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Old 09-05-2013, 09:49   #1
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B&G (Simrad) 4G Radar

I've now got my new radar up and running. Haven't taken it out to sea yet, but some of its characteristics are already evident.

Boy, they were not kidding about the short range resolution! I can clearly make out boat shapes for the boats on moorings just ahead and behind mine. What is really insane, is that I get a radar return from my own deck!!

This despite the fact that I have mounted the radar scanner 10 meters above the waterline, in the same place as where the old Raymarine 4kW pulse radar was mounted. I had thought that this would be too high up for optimal performance of the 4G radar, but it seems to be able to look down at more than 45 degrees! Wow!

I can clearly see the Bursledon Windmill, a few miles away over terrain and not visible by eye from here.

So far looks pretty amazing. I will report in more detail once I've had a chance to go to sea with it.
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Old 13-05-2013, 12:56   #2
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Re: B&G (Simrad) 4G Radar

I'm looking forward to hearing about your experience with it. I'm trying to decide between Furuno (pulse radar) and Simrad 4G. Like you, I'm doing the entire nav suite. I'm especially interested in hearing how things work out with the dome as high as it is. My rigger is trying to convince me to buy a self-leveling backstay mount for the radar. He says that mast mounting is too high for good close in radar, but I believe his only experience is with pulse radar. I'd prefer mounting the radar where yours is (mast at the spreaders), but only because putting the dome on the backstay may shade my solar panels. Does B&G/Simrad have any recommendations for height? I couldn't find anything published. I don't want to compromise radar performance.
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Old 13-05-2013, 14:23   #3
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Re: B&G (Simrad) 4G Radar

I don't see why continuous radar would be any different than pulse radar with regards to heeling and height. Is the vertical beam width for continuous that much wider (ie, 180 degrees if you are seeing your deck from 30 meters straight up)?

Mark
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Old 13-05-2013, 14:25   #4
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Re: B&G (Simrad) 4G Radar

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Originally Posted by colemj View Post
I don't see why continuous radar would be any different than pulse radar with regards to heeling and height. Is the vertical beam width for continuous that much wider (ie, 180 degrees if you are seeing your deck from 30 meters straight up)?

Mark
I can see those yankee braincells working: 10 meters that must be what, 30 feet and before we know it, it has become 30 meters
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Old 13-05-2013, 14:44   #5
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Re: B&G (Simrad) 4G Radar

I've now installed several of the 4G units. It is really weird to see a return on a paddle boarder. Weirder, still, to see it on a common duck swimming by. Imagine what this is going to be like operating in close quarters in really dense fog and dead of night seeing individual lobster pot floats ahead and sliding by.

Have you folks checked out the Structure Scan sonars? It's like a sepia-toned photo of the bottom. I'm going for the whole enchilada when I upgrade.
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Old 13-05-2013, 14:47   #6
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Re: B&G (Simrad) 4G Radar

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Originally Posted by colemj View Post
I don't see why continuous radar would be any different than pulse radar with regards to heeling and height. Is the vertical beam width for continuous that much wider (ie, 180 degrees if you are seeing your deck from 30 meters straight up)?

Mark
Well, that's what I'm wondering. If Dockhead can see the front of his own boat and the dome is 10 meters up, the vertical beam must be pretty good. I guess the real question is how well does CW radar work on targets at 50 - 100 meters when the dome is 10 meters above the water? I'm *guessing* it would still be pretty good. I also don't have any problem putting a leveling mount on the mast if that's appropriate. What would be the problem with mounting the dome lower than the spreaders on the mast? Maybe 3 - 5 meters above the deck? I've never understood why when you want to mount the dome lower, it automatically ends up on the stern on a pole or backstay. I've only seen the dome mounted lower on the mast on one sailboat.
-Tom
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Old 13-05-2013, 14:49   #7
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Re: B&G (Simrad) 4G Radar

