Koden & Simrad 4G Radar at same time?

[HenryD]

It looks like I am back to the research mode. The local Simrad installer advised me that the last two ship dates were missed and now Simrad is delaying the shipping until some time in June. I want the broadband radar but if Simrad can't ship their product, I might be moving over to Garmin.

 

[twistedtree]

What product is delayed? NSS EVO? I ordered and received an NSS7 EVO, but I think that was the first to ship of the family.

 

[Wxx3]

What I'm finding very interesting is more than e technology, it's how others use their radar.

I think my radar will go down to .75nm as its lowest setting but I'm not sure.

I run ours at 3nm as the lowest I've thought of needing for our area.

Typically I run it as 6 or 12 nm which seems to work great.

I suppose in a dense fog, in a very crowded narrow seaway you might need the really short ranges but 1/8 mile is what 400 some odd feet?

That's really tight!

Thanks Kevin and Oliver for a good discussion.

I had actually assumed that pulsed radar would do better at all ranges. That seems incorrect now. Also, while i occasionally have my radar at 3nm range, even hen I'm on the ocean I seldom have it further since I can avoid easily anything that gets within that range and when they do, I decrease the range.

But in fog or at night, I like it 1/2 mile at most.

 

[cappy208]

Reading this reminds me of the completely awful tech support, dumping product support, eliminating repairs and parts availability from Simrad.


What was I thinking, contemplating a purchase from them?

The company I work for had invested in around 32 15" or 17" Simrad Chart plotters, later upgraded to MaxC plotters, LCD radar screens and some flat panel displays with 3 to 6' open arrays. 20 Autopilots, around a dozen gps heading sensors, and joysticks. This was in the vicinity of around a half million dollars in sales!

One by one they have all died, or been junked. It is true Simrad abandons products after the production run is finished.

I can't believe that they haven't cleaned up their act. Denton Md.... are you listening? Thanks for the trip down memory lane. (bad memories they are!)

Athough, in their defense, the autopilots are excellent both in performance and reliability. The radars and plotters are junk though.

 

[River Cruiser]

I have Si-Tex 5' open array that I've had for 2 years. Have not been out at night, in fog or rain, I've only used it in good conditions to become comfortable with trusting it for the time I get caught out in adverse conditions. The one thing I've noticed is that channel markers will show up in front of till I'am about 200' away but when I pass them they'll show up around 50' beside the boat. If I get a mount with a forward tilt of a few degrees would this help on targets showing up closer to the boat? I'am comfortable and happy with it's operation now but a target showing up in front of me till I get closer would help if in a small harbor or marina in the fog.

 

[AKDoug]

No, changing the angle will not remove the dead spot close in. Military vessels use a combination or radar arrays to cover all distances, only the broad band radar will work well close in. Broad band radar installations require a mounting position as low as possible without obstructions to have good close in performance, or they will "overlook" targets close in. I have broad band G3 only on board, pretty much good only close in but what you need to find an anchorage in dark, fog, and rain.

My opinions are based on my military service as an Operations Specialist (surface radar operator), and my own broad band Simrad G3 unit. To do it right, you really need both.

 

[River Cruiser]

Thank you.

 

[Ted]

Yes. Look at the specs for the vertical beam angle, then visualize it projecting
directly off the face of your antenna.
The radar will "see" only what's in the beam. If the bottom of the beam is too high
you will "miss" objects in close.
Tilt (shim) the unit to angle lower forward. Don"t forget to allow for running trim
(bow rise at cruise).
Tried and tested, it works.
Ted

 

[cappy208]

The phenomenon you are describing is able to be adjusted to (almost) eliminate the 'warp' in the center. It has been years. But IIRC it is 'Main Bang Suppression' adjustment.

When you go out, try to find a long flat object. jetty, sea wall or container ship. Travel parallel close to ( maybe 200' off) and see if the 'warp' follows you along.

Out of curiosity, how high is your scanner off the water? Is this on Northern Lights? Is it any different up on plane versus when barely moving? As previously suggested, A large change in trim may be the issue also.

 

[River Cruiser]

The phenomenon you are describing is able to be adjusted to (almost) eliminate the 'warp' in the center. It has been years. But IIRC it is 'Main Bang Suppression' adjustment.

When you go out, try to find a long flat object. jetty, sea wall or container ship. Travel parallel close to ( maybe 200' off) and see if the 'warp' follows you along.

Out of curiosity, how high is your scanner off the water? Is this on Northern Lights? Is it any different up on plane versus when barely moving? As previously suggested, A large change in trim may be the issue also.

