• the netgear prosafe gs11t is the same switch but without the power over Ethernet.
  

06sep12:netgear gs110tp switch emissions in the screen room:

   Luis measured the emissions of the netgear prosafe gs110tp switch  in the screen room on 06sep12.

Luis' setup and results (.pdf)

The setup was:

• Agilent E4445A spectrum analyzer:
• average 20 sweeps
• 8192 points/spectra
• 6db attenuation , preamp on
• 100 MHz span, 12.5 Khz/rbw. covering 0 to 3000 MHz in 30 spectra
• 904 Efield probe with a 15 foot coax cable.
• activity
• copper port 8 was plugged into ao net
• linksys 1GbE SX Mini-GPIC SFP module installed, but no fiber connected to the module.

• Luis measured the emissions with the 904 Efield probe close to the connected copper Ethernet port 8.
• He also measured the emissions at the power supply module (external to the device).

The plots:

    The plots show the emissions from the devices.

• The first page shows plots of 0-1000 MHz, 1000-2000MHz and 2000-3000MHz
• The 2nd page shows some blowups around some of our receiver bands:
• 300-500 MHz (327,430)
• 1350-1550 MHz (lbw)
• 2000-3000 MHz (lbw)
  
• Emissions at switch port 8 output (.ps) (.pdf)
• The strongest birdie is around 800 MHz at -78dbm
• page 2 shows that there are 3 combs:
• 14.2854 MHz .
  
• You can see it  from 200 MHz up to 2000 MHz
• The strongest birdie within our rcvr bands is: 428.55 MHz  at -84dbm.
  
• 20.8358 MHz
• You can see this from 300 to 3000 MHz.
• the strongest birdie within our rcvr bands is: 2812.83 at -89dbm
• 100.00 MHz comb
• this is seen 100 through 3000 MHz.
• I thought it might be coming from somewhere in the screen room (our 100 MHz distribution), but it is not seen in the power supply plots, so it must be coming from the network switch.
  
• The strongest birdies  is at 800 MHz at -78dbm.
• The strongest birdies in our receiver bands:
• 1600 MHz -87 dbm
• 2500 MHz -92 dbm
  
• Emissions from the power supply (.ps) (.pdf)
• These emissions are similar but much weaker than the port8 output. Nothing is seen about 800 MHz.
  

Summary:

• The emissions from the switch are much stronger that the power supply
• there are 3 combs
• 14.285 MHz
• 0-2000 MHz
• 20.836 MHz
• 2000-3000 MHz
• 100.00 MHz
• 0 to 3000 MHz
• This comb over laps with the two previous combs:
• 7*14.285=100 MHz
• 12*20.836=250 MHz.
  
• The table below summarizes the strongest birdies
  

• freq MHz	amplitude dbm	Notes
  285.366	-75	14.284 comb. strongest birdie
  328.56	-83	14.285 comb. strongest element in 327 rcvr
  416.716	-86	20.836  comb. strongest elements in 430 rcvr
  800	-78	14.285 and 100 MHz combs overlap here. strongest birdie 0 to 3000 MHz
  1375.16	-84	20.836  strongest birdie lbw rcvr
  1200 1400 1500	-79	100 MHz birdie strongest values in lbw overlaps with combs:
  2500	-85	100,20.836,14.284 combs . largest value in sbw rcvr

• 'comparing the gs110t ad gs110tp switch
• The birdies occur at the same frequencies
• the gs110tp birdies are stronger
• the 20.836 comb is seen all the way down to 300 MHz in the gs110tp device. In the gs110t it is weak below 2ghz.
• gs110tp  baseline has large variations (15db) over 10 to 700 MHz with a period around 100 MHz. Part of this is also seen in the power supply.  I don't know if this is coming from the switch or maybe the cable from the probe to the spectrum analyzer.
  
• This switch probably needs to be shielded.
• We also need to test this switch with a fiber optic cable installed to check on the fiber transceiver.
  

processing: x101/rfi/miscdevice/netgearsw_gs110t_120006/do_gs110tp.pro

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