********************************************** *** Sound Sweep - Radio Prompt Generator *** ********************************************** The new grid-search technique, the Sound Sweep, gives ground-search SAR teams the capability of searching a 4-5 times larger area than is possible with the standard visual grid-search procedures. The standard Sound Sweep ground search conditions are: 80% POD: 3 Sweeps at 210m / 689 feet / 286 paces Searcher Spacing 40% POD: 1 Sweep at 210m / 689 feet / 286 paces Searcher Spacing The Sound Sweep technique does require that a Base radio transmit an audible prompt to the field teams at a regular intervals, so that the searchers may synchronize their whistle blasts and listen for the audible response from the missing person. To ensure that the missing person's audible response is heard by the searchers they must perform their whistle blasts at very frequent intervals, typically every 17m / 44 feet of travel, where POD research has shown(1) that searchers have a 100% POD for hearing the missing persons voice. For field teams travelling through a search area this corresponds to a "5, 4, 3, 2, 1, Blast" radio prompt from base every 120 seconds when travelling at 0.4km/hr, 0.25 miles/hr or every 60 seconds when travelling at 1km/hr, 0.62 miles/hr. While this manual voice prompt can be performed with no more equipment than a base radio and an operator with a wristwatch it is monotonous and typically requires a couple of volunteers to spell each other off at the Base radio microphone. Lions Bay Seach & Rescue have developed an electronic radio Prompt Generator that will automatically transmit the required radio prompt, as four short audible tones followed by a longer 'blast' tone, for a choice of multiple time intervals, corresponding to seven ground-search search speeds. This Prompt Generator is a small electronic box that connects between the Base microphone and the Base radio. In standard operating mode it will overide any voice tranmsission with the radio prompt at the pre-selected time interval. An 'overide' mode permits the Base radio operator to tranmsit voice communications at any time. The Prompt Generator has LED's and a loudspeaker that permit the Base operator to either see or hear that the prompts are being generated. The unit operates on 8 to 20 volts DC, and can use either the Base radio's 12 volt power supply, or a standard 9-volt battery. The Prompt Generator can transmit at the following time intervals: Prompt Interval Search Speed Typical Ground-Search Conditions 120 seconds 0.4 km/hr 0.3 miles/hr Rugged mountain forest 60 seconds 1 km/hr 0.6 miles/hr Fairly flat bushy forest 30 seconds 2 km/hr 1.2 miles/hr 20 seconds 3 km/hr 1.9 miles/hr 15 seconds 4 km/hr 2.4 miles/hr 12 seconds 5 km/hr 3.1 miles/hr 9 seconds 6 km/hr 3.7 miles/hr For more information on the 'Resound' Sound Sweep Prompt Generator please contact: Craig Hollinger Alpen Engineering 610 Latimer Street Nelson British Columbia Canada V1L 4V3 Phone Craig Hollinger at: (250) 352 5293 email: craigh@netidea.com or Martin Colwell at: (604) 325 3017 email: sarinfo@mindlink.bc.ca May 1997 ---------------------------