Radar Echo

[Rick D]

So, I noticed on my last trip a persistent false port echo at about 10:00. Not always, but most of the time. In a duh moment, I realized my newish 4G radar scanner is on a pole and the radar reflector is just above the port lower spreader. The old radar no doubt wasn't sensitive enough to bounce that close in; this (B&G) evidently is. Kinda funny, but now I need to think where to mount a reflector that isn't in front of the scanner. Maybe on top of it on an antenna loop.

 

[Rich Stidger]

Are you getting a reflection from your mast as well?

 

[Rick D]

Are you getting a reflection from your mast as well?

You are quick; great question! Nope. Just from the (tubular) reflector.

 

[Mark Maulden]

Have you established that the reflector is beyond the published min distance and within the published beamwidths?

 

[chuckwayne]

yea, the fact that the broadband radar can see things really close is actually good, but it takes getting used to - when Panbo first tested the BR-24 he got a spurious reflection - turned out to be the pig stick on the bow 10 feet away. conventional radars have a dead zone while the pulse antenna switches from send to receive that can go for 100 feet

 

[Rick D]

Have you established that the reflector is beyond the published min distance and within the published beamwidths?

No. I'm sure it is not beyond the minimum distance, if for no other reason than being conservative.

 

[Brian D]

How about on the back stay above the radar dome? Or, do you by chance have a function on the scanner to block out that signal?

 

[Rick D]

How about on the back stay above the radar dome? Or, do you by chance have a function on the scanner to block out that signal?

No block function that I recall, although the manual is a bit sketchy. But the idea of putting it on the backstay is an excellent option. Thanks.

 

[Brian D]

Is your radar reflector the kind that needs to be vertical for best performance? If so, you can hang it from the backstay so it acts like it's on a gimbal. Keeps it vertical when the ship is heeling. Just a thought. Not sure how much space you have between the luff of the main and the backstay.

 

[Rick D]

Is your radar reflector the kind that needs to be vertical for best performance? If so, you can hang it from the backstay so it acts like it's on a gimbal. Keeps it vertical when the ship is heeling. Just a thought. Not sure how much space you have between the luff of the main and the backstay.

I think I have plenty of room where it would likely go. I don't know what the degree of effectiveness is, but that should be available. I have a new one ready to mount, coincidentally.

 

[Brian D]

Nice. Break a shroud!

 

[jssailem]

Break a shroud!

You mean that figuratively not literally, Right!

 

[Brian D]

Synonymous to break a leg. Figuratively, of course.

 

[Gunni]

Rick; The radar ranging function should resolve the location of the target as being way close and predictable. Set it a 4 mile and see if that doesn't make it go away.

 

[Brian D]

Gunni... if the range is set to 4 miles, then what is the minimum range? Not having radar, this is a little confusing. If the reflector is indeed the cause of the illuminated target, what happens if a vessel is right up on you? Hypothetical situation or course. (Showing my lack of knowledge here)

 

[justsomeguy]

if the range is set to 4 miles, then what is the minimum range?

The display should show all echos that are inside it's ranged field of view. This instance, 4 miles down to "Holy crap!"

 

[Rick D]

I run the radar at four miles offshore, two miles nearer the coast, one mile in large commercial harbors and an eighth mile on a small boat harbor. Of course, I check longer distances offshore and less too to be sure I am not missing anything like small skiffs fishing off the Mexican coast. I can still see the false target at four miles. Not all the time, but often enough that I will do something about it. It reflects out like a ray or a feedback signal from a buoy or a close-in commercial unit.

 

[jssailem]

I'm going to guess it is like a flare on the screen?
Unlikely you can do anything other than:

1. block that area off (no send receive on that radian)
   
2. relocate the offending object
3. relocate the radar dome

 

[Gunni]

I have the 3G version of your radar, an earlier Simrad mult-frequency on an aft pole mount and a Davis Echomaster on the lower spreader...do not have this problem. My reflector is probably 10deg above the radar unit. Perhaps that is why it does not show. Generally these new radars filter out false targets and they disappear from display. Near-in clutter gets filtered when you expand the range. You can also adjust the gain to force a filter. But the great thing about the multifrequency radar is the spectacular close in detail when you want it. I rarely use close in but I don't see the kind of fog they get in Cali.

 

[Rick D]

I'm going to guess it is like a flare on the screen?
Unlikely you can do anything other than:

1. block that area off (no send receive on that radian)
   
2. relocate the offending object
3. relocate the radar dome

I'll take door two! Easy to move the reflector to the back stay as Brian suggested. Here is an image without the flare present, although that target at 300 degrees just might be it.