Acknowledge back pager with apparatus for controlling transmit frequency
US4891637A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 7, 1988 |
| Grant date | Jan 2, 1990 |
| Priority date | — |
| Expiry date | Jan 7, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L1/1829
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
An acknowledge back (ack-back) pager is provided for use in a paging system including 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. To accurately control the ack-back transmit frequency, the pager receives and down-converts the F.sub.RX signal thus producing a down-converted F.sub.C signal, the frequency of which is measured and stored. The pager selects which sub-band of a plurality of frequency sub-bands within a predetermined range of frequencies is to be used for transmission of the ack-back signal. The pager determines a frequency offset F.sub.D corresponding to the selected sub-band, such offset being with respect to a predetermined frequency within such range of frequencies. The pager generates an acknowledge back signal at a freq…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.