Notes from run at Goldstone  6/20/00 -- 6/21/00
observers: PG, CN, DS

Highlights
----------
* We have a cabinet.  Combination 8041.

* We used the MMS filter bank (* Is this the right name? *) to split
the S-band RF at DSS13 into two channels before downconverting.
  
This way each channel can trigger at a higher rate as long as the
coincidence rate is below about 1kHz.  The coincidence at DSS13 is
used to make the 150 usec gate in RARG which is "and"-ed with the
coincidence from DSS14.

  center frequency IF1= 210 MHz,  IF1 attenuation= 3dB
  center frequency IF2= 330 MHz,  IF2 attenuation= 3dB

Using the spectrum analyzer, the 3dB pass band is:
  IF1:  380--342 MHz
  IF2:  193 -260 MHz

Note that each IF band was down 15 or 20 dB by the beginning of the other
band.

We timed them in using sparks and found them remarkably consistent 
(<5 ns).

* We checked how low of a pulse one can reliably trigger the SR400 and
found 5-6mV  (display says 1mV) is it. 

* We set up the trigger as 4 signals -> IF amps (3 minicircuits, 1 HP)
-> attenuators -> diodes -> DC block -> LP filter -> SR445 DC-300MHz
amplifier -> SR400 for discrimination -> Nim discriminator for pulse
stretching to 10 ns.  The DSS 13 signals only were used this night
since DSS14 was unavailable.  They were and-ed in a NIM coincidence
unit.

* Using a DSS13 signal at -35dBm (V_rms=4.05 mV) we measured the
trigger rate vs. threshold.  See plot thr_vs_rate_1.eps.  Drops ~x2
every 2mV.  From this plot we conclude that we should not try to
trigger below 15mV where it becomes non-exponential.

* We checked that the singles rates from the two IF channels at 13 were
independent by using thermal noise.  We found that the singles rates were
exponential and that the coincidence rate followed R^2 delta-T  very well
until about 100 Hz, which may be RFI.   See plot doubles1.eps.

* Using the new trigger at DSS13 we took noise data from the moon for
about 2 hours.  We estimate that the discriminator levels were each
about 3.5 sigma.  A total of 22 events were written to disk.  There
were two events that did not look like obvious RFI (events 3 , 19)


To do for next time:
--------------------
* Finish replacement of RG-214 with hardlines at DSS14
* Remember to check timing of trigger overlaps from DSS13!
* Purchase more assorted filters and esp. BLP-100 and BHP-50.
* Purchase a 4th minicircuits amplifier for the IF
* Buy more short cables
* Call vendors to find delivery times on existing orders
* Purchase/make  some DC blockers
* Need the diodes next run (T. Couse says our new 8 will arrive in time)
* Bring an SR400 from loan pool just in case
* Make photocopies of manuals to store in cabinets
* Bring a new  8110A from loan pool and return other for calibration
* Bring back power meter
* Bring lemo--BNC connectors  
* Bring rack mount project boxes