How They Work
Very simple, they make a noise and measure the echo. Knowing that sound travels at 144 metres a second through water allows us to calculate the depth by measuring the interval between the sound being made and the echo being heard. The NASA Stingray Echo Sounders have a transducer with high quality Lead Zirconate Titanate Piezodisc crystals which creates ultrasonic ‘sound’ pulses at a frequency of 150kHz (imperceptible to the human ear). These pulses pass through the water and bounce back of the bottom.
The returning echo pulse is then sensed by the transducer crystal. On these rotary flashing LED type sounders, a pulse is generated as the LED flashes at the 12 o’clock position . The rotor arm is calibrated to run at a speed whereby when it flashes on receiving the returned pulse this flash will be in the correct position on the dial to indicate the correct depth.
- Standard – This is the basic dual alarm, dual range unit with LED display unit
- Twin – Dual alarm, dual range sounder with LCD depth readout in addition to the flashing LED display