hand-held radar

sarabande

sarabande

Well-Known Member
Joined
6 May 2005
Messages
36,182
Visit site
many a time and oft... or rather, quite a few times, I have been sitting on a boat in mist or fog and listening to the low, visceral vibrations of big-ship engines.

It is a nervy time, and I've wondered why it seems impossible to buy a radar which just sends a blip out in the direction of the gun, and on receiving an echo, shows it up on a screeen or set of LEDs as a target at nmiles distance.

When I took my old radar to pieces, there was a fair amount of shielding, granted, but if the object is to identify a cliff or a ship in a particular direction, rather than having a set 'paint' a 360 degreee picture, could a handheld set be built like one of those gazillion-power torches ?

OK, one might have to be careful to point it away from the crew's essentials, but would it work and could it be, like a budgie, cheap ?
 
sarabande said:
.....I've wondered why it seems impossible to buy a radar which just sends a blip out in the direction of the gun, and on receiving an echo, shows it up on a screeen or set of LEDs as a target at nmiles distance.
Click to expand...

Had a similar idea a few years ago. I did a fair amount of searching and only found doppler guns that read out target speed. Couldn't find a handheld range finder, but would still be interested.
Bob
 
Been done. If it can track Aliens it should find a ship...

1192797-tracker04.jpg
 
sarabande said:
When I took my old radar to pieces, there was a fair amount of shielding, granted, but if the object is to identify a cliff or a ship in a particular direction, rather than having a set 'paint' a 360 degreee picture, could a handheld set be built like one of those gazillion-power torches ?
Click to expand...

You're peering into the realm of airborne ( probably shipborne ) military radars, which have long been provided with the capacity to do 'selective sector scan' which, in practice, means horizontal beamwidth sharper than 2°. Provided you can maintain relative position and azimuth between the emitter and the receptor ( second -term stuff at Dratmouth, I wot ) for the duration of the cycle, you may get a usable and resolvable return. Or not.

Then there are Radar Warning Receivers of varying sensitivity..... the better of which are budget-dependent and often US-specific - or Israeli.
Determine what may be possible - remember the Inverse Square Law and take the Association of Old Crows intro courses....

https://www.crows.org/
 
"Provided you can maintain relative position and azimuth between the emitter and the receptor"

Given the speed of the 'ping' emitted, and the speed of the 'pong' returned, is any local movement of the handheld set likely to degrade the return more than, for instance a radar mounted higher up on a mast and subject to greater magnitudes of movement ? A rough calc is that for an object 6km away, the signal reaches there in 0.00002 of a sec.

Thus a full emit and return takes place in 0.00004 sec. It's hard to imagine a handheld radar moving very far from bearing and azimuth in that time.
 
The device you dream of does exist - its called AIS. Any vessel likely to cause you any level of concern is obliged to have it permanently switched on. I appreciate clutter from the myriad of class B transponder owners who feel an emotional need to be seen electronically in the middle of the Solent on a Saturday afternoon in July can be a right PITA, but then these jollyboys won't be out when its foggy.
 
Aren't Police speed radars pretty much what you want? Can't be hard to include a range as well as closing speed. OK it's daft for cars doing over 30 and only a few 100 yards away, but a similar device for ships up to 1 mile away & maybe max 30kts say would be fine. Got to be possible, surely.

I'd certainly go for something like that, the low rumble of engines coming out of the fog off South Stack (no shallow water to hide in there) as the Irish Ferries head into Holyhead at 15-20 kts is pretty scary & you can only relax when the wash hits you so you know it's past.
 
By the time you've invented and developed the handheld thing, which I'd hope more reliable than the police jobs, you might as well have a relatively light and low power consumption radarlike a Vigil, at least that will work.

In Searush's case with the ferries AIS would do the trick, if it's within mobile phone range one could use a tablet or laptop and the free AIS website www.marinetraffic.com ( the info can be 2-3 minutes old ).

Years ago one of the sailing mags did an April Fool on ' personal radar ' showing a bloke on the side deck with a flat scanner array hung over his chest by shoulder straps; he was wearing a clown outfit...
 
Sarabande etc,

What would you/could you do with such kit? Ok, if the range is increasing (do nothing, but feel safer earlier), but what if it is reducing?

Just asking!
 
What you talk of is called a 'Pointing Radar'. Yes it would be possible to make a hand held version similar to the cops radar traps, but the power output requirements to give the increased range you require would, I believe, not be allowed.

Incidentally, I worked for a number of years on one of the most powerful pointing radar ever produced in the UK.
Some wag worked out that if we could lock-on to a sh itehawke at 1250yds we could fry it :D :D
 
James_Calvert said:
What would you/could you do with such kit? Just asking!
Click to expand...

The scenario that prompted me to investigate was:-

Entering Dartmouth after a cross-channel. The sea offshore was flat, visibility offshore excellent and the sun was burning down from a clear sky. According to the HM office (by radio) it was the same in Dartmouth. Between us was extremely thick fog (caused by air of the right humidity flowing down the ria and meeting the sea) . We entered very slowly with a set of eyes on the GPS/compass and another set in the bow and we buoy-hopped.

That yacht did not have radar but even if it did, many years of seeing what the finger of a watchkeeper can do makes me mistrust a 'paint' until I am comfortable that heading/gain/swept gain etc. has been correctly set up - much easier to point a 'gun' to augment the eyes in the bow.

Bob
PS Now equipped with radar, it was turned on once last season.
PPS I would appreciate a radar tool that was inexpensive, low power, immediately reliable and easily maintained/tested
 
James_Calvert said:
presumably it would need some kind of heading reference to make sense of what it was pointed at ... and to provide a useable plan display?
Click to expand...

No JC, the analogy with the supertorch holds good. You don't need a heading reference as the radar points directly from you as the interrogator. (Am I assumng that everone know roughly 0 - 360 where they are looking ?) And all I'd want to know is that there is an object in the direction of the beam, and how far away it is. Bells and whistles like bearing, size of return, are marginal but could presumably be added in, but increase the cost. The whole point is for the H/h radar to emulate the human eye; plotting numerous targets 360 degrees is the job of a rotating scanner.

Safety considerations advice. Would it be dangerous to use one in harbour ? At a nearby boat ?
 
sarabande said:
No JC, the analogy with the supertorch holds good.

So how do you envisage "seeing" the output, or perhaps hearing it?

Safety considerations advice. Would it be dangerous to use one in harbour ? At a nearby boat ?Sorry no idea; I'm just interested in the idea - it occurred to me as well.
Click to expand...

James
 
Last edited:
You must log in or register to reply here.

Share this page

Top