The DHI-1 Diver Held Interrogator will quickly locate a acoustic sonar transponder transmitting a frequency of 24, 25, 27, 28, 29, 30, 31, 32, or 33kHz (special frequencies are also available). The DHI-1 acoustic sonar interrogator can be carried by a diver or deployed from a boat using the optional Boat Deployment Kit.

Operating the DHI-1 is easy; select the transponder frequency to be located and scan the area with a 360 degree sweep. When the diver points the DHI-1 in the direction of the transponder, an audio alarm sounds through the underwater earphone and the LED light bar flashes. The DHI-1 displays the distance to the transponder and a compass mounted on top of the DHI-1 provides the diver with the precise heading to the target. The DHI-1 acoustic sonar interrogator calculates the distance to the transponder by measuring the time between the transmit signal and the return signal. As the diver moves in the direction of the target the distance (in feet or meters) is constantly updated to give the precise distance.

If several transponders are operating in the area, the diver can switch the DHI-1 frequency to match the next acoustic transponder and repeat the procedure to the next target.

The DHI-1 can detect and give range and bearing on acoustic transponders at a distance in excess of 3,000 feet, and is compatible with most other manufactories transponders.