[TG11] Axiom 9 with rv 100 - increasing clutter as I speed up

[Tom - Raymarine - Moderator]

Hello Westernport,

I'm sorry to say I can't see the attachments you mention, but it would be great to see any clear, high-resolution images you have of the sounder performance both at low and higher speeds.

There are three things which can affect the quality of the sounder image as you speed up. In order of how frequently we come across them:

1. Air bubbles across the face of the transducer: air blocks the ultrasonic sound very effectively and cause a big drop in the signal levels getting back to the transducer
2. Electrical noise from engine electrical systems, picked up through transducer or power cabling
3. Acoustic noise (the hull resonating with engine vibration at a harmonic of the transducer operating frequency.)

Air across the face of the transducer is the one everyone knows about, but the other two are also surprisingly common. Any one of these can lead to an increase in clutter as you speed up, even air, because if the signal level from the bottom return drops, the sounder will increase the auto Gain level in order to try to keep the bottom echo visible.

The way to find out whether the problem is noise or aeration is to look what happens with the sounder image when in all Manual Gain/Intensity/Surface Filter. Using manual settings means that you can objectively see what changes as you speed up.
If you can post clear, high-res images or screenshots of your Axiom's screen at a range of speeds from idle to normal cruise, with Speed Over Ground displayed in a data overlay or the side data bar, withe the sounder in:
65% Gain
15% Intensity
0% Surface Filter
then we can see what's going on. The attached document gives some more detail.

Regards,
Tom