Calibrating weather radar
Thread Starter
Calibrating weather radar
I have always wondered how a weather radar is calibrated.Is it done on the aircraft or on a test bench and should it be re calibrated if the radome is changed?
From a Line Engineering point of view, arrives pre-calibrated from workshop, just slam the various bits in and function test.
Radome exactly the same just hang it on and function. Most problems with a dome are only detectable at range in the air.
Radome exactly the same just hang it on and function. Most problems with a dome are only detectable at range in the air.
Thread Starter
How are they calibrated before they leave the manufacturer then,and how do you build into the calibration process a 20 year old radome that has probably been repainted four or five times?
Cunning Artificer
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Radomes are stripped and inspected before repainting. Scheduled maintenance includes using a test meter to check for moisture ingress. Moisture is plotted and for minor defects, the contaminated area repaired before repainting and return to service. In the event of major repairs, radomes are sent out to specialist centres that can perform attenuation testing after the repairs are completed.
Radar equipment is calibrated on the bench in accordance with the overhaul manual, prior to certification and return to service.
The Weather Radar equipment, like all other equipment installed in a commercial transport aeroplane, is built to a standard (TSO or Technical Standard Order) and certified to meet those specific measurable standards. Whether it is brand new from the manufacturer, or returning to service after repair or overhaul, all equipment is tested against the certified design standard prior to release to service.
(The above comments apply to commercial air transport operations under an AOC, that must comply with an Approved Maintenance Programme. I can't speak directly for General Aviation, but their requirements are similar.)
Radar equipment is calibrated on the bench in accordance with the overhaul manual, prior to certification and return to service.
The Weather Radar equipment, like all other equipment installed in a commercial transport aeroplane, is built to a standard (TSO or Technical Standard Order) and certified to meet those specific measurable standards. Whether it is brand new from the manufacturer, or returning to service after repair or overhaul, all equipment is tested against the certified design standard prior to release to service.
(The above comments apply to commercial air transport operations under an AOC, that must comply with an Approved Maintenance Programme. I can't speak directly for General Aviation, but their requirements are similar.)
Blacksheep, how eloquent, you obviously do not have my terse engineering prose !
I wrote a tale about visiting a fleet of 1-11s in Nigeria all of whose Wx Radars were "weak returns" and were all radomes eroded and full of moisture. I recommended replacement but on they flew until the "C" checks in the UK when they were grounded.
Drunk I forgot to send it.
I wrote a tale about visiting a fleet of 1-11s in Nigeria all of whose Wx Radars were "weak returns" and were all radomes eroded and full of moisture. I recommended replacement but on they flew until the "C" checks in the UK when they were grounded.
Drunk I forgot to send it.
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ANTENNA
Blacksheep, you are right.
But if you are working in a company, with different type
of aircraft , with the same type of radar installed,
you jack it up to 0-level and adjust antenna
stabilization. According the AMM.
But if you are working in a company, with different type
of aircraft , with the same type of radar installed,
you jack it up to 0-level and adjust antenna
stabilization. According the AMM.
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Most of the stabilisation set-ups with which I'm familiar (Boeings & Fokker)are done against Vertical Gyro or IRS reference attitude with no need to jack the aircraft to zero/zero. The topic though, is more about receiver sensitivity and the possibility of variations or attenuation of the returns due to differences between radomes.
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Yes
Yes, the thread is about radomes.
But the first question was about "adjustment"
Yes, the vertical gyro gives attitude reference to the antenna.
0-Flight attitude is different between a bell-212 +
Fokker 50 .
The gyro does not know, where its installed.
That explains the antenna-adjustment.
Its not interesting, to see, how the weather is in "outer space"!
But the first question was about "adjustment"
Yes, the vertical gyro gives attitude reference to the antenna.
0-Flight attitude is different between a bell-212 +
Fokker 50 .
The gyro does not know, where its installed.
That explains the antenna-adjustment.
Its not interesting, to see, how the weather is in "outer space"!
Last edited by connector; 26th Jun 2009 at 14:25.
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Part of my job when I worked at Hatfield was the testing of Radomes for signal attenuation. most repaired radomes actually had less signal loss as a rule than new ones.
Thread Starter
When I was referring to calibrating of the radar in my original post I meant calibrating the radar image and gain on board the aircraft.The radar in my aircraft is stabilized by the IRS.
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Radar Calibration
The automatic gain and image are calibrated on a bench in a repair shop or repair station using special test equipment. If you mean some field adjustments (e g manual gain control, contrast etc.) then this information can be found in a flight manual.
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But the first question was about "adjustment"
The gyro does not know, where its installed.
That explains the antenna-adjustment. Its not interesting, to see, how the weather is in "outer space"!
That explains the antenna-adjustment. Its not interesting, to see, how the weather is in "outer space"!
Adjustment of antenna stabilisation comes under what airflorida1 correctly describes as "field adjustments".
