Yacht Radar Beam Detection By Another Vessel's Radar Set

[Deleted member 36384]

Quick Question

If I fitted a radar set and it was transmitting, would another vessels Radar pick up the sweep from mine and show it as a contact, or does Radar only pick up its own signal reflected back?

Wonderingly Yours,

BlowingOldBoots

 

[fireball]

My understanding is that Radar only processes it's own signal reflected back ...

Seame will detect (and enhance) someone elses radar signal - but it isn't directional and doesn't tell you where it came from...

 

[Skysail]

The other vessel's radar might on rare occasions pick up your radar signals and display it as interference signals, but not as a sharp contact. Personally I have never seen it happen. Sets have an 'Interference Rejection' (IR) control that eliminates it from the display.

IIRC the wooden MGBs that ferried agents across the Channel in WWII did not use their radar for that reason. Makes their navigation even more impressive. See 'Secret Flotillas' for an incredible history.

 

[Deleted member 36384]

Oaky thanks for the information. I was thinking if one had a radar set then a radar reflector would not be needed if other vessels picked up the radar transmission. Both devices are required to enhance visibility then. Ta.

 

[nimbusgb]

The only time it MIGHT happen is if your antenna is pointed directly at his antenna at exactly the same moment in time. Remember that the antenna rotates and fires out and listens for pulses of energy as it goes around. the chances are pretty slim of it happening even in a busy seaway.

Radar transponders operate in a slightly different manner. They have an omnidirectional antenna that 'listens out' for an incoming pulse of radar energy and promptly sends out a pulse of energy when it does hear something.

 

[johnalison]

My fairly old Raytheon set has a function that suppresses stray radar signals from other vessels, and I imagine it is a standard fitting. If I switch it off I can see transient lines of dots spiralling around the screen which don't appear to show the position of the other vessel. In the unlikely event of another vessel also switching his set similarly, all he would know is that there is another vessel somewhere within range or even a bit beyond.

 

[ithet]

If it was another yacht or commercial vessel it would at most cause some interference. If it was a warship it could use your radar signal to target and blow you clean out the water!!

 

[Deleted member 36384]

... If it was a warship it could use your radar signal to target and blow you clean out the water!!

I wonder how many leisure vessels have been targeted by exercising RN vessels?

 

[david_bagshaw]

Quick Question

If I fitted a radar set and it was transmitting, would another vessels Radar pick up the sweep from mine and show it as a contact, This is similarwith a Racon beacon, where the return is a thick band, some times broken into daashes to identify the buoy etc, in the direction, and where the enhanced setion ends gives the distance. however the racon makes a sweep across the frequency band till it matches your radar, not by chance & not by a rotating ariel.

Wonderingly Yours,

BlowingOldBoots

hope that is of use

 

[Bosun Higgs]

I wonder how many leisure vessels have been targeted by exercising RN vessels?

Not many. When did you last see a naval ship? There are very few about.

 

[Beadle]

Isn't this what an active radar "reflector" does?

 

[maxi77]

Quick Question

If I fitted a radar set and it was transmitting, would another vessels Radar pick up the sweep from mine and show it as a contact, or does Radar only pick up its own signal reflected back?

Wonderingly Yours,

BlowingOldBoots

Because one radar squirtig into aniother radars antenna could do pretty serious damage to the rx they are designed to avoid this. Anyway at best all this could do is provide bearing information but because it tends also to come in through the sidelobes too you end up with many bearings and ranges, not very helpfull hence the desire to suppress the possibility to both protect your set, and not confuse your display.

Sometimes you do get some feed through from a powerful radar but this tends to appear as strange lines accross your screen. Many RN radars used to get this from the big airtraffic radar at Prestwick.

 

[Deleted member 36384]

Isn't this what an active radar "reflector" does?

I could be wrong on the method but I believe that an active reflector sends back the received signal amplified, not its own signal.

I was wanting to understand if a radar reflector was required on a boat using its own radar set if its own radar signal would be picked up by another vessel as a target. As advised above this is not the case, so to see and be seen, as best as one can, both radar and a radar reflector are required on the same vessel.

I had never given this any thought before, not being competent in Radar, but the recent reflector thread made me wonder about it.

Thanks again everyone for the input and advice.

 

[Piers]

Interference from another radar usually shows as “streaks” or “spiral lines” eminating from the centre of your screen. Most radar sats have a control to eliminate this called Interference Rejection or IR.

The Sea-Me active radar reflector detects a radar pulse, amplifies it and re-transmits it. Without it, a return may show your boat as a weak and maybe intermittent target, but with the Sea-Me, the return is slightly larger but much more pronounced.