The datataking setup
  xmitting a birdie from the visitor center platform to find the az peak.
The  shutdown sequence
Monitoring the turnoff, turnon with 327.
Processing, plotting the On,Off,On datasets
Table of rfi found during test.
Notes on the test.


  The power at the visitor center was shutdown on 01nov11 starting around 13:00 hours. Data was taken with various receivers, before, during, and after the shutdown to investigate rfi coming from this area. Prior to the shutdown birdies were transmitted from different positions on the visitor center platform to find the azimuth of the strongest signal.
    The shutdown included the visitor center, learning center, coffee bohio, sband power supply building. The air compressors for the backstay cables were not shutoff.

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The datataking setup:

• telescope: az 364.82, dome=19.0034, ch at stow.
• this position was determined by transmitting a birdie from the visitor center platform.
  
• Mock setup:
• 8192 channels, polA,B dumped at 1 second integrations.  Bandwidths varied by receiver.
  
• Receivers used. The sequence listed is the order the data was taken (by position on the turret floor).
  
• 327 receiver:  entire band. Resolution bandwidth (rbw):5.2 khz.
• lbw receiver: entire band. rbw: 7.0Khz
  
• 430 receiver. entire band. rbw: 1.9 KHz
• 800 receiver. entire band. rbw 2.3 Khz
• sbw receiver. bands within our filters:
• 1700-1880. rbw: 10.5Khz
• 2040-2400. rbw: 7khz
• 2600-3100. rbw:7khz
• prior to turn off, after turn off, after turnback on:
•  data was taken for 200 seconds for each reciever (sbw needed two sets of 200 secs to cover the entire band).
• The command file is in /share/obs4/usr/x111/shutdown.cmd
  
• During the turn off, turn Back on.
• the 327 receiver was left running during each transition to catch changes as they occurred.

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The  shutdown sequence: (top)

1.   prior to shutdown start of 200 sec monitoring for each band:
   
• 12:57 327
• 13:02 lbw
• 13:06 430
• 13:10 800
• 13:16 sbw1
• 13:19 sbw2
  
2. shutdown
• 13:25 start 327 continous monitoring
• 13:30 main power off to trailer,learning center,visitor center
• (need better resoution on this)
• 13:32 learning center completely off (does this mean ups's?)
• 13:33 trailer off (ups's?). learning center lacks 2 cpu's to shutoff (what was 13:32?)
  
• 13:45 wait to turn off ups in power supply building
• 13:49 all off.
  
3.  start data taking cycle all off.
• 13:50 327
• 13:54 lbw
• 13:58 430
• 14:03 800
• 14:07 sbw1
• 14:11 sbw2
4. Turn back on:
   
• Below are the times reported over the radio.. some locations are a bit general.
  
• 14:17 start continuous monitoring with 327 (all still off)
• 14:37:00 main breaker closed
• 14:37:30 visitor center breaker closed
• 14:37:55  480 breaker ?
  
• 14:38:09  breaker ac main building
• 14:38:27  breaker ac main building
• 14:38:39  breaker ac main building
• 14:38:50   breaker #5 ac main building
• 14:38:59  learing center breaker
• 14:39:12   ac breaker
• 14:39:25  ac offices main building
• 14:41:16   ups trailer on
• 14:43:50   all trailer is on (different than 14:41:16?)
• 14:45:00  bohio on, visitor center on (ups's??)
• 14:46:00   all back on including sband piower supply building.
  
5.  datataking cycle all on again
• 14:47 327
• 14:52 lbw
• 14:54 tiedowns turned off for bad weather
• 14:55 430
• 15:00 800
• 15:05 sbw1
• 15:09 sbw2

During the process we had occasional lightning induced rfi (increasing toward the end of the test).

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monitoring the turn off, turn on with 327 (top)

    The dynamic spectra  images show the 327 receiver during the turnoff and then turn back on.

