US 5,179,360 AGranted

Transmitting/receiving apparatus switchable between digital and analog modulation modes

AssigneeSony Corporation

InventorMitsuhiro Suzuki

Life of this patent

Estimating the term…

Loading patent…

Abstract

Upon transmission, when the digital transmission mode is set, an analog audio signal is A/D converted, the digital audio signal is coded, a first carrier is modulated by the coded signal and multiplied by a first multiplier, and the multiplied signal is sent to an orthogonal modulating and D/A converting circuit. When the analog transmission mode is set, a second carrier is modulated by the digital audio signal and multiplied by a second multiplier, and the multiplied signal is sent to the orthogonal modulating and D/A converting circuit. A signal of a frequency which is equal in both of the digital transmission mode and the analog transmission mode is given to the orthogonal modulating and D/A converting circuit. Upon reception, when the digital transmission mode is set, an output of an A/D converting and orthogonal demodulating circuit is frequency divided by a first frequency divider and demodulated and decoded. When the analog transmission mode is set, the output of the A/D converting and orthogonal demodulating circuit is frequency divided by a second frequency divider and demodulated. A frequency of a reference frequency signal is set to a common multiple of a coding rate of the A/D converter, the frequency of the first carrier, and the frequency of the second carrier, so that a necessary signal of each section can be easily formed from an output of a reference frequency signal generator.

Claims16

Dependent claims

A transmitting apparatus comprising:

A/D converting means for converting an input audio signal into a digital audio signal;
mode setting means which is switched between a digital transmission mode to transmit a digitally modulated audio signal and an analog transmission mode to transmit an analog modulated audio signal;
digital transmission signal processing means to which the digital audio signal is given when said mode setting means is set into the digital transmission mode and which encodes the digital audio signal and modulates a first carrier by the coded signal;
analog transmission signal processing means which modulates a second carrier by the digital audio signal when the mode setting means is set into the analog transmission mode;
first multiplying means for multiplying a frequency of an output signal of the digital transmission signal processing means by integer times;
second multiplying means for multiplying a frequency of an output signal of the analog transmission signal processing means by integer times;
orthogonal modulating and D/A converting means for orthogonal modulating an output of the first multiplying means or an output of the second multiplying means and for D/A converting;
and
reference signal generating means for supplying signals of necessary frequencies to the A/D converting means, the digital transmission signal processing means, and the analog transmission signal processing means on the basis of a reference frequency signal,
wherein the frequency of the reference frequency signal is set to a common multiple of a coding rate of the A/D converting means, a frequency of the first carrier, and a frequency of the second carrier.

7 more elements

A receiving apparatus comprising:

A/D converting and orthogonal demodulating means for A/D converting and orthogonal demodulating a reception signal;
mode setting means which is switched in accordance with a digital transmission mode to receive a digitally modulated audio signal and an analog transmission mode to receive an analog modulated audio signal;
first frequency dividing means to which an output of the A/D converting and orthogonal demodulating means is supplied and which forms a signal of a first carrier frequency;
second frequency dividing means to which the output of the A/D converting and orthogonal demodulating means is supplied and which forms a signal of a second carrier frequency;
digital reception signal processing means for demodulating an output of the first frequency dividing means when the mode setting means is set into the digital transmission mode and for decoding the demodulated signal and forming a first digital audio signal;
analog audio signal processing means for demodulating an output of the second frequency dividing means when the mode setting means is set into the analog transmission mode and for forming a second digital audio signal;
D/A converting means for converting the first or second digital audio signal from the digital reception signal processing means or the analog reception signal processing means into an analog audio signal;
and
reference signal generating means for supplying signal of necessary frequencies to the digital reception signal processing means, the analog reception signal processing means, and the D/A converting means,
wherein a frequency of the reference frequency signal is set to a common multiple of the frequency of the first carrier, the frequency of the second carrier, and a coding rate of the digital audio signal.

7 more elements

Dependencies are inferred from the claim text.