radar

What are limitations of RADAR ?

Limitations  of RADAR are:
RANGE DISCRIMINATION:

It is the ability of the RADAR set to clearly distinguish two small targets on the same bearing at slightly different ranges. The distance between the two targets is equal to or less than ½ PL .

BEARING DISCRIMINATION:

It is the ability of the radar set to clearly extinguish two targets of the same range and slightly different bearings.Factor affecting bearing discrimination  : HBW

MINIMUM RANGE:

THE PULSE LENGTH : The TR circuit prevents the TX of any signal before receiving it. Hence, the theoretical minimum range of detection is repeated by half PL in minutes.

A PL of 0.2 micro  would have a range of 30 mtrs.

DEIONISATION DELAY:

A small delay occurs in the TR cell between the completion of TX & Receiving. A delay of 0.5 microsecond would increase the minimum range a further by 7.5 mtrs.

THE VBW +THE HEIGHT  OF THE SCANNER MAXIMUM RANGE:
  • Height of the scanner increases the scanner , the increase of range.
  • Power of the set, marine radar set transmits around 25 to 60 kwt.
  • Wavelength: 10 CMS have extended range as compared to 3cms
Pulse Repetion Frequency

Pulse Length: Long pulses ensures better maximum ranges than shorter pulses cause , Long pulses  have more wavelength in them.

VBW/HBW: The narrower the beam width the greater the directional concentration, increases the range.

ANOMALOUS PROPAGATION:

Super refraction causes an increase in maximum detection range. This is caused due to meteorological factors like temperature inversion.

RANGE ACCURACY:

According to IMO performance standards the error in the range of an object should not be more than 1.5% of the maximum range scale in use or 70 mts whichever is the greater.

BEARING ACCURACY:

According to the IMO performance standards the object should be measured with ( PLUS & MINUS) +-1 degree of accuracy.AWDHESH KUMAR

Leave a Comment