Yes it's on " Northern Lights", I've never used it up on plane because I figured if I got caught out in the fog or such I would be moving rather slow, with the bow rise without using tabs I'ld probably be seeing satellites. The scanner is about 16' above the water the vertical beam is 25 degrees and the horizontal is 1.7 degrees. I did the MBS adjustment after getting it mounted when I put it into operation. I also used the auto tune function because of my lack of experience with radar. I've not played with the forward tilt on it because the arch has rot and I'am leaning towards a Atlantic Towers replacement and didn't want to mess with it till that is taken care of.

 

[cappy208]

Since you have already been into the fine adjustments, you probably have the manual. Try checking next to a long straight wall. See if it's constantly a warp near the center. That's adjustable. If it's only on targets from ahead (but not the side or rear) then it's the angle. If it's all targets within the center it should be adjustable. I'll be back in the brain box in a couple hours. I'll look in the furuno manual to see how they are tweeked.

 

[AKDoug]

The mounting height alone will cause an open array radar to overlook the close in area. Installation instructions for open array systems always suggest high mounting positions, probably somewhat due to the radiation, but mostly to increase their range.

Mounting instructions for broad band will direct you to mount it as low as possible without obstructing the beam so the close in performance does not suffer from the overlook issue, which is partly mounting position and partly a power issue with high output radar systems.

If you tilt the array you will lose your rear view beam angle and increase what we called "backscatter" when I was as radar operator. The amount of power projected causes a bright spot where too much radiation is reflected back into the array. The rougher the water the more radiation reflects back at you and the brighter the display and small targets get lost easily. If you tuned it to see only close in, you could tune out some of the backscatter, but lost your longer range capability.

If you are to turn your radar into a shorter range unit, tilting the angle forward might gain you better targeting if you are also willing to tune your unit for short range use. A better choice would be to add a broadband unit, which might possibly use the same display as your current unit.

Radar is a compromise.

 

[twistedtree]

This is very timely as I'm just finishing up my radar certification. All radars have a minimum detection distance. "Visibility" based on vertical beam width and antenna height are part of and can result in blind spots. But the more restrictive limit is the minimum pulse time that the radar can emit. When targets are too close, the echo comes back before the transmit pulse turns off, and the echo is never heard. We were taught that the limit is 160 yds, but that makes some assumptions about the fastest pulse time and that may be different for different radars. Anyway, you can't see right up next to you. But if you are that close, even in poor visibility, you should be able to see.

 

[twistedtree]

I don't think the overlook issues is a big one unless you have a planing boat where the boat lifts up and significantly changes the view from the antenna. In that case there are wedges made to correct the antenna angle.

I'd have to go reconstruct the math, but I think I figured that the visibility limit was something like 2-4x the antenna height, assuming a 20deg vertical beam. Or around 1-2 boat lengths away. If you are using radar to navigate amongst objects 1-2 boat lengths away - well, don't do that.

 

[cappy208]

I don't see 160 yards as a minimum. I routinely can get targets at 200' in front, beside and behind. And this is with my antenna up at 80'. So you may have some erroneous info there. 160 Yds may be the theoretical minimum. BUT having been using RADAR commercially for over 35 years, that has never been an issue.

I would suspect that the RADAR needs to be 'initially tuned' correctly. The mention of using 'auto tune' is suspect. AutoTune is not a replacement for a correctly tuned RADAR.

The installation and Owners manual are where to start. Like you just finished the install. Go out, and find a strong, long, straight target to tune and adjust on. Then find a long wall to run along to check the adjustment. The Furuno installation manual shows: 'Adjustment Sweep Timing' being the center distortion to adjust out first, then MBS.

Have you made certain that the range rings are correct? Accurate? Make sure that something a mile away IS showing a mile away on the screen.

Check those two things out and come back. 1. Range Ring accuracy and 2. that when along a straight long target there is no 'indent or deflection' in the center of the screen.


Anyone know why I can't edit and insert a picture?

 

[cappy208]

from the furuno installation manual.

Figured that was better than my hen scratching. The picture represents the boat (in the center) along a long straight target. Sea wall, bulkhead, ship. Whatever. And making sure you don't have these deflections.

 

[River Cruiser]

My range rings are accurate checked them between 2 bridges that are 1 mile apart, I can set it to a 1/8 mile is the shortest distance. I normally run at 3/4 to 1.5 mile range on the river that seems to work best for me. The only long target I've ran by are 1200' tows and there is no warping. I can see my wake on the screen and that is one reason I thought a few degrees forward tilt may improve returns closer to the boat. The only problem I think I have is in the location of objects in relation to where they show on the screen. If a channel maker is dead ahead it appears on the display a few degrees to starboard perhaps 5 degrees at most more likely 2 or 3. This hasn't seemed to be a problem that need to be solved at this time seeing as I'am planning on changing the arch and will adjust it then.