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To all interested in passive sonar or underwater communications: With six passive sonar/underwater communications console thus far in the field, I have been able to establish a range for such a system having performed in-water testing over the past two weekends. Although the equipment I was using may differ from that which you may possess, a round idea can possibly be derived from this provided report. One thing that was established early on, is that by doubling the output from one's transmitter, you will not double the range at which you can be heard. This is not a linear equation. The first session the following equipment was used: A 5 watt off the shelf amplifier that ran a 9 volt dc battery was used in conjunction with a standard HBH-2 hydrophone to serve as the receiving station. A 5 watt off the shelf amplifier was also used as the transmitter using a transducer for solids underwater speaker (potted) The weather was clear and in the lower 60's. It was windy and our testing site was near a boat ramp so some boat traffic was observed. Once back at the lab following the testing, google was utilize to verify the estimated ranges for accuracy using known geographical landmarks such as buoy's and viewable foliage. The transmission reception and interpretations were good (understood 90 percent of the time) up to 285 feet. Beyond this point, music could be identified some but words could not be distinguished. These ranges could have been extended with the use of the earlier discussed Alfa, Bravo, Charlie alphabet, and the use of headphones would have rid us of wind in the ear interference problems. Both transmitter and hydrophone were at three feet depth. Local boat traffic did come into play but not all the time. (some communications could be heard even thru this added ambient noise being of differing frequency) Following the initial in-water testing performed on the first day, we absorbed that which we had thus far learned and in-shop testing some ideas were done. We surmised that the hydrophone and 5 watt amplifier used to listen was more than adequate. The transmitter or underwater speaker was at this point using but 4 watts of output power and was said to be able to handle a full 30. It is this area of underuse that we concentrated for our second planned testing session. David Bartsch Windows 7: It helps you do more. Explore Windows 7. |