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The HORIZON

#1
How high would you have to be for your horizon to be 16km away?
I am looking at the new MSTAR that DRS are offering with a range of 42km against a MBT. How high would you need to be to see an MBT at that range. Plexter do a shorter range FMCW radar, blighter 400, that has a range of 16km against a MBT and I wondered if the 42 km range was a waste of energy in many ways?
:?
 
#2
By the wonder of Google, lots of sites about this type of problem from Jolly Jack, but using nautical miles and feet.

However, on my calcs working from:

Distance to the horizon with the antenna height of 121 feet:
(√121ft) * 1.23 = 13.53 nm

I get 340 ft or roughly 104 metres.

Note that radar waves do bend somewhat around the earth's curvature.

Have a look at:

http://www.ssreng.com/pdf/Radar_Horizon.pdf
http://www.navweaps.com/index_tech/tech-011.htm
http://radarproblems.com/chapters/ch04.dir/ch04pr.dir/c04p3.dir/c04p3.htm

note that 1 nm is usually taken as 1852 metres.
 
#4
Basic height of eye to the horizon works fine at sea but on land you are realy looking at the height differentce between the objects assuming a clear line of sight, and either object can be the high one. I can regularly see 42 km looking at the hills around where I live, assuming the vis is OK.
 

Captain_Crusty

War Hero
Kit Reviewer
Book Reviewer
#5
Resurgam said:
Plexter do a shorter range FMCW radar, blighter 400, that has a range of 16km against a MBT and I wondered if the 42 km range was a waste of energy in many ways?
:?
Saw the blighter in action recently - not convinced at all. Gucci digital mapping screen but the small version had about a 10m range and the larger version is not an act of war as a bit of portable OP equipment (good on FOBs though?).

C_C
 
#6
Captain_Crusty said:
Resurgam said:
Plexter do a shorter range FMCW radar, blighter 400, that has a range of 16km against a MBT and I wondered if the 42 km range was a waste of energy in many ways?
:?
Saw the blighter in action recently - not convinced at all. Gucci digital mapping screen but the small version had about a 10m range and the larger version is not an act of war as a bit of portable OP equipment (good on FOBs though?).

C_C
Hope it was more than 10m!

They quote up to 8km for the 202 and 16km for the 4 series with a 32 km one on its way.

Bit worried now about its abilities. A little dicky bird tells me we may have bought some.

Where did you see it, can you tell me? I am seriously interested. We have just been briefed by the company and they are offering a demo on both flat and v hilly/mountainous terrain.
 

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