초록 ▼

A dual speed, full duplex modem for transmitting and receiving data on a dialed-access telephone line includes a signal processor for storing samples corresponding to a sinusoidal waveform, for selecting samples at intervals determined by the mode in which the modem is operating to synthesize a sign

A dual speed, full duplex modem for transmitting and receiving data on a dialed-access telephone line includes a signal processor for storing samples corresponding to a sinusoidal waveform, for selecting samples at intervals determined by the mode in which the modem is operating to synthesize a signal for modulating by data for transmission, and for autocorrelating a received signal at a frequency determined by the mode in which the modem is operating to recover data from the received signal. The signal processor includes configuring input ports, and a microcomputer receives instructions related to the mode in which the modem is to operate to output a mode-configuring word to the configuring inputs. Conversion from the signal processor\s digital output to the analog signal to the line and from the line\s analog signal to the signal processor\s digital input take place through two time-division multiplexed coder-decoders. The stored sinusoid is mu-law compressed. The modem can dual tone, multiple frequency dial. The DTMF pair requires a different amplitude from the amplitude of the synthesized signal for modulating by data for transmission. A power series expansion of the required amplitudes of the DTMF tone pair permits both the synthesized signal for modulating by data for transmission and the tones of the DTMF pair to be calculated from the mu-law compressed sinusoid.

대표청구항 ▼

A telephone network between an originate modem and an answer modem, at least one said modem comprising a two speed, full duplex modem for transmitting and receiving analog signals through said telephone network, said full duplex modem comprising: (a) a data terminal means for transmitting and receiv

A telephone network between an originate modem and an answer modem, at least one said modem comprising a two speed, full duplex modem for transmitting and receiving analog signals through said telephone network, said full duplex modem comprising: (a) a data terminal means for transmitting and receiving digital data; (b) a microcomputer means in communication with the data terminal means; (c) a signal processor means in communication with the microcomputer means, said signal processor means further providing a means for storing a plurality of digital data samples corresponding to a sinusoidal waveform; (d) a converting means in communication with the signal processor means for converting digital data from the signal processor to the analog signal for transmission over the telephone network, and for converting the received analog signal from the telephone network to the digital data; (e) a filter means in communication with the converting means and the telephone network for filtering the analog signal for transmission between the converting means and the telephone network, and for filtering the received analog signal; and (f) a selecting means in communication with the microcomputer means for selecting a bit rate mode using the digital data from the data terminal means; said selecting means further providing a means responsive to the bit rate of the originate modem, to selectively communicate either a relatively higher bit rate by differential phase shift keying, or a relatively lower bit rate by frequency shift keying; the selecting means further providing a means for selecting digital data samples at intervals determined by the bit rate mode, to synthesize the digital data modulated for transmission through the converting means to the analog signal for transission through the filter means over the telephone network for communication between the originate modem and the answer modem.