ethernet switch rfi
26apr06
26apr06 trenddata 1 gigabit
switch
The trenddata gigabit switch makes rfi
that can be seen in the 327 Mhz receiver. On 26apr06 we looked at one
of the switches in the digital lab using the tektronix portable spectrum
analyzer. Most measurements used a 1 Mhz span (probably a 1 or 2 khz rbw).
The findings were:
-
When the fiber optic module is not inserted in the switch, there is very
little rfi.
-
When the fiber optic module is inserted in the switch there is lots of
rfi. This rfi changes depending on whether or not the fiber is connected
to another switch or not.
-
Fiber not connected:
-
Largest birdie at 476.6 Mhz. When placing a loop antenna close to the box,
the amplitude is 40 to 50 db above the noise floor (1 Mhz span Probably
1 kHz rbw).
-
There are lots of similarly large birdie throughout the 300 to 500 Mhz
band.
-
Fiber connected:
-
The largest biride is now 437.6 . Gets up to about 60 db above the noise
floor. Most of the other birdies in 300-500 Mhz band have gone away.
-
The strongest birdies were at (freq, amplitude above the noise floor):
-
437.6, 60 db
-
562.5, 50 db
-
1125, 30 db
-
1937, 40 db
-
2062.5, 42 db
-
In both cases the birdies have side bands that are about 200 Khz away.
<--
page up
home_~phil