Author Topic: Helix 7 Mega side and down imaging in 30 + Ft  (Read 531 times)

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Offline davidgronskei

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Helix 7 Mega side and down imaging in 30 + Ft
« on: June 18, 2019, 01:57:42 PM »
Hey guys,

New to the forum so apologies if this isn't the right place to ask this. I'm having an odd issue with Mega Side and Down imaging. It works great up to about 30 ft deep where it will turn dark and basically unreadable. If I flip it over to the 455khz setting it will show normally again. Correct me if I'm wrong but I thought Mega was good to about 75ft deep and with an SI range of about 120ft on each side. I was not able to grab any screen shots but I will post them later if needed.

Thanks!


Offline rnvinc

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Re: Helix 7 Mega side and down imaging in 30 + Ft
« Reply #1 on: June 18, 2019, 09:25:36 PM »
Marketing specs are always "best case scenario"  ...

Your experience of limited range in the MEGA frequency is normal (G2 MEGA)  ... Higher frequency simply attenuates (absorbs into water) quicker than lower frequency  ...

MEGA + (G3N) marketing specs are expanding that range somewhat with higher power (and better processing)  ...

This is why the other options of 800kHz and 455kHz are still available - so you still have tools to reach farther (albeit with less detail)  ...

Sonar physics cannot be totally overcome :
Higher frequently has more detail with less range  ...
Lower frequency has more range with less detail  ...

Rickie

Offline davidgronskei

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Re: Helix 7 Mega side and down imaging in 30 + Ft
« Reply #2 on: June 19, 2019, 08:30:04 AM »
Thanks Rickie.


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