Patent ID: 11968324
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Telecommunications (Electrical engineering)
Classification: CPC H | IPC H

Claim 4:
5. A signal transmission method for transmitting an analog signal, in which a billing signal is superposed on an audio signal, from a transmitting device to a receiving device, the method comprising:
a separation process for separating the audio signal from the analog signal;
an AD conversion process for performing AD conversion on the separated audio signal;
a detection process for detecting the billing signal from the analog signal;
a coding process for encoding the detected billing signal;
a transmission process for transmitting the AD-converted audio signal and the encoded billing signal to the receiving device;
a reception process for receiving the transmitted audio signal and the transmitted billing signal;
a DA conversion process for performing DA conversion on the received audio signal;
a decoding process for decoding the received billing signal;
a conversion process for converting the decoded billing signal into an analog wave; and
a combination process for combining the DA-converted audio signal and the analog wave.