Digital FM modulator
US5111163A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 6, 1991 |
| Grant date | May 5, 1992 |
| Priority date | — |
| Expiry date | May 6, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03C3/40
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A digital FM modulator (10) which functions to modulate a fixed frequency, e.g. RF, reference signal f.sub.r with an incoming AM analog signal v(t) by way of utilization of digital signal processing circuitry (14, 18, 22, 26, 28, 38, 48). The digital FM modulator 10 includes a digital encoder, e.g. a codec 14, which samples the incoming analog signal v(t) at a prescribed sampling rate f.sub.s, and converts it into a digital signal S.sub.D comprised of successive digital words representative of a prescribed parameter (e.g. amplitude) of the analog signal v(t) at corresponding, successive sampling times t.sub.i. This digital signal S.sub.D is a digital data stream which is subsequently conditioned for input to a direct, digital synthesizer (DDS) (48), which, in response to this input, synthesizes an output signal having I.sub.A and Q.sub.A components disposed in phase quadrature relation to each other. The DDS output signal components I.sub.A and Q.sub.A are coupled to respective first and second mixers (62, 68) of an I/Q hybrid circuit (59), with the I.sub.A and Q.sub.A DDS output signal components serving to modulate the reference RF carrier signal f.sub.r, which is also coupled to…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.