The DTA-1 Board is used when it is necessary to combine two tone sensor channels ( A and B ) to derive 3 distinct signals: A only, B only, or both A and B.
In some cases, the A and B channels may be 25 Hz tones on right and left tracks of a stereo audio source such as a tape deck.
In other cases, two frequencies may be used on the same audio channel. This is the case with some satellite systems, where 25 Hz and 35 Hz tones are used in combination. Even though tone sensor relay contacts may be connected to generate the proper logical responses to A, B, or Both, a problem can arise in some cases. When both tones are sent, one tone may be detected a fraction of a second before the other. In this case, the first tone sensor may briefly generate an output signal which cannot be distinguished from a deliberately sent single tone.
The DTA-1 (used to detect 25 Hz, 35 Hz and 25/35 Hz) receives a simple contact closure from each sensor (A and B). In response, one of three relays is actuated, one for each combination. A time delay is introduced ( adjustable from 0 to 1 sec. ) such that a single tone relay will not be actuated unless that tone is at least as long as the delay. This eliminates the transient condition described above. One SPDT and one SPST set of contacts for each of the three relays is brought out to the DB-15 connector. The DTA-1 has two short cables with DIN connectors to plug directly into the dual sensor boards used in the Conex CS-25B tone sensor. The DTA-1 mounts directly in the same chassis as the sensor and filter boards of the CS-25B.