Method and device for digital frequency modulation
US6130919A · kind A · utility
Inventor
Key dates
| Filing date | Dec 21, 1998 |
| Grant date | Oct 10, 2000 |
| Priority date | — |
| Expiry date | Dec 21, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03C3/06
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method and device are adapted to perform digital frequency modulation. First, an input frequency modulation signal is converted into a digital signal via an A/D (Analog/Digit) adapter, then a varied carrier frequency parameter "a" for each different system is added to the digital signal by an adder; next, the digital signal is multiplied by a various frequency variation parameter "b" assigned to each different system accordingly, and is further multiplied by another number 2.sup.-U, U=10 for SVHS system and U=11 for VHS system, by a multiplier; afterwards, the digital signal is processed by a digital integrator; then corresponding amplitudes in mapping with all angles .theta. and .theta.' within 360 degrees are obtained by sin.theta. ROM and Cos.theta.' ROM, wherein Z.sup.-1 is a flip-flop, the parameters "a", "b" are variable corresponding to specifications of PAL, NTSC, VHS, SVHS systems and the interlace scanning so as to make the design applicable to various systems.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.