How to tell when someones radar is left on?

[Kelkara]

Originally Posted by EmeraldCoastSailor

Can my radar interfere with someone's else radar? I have never seen other's radar interfere with mine; well at least I never detected any interference.

I regularly see interference on my 3G radar, but only for a brief flash ... As the two radar antennas rotate, if for a brief moment they are pointing directly at each other then I will see interference between me and the other ship ... Unless they are rotating at exactly the same speed, then the next sweep of the antenna they will not align and the interference will be gone.

[mickt243]

Originally Posted by a64pilot

They can if they are close to the traffic, but with a transponder it increases their range greatly.
Which is exactly what we want on our boats right, not only to be seen, but to be a large bright target when far away.

They can see cars depending on how they have their Doppler notch adjusted, a Doppler notch is of course based on Doppler shift and is a way to filter out all stationary targets, or targets below a set speed to eliminate ground clutter.
You can use the Doppler notch to defeat threat Radar by making sure your closing speed is lower than its Doppler notch, a fixed wing can do that by flying a circular route spiraling in towards the Radar.

Of course a standard pulsed Radar can tell the speed of an object by knowing precisely the frequency transmitted, then the difference in frequency of the return signal will equate to a speed, due to Doppler shift.
The Longbow Radar on the Apache would often display highway traffic as aircraft due to their speed, no ground vehicle on the battlefield cruises at 80 MPH.

What I have yet to figure out is how a FMCW Radar which sweeps frequency up and down handles Doppler shift. You see it knows range by knowing the exact time the frequency that is received was transmitted, since the speed of light is a constant it can compute distance.
But a moving target will change return frequency and would therefore interfere with range estimation.
I assume it just ignores Doppler shift assuming nothing is going very fast on the water?

I’ve called B&G tech support and I don’t think they know, or at least the guy I talked to didn’t.

Ex RADAR tech here...

“standard” pulse RADAR cannot detect velocity as they aren’t Doppler capable. Only gives range bearing and approximate target size.

“pulse doppler”, does the same as a standard one, adds ability to track target velocity (only toward or away from RADAR antenna)

pulse style RADARS can be easier to jam. They use transmission time of return to determine range, and antenna angle at time of reception to determine bearing, target size is inferred from the strength of the return vs it’s range. If backed up by a decent computer or operator, speed and track can be computed from comparing individual returns.

CW RADARS are later technology, can be harder to jam, typically get better range out of lower power. Depending on what computer power they’re backed with, they can do all RADAR functions or they can be simple velocity only to trigger a speed camera.... they determine velocity toward or away from the antenna by Doppler shift, to determine range they need some kind of modulation, can be FM (like your freq sweep mentioned above), or simple transmission interruption, or more complex like barker codes (the modulation can also be used to update guided weapons in flight) to determine bearing they can either use simple angle of antenna, or can be computed by phase shift across a multi aperture array. When the user of a modern Doppler RADAR is in motion it can compute own ground speed and relative ground speed of targets by noting the Doppler shift in the noise from the ground return to recalibrate what zero is....

The old tech RADARsI used to work on transmitted in the hundreds of kilowatts and received in the order of nano watts. Modern RADARS can transmit in the order of tenths of watts and up, and receive down to picowatts.

With the transponders in question- there is a risk with more modern CW type RADARs that because they’re not frequency coherent with what got transmitted they may be ignored by the receiver (or show up as wrong range or wrong velocity)

[thomm225]

Originally Posted by NorthernMac

I’ve seen aircraft and airport radars cause RF interference.
Had a guy try to do a photo shoot for a aircraft even, had one of those remote wireless flashes, he couldn’t understand why it was going off on it owns, pointed at the radar, every time it would sweep past off the flash would go.

Also always good to be thoughtful of your bright lights, radar, wake, etc around others.

My money would be it messed with his TV or Bluetooth speakers or something.





Not sure about that, I’ve had ATC call primary targets for me quite a few times “primary target only, altitude and type unknown”, even had them call possible bird activity. Lots of the airport radars can even show cars on the roads by the airport.

Most all Air Traffic Control Radars (especially ASR) should show cars on the road.

The ones I maintained in the 1970's could do that and with MTI on/off you could also tell which ones were moving and which were sitting still. MTI reflectors would still show up though with MTI on.

Many times we would align runway center line with the runway lights reflection along with the centerline reflector and verify when a plane/jet came in. The Harriers Jets weren't much help with that though.

