Frequency synthesizer with unauthorized frequency inhibiting means
US4247951A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 31, 1978 |
| Grant date | Jan 27, 1981 |
| Priority date | — |
| Expiry date | Oct 31, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/40
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A radio which has assigned frequencies or channels for operation is prevented from operating on other channels. The frequency synthesizer in the radio is a large scale integrated circuit in a single semiconductor chip which is controlled by input codes from channel select switches. The synthesizer includes circuitry which responds to input codes for illegal channels and produces an inhibit signal thereby preventing generation of unauthorized frequencies. The circuitry may include a read only memory which is addressed by the input code. Alternatively, logic circuitry may be provided which responds to codes for illegal channels. Due to the circuitry being in integrated form, the method of inhibiting unauthorized signal generation cannot be easily circumvented.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.