Can we talk a bit about "down scan" and CHIRP?

S

Sunbeam

Active member
thataway":1kiqdnoy said:
Also got a chance to try out the Garmin 1040xs and 740S. ...The Down scan/chirp is great!
Click to expand...

Just read this in another thread and it's something I have been wondering about. Figured maybe I'm not the only one, so am starting a new thread.

Background: My 22 came to me with outdated electronics, so the plan was always to fit her with new/additional stuff. Last year I decided just to use what I had, and plus none of the new units felt "just right" to me. Now I'm excited about the Raymarine A9, so I think it may be time now. Last year I would have made a point to go all Garmin, but now I'm thinking to go Raymarine.

Anyway, that's getting off the topic but is why these things are on my mind. Question I have is .... can someone tell me more about Down scan and CHIRP, but in "real world" terms (vs. looking at the whiz-bang website descriptions). I know I don't need it, and I'm most likely not going to get it (already having sticker shock!), but.... it does look as though it's a different chartplotter model for that or the "usual" depth sounder (for example, A98 vs. A97).

At any rate, me being me, I want to know what I'm "not getting," presuming I just stick with the usual sounder. I don't fish (particularly), so mostly curious about what it does or would do for the non-fishing boater. Would it just be a "gee whiz" thing (not that there is anything wrong with that :D :D), or....?

I am a diver, although I've been inactive for the last few years. Not sure if I would ever dive from the 22 in any case.

Thanks!
 
I just installed a new Furuno DFF1-UHD sounder and Airmar B175HW on my Tomcat. Haven't really tested it but the resolution is great. Furuno has Bottom Discrimination (which would be suitable for cruisers) and Accu-fish which is more about fishing.

Your sounder needs to be Chirp compatible. Furuno doesn't have the software for the sounder to recognize the transducer but they are ways to make it work in setup.
 
There has been some discussion in several other threads recently:
http://www.c-brats.com/viewtopic.php?t=20917
And the thread on DragonFly:
http://www.c-brats.com/viewtopic.php?t=21281

The Hull Truth series of posts that Chromer noted are now 19 pages and found at:

http://www.thehulltruth.com/marine-elec ... ained.html

What you get with the basic chart plotter with included transducer is


cf-lg.jpg

This photo shows the basic down scan image you will see. There is some debate about if CHIRP is actually utilized in the basic image. From what I saw today, with a 740S (the discontinued model) and the 1040xs is that the bottom scan and fish were better images in the 1040xs, discounting the size of the image.

This image shows the transducers side by side--the longer transducer is the down scan for the 1040xs, the smaller, inboard is the standard Garmin 740S transducer:

Transom_C_Dory.jpg

If you want to get the full potential of the Garmin xs and want to go with full CHIRP capability, is you will have to buy the spread spectrum transducer starting at $299 for a 95-155 kHz 300 watt transducer and if you want to get the full 1000 watts then a dual frequency transducer for about $1400 or more.

Another option is the GCV10 which includes a side scan/chirp transducer (I believe)--actually only about $300 more if in a package with the 1040xs, or $600 purchased alone.

Most of the major manufactures are now offering the CHRIP and downscan basics in the middle of the line, and some lower line units. Garmin has the echoMap series, which for $100 over the base price, has the down view transducer.

Why down view--we do fish, and it certainly shows structure much better than the A scan in a graphic way. It also allows me to see what I am dealing with in our bayous which are filled with structure--is a a log, a school of bait fish, or brush?

If you want Radar along with the sonar, then you end up with the sx series.

I had originally wanted just the 740S--but after looking at the size of the radar screen when I had chart and sonar, it was just not as large as I wanted. So I went with the 1040xs--and it gives the added capability of the full/ or split screen Radar--larger than the horizontal format of the 740, and still a good sonar picture. I am keeping the 740 mostly for the chart plotting. The new 1040xs also includes the US coastal and Lake Vu HD charts built in. Many manufactures units now include the 10hz GPS/GLONASS GPS--the 10x update per second makes for radar overlay without a heading sensor when underway, even at a low speed. (not when standing still).

Some of the other brands may be cheaper or have other features you prefer, so it is worth looking at all of them.
 
Sunbeam":3arsyzlw said:
thataway":3arsyzlw said:
Also got a chance to try out the Garmin 1040xs and 740S. ...The Down scan/chirp is great!
Click to expand...

