Navico FMCW (Broadband) Radar..will it deliver?

[Kieran_Breheny]

I posted this on another section of the forum, although I believe its of interest to all sections of boating, so I have repeated it here.

I previously posted a note about the launch of the Navico broadband radar at Mets. Since then I commissioned a report outlining the pro's and con's of Traditional Pulse radar (Raymarine, Furuno et cetra) versus the Navico's new FMCW radar. If you are thinking about a new radar or just want to keep upto date please take a look.
The report is free and can be downloaded from
http://www.navigate-us.com/site/guidance/radar

 

[jfm]

Navi, the paper on FMCW radars was well written and very helpful. Thanks for the pointer.

But I just took a look at the product specs listed on that website to compare radars, having just bought a new one. The data tables seem full of errors. Like, the Raymarine superHD 4kw has a 1deg beam width whereas the 12Kw has 1.85deg (neither of which is correct, according to Raym's website). And they require 12v power (correct answer is they run on 48v and come with a voltage converter box that will accept either 12v or 24v input). That's based on a 2minute review of the website but if I found those errors on such a cursory look I'd be concerned that much of the data has been keyed in incorrectly.

 

[Hurricane]

jfm

I cant remember the exact conversation but when we installed our Raymarine kit last year there was something about it not working properly with anything but 12v and we had some converters fitted as recommended by Raymarine.

I hope I'm not scaremongering but it might be worth checking out.
Might have been something to do with our G series though.

 

[Kieran_Breheny]

The data on the website has been added, in some part, by the manufacturers and although we try to check all the entries some errrors do occur. We continue to check the enteries and we will look at the points mentioned.

 

[Kieran_Breheny]

After checking the radar specification there is an error on the Raymarine website, the 48" spec is repeated for the 72", SHD beamwidth after processing can be found on the downloadable spec, so the effective beam width is stated as less than 1deg. (48" <1, 72" 0.6 deg)

 

[jfm]

Ah, ok. Mine isn't switched on yet. The gubbins in the box for the SHD radar says it needs a 10-32v feed into the voltage convertor module, which then supplies 42v to the radar array unit itself. I've wired it to the 24v supply, or rather I'm in the process of, so I'll let you know if it doesn't work!

 

[grumpy_o_g]

Thanks, I wondered if "broadband RADAR" was actually FMCW or maybe Pulse Compression - between your site and Panbo we're starting to see some decent coverage of marine electronics at last.

It's not just the Military that have been using FMCW, although it is rare to see it as a "conventional" RADAR display. Radio Altimeters are the classic example but it's used all over the place. I would imagine that most parking sensors are just FMCW RADAR and I know that the cruise control/automatic braking systems (that avoid rear-ending the car in front) use FMCW. It's a very proven technology.

That was a good write up but a couple of things I'd question (and I do mean question, not argue about - the author probably knows a lot more than I do about the subject).

The HD RADAR's (which Garmin and Furuno do as well) don't actually reduce the beam width; as the author infers, they process the signal to enhance the returns. The trouble is they can be fooled under some circumstances. A flat target at right angles with an end that angles away is the classic example (such as a harbour wall with rounded ends). I'm just a little wary of claims that signal processing can replicate completely a hardware improvement. It's a bit like 1080p vs. 1080i on HD TV's - a lot of the time you won't notice the difference but there are occasions you will.

The power consumption characteristics are a bit mis-leading - one of the key advantages is that FMCW doesn't have a Magnetron so can be powered up instantly. This is very useful in good vis if you want to check CPA of something. The other thing is that Magnetron in a small RADAR doesn't use that much of the total power consumed. The array will use a fair bit and the processing will probably use the most but the two technologies are totally different. FMCW is normally more efficient but pulse is better at longer ranges (hence the use of pulse compression of course).

For the leisure user the RADAR horizon isn't normally that far away and you should get well over 10 miles from FMCW, probably 20 or more, but I couldn't find any mention of maximum range on the Navico websites (which makes me wonder why not).

Another thing I'd be wondering if I were in the market for one is exactly what hardware they're using. As the reviewer notes, there's a danger of "swamping" with FMCW - I don't know how they solved that with the car systems but I assume they have. They other problem would be if they've adapted an off the shelf product - probably not that robust in a Saltwater environment. I guess time will tell on that one but it would be interesting to know. Theoretically the magnetron should be the bit that needs replacing first on a RADAR but it doesn't seem that way in reality.

The summary to me is pretty simple:

Pulse (i.e. the traditional) RADAR for longer ranges, more resistance to interference (from storms and heavy rain as well as other transmitters and very close objects)

FMCW (i,e the new "Broadband") RADAR for short and medium ranges, better range accuracy, instant on (no warm up time), probably better power consumption (depending on the model and how you use it).

Beam Width and bearing resolution is identical in both technologies.