Thread: Bow Mount sonar unit- SI, DI, 2d, or something else?

You guys are using 2 different calculations to get to a moniker "terminology" called ppi that doesn't even mean the same depending on which calculation you're using ...

This is from the wiki ...


This calculation to get the moniker "terminology" ppi (used in monitor measurements) is not the same as the calculation to get "total pixels in a 1 square of screen space" that Bob is calculating - but both using the same moniker terminology of "ppi" ...

Both calculations are correct - but the term used as "ppi" in each calculation does not mean the same thing ...

Regardless of which calculation used - or which term used to express the pixel density in a monitor/screen = the HELIX 10 should give better images than the HELIX 9 ...because each calculation sums higher with HELIX 10 ...

Rickie

Originally Posted by BobB

Since the Helix 10 has 614,400 total pixels.....

I appreciate you answering, forced me to do the research and the math.

I did the same exercise with my 899C HD SI unit. 133 ppi. Interesting, the 899 has more ppi than the Helix 9. However everyone claims the Helix units have better image quality, and based on my Presleys store visits I would agree. I am still digging, both unit are using TFT (thin film transistor) LED screens, see below for technical explanation.

Thin Film Transistor Displays
http://techin.oureverydaylife.com/tf...lay-37558.html
TFTs are a type of active matrix display that controls individual pixel updates several times per second on the screen to update the image relative to the content source. These displays are built from a thin layer of transistors located on the back of the screen that handles screen animation. The display receives information from a computer or video source and updates the screen contents row-by-row so many times per second that it looks like the entire screen is updating content in real-time as opposed to being a collection of frames. A more advanced type of TFT technology called In-Plane-Switching improves the screen viewing angles.

This ties in with Rickies comments. Should give a better image because it has more pixels, regardless of the math used. How/why does the Helix 9 have a better screen image than the 899 when the Helix unit has less ppi and both units are using TFT screens?

The brighter 1500 nit screen of the HELIX makes the images "perceive" as better ...

We can't compare apples to apples of HELIX vs previous core units because the "nit" is different ...and the way the human eye perceives this "brighter screen" factor ...
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Simply raising the brightness level on your smart phone makes the images on the phone screen "look" better ...

Rickie

Originally Posted by rnvinc

The brighter 1500 nit screen of the HELIX makes the images "perceive" as better ...

We can't compare apples to apples of HELIX vs previous core units because the "nit" is different ...and the way the human eye perceives this "brighter screen" factor ...
----

Simply raising the brightness level on your smart phone makes the images on the phone screen "look" better ...

Rickie

What is NIT? - Never mind, I goggled it.
No idea about smart phones. I don't have one and never plan on getting one.
If the only difference is a brighter screen why bother? I can see my 899 screen just fine in all light conditions. I was hoping the video processing was better or some other technical aspect was enhanced to give a better image.

I have had an 897 2d, 597 di, 859 di, and helix 9 and the 2d is much easier to read and more clear on my helix. I dont know what to attribute this to as far as hardware but the returns are much more distinct and with less clutter. And not just from a larger screen the same goes for watching 2d in the triple view. Sometimes i wonder if the transom di ducer i have on my trolling motor is worn out but i really cant say.

Originally Posted by OrangeAgent

I have had an 897 2d, 597 di, 859 di, and helix 9 and the 2d is much easier to read and more clear on my helix. I dont know what to attribute this to as far as hardware but the returns are much more distinct and with less clutter. And not just from a larger screen the same goes for watching 2d in the triple view. Sometimes i wonder if the transom di ducer i have on my trolling motor is worn out but i really cant say.

The 2d sonar beams on di units are 200/455 khz with 20/16 degree cones. A regular 2d sonar is 83/200 khz and 60/20 degree cones so you see much more of the bottom. DI in the bow only shows what is now under the boat...if you want to see what's coming and what's under a spider rig right now then regular sonar will be better. The cone on DI units using 2d sonar is likely less than 3 feet at 10 ft of depth while on a 2d unit it would be 10 feet.

Originally Posted by JohnK9027

The 2d sonar beams on di units are 200/455 khz with 20/16 degree cones. A regular 2d sonar is 83/200 khz and 60/20 degree cones so you see much more of the bottom. DI in the bow only shows what is now under the boat...if you want to see what's coming and what's under a spider rig right now then regular sonar will be better. The cone on DI units using 2d sonar is likely less than 3 feet at 10 ft of depth while on a 2d unit it would be 10 feet.

How does that compare to a 360?

I have read the entire thread again, great info.


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With your snow removal money, get a 360!


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