(galfacts) reported strong rfi (lots of overflows from the mock
spectrometer) on the evening of 02nov11. The punta salinas
frequency agile radar was running in all frequencies until about
ast (it then changed to mode A 4 frequency mode). After the mode
switch, the users reported still having some trouble with rfi
less than before the radar moved to mode A).
A2130 used the mock spectrometers with 172 MHz bw, 4096
millisecond full stokes dumps.
Data from 22:35 ast was used to check the
The dynamic spectra
record of data (600 ms) (.gif)
- the dynamic spectra has a time resolution of 1
- the pulsed radar have ipps of 1.4 to 3 millisecs.
- The horizontal axis has increasing frequency to the left.
- Some of the rfi is:
mode A 4 frequencies:
- 1258.34, 1248.9, 1242.2, and 1234.1440.
- The radar transmits two frequencies (separated by 15
simultaneously then hops to the next pair:
- (1258,1242) and (1248,1234).
- There is also a long and short range mode.
- 1270 boriquen radar
- faa Radar 1330,1350
- Many intermods which look to line up in time with the
salinas 4 frequencies.
The punta salinas radar blanks their transmitter when it points
observatory. 65 seconds of data (1 file) was checked to see that
the blanking was still aligned with the direction of the
The plots show the
power vs time for the 4 punta salinas mode A frequencies (.ps)
- The 4 frames are the total power vs time for the 4 punta
- I took the peak channel value around each radar
- The plot shows 65 seconds of data with 1 millisecond time
resolution. The horizontal axis is label hr.hr ast.
- You can see where the power from the radar completely goes
- This is when they blank in our direction.
- The blanking is spaced by 12 seconds (the radar rotation
- The power levels on each side of the blanking is close
peak value. This tells us that the radar blanking is
aligned with the
600 milliseconds of data was used to verify that the intermods
the dynamic spectra) are actually coming from the punta salinas
The plots show the total
vs time for the punta salinas radar and the intermods (.ps)
- Page 1: avg and rms for the 600 milliseconds.
- Top; average spectra. The colors are polA,B,stokes U and
- The vertical scale in spectrometer counts (16 bits
- Bottom: rms/mean for each channel.
- The puntasalinas have strong variability (probably
- Page 2: overplot the punta salinas pwr vs time and the
- Top: 300 seconds of data.
- black:1256,1241 frequencies transmitted together
- red: 1247.8, 1232.8 freq transmitted together
- green: 1298.6. this aligns with the black frequencies
- blue: 1289.5. this aligns with the red frequencies.
- blowup in time showing the alignment of the intermods
- Overflows in the fft butterfly section of the mock
can splash radar power across the band. I checked and this
I looked at the number of mock overflows a2130 has had in its
The plot shows the number
mock overflows by observing session (.ps)
- The vertical axis is a log scale
- the session dates were:
- So the dates were not contiguous.
- the blue dashed line is where the cals started.
- the red dashed line is the night punta salinas ran in all
till 20:00 ast
- If i throw out the data prior to 20:00 for this date,
about 500 overflows. This is similar to other nights. So
comment about continued problems after the modeA switch
something different from other nights.
- There is a large variation in the overflow errors vs
- They are covering the same za range (except the cals add
counts in a few regions).
- The scattering of rfi into the dome is za dependent
with much more getting in at some narrow za ranges.
- The radars have 12 second rotations.
- The variation in counts by session may be the
when the dome was at certain za's vs when the radar
- punta salinas radar ran in all frequencies for the first
(till 20:00 ast) of the a2130 run on 02nov11.
- They then moved to mode A.
- mock spectrometer overflows continued as well as birdies
appearing at frequencies other than the standard radar
- Looking at the dynamic spectra and the plots, many of
birdies were being created (probably in our system) by the
- The blanking of the punta salinas transmitter was working
correctly during this period.
- The radar was blanked for 2.537 secs
- 2.537sec/12sec * 360. = 76.1 degrees blanking.
- This is a less than the +/-45 degrees we had back in
- Looking at the mock spectrometer overflow errors, they
grouped in time. This was probably a geometric affect (the
moving from 2 to 20 degs za).
- The faa radar was also running during this time..
- Excluding the mock overflows before the radar went to mode
02nov11 session overflows was similar to other nights.
- There is a large variation in overflows by observing
This may be a beating of the dome being at a particular
postion and the
12 second rotation period of the radar.