RFI Identification at AO

Thanks to Phil Perillat for providing a copy of his personal RFI notes which was used as a starting point for this documentation effort. Some of the items on this page are most likely out-dated, and the lists are far from complete. Changes will be made as new sources of RFI are located and identified, and items that are already listed are being verified.

If you have any possible contributions, please contact me.

Rey rey@naic.edu
 

  • by Frequency
  • by Source/Type
  • Found and Fixed


  • RFI Identification BY FREQUENCY (MHz)
     

    410-445  bw = 6 MHz, 10 or 12 sec rotation ipp 3.28 millisecs  Hawkeye airborne radar

    427.485  cabinet door open 5aug99 MULTI METER in dome

    428.??   digital multimeter for dome tilt sensors..

    428.615  Data burst every 5min. May be Amateur.  SE of AO. In process of locating (when??) or digital multimeter for dome tilt sensors...

    429.096  visible door closed  5aug99 CAMERAS in dome

    429.098   narrow  aug99   CAMERAS in dome

    429.157  5aug99 PWRMETER in dome

    429.544   narrow aug99   CAMERAS in dome

    429.550  visible cabinet door closed  5aug99 CAMERAS in dome

    429.741  cabinet door open strong  5aug99 MULTI METER in dome

    430.486  cabinet door open strong  5aug99 MULTI METER in dome

    432.428  bw=2MHz radar ipp 3.5,4.6,3.3,4.2 millisecs antenna sweep rate about 7.8 rpm appears to southeast dec96

    433  LATR (Large Area Tracking System - airborne)  activity reported for period of 1-21 Apr. 2002 0900 to 2300 hours.

    432.024  narrow aug99   gets smaller when cameras in dome are turned off, but doesn't go away completely.

    433.325  strongest visible birdie with cabinet door closed 5aug99 PWRMETER in dome

    436.??   1MHz  birdie appeared when we went off the air for hurricane season, see it on the line feed and in the interference monitoring system. hops in freq across about 1 mhz in a short time span (seconds). IntfMon sees it start up around 10am. the line feed is much more sensitive to it... sep95

    452.275  single peak  19jan99  beeper or data comm.  (harmonics: 904.55-2, 1356.825-3, 1809.1-4)

    462.875 beeper.. strongest around center 462.8752                    19jan99
                harmonics @
                  925.75     2          1 peaks separated by 8khz at the fundamental
                  1388.625  3
                  1851.5     4
     

    1160     tone     apr99    ch1 synth for lband feed for serendip.

    1227.60  gps L2

    1246.2  aerostat radar

    1246+.4375n    GLONAS satellites L2.n=1->24,n13-24 shutdown soon. leaving n=12,21,22, and 24    aug98

    1261.2    aerostat radar aerostat mou. L-88A RADAR. 160 usec 1261.2 then  160usec 1246.2  bw 1.67Mhz, prf 305(avg)

    1270.9     remy  14apr99

    1275      Punta Salinas Radar???    ipp 2736.467 ms. drifts by a usec in say 10 minutes rms/mean of period for 4 secs.. .0025             31dec96

    1284.5   bw=2.5MHz  Strong, time variable

    1294.8   bw=1.5MHz   Radar 5rpm ipp 2.7ms, 5us pulse, not locked to 1307.5, Punta Salinas Radar nov92

    1300      bw=39kHz   CH2 synthesizer

    1305.6   present whenever observed   Mar., 2002

    1306.7   bw=78-156kHz          Borinquen Radar

    1307.5   Radar, 5rpm, 5us pulse, ipp 2.7 ms was Borinquen Radar.  nov92

    1314.5   bw=1MHz    Weak, time variable

    1315.4   bw=78-156kHz  Weak, time variable

    1317.8   bw=1MHz       Weak, time variable

    1324.8   bw=78-156kHz    From 1420 LO system when HP    synth. not plugged in. Plug       synth. into rack B. nov92

