153 (1980-03-01), Masaki et al.
patent: 4245347 (1981-01-01), Hutton et al.
patent: 4315249 (1982-02-01), Apple et al.
Dittmer William H.
Wycoff Keith H.
Wycoff Keith H.
Yusko Donald J.
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