• U-NII -is an abbreviation for Unlicensed National Information Infrastructure radio band used for internet communications
  

 Intro: (top)

• 4990-5000: radar astronomy, space research (passive)
• 5000-5010: aeronautical radionavigation, radionavigation-satellite (earth-to-space)
• 5010-5030: aeronautical radionavigation, RADIONAVIGATION-SATELLITE (space-to-Earth) (space-to-space)
• 5030-5091: AERONAUTICAL RADIONAVIGATION
• 5091-5150: AERONAUTICAL RADIONAVIGATION
• 5150-5250: 
• federal: AERONAUTICAL RADIONAVIGATION
• non-fed:AERONAUTICAL RADIONAVIGATION,FIXED-SATELLITE (Earth-to-space), RF devices

• The data from a2765 is examined (01mar13).
• The hilltop monitoring data shows when this rfi increased
• a spectrum analyzer and helix antenna was used to find a direction for the rfi.
• A trip in the rfi van was made to yiyi avila's tower.

01mar13: 5020 rfi in a2765 data. (top)

• the 5015-5025 rfi is present for the entire time.
• a weaker 4970-4950 is also seen.

Hilltop rfi monitoring sees the rfi appear.  (top)

• Page 1 Top: power vs date:
• For each 1 minute peak hold, 20 MHz about 5020 was averaged and then plotted vs time.
• 12feb13: jumps from -58 to -56 db
  
• 22feb13:increases from -56dbm to -47dbm on 26feb13.
• Page1 bottom: power vs hour of day
• The power is plotted vs hour of day.
• There is a slight increase in power peaking around noon. This may temperature variation of the amps .

• The average spectra at 5000 - 6000 MHz is plotted for each day.
• The data yymmdd is printed at the top left of each plot
• the 5020 rfi starts to increase on  13feb13. 
• a second increase in intensity occurred around 21feb13.

• each image is a separate day (the date is in the upper left).
• There is weak rfi in 5015 - 5035  until 12pm. 12feb13 .. this is on the left side of each plot.
  
• at 12pm 12feb13 the 5015-5025 rfi gets a lot stronger.
• there is a small step down in frequency at 19:30 on 22feb13
  

24may13: looking for the rfi from the platform.  (top)

• The amp was a jca48-200: 4-8 Ghz, 20db gain, 1.6 db noise figure.
• denis and i then went to the platform with this setup.
  
• The rfi was coming from the direction of yiyi avila's tower.

30may13:1st trip to yiyi avila's tower:

    On 30may13 dana and i drove out to within 2 km  of yiyi avila's tower in the rfi van.
the plots show the strength of the rfi close to the tower (.ps) (.pdf):

• The receiver setup was:
• cband helix with jca amp.
• short cable then anritsu spectrum analyzer with preamp on:
• rbw set to 1 MHz
• average 10 sweeps and do a peak hold in trace b.
• The black trace is an average of 10 sweeps. the red trace is a max hold.
• The colored vertical lines show some of the prominent bands:
• 5010 -5029
• 5028-5044
• 5101-5118
• 5120-5182
• These band are wider than those seen in the AO data. If the limits were set at the 3db points they would be much closer in width.
• These strong rfi went  down in strength when we pointed the helix 90 degrees from yiyi's tower.
• There are weaker bands. It was hard to see if they went down when we pointed away from yiyi's tower since they were so close to the noise floor.
• The van was 1.8Km from the tower.
• The google maps image shows the location of the van (pointA) and the tower (point B) (.pdf)

04jun13: 2nd trip to yiyi avila's tower.

    On 04jun13 angel and i drove out to yiyi avala's tower. We arranged to meet the tower engineer at the site. We used the anritsu spectrum analyzer for the measurements. Its setup was:

• helical antenna centered at 5 ghz.
• jca amp then short cable to spectrum analyzer (about 1 meter).
• preamp on (when 2km from the tower). preamp off when at the tower.
  
• avg 10 sweeps, and also record peak hold.

• The black trace is an average of 10 traces. red is a peak hold.
• Top: Measurement taken 1.8 km from tower with helix pointing at the tower.
  
• This is from the same location as the 30may13 data above.
• The dashed green line shows the start of the unlicensed band. All of the Internet communication bands should be above this.
• Bottom: 
• data taken at the bottom of yiyi avila's tower.
• This is after the del Vivi net equipment had been turned off by the tower engineer.
  
• The rfi 5010 -> 5080 went away when this equipment was turned off.
• The engineer then called the  company and they stopped broadcasting on these frequencies.
  
• The engineer also turned off the 4net equipment. This caused the 5100 rfi to go away.
• He then turned the equipment back on (he didn't leave it off long enough for me to record a spectrum).
• The engineer called the company and left them a message (they were out at the time of the call).
  