Just read this in another thread and it's something I have been wondering about. Figured maybe I'm not the only one, so am starting a new thread.

Background: My 22 came to me with outdated electronics, so the plan was always to fit her with new/additional stuff. Last year I decided just to use what I had, and plus none of the new units felt "just right" to me. Now I'm excited about the Raymarine A9, so I think it may be time now. Last year I would have made a point to go all Garmin, but now I'm thinking to go Raymarine.

Anyway, that's getting off the topic but is why these things are on my mind. Question I have is .... can someone tell me more about Down scan and CHIRP, but in "real world" terms (vs. looking at the whiz-bang website descriptions). I know I don't need it, and I'm most likely not going to get it (already having sticker shock!), but.... it does look as though it's a different chartplotter model for that or the "usual" depth sounder (for example, A98 vs. A97).

At any rate, me being me, I want to know what I'm "not getting," presuming I just stick with the usual sounder. I don't fish (particularly), so mostly curious about what it does or would do for the non-fishing boater. Would it just be a "gee whiz" thing (not that there is anything wrong with that :D :D), or....?

I am a diver, although I've been inactive for the last few years. Not sure if I would ever dive from the 22 in any case.

Thanks!
Click to expand...

Let's see if I can shed some light on this for you.
The typical downscan SONARs are higher frequency, 455/800kHz vs 50/200kHz. What you gain by increasing the frequency is resolution or detail. This is where you get those 'picture quality' screen shots. What you are giving up by increasing frequency is range or in this case depth. Generally, the higher the frequency the greater the loss due to absorption. The more loss a signal suffers the less signal excess you have available at the receiver. Reliable depths for 455/800kHz are 210'/120' respectively.

CHIRP: CHIRP is about target seperation or target resolution. Typical Continuous Wave (CW) sounders have horrible target resolution. Anything within about 1.5' from one another shows up as a big blob on the sounder screen. This is why when you see a blob on the bottom the question almost always gets asked, 'Is that a rock or a school of fish'?
Enter Broadband (BB) SONARs. BB SONARs are able to give you more seperation than CW sounders by having a bandwidth of frequency to work with. This where we start talking about center frequency. The amount of bandwidth will determine the amount of seperation you able to get between objects. Example: We fish for winter blackmouth here. They are very bottom oriented and to see them, you need to be able to distinguish the salmon from the bottom. With a BB sounder you can seperate the fish from the bottom as long as they are at least 6" off the bottom.
CHIRP takes this an incredible step further. By sweeping through a wide frequency range AND using a match filter, you are able to see targets that are within 1/3 of an inch (yes, I said .3") of each other. This translates to not only being able to see a school of targetable fish but being able to count the number of fish within the school. Commercially this is a big plus. Recreationally, I think this is a nice/fun to have feature but the prices are not quite there yet to be affordable by the average non-sponsored guy. The good news, the prices are dropping quick. As more manufacturers compete for market shares, the recreational guys will benefit.

Hopefully this helps out.

Steve
Sounder Solutions
soundersolutionswa.com
 
Thanks Steve. I am a techy kinda guy in general but still found myself going old school (very rare) with a purchase of Garmin 740 radar/chartplotter combo last week because we just don't have a good reason for these newer sonar types. I compared the old to new and it just didn't add up for us. We don't fish seriously and it would just be a quiet form of added entertainment to see that well under water. I would likely just end up hitting more wood while staring at the screen. I will wait for the cost to come down on smaller units with more built-in integration, and maybe just add an advanced "sounder" display in the future to what we already have mounted.

Greg
 
I suspect that in the next year or so, you will see nothing but these type of units with down view. Going to Garmin current line up: you see the only difference on the surface between the least expensive (echoMap 50dv) and the most expensive is that the more expensive have "chirp" added to the DV. The basic echo map 50 has down view. Only the discontinued series don't.
 
Just bought a Garmin Echo 551dv for a new kayak that i have been rigging it was $275. I will know after this weekend how good it works. In order to get the down vue on the C-dory I would have to change my MFD to get compatible. Then a new black box and transducer. So right now I am thinking about it. I could just buy a 551dv and not try to integrate it with the system. I guess if you want to keep the cost down then get a small fish finder and a small GPS and your good to go. It might be a while before I can do the full blow Chirp stuff.
 
