Knowledge back pager with frequency control apparatus
AssigneeMotorola, Inc.
InventorKazimierz Siwiak
Life of this patent
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Abstract
An acknowledge back (ack-back) pager is provide for use in a paging system which includes a central station which transmits a group of message signals to a group of ack-back pagers which are addressed as a group. The users of the group of addressed ack-back pagers indicate a response to their respective pagers thus providing ack-back data. The pagers in the group of addressed ack-back pagers then simultaneously transmit back to the central station their ack-back data on different frequency sub-bands, a different frequency sub-band being allocated to each of the pagers in the group. The invention provides apparatus for controlling the frequency of the selected sub-band with very high accuracy.
Claims7
An acknowledge back pager for processing paging signals transmitted at a paging channel frequency of F.sub.RX from a central paging station, said pager comprising;
- a local oscillator oscillating at a frequency F.sub.LO to generate an F.sub.LO signal;
- first mixing means, coupled to said oscillator, for mixing said paging signals with said F.sub.LO signal to generate a down-converted signal at a frequency F.sub.C ;
- frequency determining means, coupled to said first mixing means, for determining the frequency F.sub.C of the down-converted signal;
- sub-band selection means for selecting one of a plurality of frequency sub-bands on which said pager is to transmit an acknowledge back signal, said selection means determining a selected sub-band and a frequency offset F.sub.D corresponding to said selected sub-band, said offset F.sub.D being with respect to the frequency F.sub.RX ;
- memory means for storing the value of the frequency F.sub.RX ;
- determining means for determining the value of N for the selected sub-band wherein
- N=(F.sub.RX -F.sub.C)/(F.sub.D +F.sub.C)
- dividing means, coupled to said determining means, for dividing the F.sub.LO signal by N to generate an F.sub.LO /N signal, and
- second mixing means, coupled to said dividing means and said oscillator means, for mixing said F.sub.LO signal with said F.sub.LO /N signal to generate a carrier signal for said acknowledge back signal.
An acknowledge back pager for processing paging signals transmitted at a paging channel frequency of F.sub.RX from a central paging station, said pager comprising;
- a local oscillator oscillating at a frequency F.sub.LO to generate an F.sub.LO signal;
- mixing means, coupled to said oscillator, for mixing said paging signals with said F.sub.LO signal to generate a down-converted signal at a frequency F.sub.C ;
- frequency determining means, coupled to said mixing means, for determining the frequency F.sub.C of the down-converted signal;
- memory means for storing a look-up table including indicia of a plurality of frequency offsets, F.sub.D, with respect to said frequency F.sub.RX, said offsets F.sub.D corresponding respectively to a plurality of frequency sub-bands, and for storing the value of F.sub.RX, and further for storing the frequency F.sub.C determined by said frequency determining means;
- sub-band selection means for selecting which one of said sub-bands on which said pager is to transmit an acknowledge back signal, said selection means thus determining a selected sub-band;
- microcomputer means for determining the value of N for the selected sub-band wherein
- N=(F.sub.RX -F.sub.C)/(F.sub.D +F.sub.C)
- dividing means, coupled to said microcomputer means, for dividing the F.sub.LO signal by N to generate an F.sub.LO /N signal
- mixing means, coupled to said dividing means and said oscillator means, for mixing said F.sub.LO signal with said F.sub.LO /N signal to generate a carrier signal for said acknowledge back signal.
In a radio paging system including a central paging station for transmitting paging signals on a paging channel frequency F.sub.RX to a plurality of remotely located acknowledge back radio pagers, said pager including a memory for storing the value of the frequency F.sub.RX, a method of controlling the frequency on which said acknowledge back pager transmits an acknowledge back signal comprising the steps of:
- generating a local oscillator signal at a frequency F.sub.LO, said local oscillator signal being designate the F.sub.LO signal;
- mixing said paging signals with said F.sub.LO signal to generate a down-converted signal at a frequency F.sub.C ;
- determining the frequency F.sub.C of the down-converted signal;
- selecting which one of a plurality of frequency sub-bands said pager is to transmit acknowledge back signals on, thus determining a selected sub-band, said selecting step including selecting a frequency offset F.sub.D corresponding to said selected sub-band, said offset frequency F.sub.D being with respect to the frequency F.sub.RX ;
- determining the value of N for the selected sub-band wherein
- N=(F.sub.RX -F.sub.C)/(F.sub.D +F.sub.C)
- dividing the F.sub.LO signal by N to generate an F.sub.LO /N signal
- mixing said F.sub.LO signal with said F.sub.LO /N signal to generate a carrier signal for said ack-back signal.
Dependencies are inferred from the claim text.