Thread: Garmin images

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I'm learning also

Down scan is easy..

Side imaging is kicking our butt

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About time varied gain

Time varied gain (TVG) is signal compensation that removes transmission loss effects from echosounder data. Transmission loss is two-way and is due to acoustic beam spreading and absorption in the acoustic medium. Signal compensation is applied by the echosounder or by receiver electronics through analog or digital signal processing. The desired result is that targets of the same size produce echoes of the same size, regardless of target range.

The important part is the last sentence above ...meaning (in 2d) a 2lb fish at 10ft and a 2lb fish at 30ft create the same size target on the 2d display (adjusted by software - even tho the 2lb fish at 30ft has less echo because it was farther away) ...

Rickie

TY. I read similar data on a few places, caused as many questions as it answered for me. Appreciate your explanation and input. Was hoping you might come to the conversation. What is your position on using it? Or not. I know I am in less than 15 fow, usually have my sv on 40' range. Welcome your thoughts.

I cannot imagine why TVG has beneficial merit in shallow water situations (meaning I don't understand why the brands even input it in shallow water situations) ...

TVG was designed such that deep water targets (think ocean depths) were not painted as 1/4" long fish arcs while the same size target at 100ft we're painted as 1" long fish arcs ...

Now, what is not clear (even in my mind) is that the brands may be using the TVG technology (originally designed for deep water scenarios) in these shallow water scenarios for a result not even related to actual target echoes... But maybe as a filter of some kind for environmental anomalies ...

There are discussions in other forums describing the HB Surface Clutter setting being a sort of TVG technology ...

Rickie

I see a blob on the gps location. Needs fixin. Outside that, I mostly understand what is on the screens.

The best I did on side scan so far was when the walleye were spawning

I could go by a point and see them ,then stand up and spotlight to see for sure.

I have not used the blue color yet
In pics it looks best, but on the water I don't like it..

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I tried it with the TVG turned OFF yesterday. That didn't fly so well for me. Screen got very busy, not clear At all. Mine was originally on MED for whatever reason. Doubt I did it as I didn't know I owned it before this. Took it back to LOW. I need to ask do I need to make further adjustments now to Brightness and/or Contrast? I'll play with it, just wondering if there were suggestions as a starting point? Not discrediting the suggestions here, Todd D has also said that he sees little advantage for TVG being ON in freshwater, period. So, some knowledgeable folks are saying we don't need it. Steer me in the right direction for further set-up. Thanks

TVG is set to high on my 73sv in down and sideview.