[TG] [TG11] Element 9 HV digital depth loss

[Tom - Raymarine - Moderator]

Hi Olygreen,

All of our sounders adjust their ping rate to the current range scale. This is because as a user you generally want the highest number of pings per second possible for greatest clarity, but the sounder needs to leave sufficient time between each ping for the sound energy to travel down and back up. In deeper water this takes longer of course, so as you go deeper the ping rate and hence scroll rate has to reduce. In order to prevent picking up echoes from previous pings (so-called first-echo interference) and avoid wasting CPU time processing sounder data that won't be displayed, the sounders don't attempt to process any echoes below the current range scale. All this means that if you're in 600' of water but range shallower than this, the system can no longer receive and process the bottom echo and give you a depth number.

There are a couple of workarounds to allow you to look near the surface and also track the bottom at the same time, each with their own advantages and disadvantages:

1. As I see that you are in the video, use Zoom to look at the near-surface band for pelagic fish and track the bottom in the un-zoomed bar with Auto Range. This is easy, but has the disadvantage that you lose resolution - as you have seen - in the near-surface view because the system sets the ping 'pulse-width' and gain to something suitable for the full range, instead of using a narrow, high-detail pulsewidth and low gain as would be normal if the range were set shallow. This will have a slower ping-rate than you would get using a manual range looking just near the surface, but I think that this is the best compromise on the Element hardware.
2. Use two different sounder channels, one set to a shallow manual range and one set to track the bottom. On our top-of-the-line CP570 sounder this would be the recommended solution, and in fact this is the key differentiator of the CP570, that it can do this still with fast scrolling. On all of our other sounders, including Element, this will result in even slower scrolling as the system will alternate pings between the two channels, with the combined ping-rate set to that of the deeper range. This is because there's one set of receive-transmit hardware within all sounders except the CP570, which is either working on one channel or the other but not both together. The only way to do this with the much simpler Element is to set up a split-screen dual-fishfinder page, and use auto-range tracking the bottom with the Sonar channel on one side and manual range looking at the top part of the water column with the DownVision channel on the other side. This isn't ideal, but it's the only other option without going up to an Axiom display.
   

In short, what you're seeing is normal behaviour for most simpler sounders when set up as you have yours set. It's specifically to allow true dual range with fast scrolling on the shallow range that we have the CP570 in our range, but that of course comes at a much higher cost.

Regards,
Tom