Abstract: A pager receiver for receiving signals transmitted in the POCSAG code format which includes a preamble signal followed by at least one batch, the pager receiver including a preamble absence detector circuit for detecting whether or not a received signal includes the preamble and a power saving circuit responsive to the preamble absence detector circuit for deactivating signal processing circuits of the pager receiver as soon as detection is made that the received signal does not include the preamble signal.

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.

Abstract: The filter has a fixed Q and is coupled to a source of AC signals. A source of pulses is applied to a variable-voltage circuit, the circuit being responsive to each pulse to produce a threshold voltage which varies from a first value toward a second value. A comparator circuit has one input coupled to the filter and a second input coupled to the variable voltage circuit. The comparator produces a signal for a duration related to the time the amplitude of an AC signal from the filter is at least equal to the threshold voltage.

Abstract: The signal absence detector controls an operator circuit which periodically provides an operator signal to render the processor circuit in a communication receiver operative. The absence detector responds to a processed signal which is not of a predetermined character to terminate the operator signal. In one form of the invention, the operator circuit is a battery saver which intermittently provides a supply voltage. When the incoming signal is of the predetermined character, the supply voltage continues. The absence detector terminates the supply voltage when it is determined that the incoming signal does not have that character. In another form of the invention, the absence detector is employed in a scanning receiver, in which case the operator circuit steps the receiver between the various channels. The receiver will remain tuned to a channel as long as the incoming signal may be of the predetermined character.

Abstract: A decoder circuit responds to a given code to provide an enabling signal for rendering an audio circuit operative. A push-button switch actuatable to monitor the channel is associated with timer and electronic switch.One connection places the receiver in either a monitor mode or a tone-squelch mode. A second connection places the receiver in condition to be unsquelched manually or by the carrier wave or by the proper code. The battery saver provides a continuous supply voltage during the first tone, the entirety of the code and for a time thereafter. The rate of the pulsed supply voltage produced after such time will be increased. Alternately, the receiver can be placed in the carrier-squelch mode. The receiver can be reset to the code-squelch mode and cause the pulsed supply voltage to revert to its usual rate. After the start of detection, pulses render ensuing circuitry nonresponsive to glitches.

Abstract: A memory device stores signals representative of a predetermined number of words constituting a given code. When and only when all the words have been received, a release signal causes the stored signals to be released to a device that displays or otherwise furnishes the information contained in the code. If more or less than the predetermined number of words is received by the decoder, a release signal is not generated.