Cordless telephone
First Claim
1. A cordless telephone consisting of a base unit connected to a PBX and a handset unit which wirelessly transmits or receives signals to or from said base unit, wherein a control circuit incorporated in said base unit comprises:
- a first D/A converter for converting a digital signal from said handset unit to an analog signal;
a first A/D converter for converting the analog signal from said first D/A converter to a digital signal to transmit it to said PBX via a data transmission/reception circuit of said base unit;
a second D/A converter for converting a digital signal from said PBX to an analog signal;
a second A/D converter for converting the analog signal from said second D/A converter to a digital signal to transmit it to said handset unit via a transmitter of said base unit;
a first synchronization means for regenerating a first clock signal synchronously with a synchronization signal provided from said PBX to render said first A/D and second D/A converters to operate in synchronism with said synchronization signal from said PBX; and
a second synchronization means for generating a second clock signal which is independent of said synchronization signal from said PBX to render said first D/A and second A/D converters to operate in synchronism with said second clock signal, whereby the synchronization between said base and handset units being effected independently of the synchronization signal from said PBX.
1 Assignment
0 Petitions
Accused Products
Abstract
A cordless telephone consisting of base and handset units is disclosed wherein a control circuit incorporated in the base unit comprises first and second D/A converters, first and second A/D converters, and first and second sync. signal generation circuits. The first and second D/A converters respectively convert digital signals from the handset unit and a PBX. The first and second A/D converters convert the analog signals provided from the first and second D/A converters to transmit them to the PBX and handset unit, respectively. The first sync. signal generation circuit regenerates a first clock signal synchronously with a sync. signal provided from the PBX to render the first A/D and second D/A converters to operate in synchronism with the sync. signal from the PBX. The second sync. signal generation circuit generates a second clock signal which is independent of the sync. signal from the PBX to render the first D/A and second A/D converters to operate in synchronism with the second clock signal. Accordingly, the synchronization between the base and handset units is effected independently of the synchronization signal from the PBX.
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Citations
2 Claims
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1. A cordless telephone consisting of a base unit connected to a PBX and a handset unit which wirelessly transmits or receives signals to or from said base unit, wherein a control circuit incorporated in said base unit comprises:
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a first D/A converter for converting a digital signal from said handset unit to an analog signal; a first A/D converter for converting the analog signal from said first D/A converter to a digital signal to transmit it to said PBX via a data transmission/reception circuit of said base unit; a second D/A converter for converting a digital signal from said PBX to an analog signal; a second A/D converter for converting the analog signal from said second D/A converter to a digital signal to transmit it to said handset unit via a transmitter of said base unit; a first synchronization means for regenerating a first clock signal synchronously with a synchronization signal provided from said PBX to render said first A/D and second D/A converters to operate in synchronism with said synchronization signal from said PBX; and a second synchronization means for generating a second clock signal which is independent of said synchronization signal from said PBX to render said first D/A and second A/D converters to operate in synchronism with said second clock signal, whereby the synchronization between said base and handset units being effected independently of the synchronization signal from said PBX.
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2. A method of transferring signals from/to a handset unit of a cordless telephone to/from a PBX through a base unit of said cordless telephone, comprising the steps, which are executed in said base unit, of:
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regenerating a first clock signal synchronously with a synchronization signal provided from said PBX; generating a second clock signal which is independent of said synchronization signal from said PBX; converting a digital signal from said handset unit to an analog signal by a first D/A converter, synchronously with said second clock signal; converting the analog signal provided from said first D/A converter to a digital signal, synchronously with said first clock signal; transmitting the digital signal provided from said first A/D converter to said PBX via a data transmission/reception circuit; converting a digital signal from said PBX to an analog signal by a second D/A converter, synchronously with said first clock signal; converting the analog signal provided from said second D/A converter to a digital signal by a second A/D converter, synchronously with said second clock signal; and transmitting the digital signal provided from said second A/D converter to said handset unit, whereby the synchronization between said base and handset units being effected independently of the synchronization signal from said PBX.
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Specification