[evlatests] C-band 6200 MHz RFI IF BD ea28

[Dan Mertely]

The 6182-6212 RFI seen on ea28 and adjacent antennas on the north
arm is almost certainly due to the State of NM digital data transmitter
on Davenport.  The path is from Davenport to Mangus mountain.  Both
are electronic sites with a number of C and VHF/UHF transmitters.
I've attached a screen shot from the FCC search page.  These are all
fully licensed transmitters and have a legal right to operate.  (See
attached.)

I will discuss the operation with their engineer to see if they can
modify the station parameters some in order to reduce the side lobe
hitting our north arm.  Otherwise all we can do is log the frequency
and know that it is there.  Updates pending.

C-band is filled with these high power point-to-point digital data
links.  Multiple paths originate from electronic sites at Davenport,
Mangus, Gray Hill, Magdalena, Socorro Peak, Luis Lopez, Lemitar, ...
etc.  Sigh!  If only we owned the airwaves!

-Mert


On 4/13/2015 9:48 AM, EVLA Operations wrote:
> Hi Dan,
>
> Here's the screenshots of the bandpass plots, with the strong noise on
> ea28 IF B and D on pad BN7/N28.  It looks to be from around 6182 to 6212
> MHz.  Also attached are plots from nearby ea06 (BN5) and ea07 (BN8).
> (ea22 was parked, not in use and was at a different band, so there's no
> info from that pad.)
>
> Thanks.
>
> Matt

On 4/13/2015 10:40 AM, Jim Ogle wrote:>     Work Order		:  C136361
 >
 >   * WO Status		:  OPD
 >     Asset Number		:  03-08-006.0CM-0VL
 >     Asset Short Desc	:
 >     Asset Location		:
 >     Originator		:  Gardiner, Matt
 >   * Asset Status		:  ISF
 >     Safety			:  N
 >     Plan Priority		:  3
 >     Origination Date	:  4/13/2015
 >     Due Date			:  4/13/2015
 >     Fault Code		:  REPORT
 >
 >     Work Requested		:  Ant. 28 C-band IFs B & D showed very
 > strong RFI from about 6182 to 6212 MHz in bandpass plots with power of
 > -50 to -30 dBm/channel.  Seen in 15A-070_sb30423823 which switched
 > between C & L bands from 12:22-15:00 UT 4/13.  ea28 C-band IF B & D pwr
 > into/out of T304s was weak and fringes very weak. ea28 is at BN7/N28.
 > ea07 (BN8) and ea06 (BN5) plots also show some RFI, much lower, at the
 > same freq.  Screenshots of the plots sent to Dan.
 >
 >     Employee ID		:  =>IPGRFI
 >   * Completed (Y/N)	:
 >   * Date (MM/DD/YYYY)	:
 >   * Time worked		:
 >   * Corrective Action	:
 >
 >   * Values required when email is returned.

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