We offer different compared to published in [1]. phone interface. It is designed to connect simplex radio station with the telephone line.
In this scheme, an algorithm of mixed control. Turn on the base station to the transfer happens at the disappearance of the carrier or signal CTSS, and off - at the end of the phrase subscriber's PBX (system monitoring the presence of voice). This algorithm allows to significantly reduce the loss of information from the subscriber-side PBX, characteristic of systems operating only on the voice key with a delay.
In this scheme, the following features are implemented:
- individual access code;
- storing the last number dialed;
control the availability of the caller to speak the PBX;
- providing the subscriber PBX fixed time intervals (in the case of poor signal on the telephone line. not allowing the system to run controlling for the presence of votes);
to protect the line from "hang" cut "loss" of subscriber's ID;
- operation of pulse and tone dialing TONE/ PULSE;
- programming user-interface modes; - work with the Manager.
(click to enlarge)
The station manages the interface by using the DTMF keypad. in its absence, you can use the beeper.
The use of standard DTMF codes allows you to abandon the mobile part of the interface.
The management interface provides PIC controller D3. Microchip PIC16C84 has a non-volatile memory. In this memory stores the operating modes of the interface. Programming mode is carried out with a mobile radio using DTMF codes.
The user can change the code and access your interface.
For processing the DTMF codes used by the decoder D2. Chip MTBE can handle incoming signal over a wide dynamic range (50 dB).
To control the availability of the caller's voice PBX it is necessary to analyze the signal on the telephone line. For this purpose, the elements of the chip D4 assembled a comparator. He handles the tone PBX.
Relay K1 is used for switching the signal from the phone line to the MIC input of the radio station or radio station in the telephone line. The signal from the radio is supplied to the amplifier assembled on the chip D 1. Galvanic isolation from the telephone line is made on the transformer T1. Relay K2 is used to hold the line and dial the number.
To purchase customized cards or finished products can the authors of the article.
Literature
1. Cats.. Golovko A. Telephone interface. - Ham, 1997, No. 2,p.18.
Authors: V. Kotov, A. Golovko, Ukraine, Donetsk region, Marinka; Publication: N. Bolshakov, rf.atnn.ru