Parrot

[finbar_s]

I have a question regarding "fixed target radar calibration devices". Specifically I'd like to know the typical use of a "Position Adjustable Range Reference Orientation Transponder" (Parrot). As it's name suggests it seems to be able to electronically alter the response time of the echo allowing the device to "fake" it's distance from the interrogating radar. The Question I have is: Can this device electronically modify it's location (bearing from the radar) thus allowing the return information to be located at a bearing other than it's physical location?

My assumption is that it can not do this, and the Parrot is always a specific bearing from the radar, but I'd just like some confirmation on this.

Thanks in advance.

[Not Long Now]

Very good question, I've been wondering about that myself for a while...

[Lew Ton]

What. . . . ?

The term 'parrot' was used to describe an aicraft transponder during WWII as a code word, hence make your 'parrot' 'squawk'. I think your definition of parrot has been contrived to fit. Yes, there are fixed test transponder sites, and presumably it is not difficult to make them reply to make them appear at whatever distance you like from the radar head.

Is this what you mean? If not, sorry! :)

[finbar_s]

Thanks for the response:
The term parrot in this context is exactly what you mentioned, “fixed test transponder site” It is possible to make them appear at a distance other than it’s real distance and this is probably done by delaying the return signal. The question is: Is it possible to make this device appear at another bearing other than the one at which it is located? I believe there is a calibration to make it act as you mentioned at a distance further from it’s real location, but what about a calibration that displaces the fixed transponders location or bearing from the radar head.

So for example:

Situation # 1
*************************************
We know this situation is possible
X = radar head
P = parrot or fixed transponder at (090 degrees true)
P’ = calibrated offset of the return signal


X P P’

*************************************


Situation # 2
*************************************
But what about this situation?
X = radar head
P = parrot or fixed transponder at (090 degrees true)
P’ = calibrated offset of the return signal now at another bearing other than 090


X P


P’

*************************************

Forgive the crude maps

[Bizzy]

Parrots squawk and Budgies chirp, and you cannot 'throw voices'. Where it comes from is where it is displayed a far as all sensors are concerned

Lew Ton

'Parrot' is still a brevity code word in use today in Mil

[JuicyLucy]

The range is easy to change to a greater distance away from the head simply by delaying the reply. This was used at Sumburgh to set up the ACR430 radar, there are no PE`s in the sea!
The problem with angular displacement is that as you are off boresight you would need to blast a largeish amount of power back at the head to utilise a sidelobe. This would not be reliable and would only work at fixed angular displacements dependant on the aerial design.

[finbar_s]

Thank you all for your responses, I now have the answer, PE's are not bearing adjustable.

[Chis, Colin Chis]

Finbar
I could really do with you on my PPP team, because it is quite obvious you have that special art to talk complete cods-wallop.

These are skills i've been trying to introduce to the management team for some time now.

Welcome aboard.


------------------------------------

I'm off to the Bahamas now with my big fat pay off.