[FedCom] Plattsburg ICE

[john wilson]

   I have some "hands on" experience in 2 ghz. monitoring.  I have a
videoscanner  mentioned in my last post.  Basically mine is a special
order videoscanner with an analog scanning circuitry tuning range from
2,300-2,600 mhz. incorporated in a 5 inch monitor.  The normal
videoscanner tuning range is 2,300-2,500 mhz. (See www.videoscanner.co.uk)
The videoscanner  was designed for monitoring NTSC analog video with
accompanying subcarrier audio, if any and it works real good..  It is
powered by 12VDC and can be used mobile.   Conventional wisdom is that 2
ghz. signals have a very limited range.  This is true in some cases and
not true in others.  I have been pleasantly surprised with the distance I
have been able to monitor some 2 ghz. signals mobile.  Some law
enforcement entities are licensed for up to 30 watts on their 2 ghz.
frequencies.  Rarely mobile do I go anywhere in a suburban or urban area
without getting a "hit" within portions of every mile.  The signal may be
wireless lans, security cameras or point to point tv relay intercepts or
videosenders.  The 2,400-2,500 mhz. spectrum contains many signals
including a amateur radio repeaters.  In my opinion, because of potential
RFI, installing a 2 ghz. amateur radio repeater is a bad idea, but there
are some operational typically in urban areas.  I modified my videoscanner
2 ghz. "paddle" antenna with a RF cable jumper and female barrel N
connector that I can connect to a cable attached to a roof mag mount 2
ghz. antenna designed for wireless lan operation.  It works great.

  According to my ITU Region 2 spectrum chart, excluding some 2,300 mhz.
frequencies dedicated for aircraft experimental testing usually involving
air/ground telemetry and possibly some video, the only 2 ghz. portion
applicable for an AWAC'S application is the radionavigation portion from
2,700-2,900 mhz.  Unless I am misreading the chart that range is assigned
to RadioNavigantion and possibly used by search radar,  navigation radar
or possibly radar fire control detection system applications.  I cannot
envision any voice comms in that frequency range.

  I fail to see the benefit of downconverting a sweep radar or possibly an
aircraft transponder signal to a lower frequency so it can be viewed on a
spectrum analyzer or communications receiver to see a radar trace or
listen to a radar audio "whine".  Possibly given the right circumstances a
2.4 ghz. videosender or other transmission may be seen but the signal
downconversion loss combined with cable loss has to be high even using a
respectable 2 ghz. antenna and sensitive receiver.  I have a spectrum
analyzer and it is notiously insensitive even on VHF.  I used to have the
TV adapter for the ICOM 7000.  The sensitivity was so bad on VHF and worse
on UHF that I finally sold it as its performance was unacceptable.
Wavecom/Radio Shack units typically are 4 channel 2.4 ghz.  frequency
unique with  narrow bandpass filtering. The modification does not appear
to lend itself for mobile operation.  Few if any 2.4 ghz. signals of
interest usually will be found close to your home.  In the past I have
experimented with MDS and MMDS downconverters.  The noise factor was
terrible and as previously stated the audio/video relationships are
inverted.  However, tower mounted at 100 ft. I received a 100 watt input
omni directional MDS transmission 23 air miles away with some redness in
the video indicating a signal strength deficiency due to trees and small
physical attenuators between my location and the transmiter site.  The MDS
service could not compete with DTV and Dish Network and terminated.
Minimally a 2.5 mhz. bandwidth will be required for an analog NTSC video
and preferably 4+ mhz.  To each his own, but for me the most practical
solution offering the greatest benefit for the cost  with the least hassle
is the videoscanner.  I prefer to monitor NTSC video signals of interest
and not analog telemetry or sweep radar displays that mean nothing or
other noisy 2,400 mhz. signals..  For general information most of the
interesting 2,400 mhz.  video signals are above 2,450 mhz. and below 2,600
mhz. and definitely none in the 2,700-2,900 mhz. range.

  The USA Surveillance and Detection Directory was created as a 2 ghz.
tuning aid publication documents many 50 state 2,300-2,600 mhz. users of
interest (land and air surveillance, robot bomb disposal, IR on scene
fire/rescue SAR, wildlife monitoring,contractors, etc.) and other special
purpose frequencies/users of interest.(air and body mike
surveillance,SWAT, bomb disposal, TAC, etc.).

  Thanks for your response and if anyone attempts the modification I hope
he has good results.

  If anyone is interested I have some jpgs of my 2.4 ghz. Radio Shack
videosender testing with a mobile configuration showing the system
equipment components, reception quality and testing distance.


Tom Berkshire wrote:

> It is my understanding that the AN/APY-2 radar system used in the
> AWACS Aircraft is an S-Band system.
>
> Steve WA1YKL (a member of this list) has published articles in
> Scanning USA on how to modify Wavecom units for expanded frequency
> coverage up to ~3 GHz., as well as information regarding tapping the
> IF output of the Wavecom's tuner module in order to hook it up to a
> communications receiver or spectrum analyzer.
>
> So depending on where in the S-band the system is operating, it indeed
> would be possible to detect and monitor the signals with "commercial
> off-the-shelf" equipment.  Those who have played with the Wavecom
> units know how they have excellent sensitivity, but poor selectivity,
> so even if the system was up on the high end of the band it still
> might be a possibility.
>
> Now if my OSINT is incorrect, the S-band is still interesting enough
> to play with.