CHIRP Frequency Selection

[Jager]

I’ve narrowed down my choice of a Chartplotter/sonar to the GARMIN GPSMap 942xs to be used solely for trolling for salmon on Lake Ontario. Looking for advice as to the best Chirp frequency range (Low, Medium, High) for this purpose.

Thanks for any help!

Mike

[holy mackerel]

I have the 93 Garmin and hated the transducer it came with. Bought a 50/ 200 and it seems to be working good. This unit replaced a Lowrance LCX 37C.

[Never Ends]

I was a sonar tech on submarines for 9 years... the best frq depends on what you want to do. Low frq will cover a greater area due to the cone angle of the transmission while a higher frq covers a much smaller area. However, a higher frq will pick up more in that concentrated area than low frq. Think of a low powered flood light with bad eye sight as low frq and a high powered, alpha male, mag light with eagle vision in a concentrated setting as high frq.

[Chas0218]

Nice unit but I would make sure you can actually choose the CHIRP frequencies. I have the A68 by raymarine love it but can not change the CHIRP freq. unless I buy a standalone CHIRP Module. The module alone is the price of your unit so I doubt the unit you are looking at will allow you to change the freq. I don't know for certain so take it with a grain of salt. I would look through the entire owners manual even call Garmin to verify. My unit has CHIRP downvision built into it but I am not able to tweak it other than the return strength and similar settings. If I were to buy the module I could adjust the frequencies and all sorts of other things.

[Sk8man]

A consideration if you are able to adjust is if you are running other items that use transducers like the Fiahawk Xseries. The 70 khz frequency of the Fishawk may reside in that low or medium range setting and conflict.

[Chas0218]

The freq. for CHIRP is around 350kHz so if he runs Chirp it shouldn't interfere with any traditional sonar freq.

Edited May 22, 2018 by Chas0218

[Traveling Circus]

Lots of discussion here.

https://www.thehulltruth.com/marine-electronics-forum/834854-garmin-942-xs.html

 

If you have questions, contact semperfifishing........ I recently purchased an echomap chirp plus 93sv and Gil recommended a GT52HW for my application. I purchased the unit and ducer through him with good results. 

 

Edited May 22, 2018 by Traveling Circus

[Sk8man]

Chas - CHIRP isn't a single freqency. It refers to a RANGE of frequencies. May differ according to different manufacturers and transducers but there are basically three sometimes separate ranges that can be selected on SOME finders: Low, Medium, and High. The 350 you refer to would probably fit in the medium range.

[shawn393]

5 minutes ago, Sk8man said:

Chas - CHIRP isn't a single freqency. It refers to a RANGE of frequencies. May differ according to different manufacturers and transducers but there are basically three sometimes separate ranges that can be selected on SOME finders: Low, Medium, and High. The 350 you refer to would probably fit in the medium range.

yes chirp can be any frequency.i think he is talking about about the down vision frequency on his garmin. my medium chirp ducer operates at 95-155 khs

[Chas0218]

On 5/22/2018 at 4:02 PM, Sk8man said:

Chas - CHIRP isn't a single freqency. It refers to a RANGE of frequencies. May differ according to different manufacturers and transducers but there are basically three sometimes separate ranges that can be selected on SOME finders: Low, Medium, and High. The 350 you refer to would probably fit in the medium range.

Yes that is correct but it is much higher than the traditional sonar units. Mine is a fixed range where the OP was referencing changing the ranges. I know some units allow you to change the operating ranges to give better clarity at different depths but a lot of the FF units that have CHIRP built in are generally low and medium range and automatically adjust the freq range based on depth. I can say Raymarine units need a separate module to or the high end FF allow changing the range. Anything around $1000 is going to be hit or miss dependent on brand.

 

My Raymarine mid band is 75-130 and high is up to 250 (sorry for the typo above). My current setup didn't interfere with my older Humminbird that ran a 200/83 ducer, side by side they both had a clear screen. I will say that after getting the CHIRP there was no need for the other unit.

Edited May 24, 2018 by Chas0218

[Sk8man]

Good points. I think some high end units may even go up to 800 or more in high range.

[Chas0218]

I will add CHIRP on my unit is only good to 600 fow so I would guess it does not have the high band. The raymarine high band is good to 10,000 fow supposedly. For me that wasn't necessary so I went with the 600'.

 

I have fished out to 200 fow and couldn't believe the detail the CHIRP shows vs traditional sonar. It almost makes me mad seeing all the fish under the boat and not catching any.

[jigstick]

On 5/22/2018 at 6:41 AM, holy mackerel said:

I have the 93 Garmin and hated the transducer it came with. Bought a 50/ 200 and it seems to be working good. This unit replaced a Lowrance LCX 37C.

 

Thats funny. My Garmin transducer can do 50/200, as well as CHIRP. Best transducer I’ve had. Better than my Airmar by a long shot