Brief introduction of speech separator

The voice separator separates the audio signal on the line from the high-frequency digital modulation signal, and sends the audio signal to the switch and the high-frequency digital modulation signal to the ADSL access system. Due to the acceleration of network transmission speed and the development of various technologies, voice separator has become an indispensable device for users. Voice separator is used for line interface to separate high-frequency ADSL signal and audio telephone signal. It mainly includes the following functions: mixing and separating telephone signals and ADSL signals; Low-pass filter and high-pass filter are used to separate the low-frequency band carrying audio signals from the high-frequency band used for ADSL modem modulation, so that the transmitting end can mix the signals and the receiving end can separate the received signals. Protect voice band services from nonlinear or other effects that ADSL signals may cause through low-pass filters; Protect ADSL signals from the interference of telephone related signals, especially the interference of dialing pulses and ringing cut-off signals on ADSL receivers. The speech separator integrates the functions of low-pass filtering and impedance isolation. On the one hand, it filters out the high-frequency energy of telephone equipment, on the other hand, it provides impedance isolation for telephone equipment on ADSL system. In addition, it attenuates broadband noise signals caused by loop current interference of telephone equipment. Since the audio frequency is about 20Hz- 20KHz, the separator must have a low-pass filter to separate the audio signal in the line. The ADSL voice separator couples the high-frequency data signals and low-frequency voice signals of the DISLAM equipment and PSTN equipment in the ADSL communication line and transmits them to the end users. When signals are transmitted to end users, ADSL voice separators separate high-frequency data signals to ATU-R and connect them to the Internet, and separate low-frequency voice signals to terminal devices such as telephones and fax machines.

The voice separator effectively separates the low-frequency audio signal (300 ~ 3400 Hz) on the line from the high-frequency digital modulation signal (20 Hz ~ 4.4 MHz/ 12 MHz) for transmitting data. Then the audio signal is sent to PSTN (Public Switched Telephone Network) switch or POTS (Ordinary Old Telephone Service) telephone fax machine, and the high-frequency digital modulation signal is sent to DSL access multiplexer (DSL access multiplexer) /DSL modem. DSL technology realizes that multiple telephone extensions, fax machines and ADSL modems at the user end do not affect each other when in use, that is, it isolates the current noise generated by broadband Internet access in POTS phones, ensures high-quality call effect, avoids broadband Internet access disconnection caused by telephone ringing, and ensures the download rate of broadband Internet access at a certain transmission distance. The following figure is the application block diagram of DSL separator.

It can be seen that both CO (local office or LE) and CPE (customer premises client) need to use voice separators. The user-side separator is generally a box separator, and the separator monomer equipment is externally connected according to actual needs. Most of the 32/48/64 local separators are assembled on a separator board, and several separator boards are installed on the local cabinet to realize the separation and transmission of voice and digital signals, voice exchange and management, and broadband convergence together with the control switch board, backplane, line interface board and uplink board. In addition, there is an over-current and over-voltage protection circuit on the isolation board to realize the protection functions such as lightning strike, power line touch and induction.