    1330     bw=1.5MHZ       FAA Radar, Pico del Este

    1333.8   bw= 1MHz         Time variable, infrequent

    1349.6   bw=1.5MHz        FAA Radar, 6 us pulse 1330,1350,  ipp 2.813896ms

    1350      bw=39kHz         CH2 synthesizer, also FAA radar Pico del Este

    1350         constant when using the blanker     Mar 2002

    1353.3       Riccardo G. 13th harmonic of WERR-FM   104.1 MHz

    1357.2   bw=78-156kHz          Very time variable
    1360.2   bw=78-156kHz          Very time variable
    1360.6   bw=78-156kHz          Very time variable
    1362.8   bw=78-156kHz          Very time variable

    1370.8-1371   on occasionally but large when present     Mar 2002

    1373.122  narrow    CAMERAS in dome aug99

    1381.05  bw=1MHz   GPS L3 satellites on the air for 30secs twice a day.     sep91

    1382.646  narrow  CAMERAS in dome aug99

    1383.5   bw=39-78kHz           Strong, infrequent
     

    1386.3           jan93

    1386.7???     jan97   time variable , strong. modulated..

    1387.5           jan93

    1388.55        3rd harmonic 462.85 beeper system. megapage  1996
                       angel padilla..288-1210..bayamon.. 1998

    1388.6        3rd harmonic of Borinquin Beepers at 462.875 MHz     apr93
                        For 6 sec integration time,over multiple days this birdie appears in almost every scan
                        with vairing intensity.                                                     9sept99

    1388.??        two birdies at 1388.539,1388.563. delta=24khz. avg is the 3rd harmonic of 462.85 .
                        there is a station 18 (km,mi?) away in villaba. Although there are many stations in this range.
                        All have 8khz spacing which would fit the 3rd harmonic 24khz spacing...     dec95

    1389.43    present only very briefly at night for several nights running. Observed by A1356
                   May be related to something at 1360 MHz    May 10 1999

    1389.6     Present about 4% of time

    1390.8        Possibly 3rd harmonic of 463.6 paging system Cerro Punta.
                        Belongs to "Mr. Beeper". Was measured on a visit to
                        Cerro Punta (may not be within FCC specs,just barely).      feb93

    1392.195  narrow CAMERAS in dome  aug99

    1393     bw=39-78kHz      Always present, drifts slowly in freq between 1392.0-1393.3

    1400      bw=39  CH2 synthesizer

    1417.5-1418  always present     Mar 2002

    1418.8          Not always present      sep92

    1420.798 narrow  camera in dome  aug99

    1420.808         cameras in turret room.  jul99
    1422.5      2nd harmonic of WCCV-TV CH 54 and other unidentified source, seen when WCCV off

    1430.2   bw=1MHz            Military radar

    1430.347 narrow  CAMERAS in dome aug99

    1432.2   bw=1MHz            Military radar

    1434.1   bw=1MHz            Military radar

    1449.397 narrow CAMERAS in dome aug99

    1575.42                  GPS L2

    1602+.562n          GLONAS.n=1->24,n13-24 shutdown soon. leaving    aug98
                             n=12,21,22, and 24

    1612.34 Mhz - Very narrow ~ 1 channel ( total bandwidth was             sept99
       .2 MHz, over 1024 channels=> 1channel = 0.1953 kHz)
       It was not seen last July, 1999.  Always present, Mike Davis thinks it is internal (variable strength).