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Originally Posted by Roy M View Post
I've now installed several of the 4G units. It is really weird to see a return on a paddle boarder. Weirder, still, to see it on a common duck swimming by. Imagine what this is going to be like operating in close quarters in really dense fog and dead of night seeing individual lobster pot floats ahead and sliding by.
Where (how high) did you mount the dome for the installs? Does it make as much difference with the 4G's as it does with a good pulse radar? Thanks.
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Old 13-05-2013, 15:20   #8
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Guys, seeing the deck is nothing special. Every antenna has side lobes in it's radiation pattern

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Old 13-05-2013, 15:31   #9
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Re: B&G (Simrad) 4G Radar

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Guys, seeing the deck is nothing special. Every antenna has side lobes in it's radiation pattern

Well that makes sense. So assuming nothing different regarding the rules or preferences for mounting height as it relates to vertical beam, is there any reason to prefer mounting the dome on a stern pole / back stay vs. on the mast at about 15 feet above deck? It seems to me that would be the best of all worlds, yet I see very few doing that. What am I missing?
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Old 13-05-2013, 15:33   #10
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Re: B&G (Simrad) 4G Radar

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Originally Posted by Saltyhog View Post
Well, that's what I'm wondering. If Dockhead can see the front of his own boat and the dome is 10 meters up, the vertical beam must be pretty good. I guess the real question is how well does CW radar work on targets at 50 - 100 meters when the dome is 10 meters above the water? I'm *guessing* it would still be pretty good. I also don't have any problem putting a leveling mount on the mast if that's appropriate. What would be the problem with mounting the dome lower than the spreaders on the mast? Maybe 3 - 5 meters above the deck? I've never understood why when you want to mount the dome lower, it automatically ends up on the stern on a pole or backstay. I've only seen the dome mounted lower on the mast on one sailboat.
-Tom
Well, the 4G radar obviously has a very wide beam in the vertical aspect, if I get a return off my own deck at 10 meters height. It means that the beam is more than 45 degrees wide, vertically. Targets at 50 to 100 meters give an almost photorealistic return -- I see the shape of the decks of boats moored around me, not just a blob, but a recognizable boat shape. I can make out the shapes of cars parked near the shore. I haven't yet used it at sea, so I don't know what that will look like, but I am hopeful that it will be really good. If it will show lobster pots, I will be in heaven, but I am not really hoping for that -- I reckon that's not actually possible.

As to mounting height -- I guess that with practical range of not more than 20 miles, there is not much reason to mount it as high as mine is. Five or six meters? You want it high enough to filter out sea clutter easily, and to look beyond close-range obstacles. There is nothing in the manual about it.
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Old 13-05-2013, 15:35   #11
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Quote:
Originally Posted by Saltyhog View Post

Well that makes sense. So assuming nothing different regarding the rules or preferences for mounting height as it relates to vertical beam, is there any reason to prefer mounting the dome on a stern pole / back stay vs. on the mast at about 15 feet above deck? It seems to me that would be the best of all worlds, yet I see very few doing that. What am I missing?
Well, on a stern pole, the scanner is on top of the pole. When 15' up the mast, it has the mast blocking it's view in the aft sector. That's it.
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Old 13-05-2013, 15:37   #12
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Re: B&G (Simrad) 4G Radar

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Originally Posted by s/v Jedi View Post
Guys, seeing the deck is nothing special. Every antenna has side lobes in it's radiation pattern

I'm not sure the return is from side lobes. I don't think that the radar can interpret side lobe returns other than as noise.

In any case, I have never seen the deck of my own boat with normal pulse radar, even on a 90 foot boat with open array radar. Everything within 30 or 50 meters or so is always lost in the Main Bang.
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Old 13-05-2013, 15:45   #13
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Quote:
Originally Posted by Dockhead View Post

Well, the 4G radar obviously has a very wide beam in the vertical aspect, if I get a return off my own deck at 10 meters height. It means that the beam is more than 45 degrees wide, vertically. Targets at 50 to 100 meters give an almost photorealistic return -- I see the shape of the decks of boats moored around me, not just a blob, but a recognizable boat shape. I can make out the shapes of cars parked near the shore. I haven't yet used it at sea, so I don't know what that will look like, but I am hopeful that it will be really good. If it will show lobster pots, I will be in heaven, but I am not really hoping for that -- I reckon that's not actually possible.

