Subscriber validation system
US4626845A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 21, 1986 |
| Grant date | Dec 2, 1986 |
| Priority date | — |
| Expiry date | Jan 21, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04W76/45
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A system provides for the validation of users of a trunked radio system. The system includes a controller and at least one microcomputer-controlled repeater module for user identification and validation. Each repeater module includes a tracking filter for removing unwanted noise from the two-tone signal sequentially transmitted by the user's radio as well as a digital signal processor utilizing a novel filter algorithm to quickly and reliably identify and validate user group tones. If identified as a valid user, the repeater module allows the call to pass. If the identity and validity, i.e., a paying customer, of the user are not validated by the repeater module, the repeater is shut down and the user is unable to communicate, and only hears alert tones from his speaker. A microcomputer in the repeater module performs a period measurement of the received two-tone sequence over a fixed interval, generates a histogram representing the period spread of the tone versus time over that fixed interval, calculates the mean of this histogram which represents the average period measured in accordance with the novel algorithm, and converts this average period into a tone number which is used …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.