Humminbird Side Imaging Forums

General => General Discussion => Topic started by: Kimi on February 28, 2011, 10:48:44 AM

Title: The width of the horizontal beam
Post by: Kimi on February 28, 2011, 10:48:44 AM

Hi folks! Just wonder how wide/narrow the horizontal SI-beam is. And (is there a) difference betwean 455 and 800 kHz.

Kimi..

Title: Re: The width of the horizontal beam
Post by: Humminbird_Greg on February 28, 2011, 03:01:19 PM

Kimi,
Are you meaning how wide the beams are left-to-right or front-to-back?

Left—right they are:
455kHz  86 degrees
800kHz  55 degrees

Front-to-back they are both 0.5 to 1.5 degrees.  I’m not sure what the exact measurement is but they are pretty thin.

Title: Re: The width of the horizontal beam
Post by: Kimi on February 28, 2011, 03:23:06 PM

Thanks !

Those numbers are close enough!

Kimi :)

Title: Re: The width of the horizontal beam
Post by: Rickard on March 01, 2011, 02:52:05 PM

Kimi,

Edgetech has a good text on beam widths here: http://www.edgetech.com/docs/app_note_beamwidth.pdf (http://www.edgetech.com/docs/app_note_beamwidth.pdf)

If the approximate formula is applied to the HDSI transducer the result is 1.5 degrees at 455 kHz and 0.9 degrees at 800 kHz. As Edgetech explains, this is the one-way -3 dB measure. Actually, the practical widths are even narrower because the beam is further slimmed when the transducer receives the echo. This two-way width is 1.1 degrees at 455 kHz and 0.6 degrees at 800 kHz.

Rickard

Title: Re: The width of the horizontal beam
Post by: Kimi on March 01, 2011, 03:05:47 PM

Thanks Rickhard!

Great information

Kimi... :D