Host signal processor modem and telephone

• US 6,252,920 B1
• Filed: 06/08/1999
• Issued: 06/26/2001
• Est. Priority Date: 07/09/1996
• Status: Expired due to Term

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: PC-TEL Incorporated
• Inventors: Hsu, Wen-Liang, Hsu, Tseng Jan
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): Corrielus, Jean B.
• Application Number:
  US09/327,945
• Time in Patent Office: 749 Days
• Field of Search: 375/222, 375/377, 375/220, 375/372, 375/259, 455/73, 455/75, 710/52, 710/69, 710/70, 379/67, 379/88, 370/468, 370/505
• US Class Current: 375/377
• CPC Class Codes: G06F 3/162 Interface to dedicated audio devices, e.g. audio drivers, interface to CODECs
• CPC Class Codes: H04M 11/06 Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors

Abstract

A host signal processor (HSP) modem has a software interface between HSP modem hardware and native audio hardware in a host computer. No hard wire connections between modem hardware and audio hardware are required for synchronization. Instead, a software clock recovery system matches a transfer rate of the HSP modem hardware and a transfer rate of the audio hardware by duplicating or deleting samples. The software interface allows the native audio hardware to make audible the handshaking sequence during modem connections which eliminates the need for a speaker and speaker drivers in the modem hardware. The combination of HSP modem hardware, audio hardware, and software executed by the host computer also allows the HSP modem to perform voice communication such as telephone or speakerphone functions.

Claims

1. A communication system comprising:

a host computer which includes native audio hardware capable of generating audible output from the host computer, wherein the native audio hardware processes digital samples according to a first sampling clock;

a communication device that processes digital samples according to a second sampling clock which is asynchronous to the first sampling clock, wherein the communication device comprises;

an interface coupled to the host computer;

an analog-to-digital converter coupled to the interface, the analog-to-digital converter converting an analog signal from an input line to digital samples accessible by the host computer through the interface; and

a digital-to-analog converter coupled to the interface, the digital-to-analog converter converting digital samples from the interface into an analog signal transmitted on an output line; and

software executed by the host computer, the software transferring the digital samples from the communication device to the native audio hardware which plays the digital samples, wherein the software comprises;

a first procedure which transfers digital samples from the communication device to a buffer in a memory of the host computer, wherein the procedure duplicates or deletes samples to equalize a data transfer rate from the communication device and a data transfer rate to the audio hardware; and

a second procedure which transfers digital samples from a second buffer in the memory of the host computer to the communication device, wherein the second procedure duplicates or deletes samples to equalize a data transfer rate to the communication device and a data transfer rate from the audio hardware.

2. The communication system of claim 1, wherein the software provides voice communications when operated in a first mode during which digital samples are transferred between the audio hardware and the communication device and provides modem functions when operated in a second mode during which digital samples are converted according to a modem protocol to generate data.

3. The communication system of claim 2, wherein the input line is a telephone line, and the communication system provides voice and modem communications through the communication device.

6. The host signal processor modem of claim 1, wherein the communication device generates an audible modem handshake sequence solely through audio hardware native to the host computer.

4. A host signal processor modem comprising:

a communication device comprising an interface for connection to a host computer, and an analog-to-digital converter which converts analog signals from an input line to digital samples accessible to the host computer through the interface; and

software executed by the host computer, the software including a procedure which during a handshake sequence for the host signal processor modem, transfers digital samples from the communication device to audio hardware native to the host computer, the audio hardware playing the digital samples to allow user monitoring of the handshake sequence.

5. The host signal processor modem of claim 4, wherein the software deletes or duplicates digital samples being transferred, as necessary to equalize a transfer rate from the communication device and a transfer rate to the audio hardware.

7. The host signal processing modem of claim 4, wherein for voice communications, the procedure transfers digital samples from the communication device to the audio hardware native to the host computer.

8. The host signal processing modem of claim 7, wherein the input line is a telephone line.

9. The host signal processing modem of claim 4, wherein the procedure transfers digital samples from the communication device to a modem unit for conversion according to a protocol for modem communications.

10. The host signal processor modem of claim 4, wherein the communication device generates an audible modem handshake sequence solely through audio hardware native to the host computer.

11. A method for operating a communication system, comprising:

processing digital samples using native audio hardware from a host computer according to a first sampling clock wherein the native audio hardware is capable of generating audible output from the host computer;

processing digital samples using a communication device according to a second sampling clock which is asynchronous to the first sampling clock, wherein the communication device includes an interface coupled to the host computer;

converting analog signal from an input line to digital samples accessible by the host computer through the interface using an analog-to-digital converter from the communication device coupled to the interface;

converting digital samples from the interface into an analog signal transmitted on an output line using a digital-to-analog converter from the communication device coupled to the interface; and

executing software by the host computer whereby the software transfers digital samples from the communication device to the native audio hardware which plays the digital samples, the software function further comprising a first procedure of transferring digital samples from the communication device to a buffer in a memory of the host computer,

wherein the procedure duplicates or deletes samples to equalize a data transfer rate from the communication device and a data transfer rate to the audio hardware; and

a second procedure of transferring digital samples from a second buffer in the memory of the host computer to the communication device, wherein the second procedure duplicates or deletes samples to equalize a data transfer rate to the communication device and a data transfer rate from the audio hardware.

12. The method of claim 11, wherein the digital samples represent an analog signal input to the host signal processor during a handshake sequence.

13. The method of claim 11, wherein transferring the digital samples comprises duplicating digital samples from the communication device to increase a data transfer rate to the buffer and match a data transfer rate to the audio hardware which plays the digital samples from the buffer.

14. The method of claim 11, wherein transferring the digital samples comprises skipping transfer of some digital samples from the communication device to decrease a data transfer rate to the buffer and match a data transfer rate to the audio hardware which plays the digital samples from the buffer.