Tuning the HydroLite-Plus Single Frequency (SFX) Transducer

If you haven't connect the HydroLite-Plus to the Echologger control program before, please follow the steps in Trimble Access Setup.

1. Tuning should be completed prior to survey for each different body of water. If you are returning to the same location in the future write down the tuned parameters to easily apply them for the next time you visit the site.
2. Ideally tuning should be completed in the deepest part of the body of water that you will be surveying.
3. Open the SFX control program.
   
4. The tuning is done by adjusting the Echosounder Parameters on the left hand side (parameter definitions can be found at the end of this article). On the right is an echogram displaying the bottom tack of the system returns which gives a visual aid to better tune the system.
5. The default starting parameters advised by Seafloor are as follows:      

   Range, m	100000
   Tx Length	100
   Interval	0.5
   Deadzone, mm	300
   Offset	0
   Altimeter Threshold	10
   Gain	+6
   Sound speed	1500
   Output Mode	OLD Hydrolite

6. What you are looking for in the echogram is a smooth continuous curve as below:
   
7. The main parameters to adjust are:
   • Range, m - The distance between the transducer and the object. From the above example the range was set to 20m as the known maximum depth was 10m.
   • Deadzone, mm - The area surrounding the transducer where the sonar system is unable to detect echoes due to too much noise in the water or the sonar is still transitioning between sending out a signal and listening for echoes.
   • Gain, dB - The amplification of the received acoustic signal. By adjusting the gain you are adjusting the sensitivity of the transducer in receiving the sound wave echoes that it is emitting. By increasing the gain you are amplifying weak echoes, making them more detectable, while decreasing the gain reduces sensitivity to prevent saturation from strong echoes or background noise.
   • Altimeter Threshold, % - It refers to a predefined level set for the return signal strength from the water bottom. Think of the altimeter like a filter. It's a level set to determine which signals are strong enough to be considered reliable measurements. Setting this too high might mean missing weak echoes from softer bottoms, so it's about finding the right balance for accurate readings.
8. Below is an echogram example of a poorly tuned unit:
   
9. Continuously tweak and test these values until the echogram displays smoother and more sensible curves.
10. It is recommended to maintain default values for the remaining parameters.
11. After adjusting the parameters, the control program can be closed. The depth measurement will take place in Trimble Access.

Parameter Definitions

• Range, m- The distance between the transducer and the object.

• Tx length, μsec - Set transmitted pulse length in microseconds (up to 100 μsec). It refers to the duration of time in microseconds (μsec) during which the sonar system emits a sound pulse into the water.

• Interval, sec - Interval (repetition rate) between pulses in seconds. (From 0.1 to 3600 (1 Hour)) It refers to the time interval in seconds between successive transmissions of sonar pulses.

• Deadzone, mm - Area surrounding the transducer where the solar system is unable to detect echoes due to too much noise in the water or device is still transitioning between sending out a signal and listening for echoes. The deadzone value can be increased to block any unwanted surface noise that may be affecting the true bottom surface return.

• Offset, mm - Vertically offset the position of the device in millimeters.

• Altimeter threshold, % - Altimeter threshold percentage of full scale (return sensitivity). It refers to a predefined level set for the return signal strength from the water bottom. Think of the altimeter threshold in sonar like a filter. It's a level set to determine which signals are strong enough to be considered reliable measurements of depth.

• Gain, dB - It refers to the amplification of the received acoustic signal. Sonar systems emit sound waves into the water, which then bounce off objects and return as echoes. The gain setting on a sonar system adjusts the sensitivity of the receiver to these echoes.

• Sound Speed, m/s - Speed of sound in water.

• Output Mode - Select ‘Hydrolite OLD’ for HydroLite-Plus Single Frequency (SFX).

MORE INFORMATION

For additional information or assistance, contact 1800 800 874 or email support@upgsolutions.com