• There are two bands for each measurement: cfr-315 Mhz and cfr 339Mhz.
• processing to create images:
• create median bandpass
• fit a 20th order harmonic function and then divide each 1 sec spectr by this
• remove the median value from each spectra
• scale range to +/-5 sigma (using robust sigma estimator).
• average the horizont m If any rfi was coming from the visitor center (in the 327 band) you would expect the rfi to go away in the turnoff image and return in the turn on image.

	band 1 315 Mhz cfr	band 2 339 Mhz  cfr
Turn off	turn off(.gif)	turn off (.gif)
turnon	turn on  (.gif)	turn on (.gif)

Dynamic spectra notes:

• Lots of narrow birdies in 327. The alfa motor controller was also checked and it only generated 1 birdie.
  
• 337.67  birdie from area. turns off during turnoff, returns during turnon.
• turnoff timing isn't specific enough
• turnon: may be trailer or bohio..
• Birdies that disappeared in turnoff or reappeared in turnon, but not in both:
• 322.2
• turned off during shutdown
• stayed off during turnon
  
• 333.3
  
• turned off during shutdown
• stayed off durint turnon
• 335.9
  
• was not present during shutdown
• came on during turnon
• 358
• turned off during shutdown
• stayed off during turnon
• horizontal lines:
• especially during the turnon. Probably lightning.
  

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Processing, plotting the on,off,on data.

Processing the data:

   The data from the datataking sequence: powerOn,powerOff,powerOn was processed as:

• compute the average spectra, and rms spectra for each of the 200 second integrations in the on,off, and on power setups.
• This was about 150 files.
• Using the rms by channel for the power off measurement, create a mask excluding strong rfi in each band.
• for each 200 second average spectra fit a 50th order harmonic function (8192 channels in each spectra). Use this fit as the bandpass correction.
• Divide each average spectra by the bandpass correction then subtract 1.
  

Plotting the dat, finding the rfi:

• The power off, power on 1, and power on 2 were overplotted using color to separate the plots (offsets were also added to separate the plots).
• Each page contains 1 band.
• Top: polA, bottom polB
  
• rfi from the visitor center was identified by:
• The line was in the power on1, and the power on2
• The line was not in the power off.
• It was ok (although suspicious) if the rfi was only in polA or polB

The table below shows:

• the plots for each receiver with
• number frequency bands measured
• list of rfi frequency that wer in the ons and not the offs.
• Some notes onn each freq.
  

Table of rfi freq from visitor center shutdown

receiver	#numbands	rfi Freq Mhz	Page	Notes
327 (.ps) (.pdf) 302-352Mhz	2	337.67	2	only seen in dynamic spectra 327 is very noisy. alfa motor controller was on
430 (.ps) (.pdf) 422-442 Mhz	2	422.45	1	polB
		427.37	1	polA
		429.16	1	polB
		436.77	2	polA,B
800 (.ps) (.pdf) 700-800 Mhz	7	729.00	2,3	polA,B
lbw (.ps) (.pdf) 1120-1750Mhz	14	1249.97	3	polA,B.. maybe something weak in Boff?
		1485.00	9	polA
		1560.64	10	polA
sbw (.ps) (.pdf) 1700-1790 2040-2400 2600-3100	24	-	-

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Notes on the test: (top)

• The 327 band has lots of narrow birdies.
• The alfa motor controller was left on during the test. Later measurements   showed it was generating a single birdie in the 327 band.
• The dome cameras were also left on. Back in mar11 they were generating a 14 Mhz comb.
  
• For the monitoring during the turnoff,turnon it would help pinning down any rfi if we had better info on what,when  was being turned on or off.
• There needs to be a central person that oks each turnon,turnoff before it happens. Probably best if this was in the control room since they have accurate timestamp info.
• The sequence should be:
• get radio communications
• describe what is being turned off
• turn it off and report the time to within 1 or 2 seconds.

processing: x101/111101/shutdown_327onoff.pro, siteshutdown.pro, onoff1rcvr.pro,baslin.pro,fitbas.pro