Method of arbitrating speakerphone operation in a portable communication device for eliminating false arbitration due to echo

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward.
A brief description of the problem is also thought to be useful.
Referring to FIG.
1, there is shown a block diagram 100 of a connection between a portable communication device and a public switched telephone network where echo is introduced.
The portable communication device or cellular phone 102 is presently engaged in a call to another party, and operating in a speakerphone mode.
The phone comprises a speaker and audio amplifier capable of amplifying a received voice signal to a level where it can be heard at a distance by the user of the phone.
As is well known the art, the phone comprises a transceiver including a receiver and a transmitter.
The receiver, amplifier, and speaker form a speaker path.
A microphone, and the transmitter form a microphone path.
Arbitration is the process of muting the microphone path and activating the speaker path while the remote party is speaking, and muting the speaker path and activating the microphone path while the phone user is speaking.
This type of arbitration results in a simplex speakerphone mode.
Line 104 represents the microphone path signal, which is transmitted over an air interface to fixed infrastructure equipment, as is well known.
Line 106 represents the received signal that is received by the phone, and may be the voice signal of the remote party to whom the user of the phone is speaking, which converts the signal.
Eventually the transmitted signal encounters a hybrid 108, which can produce echo, due to mismatch in the hybrid, as the phone signals are passed in the public switched telephone network 110, or is used after the PSTN closer to the remote party's equipment.
Typically a portable communication device's signal passes through a mobile switching center, as is well known in the art, which comprises an echo canceller