Dual mode cellular radio communication apparatus having an echo canceller employed in both analog and digital modes

• US 5,416,829 A
• Filed: 09/01/1993
• Issued: 05/16/1995
• Est. Priority Date: 11/30/1990
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Umemoto, Yuji
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): CUMMING, WILLIAM D
• Application Number:
  US08/114,621
• Time in Patent Office: 622 Days
• Field of Search: 379/56, 379/57, 379/58, 379/142, 379/343, 379/390, 379/411
• US Class Current: 455/553.1
• CPC Class Codes: H04B 1/403 using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency
• CPC Class Codes: H04M 9/082 using echo cancellers echo cancellers per se H04B3/23
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A dual mode cellular radio communication apparatus includes an echo canceller which cancels echo signals caused by acoustic coupling between a hands-free microphone and a loudspeaker in both analog mode and digital modes. An analog-to-digital converter and digital-to-analog converter may be used both in an analog mode and in a digital mode. A second analog-to-digital converter and a second digital-to-analog converter may be selectively used in the analog or digital mode. The echo canceller may be rendered inoperative during hand-set operation. In addition, a bypass circuit may be provided between an input and an output of the echo canceller so that the echo canceller is bypassed.

Claims

1. A radio communication apparatus for use in a dual mode radio system wherein speech signals are selectively transmitted in an analog mode or a digital mode over a radio link established between a base station and the radio communication apparatus comprising:

receiving means for receiving radio frequency signals transmitted over the radio link, for obtaining signals of a certain frequency from the received radio frequency signals, and for outputting the signals of a certain frequency;

transmitting means for converting signals applied to the transmitting means to radio frequency signals and for transmitting the radio frequency signals over the radio link;

speech input means for inputting speech signals to be transmitted over the radio link;

first analog-to-digital converting means for converting the input speech signals into digital speech signals;

speech output means for outputting speech signals corresponding to the received radio frequency signals;

first digital-to-analog converting means for converting digital speech signals into analog speech signals and for outputting the analog speech signals to the speech output means;

echo cancelling means coupled to the first analog-to-digital converting means and the first digital-to-analog converting means for cancelling echo signals caused by acoustic coupling between the speech input means and the speech output means and for outputting echo-free signals;

first processing means, when the radio communication apparatus operates in the digital mode, for converting the signals from the receiving means into digital signals, decoding the converted digital signals, and outputting the decoded signals to the echo cancelling means and for encoding the echo-free signals from the echo cancelling means, converting the encoded signals into analog signals, and supplying the analog signals to the transmitting means;

second digital-to-analog converting means for converting the echo-free signals from the echo-cancelling means into analog signals;

second processing means, when the radio communication apparatus operates in the analog mode, for processing the signals from the receiving means and outputting the processed signals and for processing the analog signals from the second digital-to-analog converting means and outputting the processed signals to the transmitting means; and

second analog-to-digital converting means for converting the processed signals from the second processing means into digital signals and for supplying the digital signals to the echo cancelling means.

2. A radio communication apparatus for use in a dual mode radio system wherein speech signals are selectively transmitted in an analog mode or a digital mode over a radio link established between a base station and the radio communication apparatus comprising:

receiving means for receiving radio frequency signals transmitted over the radio link;

transmitting means for transmitting signals over the radio link;

speech input means for inputting speech signals to be transmitted over the radio link;

speech output means for outputting speech signals corresponding to the received signals;

echo cancelling means coupled to the speech input means and the speech output means for cancelling echo signals caused by acoustic coupling between the speech input means and the speech output means and for outputting echo-free signals;

first processing means, when the radio communication apparatus operates in the digital mode, for processing the received signals from the receiving means and outputting the processed signals to the echo cancelling means and for processing the echo-free signals from the echo cancelling means and outputting the processed signals to the transmitting means; and

second processing means, when the radio communication apparatus operates in the analog mode, for processing the received signals from the receiving means and outputting the processed signals to the echo cancelling means and for processing the echo-free signals from the echo cancelling means and outputting the processed signals to the transmitting means.

3. A radio communication apparatus for use in a radio system with a plurality of modes wherein speech signals are selectively transmitted in one of the plurality of modes over a radio link established between a base station and the radio communication apparatus comprising:

receiving means for receiving radio frequency signals transmitted over the radio link, for demodulating the received radio frequency signals into analog signals of a certain frequency, and for outputting demodulated analog signals;

transmitting means for modulating signals into radio frequency signals and for transmitting the radio frequency signals over the radio link;

speech input means for inputting speech signals to be transmitted by the radio communication apparatus;

first analog-to-digital converting means for converting the input speech signals into digital speech signals;

first digital-to-analog converting means for converting digital signals into analog speech signals;

speech output means coupled to said first digital-to-analog converting means for outputting speech signals corresponding to the received radio frequency signals;