    1665.36 MHz, - New birdie lasted for ~ 10 min on 09/07/1999,
       (about 4:30 am). Only on Pol B.

    1720 MHz, weak or absent from 4AM to 6AM, strong after sunrise,
       Project A1518          April, 2002

    2700       sj radar 1350 2nd harmonic seen in rfi system. maybe us          may96

    2900-3100        SPS-48 radar at Pico del Este. Radiates at 9 distinct frequencies simultaneously. Peak Power Output (EIRP):
      2.2 MW at low elevations
      600 kW at intermediate elevations
      60 kW at high elevations
      Pulse Repetition Frequency:  640 with some jitter
      Rotation rate: 15 rpm
      Pulse width: 26.5 microseconds
      A spectral plot taken at Roosey confirms the spread in transmission frequencies but with most emission confined within 2990 and 3060 MHz. The AO monitoring shows the same characteristics. It appears that the 9 frequencies can be chosen by the operator anywherewithin the band to adjust to range requirements.       jun13

    3050           pico del este navy radar.     seen in rfi system       may96

    4050            sj radar 1350 3rd harmonic    seen in rfi system. maybe us       may96

    5400             sj radar 1350 4th harmonic    seen in rfi system.       may96

    6100             pico del este navy radar.2ndH seen in rfi system  maybe us       may96

    6750          sj radar 1350 5th harmonic    seen in rfi system. maybe us       may96

    8100            sj radar 1350 6th harmonic    seen in rfi system. maybe us       may96
     
     

     return to TOP
     
     
     
     


    RFI Identification by Source/Type(MHz)
     

    Internal

     
    MULTI METER   see a Report
    93.75Kb/sec                communications with front panel processor
    1.5Mb/sec                 measurement config register comm.
    strongest birdies 425-435  door open 5aug99
    427.485
    429.741  strong
    430.486  strong
    428.??                   digital multimeter for tilt sensors..

     
    PWRMETER
    strongest birdies 425-435  5aug99
    429.157
    433.325   strongest.. visible with door closed
    CAMERAS
    strongest 425-435 .. 5aug99
    429.096   visible door closed
    429.550   visible door close
    429.098   narrow aug99   camera in dome
    429.544   narrow aug99   camera in dome
    432.024   narrow aug99   gets smaller when camera in dome turned off, but doesn't go away completely.
     
    1373.122  narrow aug99   camera in dome
    1382.646  narrow aug99   camera in dome
    1392.195  narrow aug99   camera in dome
    1420.798  narrow aug99   camera in dome
    1420.808  narrow   jul99   cameras in turret room.
    1430.347  narrow aug99   camera in dome
    1449.397  narrow aug99   camera in dome
    SYNTHESIZERS
    1160    tone     apr99   ch1 synth for lband feed for serendip.
    1300      bw=39 kHz             CH2 synthesizer

              1324.8   bw=78-156 kHz             From 1420 LO system when HP
                             synth. not plugged in. Plug
                             synth. into rack B.   nov92
              1350      bw=39 kHz            CH2 synthesizer, also FAA radar  Pico del Este
              1400      39             CH2 synthesizer
     

    External

    BEEPERS
    452.275   452.275  1    single peak. looks like a beeper/or data comm.
                  904.55    2        19jan99
                 1356.825  3
                 1809.1     4
     
    462.875   462.875  1         Boriquen Beepers.. strongest around center 462.875 . 2
                  925.75    2          1 peaks separated by 8khz at the fundamental
                1388.625   3          Contact: Luis Leva          2sept99
                1851.5      4           Phone: 782-1383
              1388.55  3rd harmonic 462.85 beeper system. megapage  1996

                                    1998    angel padilla..288-1210..bayamon..    apr93

              1388.6    3rd harmonic of Borinquin Beepers
                                 at 462.875 MHz

              1388.??    two birdies at 1388.539,1388.563. delta=24khz.   dec95
                             avg is the 3rd harmonic of 462.85 . there is a station
                             18 (km,mi?) away in villaba. Although there are many
                             stations in this range. All have 8khz spacing which would
                             fit the 3rd harmonic 24khz spacing...
                             Using the radio in nov. rey an i didn't get a good correlation
                             between the radio at 462.85 and the 1388 birdie when we
                             were up on the hill. When looking at this with specAna be sure
                             and set the rbw real low...

