JPH0165535U

JPH0165535U -

Info

Publication number: JPH0165535U
Application number: JP1987161785U
Authority: JP
Priority date: 1987-10-21
Filing date: 1987-10-21
Publication date: 1989-04-26

Description

[Brief explanation of the drawing]

第１図は本考案によるデータ伝送用モデムの交
流折返し回路の一実施例を示すブロツク回路図、
第２図は従来のデータ伝送用モデムの交流折返し
回路を示すブロツク回路図、第３図は第１図実施
例における各部信号を模式的に示すタイミング図
である。１……入力端子、２……送信機、３，９……切
替器、４……送信回路網、５……送信端子、６…
…出力端子、７……受信機、８……自動利得制御
回路、１０……受信回路網、１１……受信端子、
１２……受信信号検出回路、１３……アナログス
イツチ。 FIG. 1 is a block circuit diagram showing an embodiment of an AC loop circuit of a data transmission modem according to the present invention;
FIG. 2 is a block circuit diagram showing an AC return circuit of a conventional data transmission modem, and FIG. 3 is a timing diagram schematically showing signals of various parts in the embodiment shown in FIG. 1...Input terminal, 2...Transmitter, 3, 9...Switcher, 4...Transmission circuit network, 5...Transmission terminal, 6...
...output terminal, 7...receiver, 8...automatic gain control circuit, 10...receiving circuit network, 11...receiving terminal,
12... Received signal detection circuit, 13... Analog switch.

Claims

[Claims for Utility Model Registration] A transmitter that converts a DC digital signal into an AC analog signal, amplifies it, and transmits it; a transmission filter that removes unnecessary out-of-band noise from the analog signal; It consists of a transmission equalizer that equalizes the amplitude distortion and delay distortion of the transmission path on which the analog signal is transmitted, and a level adjuster that adjusts the level of the analog signal sent out, and receives the analog signal sent out by the transmitter. A transmitting circuit network that transmits this to a communication line; a receiving filter that removes unnecessary out-of-band noise from the AC analog signal transmitted from the other station; and amplitude distortion of the transmission line through which this AC analog signal is transmitted. and a reception equalizer that equalizes delay distortion, and receives an AC analog signal transmitted from the other station and outputs it; and a reception circuit network that receives the AC analog signal output from the reception circuit network and outputs it; an automatic gain control circuit that controls and outputs; when communicating with a partner station, the output end of the transmitter is connected to the input end of the transmitting circuit network; a first switch that connects the output end of the transmitter to the input end of the receiver; when communicating with a partner station, connects the output end of the automatic gain control circuit to the input end of the receiver; Connect to the input end,
In the case of an AC loopback test for troubleshooting, it consists of a second switch that connects the output end of the automatic gain control circuit to the input end of the transmission circuit network, and a four-wire transmission when communicating with a partner station. In the case of an AC loopback test for troubleshooting data transmission over a network, the AC analog signal sent from the other station is looped back to the other station, and the AC analog signal sent out by the transmitter is sent back to the other station. In an AC return circuit of a data transmission modem input to a receiver; inserted between an input end of the transmission circuit network and the second switch, and connected between the second switch and the input end of the transmission circuit network; an analog switch that opens and closes the connection to the receiving circuit; and a received signal detection circuit that closes the analog switch after a predetermined period of time has elapsed since the output level of the receiving circuit network exceeds a predetermined value; An alternating current return circuit for a data transmission modem, characterized in that the automatic gain control circuit is set to the time from when it starts receiving the analog signal until the output level is stabilized, or to a time slightly longer than this time.