Intro
Jade morton (now at colorado state)
brought a novatel multi frequency gps receiver to ao. It was
to be installed at the antenna test shack (next to the lidar
lab). The system consists of a computer with a coaxial cable
going out to an active antenna. A separate power supply is
needed to power the antenna. The cpu will be placed in the
antenna test shack while the active antenna will be on the
roof of the shack.
The picture shows the cpu and the
attached antenna (.jpeg)
22jan14: Measuring the rfi in the
screen room.
Luis quintero measured the rfi from the
antenna and receiver on 22jan14 in the screen room.
The setup was:
- anritsu spectrum analzyer placed inside the shielded box.
- An rf cable out to the 904 antenna probe
- a fiber cable going out of the screen room for control
of the spectrum analyzer.
- The c program anacom was used to acquire the data
- source: /share/megs/phil/x101/anritsu/anacom.c
- command file:
/share/megs/phil/x101/anritsu/cmd.dat.100_3000mhz
- The command file configured the spectrum analyzer to:
- 512 points
- 30khz rbw
- preamp was on.
- step from 100 to 3000 Mhz in 100 mhz steps
- take 10 sweeps at each step.
- store avg and peak hold at each step
- The 904 E field probe was used (more
info)
The plots show the results of the measurements:
Summary:
- The largest spikes that are inside a receiver band are
- near 425 Mhz
- above 1500 Mhz . Looks like there is a spike at 1500 Mhz
- We should test this on the telescope with some on,off's of
the device looking at 425 and 1500.
