Humminbird Side Imaging Forums

General => General Discussion => Topic started by: nicko_cairns on February 07, 2014, 02:23:17 AM

Title: A *cough* Lowrance question.
Post by: nicko_cairns on February 07, 2014, 02:23:17 AM

Hi guys,

I have a question for you that I hope at least one of you will be able to answer.

A guy I know has a Lowrance and his opinion is that there is a gap in his sidescan, i.e. his transducer cone angles don't meet up, based on this style of image:

http://www.panbo.com/assets_c/2009/07/Lowrance_LSS-1_beam_angles_cPanbo-thumb-465x249-705.jpg (http://www.panbo.com/assets_c/2009/07/Lowrance_LSS-1_beam_angles_cPanbo-thumb-465x249-705.jpg)

He thinks that if downscan is turned off the middle part of his return just isn't there.

My thoughts are that the transducer works more like this:

http://i38.tinypic.com/2tfu1.jpg (http://i38.tinypic.com/2tfu1.jpg)

So downscan is just that middle part and if it's off then sidescan continues to join in the middle.

This is all based on some pretty poor explanation images by Lowrance really, or a lack of images. Not stirring the pot but a better explanation somewhere/anywhere would be nice.

I can't blame him for being confused by the pictures, hell I could be wrong but I'm going by pictures of the lss-1 transducer too, and not even official pictures that I know of.

Help me Obi-Wan and if you're busy send R Gecy  ;)

Title: Re: A *cough* Lowrance question.
Post by: rnvinc on February 07, 2014, 08:36:53 AM

That 1st Lowrance drawing is the patent depictions for the Lowrance SideScan patent application...
___________________________________

The sound pulse of the individual beams (any brand)...do not have "sharp" edges that just "cease to exist" after the advertised beam angle...

A sound pulse is strongest at it's very center axis line...and continuously decreases as it moves out from the main axis..

This "ever-decreasing" intensity of the sound pulse continues moving outward until 0db (absolute silence)...

The "measured beam angle" is just where the specific brand measures this "ever-decreasing" sound pulse...

Here is the depiction of the right SI beam sound pulse (in its entirety from beginning to 0db absolute silence...)

(The black line 30° from horizontal is the right SI sound pulse "Main Axis"...)

Visualizing a mirrored matching left SI beam sound pulse to the left in the depiction would definetly show the left and right SI sound pulses overlapping at the bottom...in either/both of the 455kHz or the 800kHz sound pulse...

(http://i477.photobucket.com/albums/rr134/rnvinc/HB/492EB491-D36D-46CE-9080-D6E601C82DB0_zpshmz3szda.jpg) (http://s477.photobucket.com/user/rnvinc/media/HB/492EB491-D36D-46CE-9080-D6E601C82DB0_zpshmz3szda.jpg.html)

Rickie

Title: Re: A *cough* Lowrance question.
Post by: nicko_cairns on February 07, 2014, 08:52:04 AM

Thanks very much Rickie, that's excellent info.