Yearly movies from hilltop rfi monitoring system
The hilltop rfi
monitoring system does uses a receiver box and spectrum analyzer to
monitor 0 to 10 GHz (using 20 separate bands). The data acquisition
- loop over the 20 bands covering 0 to 10 GHz
- configure filters, amps, spectrum analzyer for 1 band
- do a 1 minute peak hold
- read analyzer, write data to disc
- move to the next band
Yearly movies were made by taking a daily
average over each band.
Some problems with the movies
- When the 430 or 2380 MHz radar is used, spurious signals get
generated in many of the bands.
- via software (and then manually) i tried to exclude
all spectra taken while one of the radars was on.
- Occasionally the switch driver would not switch when commanded
to. You would get data from the wrong frequency in a band.
- This did not happen very often. I tried to edit out most
of these problems.
- For some periods, the air conditioner in the rfi shack was not
working correctly. This changed the gain of the system
- some of the baselines will jump up and down a
little from this.
- The value displayed are the dbm levels measured at the
- Each band has a different set of filters/amplifiers so the
band to band values will vary.
- The high frequency bands have less sensitivity.
- They use a 1-10Ghz amp. The gain can not be increased
because of saturation from the cell phone bands.
- Some rfi makes harmonics/intermods in the system.
- The aerostat radar balloon at 1246,1261 causes birdies
at 3200, 3400
- The cell phone bands: 1900,2100 cause birdies at 3900,4100.
- In the movies i've put solid lines (white,red) around the
- dashed colored lines bound the frequencies where the
internally generated birdies may appear.
For each year 2 sets of movies were made:
- low freq movie covering 260-1250Mhz in 6 band
- hi freq movie covering 1200-7000 Mhz in 6 bands
- 31oct19: 330 and 430 bands absent.. relay failed that
controlled these two bands.