               1389.6                   Present about 4% of time

               1390.8       Possibly 3rd harmonic of 463.6 paging      feb93
                             system Cerro Punta.  Belongs to "Mr.
                             Beeper". Was measured on recent visit
                             to Cerro Punta(may not within FCC
                             specs,just barely), in the process of
                            contacting owner.
     

    FM
               1353.3       Riccardo G. 13th harmonic of WERR-FM  at 104.1 MHz    mar92

     
    RADARS
     
    radars
                    432,428 MHz   bw=2 MHz   ipp 3.5,4.6,3.3,4.2 millisecs
                        antenna sweep rate about 7.8 rpm. appears to southeast.  dec96
                    1294.8 MHz  bw=1.5 MHz    Radar 5rpm ipp 2.7ms, 5us pulse,
                         not locked to 1307.5, Punta Salinas Radar  nov92
     

                              1430.2   bw=1 MHz            Military radar
                              1432.2   bw=1 MHz            Military radar
                              1434.1   bw=1 MHz            Military radar
     
     
    Hawkeye radar (airborne)
                    410-445 MHz   bw=6 MHz   10 or 12 sec rotation ipp 3.28 millisecs

     
    Aerostat radar
                    1246.2,1261.2 MHz
                       aerostat mou. L-88A RADAR.

                                 160 usec 1261.2 then
                                 160 usec 1246.2
                                 bw 1.67Mhz, prf 305(avg)

              Pico del Este
                                1330     bw=1.5 MHz            FAA Radar, Pico del Este
                                1349.6   bw=1.5 MHz            FAA Radar, 6 us pulse 1330,1350,
                                   pp 2.813896ms
                                 2900-3100 SPS-48 radar at Pico del Este. Radiates at 9 distinct
                                                frequencies simultaneously. Peak Power Output (EIRP):
                                                2.2 MW at low elevations        jun13
                                                600 kW at intermediate elevations
                                                60 kW at high elevations
                                                Pulse Repetition Frequency:  640 with some jitter
                                                Rotation rate: 15 rpm
                                                 Pulse width: 26.5 microseconds
                                                 A spectral plot taken at Roosey confirms the spread in
                                                 transmission frequencies but with most emission
                                                 confined within 2990 and 3060 MHz. The AO monitoring
                                                 shows the same characteristics. It appears that the
                                                 9 frequencies can be chosen by the operator anywhere
                                                 within the band to adjust to range requirements.

                        3050          pico del este navy radar.     seen in rfi system

                                  6100    pico del este navy radar.2ndH seen in rfi system  maybe us
     
    Punta Salinas Radar
     
    San Juan Airport
                    2700        sj radar 1350 2nd harmonic        may96

                              4050        sj radar 1350 3rd harmonic    seen in rfi system. maybe us
                              5400        sj radar 1350 4th harmonic    seen in rfi system. maybe us
                              6750        sj radar 1350 5th harmonic    seen in rfi system. maybe us
                              8100        sj radar 1350 6th harmonic    seen in rfi system. maybe us
     
     
     
     

    SATELITTES

              GPS

                    1227.60 MHz                  GPS L2
                    1381.05 MHz bw=1MHz   GPS L3 satellites          sep91

                                        on the air for 30secs twice a day.
                              1575.42 MHz                   GPS L2
     
    GLONAS
                    1246+.4375n  MHz    GLONAS L2.n=1->24,n13-24 shutdown soon. leaving
                                 n=12,21,22, and 24     aug98
                    1602+.562n        GLONAS.n=1->24,n13-24 shutdown soon. leaving

                                           n=12,21,22, and 24     aug98
     TV
            1422.5       2nd harmonic of WCCV-TV CH 54 and
                             other unidentified source, seen when
                             WCCV off"
     
     

     return to TOP
     
     


    RFI Found and Fixed

    Aug99 S-Band  wide, strong, and random around 2380MHz.  The shutter of s-band receiver was oscillating due to a micro switch not being actuated completely.
     

     return to TOP