As to mounting height -- I guess that with practical range of not more than 20 miles, there is not much reason to mount it as high as mine is. Five or six meters? You want it high enough to filter out sea clutter easily, and to look beyond close-range obstacles. There is nothing in the manual about it.
Seeing the deck is because of side lobes. Pulse radars see it too but it gets filtered out. The resolution of objects around you is what is so cool with this radar. The point made by Mark, and I agree with that, is that it doesn't really matter if you see the shape of their decks or not.

About lobster pots: of-course you can't see them, they are on the sea bed (did you also get that structurescan thing?). The floats however will show up just like waves do. I see them on my pulse radar on a mirror calm water surface, so I assume a 4G unit will too. When they waves come up you won't be able to tell the floats apart from waves for sure.

Last time I read a review about 4G on Panbo,the guy was happy to find that he could see islands at 8nm with it. With almost the same image as a 2kW pulse radar. That is what scares me a lot, because I would sure hope to see islands from way further out! Other things to test when you sail: interference from pulse radars and from rain. You should have enough of both there in the UK
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Old 13-05-2013, 16:11   #14
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Originally Posted by Dockhead View Post

I'm not sure the return is from side lobes. I don't think that the radar can interpret side lobe returns other than as noise.

In any case, I have never seen the deck of my own boat with normal pulse radar, even on a 90 foot boat with open array radar. Everything within 30 or 50 meters or so is always lost in the Main Bang.
The vertical beam is 30 degrees. Every antenna has side lobes incl. this one. Any reflected signal is true signal incl. that returned from a sidelobe. The reason to keep sidelobes small is to concentrate energy into a narrow bundle so that you get more range. Without that, you wouldn't be able to see beyond the bow with that meagre 100mW transmit power I make a joke, but it's seriously true

The main bang on a pulse radar is the time that the pulse is fired. This is not what blanks anything, but it does show up on the radar screen. This is why it is suppressed with MBS, which is Main Bang Suppresion. Good radars allow you to tune that so that you get more short range performance. When you lose 30-50 meters then somebody without a brain has tuned MBS, or you are at a very long range setting of the radar, in which case you want to look out far, not near. I already posted the pictures from my set which show boats right next to me.
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Old 13-05-2013, 17:02   #15
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Re: B&G (Simrad) 4G Radar

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Originally Posted by s/v Jedi View Post
Seeing the deck is because of side lobes. Pulse radars see it too but it gets filtered out. The resolution of objects around you is what is so cool with this radar. The point made by Mark, and I agree with that, is that it doesn't really matter if you see the shape of their decks or not.

About lobster pots: of-course you can't see them, they are on the sea bed (did you also get that structurescan thing?). The floats however will show up just like waves do. I see them on my pulse radar on a mirror calm water surface, so I assume a 4G unit will too. When they waves come up you won't be able to tell the floats apart from waves for sure.

Last time I read a review about 4G on Panbo,the guy was happy to find that he could see islands at 8nm with it. With almost the same image as a 2kW pulse radar. That is what scares me a lot, because I would sure hope to see islands from way further out! Other things to test when you sail: interference from pulse radars and from rain. You should have enough of both there in the UK
I think he meant lobster pot floats, which, along with ducks, I would not think possible to pick up on any kind of radar in any meaningful way, but I would be pleased to be proven wrong.

As to range -- the previous version with less range -- 3G, so called -- will give a good return from a ship to at least 12 miles, according to PBO. The Panbo guy sees rain squalls at 24 miles with the 4G radar: Panbo: The Marine Electronics Hub: Simrad NSS8 & Raymarine e7, with radar in the rain -- not quite as well as with a 4kW Raymarine HD pulse radar set, but almost, he says. In general, the Panbo guy says that the range of the 4G radar, which is quite improved over that of the 3G, is getting close to that of 4kW pulse radar. He is a pretty big fan of CW radar.

I am conservatively assuming that the range will not be as good, but seeing ships out to 12 miles is ok for me. I could not see ships at that distance with my old 4kW analogue pulse radar set. If I can really see rain squalls at 20 miles, I will be delighted. We shall see.
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