Abstract: A credit inquiry service system for inquiring about the credit standing of a check or credit card uses subscriber lines of a public communication network. The system includes credit inquiry terminals connected to the subscriber lines for generating and transmitting an inquiry request message requesting information regarding the credit standing of the check or credit card. The credit inquiry terminals also receive an inquiry result message corresponding to the inquiry request message via the subscriber lines. The system further includes a line multiplex device for one by one serially selecting the subscriber lines connected to the credit inquiry terminals, receiving the inquiry request message from one of the credit inquiry terminals connected to a selected subscriber line, and transmitting the inquiry result message corresponding to the inquiry request message to the corresponding credit inquiry terminal.

Abstract: In performing data communication between a subscriber terminal and a scanner of a remote information processing system, there is provided a data modulator-demodulator apparatus of a pseudo noise spread spectrum communication system for executing the data transmission and reception at a high speed, regardless of a voice speech use on a transmitting line. The transmitter part of the modulator-demodulator apparatus has a modulator which uses a pseudo noise code, generated by a pseudo noise code generator, to band spread real data, and the band spread data is converted to analog information by a transmitting converter for transmission over a transmitting line. The receiver part of the modulator-demodulator apparatus has a receiving converter which recovers operation clock data from the received analog signal, and converts a received analog signal to digital data. A demodulator in the receiver part then de-spreads the digital data in response to the pseudo noise code generated by the pseudo noise code generator.