echo cancelling means coupled to said first analog-to-digital converting means and said first digital-to-analog converting means for cancelling echo signals caused by acoustic coupling between the speech input means and the speech output means and for outputting echo-free signals;

second analog-to-digital converting means for converting the demodulated analog signals from said receiving means into digital signals when the radio communication apparatus operates in a first mode;

decoding and encoding means for decoding the digital signals from the second analog-to-digital converting means and for outputting the decoded signals to the echo cancelling means and also for encoding the echo-free signals from said echo cancelling means when the radio communication apparatus operates in the first mode;

second digital-to-analog converting means for converting the encoded signals from said decoding and coding means into analog signals and for supplying the analog signals to said transmitting means when the radio communication apparatus operates in the first mode;

third digital-to-analog converting means for converting the echo-free signals from said echo cancelling means into analog signals when the radio communication apparatus operates in a second mode;

analog signal processing means for processing the analog signals from said third digital-to-analog converting means, for supplying the processed analog signals to said transmitting means, for processing the demodulated analog signals from said receiving means, and for outputting the processed analog signals when the radio communication apparatus operates in the second mode; and

third analog-to-digital converting means for converting the processed analog signals from said analog signal processing means into digital signals and for supplying the digital signals to the echo cancelling means when the radio communication apparatus operates in the second mode.

4. A radio communication apparatus for use in a radio system with a plurality of modes wherein speech signals are selectively transmitted in one of the plurality of modes over a radio link established between a base station and the radio communication apparatus comprising:

receiving means for receiving radio frequency signals transmitted over the radio link, for obtaining signals of a certain frequency from the received radio frequency signals, and for outputting the signals of a certain frequency;

transmitting means for converting signals applied to the transmitting means to radio frequency signals and for transmitting the radio frequency signals over the radio link;

speech input means for inputting speech signals to be transmitted over the radio link;

first analog-to-digital converting means for converting the input speech signals into digital speech signals;

speech output means for outputting speech signals corresponding to the received radio frequency signals;

first digital-to-analog converting means for converting digital speech signals into analog speech signals and for outputting the analog speech signals to the speech output means;

echo cancelling means coupled to the first analog-to-digital converting means and the first digital-to-analog converting means for cancelling echo signals caused by acoustic coupling between the speech input means and the speech output means and for outputting echo-free signals;

first processing means, when the radio communication apparatus operates in a first mode, for converting the signals from the receiving means into digital signals, decoding the converted digital signals, and outputting the decoded signals to the echo cancelling means and for encoding the echo-free signals from the echo cancelling means, converting the encoded signals into analog signals, and supplying the analog signals to the transmitting means;

second digital-to-analog converting means for converting the echo-free signals from the echo-cancelling means into analog signals;

second processing means, when the radio communication apparatus operates in a second mode, for processing the signals from the receiving means and outputting the processed signals and for processing the analog signals from the second digital-to-analog converting means and outputting the processed signals to the transmitting means; and

second analog-to-digital converting means for converting the processed signals from the second processing means into digital signals and for supplying the digital signals to the echo cancelling means.

5. The radio communication apparatus according to claim 4 wherein the receiving means processes the obtained signals of a certain frequency and outputs the processed signals of a certain frequency.

6. The radio communication apparatus according to claim 4 wherein the receiving means demodulates the obtained signals of a certain frequency and outputs the demodulated signals of a certain frequency.

7. The radio communication apparatus according to claim 4 wherein the transmitting means processes signals applied to the transmitting means, converts the processed signals to radio frequency signals, and transmits the radio frequency signals over the radio link.

8. The radio communication apparatus according to claim 4 wherein the transmitting means modulates signals applied to the transmitting means, converts the modulated signals to radio frequency signals, and transmits the radio frequency signals over the radio link.

9. A radio communication apparatus for use in a radio system with a plurality of modes wherein speech signals are selectively transmitted in one of the plurality of modes over a radio link established between a base station and the radio communication apparatus comprising:

receiving means for receiving radio frequency signals transmitted over the radio link;

transmitting means for transmitting signals over the radio link;

speech input means for inputting speech signals to be transmitted over the radio link;

speech output means for outputting speech signals corresponding to the received signals;

echo cancelling means coupled to the speech input means and the speech output means for cancelling echo signals caused by acoustic coupling between the speech input means and the speech output means and for outputting echo-free signals;

first processing means, when the radio communication apparatus operates in a first mode, for processing the received signals from the receiving means and outputting the processed signals to the echo cancelling means and for processing the echo-free signals from the echo cancelling means and outputting the processed signals to the transmitting means; and

second processing means, when the radio communication apparatus operates in a second mode, for processing the received signals from the receiving means and outputting the processed signals to the echo cancelling means and for processing the echo-free signals from the echo cancelling means and outputting the processed signals to the transmitting means.