Intro
On 22oct22 we used the field fox spectrum
analyzer to measure the 12meter spectra at the input to the
postamp chassis (before the rf filter).
Setup:
- telescope position
- We took data at 3 separate positions:
- az,el= 157.4,26.0 (location of 12meter at
start)
- az,el= 170,0,30.0 (location used 11mar22)
- az,el=236.0, 39.8 (location of 13oct22data
)
- field fox:
- freq range:1750 to 2750 MHz
- the sband waveguide has a cutoff round 1400 MHz.
- rbw=1MHz
- attn=0, preamp on
- trace: clrWrite, avg(10sweeps), peakhold (30 secs)
- 1001 points.
- input signal: polB cable that normally plugged into the
input of the postamp chassis. This is before the rf
filter.\
The spectra:
The plots show the sband polB spectra at the postamp
chassis input(.ps) (.pdf)
- This is before the sband rf filter.
- Page 1:
- Data was taken at 3 telescope positions. Each
position is plotted in a different color.
- black: az,el=157.4,26
- red: az,el=170,30
- green: az,el=236,39.8
- Top frame: Spectra of a single trace.
- The purple dashed lines show the 3db edges of the
sband rf filter
- Bottom frame: 30 second peak hold
- The upper half of the brs band are stronger at az=170
deg.
- The different bands are labeled at the bottom of
the plot:
- pcs: Personal
Communications service
- aws1: Advanced
Wireless Service -1
- aws3: Advanced
Wireless Service-3
- aws4:Advanced
Wireless Service-4
- wcs: Wireless
Communications Service
- brs: BroadBand
Radio Service
- Page 2: compare 11mar22 spectra with the 21oct22 spectra
- Black:21oct22
- red: 11mar22
- The only difference in the setups was 11mar22 had a 5db
attenuation while 21oct22 had 0db.
- rfi changes:
- 2400-2450: more rfi 11mar22. but this is the ism
(internet) band. You'd expect things to change minute to
minute depending who is online.
- 2450-2690: brs upper half. More rfi 21oct22.
processing: x101/221021/sbrfi.pro