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Thanks Bob.

Well, I guess that fixes that. Doesn't matter about the Q now.

regards

I just bought an older 360 imagining unit on 455khz.

Can anybody tell me anything about the Q of the transducer used in that model?

I want to feed 455 khz CHIRP into it as its a choice on my...

I'll bet that those fish shadows are of barramundi (lates calcarifer) and images from Australia. Broad deep vertical bodies, thin cross-section profile, flat bottom, narrow pointy heads and powerful...

I certainly don't know more than their engineers. I'm simply trying to find out why they did this so I can learn. There may be a perfectly good reason considering that the only 2 manufacturers with...

Here's a link to a site that outlines (in diagram form) Q of a bandpass filter (which is what your transducer is in technical terms). Ignore the notch filter on the right.

You'll see the -3db...

The parameters of the transducer are set at manufacture. They don't change. The transducer passes certain frequencies with the cut-off points being at -3db either side of the centre pass frequency...

Fellas the Q of a transducer refers to the pass bandwidth.

Its calculated by dividing the centre frequency by the "useable" bandwidth. The "useable" bandwidth is the width either side of the...

Thanks Wayne. Yep, 1125 - 1300 is what their marketing says.
. That gives a target separation of 4.6mm. Yet their marketing spec says 65mm which is 1/15 of that.

As a matter of fact,...

Thanks for the reply.

5118 is the speed of ultrasonic in salt water in ft per second.

I used ft per sec as that's the nomenclature used in the US.

It translates to 1560 metres/sec.

So if...

Hello all

I'm having a bit of trouble coming to grips with the new mega imaging initiatives by H/Bird and Garmin.

I see from the Humminbird Users Manual that the CHIRP function can be switched...

Hi

Target resolution (ability to see smaller target sizes)= 5118/freq = 5118 / 1115 khz = less than 2 mm. The unit can see targets just under 2 mm in size.

However, CHIRP range resolution (...

Garmin appear to have reduced the range resolution (target separation) ability of the GCV20 from what its capable of.

Using 1115 kHz gives very small target resolution down to < 2mm. However, if...