Humminbird Side Imaging Forums

Side Imaging Forums => 798c SI => Topic started by: JoeH on April 06, 2014, 08:56:29 AM

Title: Interference from 83 kHz beam
Post by: JoeH on April 06, 2014, 08:56:29 AM

I'd appreciate any feedback about a possible cause for interference between 0 and 2.5 ft on the sonar view, when the 83 kHz beam is on. It is unaffected by the outboard position and goes away when I switch to 200 kHz only. The down- and side-imaging views look fine. Here is a snapshot and picture of the installed transducer. Thanks!

Details

Title: Re: Interference from 83 kHz beam
Post by: sfw1960 on April 06, 2014, 10:47:55 AM

Try some shots in a bit deeper water.
You are shooting 4000 watts under an aluminum reflective surface!
When you have that much power pinging up and down between bottom & surface that many times - strange things can happen...
At 10' you can easily see the second bottom echo forming.
83 KHz is generally used in deeper water FWIW.

Title: Re: Interference from 83 kHz beam
Post by: rnvinc on April 07, 2014, 11:59:10 AM

You can turn the "Surface Clutter" setting down under the Sonar tab...(this setting is basically a filter)...

A lower setting is telling the unit to display "less" surface clutter...

Rickie

Title: Re: Interference from 83 kHz beam
Post by: JoeH on April 07, 2014, 01:13:15 PM

Quote from: sfw1960 on April 06, 2014, 10:47:55 AM

Try some shots in a bit deeper water.
You are shooting 4000 watts under an aluminum reflective surface!
When you have that much power pinging up and down between bottom & surface that many times - strange things can happen...
At 10' you can easily see the second bottom echo forming.
83 KHz is generally used in deeper water FWIW.

The band of interference is the same (2.5 ft) whether water is shallow or deep. I chose a shallow example to make it easier to see. Thanks for the tip about deeper water use of 83 kHz.

Title: Re: Interference from 83 kHz beam
Post by: Humminbird_Greg on April 07, 2014, 03:18:37 PM

The lower the sonar frequency the worse it reflects off of surface clutter (50kHz is even worse!). Higher frequencies work better when it comes to surface clutter.