Thanks everyone. I'm embarrassed to admit that I didn't even realize down scan and CHIRP were two different things :oops: I just knew they were new/amazing depth sounder tech.

I'm thinking I'm going to go with the Raymarine A9 MFD, and if I understand it correctly you (have to) choose whether you are going to get "old school" depth sounder or "new tech" one when you buy the main unit (old school sounder MFD is the A97; new tech sounder MFD is the A98). Then of course you have to buy the transducer too. If it could all be added later, I'm pretty sure I wouldn't get it now (just because, wow, the MFD, radar, steering, etc. are adding up); but I kind of hate to lock myself out if they become "the new normal," say, next year.

I guess I need to find out for sure if the A97 locks one out of the new tech sounders "permanently." I may be wrong in thinking that.

I will also read up on these things to understand them better - thanks for the links. I admit I was being a bit lazy but not reading up on it on The Hull Truth; but then too, I wanted a "nutshell description as it applies to a casual/cruising C-Dory person," vs. a really in-depth, fishing addict discussion :D

Welcome to C-Brats, Sounder Steve, and thanks for the summary.
 
I have the new RayMarine Dragonfly 7 inch with down scan and CHIRP, a lot of bang for the buck. Nice thing is I can run my 1KW Airmar through my Garmin and Dragonfly at the same time because they use different kHz. Been really happy with the dragonfly, only negative for me is the bracket is wobbly; once I got it how I liked it shot some hot glue in a couple of spots.
 
breausaw":184pv0s5 said:
I have the new RayMarine Dragonfly 7 inch with down scan and CHIRP, a lot of bang for the buck. Nice thing is I can run my 1KW Airmar through my Garmin and Dragonfly at the same time because they use different kHz. Been really happy with the dragonfly, only negative for me is the bracket is wobbly; once I got it how I liked it shot some hot glue in a couple of spots.
Click to expand...

Jay, how do you run both the Garmin and RayMarine sounder thru the same transducer at the same time? I was under the impression that sounders are "tuned" for specific frequencies. Do you get down scan & CHIRP thru the 1 KW Airmar transducer?

Thanks
 
thataway":28uskz28 said:
breausaw":28uskz28 said:
I have the new RayMarine Dragonfly 7 inch with down scan and CHIRP, a lot of bang for the buck. Nice thing is I can run my 1KW Airmar through my Garmin and Dragonfly at the same time because they use different kHz. Been really happy with the dragonfly, only negative for me is the bracket is wobbly; once I got it how I liked it shot some hot glue in a couple of spots.
Click to expand...

Jay, how do you run both the Garmin and RayMarine sounder thru the same transducer at the same time? I was under the impression that sounders are "tuned" for specific frequencies. Do you get down scan & CHIRP thru the 1 KW Airmar transducer?

Thanks
Click to expand...

Each has their own transducer but use different frequencies so you can run them at the same time.
 
Garmin just released an update to their newer units that adds enough features that I am cancelling my order for an older unit and I will just get the 741xs. The support for multiple android devices seals the deal for us as it will save me from adding another fishfinder to the cockpit for Cindie. The support previously for Apple devices did not float our boat one bit. We use them for work every day and they are not our cup of tea.

GPSMAP 741/741xs software version 3.60
as of June 26, 2014

Changes made from version 3.50 to 3.60:
Added support for sharing internal sonar across the Garmin Marine Network.
Added ability to select the sonar source for traditional sonar, DownVü, and SideVü if multiple sources are available.
Added support for synchronized scroll rates between traditional sonar, DownVü, and SideVü. Includes improvements to scroll rates and new and improved Auto scroll rate.
Added customization options for sonar data overlays.
Added the ability to hide individual data fields on overlays.
Added support for Garmin Helm on Android devices. Note: This requires version 1.20 of the Garmin Helm app for compatibility.
Added support for NMEA2000 and NMEA0183 GPS sensors.
Improved sailing (wind) gauge page.
Added support for hiding the menu bar while on full screen functions.
Improved the user experience for marking waypoints on paused sonar.
Fixed a shutdown when powering off device while adjusting media volume.
Fixed an issue where water speed wheels wouldn't function with DownVü transducers.
Fixed a shutdown on the engine page when the system language is Russian.
Fixed an issue with tides and currents dates being incorrect.
Other performance improvements and bug fixes.

http://garmin.blogs.com/my_weblog/2014/ ... 7OIMvlSb_8
 
Back
Top