ADPCM transcoder with integral tone generation and method therefor

An adaptive differential pulse code modulation (ADPCM) transcoder with integral tone generation comprising:

• tone generation means for providing a linear tone signal having at least one tone frequency associated therewith;
• pulse code modulation-(PCM-)-to-linear conversion means for converting a PCM input signal to a first linear signal;
• first tone insertion means for providing a second linear signal as a predetermined one of either said linear tone signal, or a sum of said first linear signal and said linear tone signal, in response to an activation of a first control signal, and for providing said second linear tone signal as said first linear tone signal in response to said first control signal being inactive;
• encoder means for receiving said second linear signal, and for performing adaptive differential pulse code modulation encoding thereon to provide an ADPCM output signal.

An adaptive differential pulse code modulation (ADPCM) transcoder with integral tone generation comprising:

• tone generation means for providing a linear tone signal having at least one tone frequency associated therewith;
• decoder means for receiving an ADPCM input signal, and for performing adaptive differential pulse code modulation decoding thereon to provide a first linear signal;
• tone insertion means for providing a second linear signal as a predetermined one of either said linear tone signal, or a sum of said first linear signal and said linear tone signal, in response to an activation of a control signal, and for providing said second linear signal as said first linear signal in response to said control signal being inactive;
• and
• linear-to-pulse code modulation (PCM) conversion means for converting said second linear signal to a PCM output signal.

An adaptive differential pulse code modulation (ADPCM) codec comprising:

• an analog-to-digital converter having an input terminal for receiving an analog input signal, and an output terminal;
• a tone generator for providing a linear tone signal having at least one tone frequency associated therewith in response to a first control signal received at a control input terminal thereof;
• a pulse code modulation-(PCM-) to-linear converter having an input terminal coupled to said output terminal of said analog-to-digital converter, and an output terminal;
• a first multiplexer having a first input terminal coupled to said output terminal of said PCM-to-linear converter, a second input terminal for receiving said linear tone signal, a control input terminal for receiving a second control signal, and an output terminal;
• an ADPCM encoder having an input terminal coupled to said output terminal of said first multiplexer, and an output terminal for providing an ADPCM output signal;
• an ADPCM decoder having an input terminal for receiving an ADPCM input signal, and an output terminal;
• a second multiplexer having a first input terminal coupled to said output terminal of said ADPCM decoder, a second input terminal for receiving said linear tone signal, a control input terminal for receiving a third control signal, and an output terminal;
• a linear-to-PCM converter having an input terminal coupled to said output terminal of said second multiplexer, and an output terminal;
• and
• a digital-to-analog converter having an input terminal coupled to said output terminal of said linear-to-PCM converter, and an output terminal for providing an analog output signal.

A method for generating a tone integrally within an adaptive differential pulse code modulation (ADPCM) transcoder, comprising the steps of:

• generating a linear tone signal having at least one tone frequency associated therewith;
• converting a digital pulse code modulation (PCM) input signal to a first linear signal;
• selecting one of said first linear signal and said linear tone signal to provide a first selected signal;
• providing said first selected signal to an input of an ADPCM encoder;
• providing an output of said ADPCM encoder as an ADPCM output signal;
• receiving an ADPCM input signal at an input of an ADPCM decoder;
• selecting one of, a second linear signal at an output of said ADPCM decoder, and said linear tone signal, to provide a second selected signal;
• and
• converting said second selected signal to a digital PCM output signal.

A signal processing apparatus comprising:

• a data processor having an input terminal for receiving an input signal, an output terminal, and an input/output terminal;
• a serial control port having an input terminal coupled to said output terminal of said data processor, and an output terminal;
• a signal encoder having a first input terminal for receiving a first digital signal, a second input terminal for receiving a first tone signal, a control input terminal coupled to said output terminal of said serial control port, and an output terminal for providing a transmit signal in response to either said first digital signal or to said first tone signal, as determined by said serial control port;
• a signal decoder having a first input terminal for receiving a receive signal, a second input terminal for receiving a second tone signal, a control input terminal coupled to said output terminal of said serial control port, and an output terminal for providing a second digital signal in response to either said receive signal or to said second tone signal, as determined by said serial control port;
• and
• a tone generator having a control input terminal coupled to said output terminal of said serial control port, a first output terminal coupled to said signal encoder for providing said first tone signal, and a second output terminal coupled to said signal decoder for providing said second tone signal.

A signal processing apparatus comprising:

• a data processor having an input terminal for receiving an keypad input signal, an output terminal, and an input/output terminal;
• a pulse code modulation (PCM) codec having a first input terminal for receiving a voice input signal and a first output terminal for providing a first digital signal in response to said voice input signal, and a second input terminal for receiving a second digital signal and a second output terminal for providing a voice output signal in response to said second digital signal;
• an ADPCM transcoder having a first input terminal for receiving said first digital signal and a first output terminal for providing a transmit signal in response to said first digital signal, a control input terminal coupled to said output terminal of said data processor, a second input terminal for receiving a receive signal and a second output terminal for providing said second digital signal in response to said receive signal;
• said ADPCM transcoder including means responsive to said data processor for inserting a tone signal having at least one tone frequency associated therewith into one of either a receive signal stream and a transmit signal stream as selected by said data processor.