• It's interesting that 2 km from the tower, the "5100" MHz rfi was centered at 5110. At the tower (with the preamp off and the 5010-5100 rfi off), the band was then centered at 5100.
  

04,05jun13: hilltop monitor data shows rfi turning off.

    The hilltop rfi monitor data was examined to see when things got  turned off:

• 04jun13:
•  dynamic spectra (.pdf)
• 11:15 - This is where the engineer shut off  del vivi.net equipment. The network owners then stopped using that frequency
• The weak  5030 and 5055 birdies both went off. These correspond to the data going off in the spectrum taken under the tower.
• The strong rfi (seen in the hilltop data) at 5020 did not go away.
• The 5020 signal did go away at yiyi's tower. This means that the company was probably also broadcasting at this  frequency from a different tower (that was probably closer to AO).
• 19:15: The strong 5020 rfi went away.
• A strong signal then appeared at 5540 MHz.
  
•  My guess is that the company operators probably decided to stop broadcasting illegally at their other tower location. They moved from 5020 to 5540 (which is a legal frequency for them to broadcast on).
  
• Average spectra from hilltop data (.ps) (.pdf)
  
• This plots shows 3 separate spectral averages from 04jun13.
  
• black: midnite to 11:00
• . this is before anything was turned off
• red: 11:15 to 19:00
• The vivi.net equipment had moved out of the 5010-5100 MHz  band
• green: 19:15 to midnite.
  
• The strong 5020 rfi moved to 5540 MHz
  
• 05jun13:
• dynamic spectra (.pdf)
• 12:15 - The 5100 MHz rfi went off the air.
• I guess the company finally got around to moving to a legal frequency
• Average spectra from hilltop data (.ps) (.pdf)
• There are two separate averages for 05jun13
• black: 00:00 to 12:00 - the 5100 MHz rfi is on
• red:    12:30 to  16:45 - 5100 MHz rfi is off.
• there is stilll some narrow rfi around 5010 - 5030.
  
• You can see this as irregular single channel spikes in the 05jun13 dynamic spectra. I'm not sure whether these are coming from the same source as the original 5010-5160 rfi.

05jun13:cband 5-6 Ghz on the telescope after rfi turned off.

• az=285, za=10
• 172 MHz/band each with 8192 channels.
• 400 1 second records were recorded.
• Dynamic spectra, average records, and rmsbychan/mean plots were made:
• PolA and PolB were averaged
  
• Processing:
• Dynamic spectra: images were divided were divided by the average bandpass
• Average spectra: 400 second average, then normalized to the median of each band
• average Spectra - fit
• A robust 31st order harmonic fit was made, and then the fit was divided into the average band (to remove the bandpass).

Summary:  (top)

• a2767 reported rfi at 5015-5025 on 01mar13 (or maybe a little earlier).
• looking at the hilltop monitoring data:
• There has been weak interference 5010-5040 for at least all of this year
• 12pm 12feb13 the 5015-5025 rfi  increased in strength.
• around 21feb13 a second increase in power occurred.
• Driving out to yiyi avila's tower proved that this interference is coming from yiyi avila's tower.
• The 5010 - 5100 rfi seen at yiyi avila's tower went away when the del vivi.net equipment was turned off
• The strong 5020-5030 rfi seen at the observatory remained on until  19:15 04jun13.It then moved to 5540 MHz (which is a legal frequency)
•  My guess is that the company was also broadcasting illegally at another tower (closer to AO).
• The 5100 MHz rfi seen at yiyi avila's tower came from 4net equipment on the tower (the signal was only turned off temporarily). On 05jun13 around 12 noon the signale went away.
• The unlicensed band that the internet operators can use is:
• 5150 - 5350 MHz
• 5475-5825 MHz.
• Some of the internet companies that were broadcasting outside of the legal band were:
• del vivi.net
  
• pr-523 km 2.7, hc-04 box 10331 utuado, pr 00641
• 787-467-6466.
• www.delvivi.net  .. there web pages shows their equipment on more that just yiyi avila's tower.
• 4net.inc 
• emanuel gonzalez was listed as the owner.
• carr 2 km 81.5 bo san daniel, hatillo, pr 00614
• Looks like they are part of tv4all .. a "dish" provider company in hatillo.
• On the telescope,
  
• 5000 - 5130 is now clean. 
• 5130 to 5150 rfi is probably illegal.
• 5415 rfi may be illegal (it's out of the U-NII band is looks like internet comm.).
• Pretty much the entire U-NII band: 5150-5350, 5475-5825 is full of internet communications and is unusable for radio astronomy.