I would like to inquire about Ping2 Sonar products

Blue Robotics Products Ping Sonar Devices
1

Hello,

Data is being logged by referring to the Ping Protocol document (1211 distance_simple).

Ping2 Sonar products are attached to self-made small ships and are used for river depth measurement.

When the ship is in operation, the confidence value is more than 70%, but when the ship stops and measures the depth, the confidence value drops to 0%, and the distance value shows an odd value.

Is the above phenomenon natural?

2

Hi @bskim, welcome to the forum :slight_smile:

This thread is the most relevant discussion of the confidence values of our 1-dimensional series of ping sonars. I’d suggest reading through that, and some of the links from there, to get a better understanding of what the confidence conveys and what goes into the distance estimation process.

I would not say that’s a common experience, but it’s at least theoretically possible if

  • the motion of the ship is pushing aside vegetation and/or scaring away marine life that then go into the beam path when the ship stops
  • the ship’s momentum is reducing pitching and/or rolling, and keeping the beam pointing at a more consistent area of the surface
    • this is mostly relevant if the water is quite rough, with significant rotation when it is “stopped”
  • moving through the water is damping the sonar’s transducer vibrations, and allowing it to detect shorter distances than normal
    • this seems unlikely, and would only be relevant if the bottom is very close to the sonar
  • the ship’s motion is temporarily solidifying a soft river bottom, so it more effectively reflects the sonar pulses
  • likely some other scenarios I haven’t thought of

Is the behaviour consistent? And have you tested the sonar in other environments, to see whether you’ve had similar issues?

3

Thank you for your prompt response to my technical inquiry.

Let me first provide details about our installation environment:

  1. Number of Units: 2 (same model, same location, on pontoons)
  2. Installation Location: River, depth between 30 to 60 meters
  3. Depth Checking Protocol: Register 1300

Both units have exhibited the same behavior: While the pontoons were slowly moved from the mooring area to the installation site over a distance of about 2 km, the sonar was continuously on, and the Confidence level was stable at 100%, indicating reliable depth measurements. However, upon reaching the installation site and once the pontoons were positioned at a fixed location, the Confidence level gradually dropped from 100% to 0%, and the depth values were no longer reliably observed.

Additional questions:

  1. What is the appropriate depth at which the sonar should be positioned? Currently, it is about 10 cm.
  2. Is it correct to use Register 1300 for depth measurement?

I look forward to your guidance and suggestions on these issues.

Best regards,

4

Hi @bskim -
If you’re running both Ping2 units at the same time in relatively close proximity to each other, this could lead to interference. You may need to trigger each sonar to pulse individually. It’s interesting that things seemed to work initially - how far apart are the pontoons? I would guess, as @EliotBR alluded to, that the system is more stable when underway then when stationary.

A 10cm depth should be sufficient, assuming bubbles from wave action aren’t getting below the sonar transducer.

Yes, the 1300 message is the correct one for depth measurements.