Method and apparatus for pulse angle modulation
US4485358A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 28, 1981 |
| Grant date | Nov 27, 1984 |
| Priority date | — |
| Expiry date | Sep 28, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03C3/00
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for phase modulating a carrier signal to convey an information signal (12) such that the carrier signal has a constant amplitude envelope. A Hilbert transform signal (14) of the information signal (12) is produced. The signals (12, 14) are sampled to produce signals (16, 18), which represent cartesian coordinate values. The cartesian coordinate values are then converted into equivalent polar vectors (20-36) which have both an amplitude (R) and an angle (.theta.). The polar vector quantity (R,.theta.) is converted into two unity amplitude vectors (A, B). The unity amplitude vectors (A, B) are offset from the polar vector quantity by an angle the cosine of which is proportional to the amplitude of the polar vector (R). The carrier signal is sequentially phase modulated by each of the angles of the unity amplitude vectors (A, B) for each sample period of the information signal. This modulation procedure maintains a constant amplitude envelope for the carrier signal and makes possible simultaneous demodulation of a plurality of carrier signals in a single demodulation channel.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.