These were old style pulse radars with peak power around 1 mega watt. We also had IFF for Altitude, number, etc (Mode 1, 2, 3A, C) except the TPN-8 which was a PAR Radar with raw video only and less power with a max 40 mile range

https://www.radarpages.co.uk/mob/tactatc/ups1_1.htm

https://en.wikipedia.org/wiki/Airpor...eillance_radar

https://www.google.com/search?tbm=is...=1574596494408

https://www.google.com/search?tbm=is...=1574596649290

[thomm225]

Originally Posted by Viking Sailor

From the Echomax FAQ:


Active X RTE response to FMWC - Broadband radar.

Solid state- FMWC - broadband radar use a low transmit power which has steadily increased since their introduction 10 or more years ago. In the early days the Simrad 4G used 0.165 watts transmit power which was not enough to be picked up by the Active X - XS in normal sleep mode outside a range of 200-300m. Fortunately the power increases are now sufficient to activate the Echomax Active RTE and respond as shown below for the various listed makes.



These ranges are in comparison to 100% trigger at ~7nm for X and S band high power ship's radars.

These ranges for the Echomax Active XS to respond are still better than nothing as I posted before and along with AIS should give you a little piece of mind for a few minutes/hours of sleep when single handing offshore

At the very least, you will be picking up the ships one way or another miles out and the smaller vessels using the chart above. Also since they are lower in the water they will have a better chance of seeing your lights etc also

[Emouchet]

Radar microwaves are dangerous for your eye balls.
On the long term, it will affect your vision.
Avoid looking at the antenna while it is transmitting.

[a64pilot]

Originally Posted by Emouchet

Radar microwaves are dangerous for your eye balls.

On the long term, it will affect your vision.

Avoid looking at the antenna while it is transmitting.

Looking at it isn’t going to bother you. Being in it’s beam and especially if your close can.
However with my 4G and its transmit power of .16 W I’m not worried a bit. So location of antenna and it’s transmit power should concern you, but not looking at it.

[thomm225]

Originally Posted by Emouchet

Radar microwaves are dangerous for your eye balls.
On the long term, it will affect your vision.
Avoid looking at the antenna while it is transmitting.

Geez, I'd be blind if that were true since some of the radars I/we aligned daily and walked in front of within 3' for 5 years had a peak power of 1,000 Kilowatts or 1 mega watts which is lots more powerful than today's radars

[Ted and Relinda]

Wondering if the car radar detector would pick marine radars. Mine used to pick up the auto door radar on grocery stores as I drove past shopping centers. Then backup alarms started setting it off. It would pick up the older K band a mile away and Ka a half mile.

[mickt243]

Originally Posted by Ted and Relinda

Wondering if the car radar detector would pick marine radars. Mine used to pick up the auto door radar on grocery stores as I drove past shopping centers. Then backup alarms started setting it off. It would pick up the older K band a mile away and Ka a half mile.

all depends on what its tuned to detect and how, vs what frequency is being transmitted by the device you are trying (not?) to detect....


old "RADAR detectors" were/are simple "crystal video receivers" which will allarm on pretty much any signal within its tuned bandwidth..... more modern stuff, like the radar warning receiver on ah64pilots apache are way more sensitive and do a lot more proscessing on the received signal, they will only alarm on signals that match a specific pattern of specific threat emitters that are programmed into them.

[a64pilot]

I don’t think a car Radar defector will work, for instance the Longbow fire control Radar is Ka band, and a car detector won’t detect it, but then it’s also a low probability of detection Radar.
Ka is of course not the OLD X band cop Radars, by the time Ka was being used I believe car detectors were actually pretty sophisticated.
I put away my Passport detector when GM’s active cruise control also set it off, being a conspiracy theorist I don’t think it’s accidental that all these devices work so close to cop Radar frequency that it’s real difficult to distinguish.

[grootsee]

Really good ears. My dog can hear radar.

[billknny]

I can see another radar transmitting on my broadband radar screen. Big commercial ones from a distance, recreational ones from closer up,

Easy to figure out where, the interferance on the screen points right to the offending unit.

[AJA]

I agree. I don’t know why it would bother anybody. I watch the Providence high speed ferry come into Newport harbor with the top deck full of passengers and the radar antenna spinning at head level a dozen feet away from them. You wouldn’t have seen that 20 years ago. But today no problem. If there were a danger there would be lawsuits.

[zeehag]

radar interrupts wifi signals so that could have been an issue.
one needs no special tester or finder when wifi is in use.
itis very hard to send the message to family that you are ok when the guy next to ye has radar running and all there is to use is wifi. btdt.

[Crazy Norwegian]

If you are worried about detecting really low signal levels, consider this:

Your GPS signal is received at a level that is BELOW thermal noise threshold. That is, the signal is so low that the natural ambient electrical noise in the atmosphere from the sun, earth, and other sources is stronger than the GPS signal.

Your receiver is able to detect the GPS signal thru the use of very powerful digital algorithms to sort out the code from the noise. All you need is to know what you are looking to detect.