Because of time constraints, only a limited test was performed with the acoustic pinger. The unit tested was the DiveTracker Sport System with factory settings from Desert Star Systems out of Marina, CA (
Welcome to Desert Star Systems LLC). The unit is designed as a SONAR navigation system for divers. The owners manual for the unit is comprehensive and well written and can be downloaded at this site. The transmitter and receiver come package in a rugged Pelican 1150 case. Both the transmitter and the receiver are built into identical cases that are 5 inches long with a diameter of 2.5 inches. The transmitter (DTS-TX) has an ON OFF dial on the side to activate the unit. The receiver (DTS-RX) has a dial with positions of OFF, HI and LO gain and comes with a lanyard to attach to the divers wrist. Both units have a low battery indicator. The transmitter uses six AA Alkaline batteries cells and the receiver uses a 9VDC alkaline battery. The battery life according to the manufacture is good for 1 week of continual operation. I have not confirmed this.
As a simple test, to determine the effect of orientation of the transmitter, the transmitter was positioned in many different orientations with the receiver positioned about 10 ft from the transmitter. No change in the receiver signal was noted.
The transmitter was held in vertical orientation about 2 ft from the surface in a location where the water depth was 5 ft. Two divers with one holding the receiver submerged approximately 200 yards from the transmitter to a depth of about 5 ft and used the receiver to try and track in on the transmitter. The initial setting on the receiver was HI. It became apparent immediately that at this distance this was much to sensitive. The divers reset the receiver to LO and proceed to rotate in the water column 360 degrees to detect the transmitter. Within an angle spread of approximately +/- 15 degrees the receiver detected the transmitter. They proceeded underwater from this point heading for the maximum intensity bearing and were able to make a direct approach on the transmitter until they were about 8 feet from the transmitter. At this point they were so close that the no matter where they pointed the receiver they were getting a strong signal. Because the water visibility was only about 5 feet, they ended up passing the receiver and had to reverse course and double back to find the transmitter. It hard to draw any significant conclusions from such a limited test particularly to confirm the 2000 ft maximum range but from what I have seen of the unit I will begin using the equipment on my boat for each dive to help divers locate the boat in poor visibility in an emergency situation. Hopefully I will be able to do a more comprehensive test on a future dive.
There is one issue that would effect this system for use at a psub convention in which multiple boats were equipped with these transmitters. The transmitter frequency can not be varied by the end user. By changing the dip switch settings in the transmitter, it is possible to change the pulse rate from 0 to 15 pps but it would still be hard to distinguish between different boats transmitting in the same area. As noted by manufacturer, if you had multiple boats stranded at the same time, you would just have to hunt down the strongest signal, mark it location and turn off its transmitter then head for the new strongest signal until all the boats are located. With the cost of these units being reasonable, I would not have a problem in recommending this system to other psubbers.
