CCD-world: Re: Influence of meteorological radar system on CCDs

[Tony Distasio]

The following was posted to CCD-world:



On Tue, 21 Sep 1999, Byeong-Gon Park wrote:

> Thanks for the information,
> The situation seems similar to ours. But what was the distance between
> their installation site and observatories? And how strong is the radar power?

The radar systems we have here are the same NEXRAD (Next-Generation Radar)
equipment installed all around the USA to monitor severe weather and
rain conditions. Probably the same equipment as that described by
Fred Harris at nofs.navy.mil, Naval Obs. Flagstaff.  Our radar sites
are much farther away than yours will be, fortunately.  We were
worried about influence of radar pulses from sites on other islands,
perhaps 50 nautical miles or more away from us! 
> 
> The KMA (Korean Meteorological Administration)'s proposal to prevent
> radar interference is the same idea. They say that they will turn off the
> radar when the beam points to our telescope. Also, the radar will not
operate on sunny days and clear nights - at least they promise during this
time of negotiation phase, but who knows after installation? Any way, do
you think  this will suffice with the frequency range and power at 500m
distance?
> I am also afraid of our solar telescope, the data of which is transported
> via RG59 video cable - obviously weaker to the EMI than optical fiber
> which carries CCD data.

You have every right to be concerned. 500m is terribly close to your
astronomical installation. Spot blanking effectiveness will depend on
the angular arc over which it is finally blanked. Plus, side lobes are
a consideration. RG59 cable may be a problem.  The "shield" braid on
that cable may not look like a "shield" anymore, but rather like an
antenna.  It is hard to predict that.  RF-EMI problems are really
a "black art" more than a science.
> 
> Thanks,
> Byeong-Gon

Hope your work with your government is successful.

Aloha,

Tony Distasio
Institute for Astronomy
Haleakala Observatories
Maui, Hawaii
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