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US6125139A Narrowband digital cordless telephone 失效
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Narrowband digital cordless telephone
摘要:
A digital cordless telecommunications unit that serves for communications when paired with a similar unit and connected with a network is disclosed. The unit receives analog receive voice signals and transmits analog transmit voice signals. In addition, the unit transmits digital baseband transmit signals and receives digital formatted baseband receive signals. The unit includes a baseband chip, as well as an audio functions circuit and a system control functions circuit. The audio functions circuit comprises an audio front end for receiving the analog receive voice signals and transmitting the analog transmit voice signals, and an adaptive differential pulse code modulator codec, connected to the audio front end, for converting the analog receive voice signals to the digital transmit signals and converting the digital formatted baseband receive signals to the analog transmit voice signals. The system control functions circuit comprises a microcontroller, connected to the codec, for controlling the baseband chip, a memory accessible by the microcontroller for storing control instructions, an interrupt controller connected to the microcontroller, a parallel port connected to the interrupt controller, a wake-up timer connected to the interrupt controller, a clock generator connected to the microcontroller, and a synchronous serial port connected to the interrupt controller.
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