Two-way paging system and apparatus

Claim 2

A wireless paging unit for receiving alert messages addressed thereto transmitted by a paging network and for transmitting an acknowledgment in response to receipt thereof, comprising: antenna means for receiving and transmitting signals; antenna coupling means coupled to said antenna means and controlled by a control means to adapt said antenna means for one of reception and transmission; a receiver connected via said antenna coupling means to said antenna means for receiving a signal and generating a time-of-arrival indication upon detecting a predetermined signal pattern; said control means also for receiving said time of arrival indication and in response thereto for adapting said antenna means for transmission and for activating a transmitter at a time based on said indicated time-of-arrival; and wherein said transmitter is coupled via said antenna coupling means to said antenna means and activated by said control means to transmit a digitally coded acknowledgment signal at said time.

Claim 3

A paging unit according to claim 1 in which said control means further comprises: high-frequency crystal reference oscillator and counter means for determining an operating frequency of said receiver and said transmitter; and low-frequency oscillator and counter means for determining a power-down period for said receiver and said high frequency crystal reference oscillator.

Claim 4

A paging unit according to claim 2 in which said high-frequency crystal reference oscillator and counter means is controlled during power-on periods to calibrate said low frequency oscillator and counter means.

Claim 5

A paging unit according to claim 2 in which said operating frequency determination is performed using a frequency synthesizer programmed by said control means to adaptively generate either a transmit or a receive frequency.

Claim 6

A paging unit according to claim 4 in which said transmit frequency is the same as said receive operating frequency and said receive frequency is a receive local oscillator frequency.

Claim 7

A paging unit according to claim 5 in which said receive local oscillator frequency is the same as said receive operating channel frequency.

Claim 8

A paging unit according to claim 1 in which said receiver is a homodyne receiver.

Claim 9

The wireless paging unit of claim 1, wherein said control means determines said time for activating said transmitter using said indicated time-of-arrival and a predetermined delay.

Claim 10

The wireless paging unit of claim 8, wherein said predetermined delay is 2-10 milliseconds.

Claim 11

The wireless paging unit of claim 1, wherein said control means includes a counter which is continuously incrementing to generate count values and said control means adds said indicated time of arrival, a starting state of said counter and a predetermined delay to identify a particular count value as said time for activating said transmitter.

Claim 12

The wireless paging unit of claim 10, wherein said predetermined delay is 2-10 milliseconds.

Claim 13

A wireless paging unit capable of receiving alert messages transmitted thereto from a paging network and capable of transmitting an acknowledgment of receipt thereof, comprising: antenna means for receiving and transmitting signals; a receiver connected to said antenna means for receiving a signal and converting said signal to numerical samples when indicated by a timing control means; memory means for storing said numerical samples in time order of reception; processing means for processing said stored numerical samples to determine a location in said memory means of a predetermined signal pattern and to generate a time-of-arrival indication based on said location; and timing control means for receiving said time-of-arrival indication and for activating a transmitter to transmit a digitally coded reply with a predetermined timing related to said indicated time-of-arrival.

Claim 14

A wireless paging unit capable of receiving alert messages transmitted thereto from a paging network and capable of transmitting an acknowledgment of receipt thereof, comprising: antenna means for receiving and transmitting signals; a receiver connected to said antenna means for receiving a signal and converting said signal to numerical samples when indicated by a timing control means; memory means for storing said numerical samples in time order of reception; processing means for processing said stored numerical samples to determine a location in said memory means of a predetermined signal pattern and to generate a time-of-arrival indication based on said location; and timing control means for receiving said time-of-arrival indication and for activating a transmitter to transmit a digitally coded reply with a predetermined timing related to said indicated time-of-arrival.

Claim 15

A paging unit according to claim 12 in which said timing control means, prior to activating said transmitter, adapts said antenna means from a receive state to a transmit state.

Claim 16

A paging unit according to claim 12 in which said processing means further processes said stored numerical samples to produce a frequency error indication.

Claim 17

The paging unit according to claim 14 in which said timing control means uses said frequency error indication in activating said transmitter at a desired frequency.

Claim 18

The paging unit according to claim 15 in which said frequency error indication is used by said timing control means to adjust a frequency synthesizer to generate transmit frequency which has been compensated for said frequency error.

Claim 19

The paging unit according to claim 14 in which said frequency error indication is used to correct a frequency of a crystal reference oscillator.

Claim 20

The paging unit according to claim 17 in which said crystal reference oscillator is used to control the operating channel frequency of said transmitter.

Claim 21

A wireless paging unit capable of receiving alert messages transmitted from a paging network and of transmitting a reply in response to receipt thereof, comprising: a first oscillator means for determining a receiver power down period based on a calibration count value; a second oscillator means for determining operating channel frequencies of said receiver and of a transmitter; said receiver being activated by a signal controlled by said first oscillator means to receive and process a signal received on a receive operating channel frequency and to produce a time-of-arrival and frequency error indication from said received signal; frequency correction means for using said frequency error indication to correct said second oscillator means and to use said corrected second oscillator means to perform a calibration measurement to determine said calibration count value; and timing control means for receiving said time of arrival indication and in response thereto for activating a transmitter to transmit a digitally coded reply having a predetermined timing related to said indicated time-of-arrival and at an operating channel frequency derived from said second oscillator means and compensated for said frequency error.

Claim 22

A wireless paging unit capable of receiving alert messages transmitted from a paging network and of transmitting a reply in response to receipt thereof, comprising: a first oscillator means for determining a receiver power down period based on a calibration count value; a second oscillator means for determining operating channel frequencies of said receiver and of a transmitter; said receiver being activated by a signal controlled by said first oscillator means to receive and process a signal received on a receive operating channel frequency and to produce a time-of-arrival and frequency error indication from said received signal; frequency correction means for using said frequency error indication to correct said second oscillator means and to use said corrected second oscillator means to perform a calibration measurement to determine said calibration count value; and timing control means for receiving said time of arrival indication and in response thereto for activating a transmitter to transmit a digitally coded reply having a predetermined timing related to said indicated time-of-arrival and at an operating channel frequency derived from said second oscillator means and compensated for said frequency error.