Speakerphone using digitally compressed audio to control voice path gain
US4741018A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 24, 1987 |
| Grant date | Apr 26, 1988 |
| Priority date | — |
| Expiry date | Apr 24, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M9/085
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A mobile radiotelephone (120) includes a microcomputer (220), speakerphone control circuitry (106) and mobile radio (112). Mobile radio (112) includes a transmitter (242), receiver (244) and a duplexer (243) for coupling the transmitter (242) and receiver (243) to the mobile antenna. In the transmit voice path, speakerphone control circuitry (106) includes switch (201), variable gain amplifier (202), compressor amplifier (203), switch (204), variable gain amplifier (205), and two registers (212-213). In the receive voice path, speakerphone control circuitry (106) includes variable gain amplifier (232), expander amplifier (233), switch (234), variable gain amplifier (235), switch (236) and two registers (216-217). Speakerphone control circuitry (106) also includes rectifier/filter (224), a companding analog-to-digital (A/D) converter (225), two latches (218-219), rectifier/filter (226) and two registers (214-215). Microcomputer (220) accesses registers (212-217) by means of a data bus (222) including address, control and data lines. Microcomputer (220) utilizes digital samples from A/D converter (225) to continuously generate and store in its memory an envelope signal and a valley s…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.