Traditional sonar vs CHIRP reading SI @ speed ?

[12poundbass]

4 minutes ago, RoLo said:

 

CHIRP is 'not' two dimensional sonar, Chirp is 'multi-frequency' sonar.

“HDI” (hybrid dual imaging) was the forerunner to Chirp, and HDI was two-dimensional sonar, but HDI is 'not' Chirp.

While Non-Chirp sonar uses a fixed bandwidth, Chirp sonar utilizes a multi-dimensional range      

 

WHY?

Different objects demonstrate different optimal reflective values, therefore by using a range of frequencies

you're able to optimize the return signal. That alone is what Chirp sonar is all about, there's no magic.

As a result of multiple frequencies, CHIRP units produce more detailed images than non-CHIRP units.

Low, Medium & High are settings WITHIN Chirp capability. The multi-frequency range of Low, Medium & High

varies from brand to brand, but the values stated below represent the mean frequency ranges:

 

 

“Low” Chirp:         ~60 to 35 kHz

“Medium Chirp:    ~120 to 60 kHz

“High Chirp”         ~230 to 140 kHz

 

Roger

 

 

A light bulb just went off in my head thanks!

[Wayne P.]

This is Humminbird's 2D CHIRP Sonar frequencies with their transducers and the adjustment highlighted for the high end of High:

 

 

The 455 kHz Imaging frequency CHIRP range is 420 kHz to 520 kHz

The 1200 kHz Imaging frequency CHIRP range is 1150 kHz to 1275 kHz

I don't have the 800 kHz Imaging range numbers yet.

 

 

[eddallen]

 

Roger can you post a pic of a three-dimensional CHIRP screen shot?  And one question for WayneP; When you effectively shorten or split the band by using, say, the middle 10, aren't you missing something you would normally see? Or does the firmware just apply filters to the lower and upper 10? I have not yet seen this. Would like to.

On ‎2‎/‎17‎/‎2017 at 5:51 PM, Wayne P. said:

This is Humminbird's 2D CHIRP Sonar frequencies with their transducers and the adjustment highlighted for the high end of High:

 

 

The 455 kHz Imaging frequency CHIRP range is 420 kHz to 520 kHz

The 1200 kHz Imaging frequency CHIRP range is 1150 kHz to 1275 kHz

I don't have the 800 kHz Imaging range numbers yet.

 

 

That's pretty kewl but I wonder IF something is missing from say 140 kHz? I'm just curious.

[Wayne P.]

No you don't miss anything by not using the whole frequency sweep except maybe some target separation. I don't use CHIRP, don't see any difference between single frequency and CHIRP in the depths I fish. Just CHIRP for testing.

 

Humminbirds don't have any frequencies in the 140 kHz range with their transducers. The ONIX has several other frequencies for AIRMAR transducers.

 

 

[eddallen]

Thanks Wayne

[LoweStinger]

Wayne is the man !!  Thank you for all your help in understanding the world of sonar, you are a wealth of knowledge that made my purchase much easier !  I was able to figure out exactly what I will need and not need and why.