18jan18: usrp: downstairs blanking turns on
01oct15: tx pulse 440 and 1000 usecs rf
can we replace the 430tx with a ring of amiser panels?
27mar12: modAnode not staying all the way
off after beam off.
16jan12: waveguide measurements
19oct10: scope trace of protect turnoff
07oct10: 430 transmit pulse sequence timing
chirp transmitter pulse output
measure klystron output of 1 Mhz chirped signal using scope
Hagens 430tx operations and
Ionizing radiation measured in 430 transmitter
mar17: directory holding 430tx power
18jan18:Usrp, downstairs blanking turns
Experiment T3150 ran a clp experiment with
a 6ms ipp and a 346 usec rf pulse. The downstairs thumb wheel
blanking was set to 160 usecs.
Data was taken with the gregorian dome
into the usrp sampling system (no ch ).
- rf signal dome ->downstairs if/lo at 260 Mhz -> 40
Mhz filter -> dana's blanker -> power combiner
(A)-> usrp input
- txSamples from waveguide probe -> atten -> 30Mhz IF
amp -> atten -> mixer (30Mhz ->260 Mhz) -> power
combiner (A) -> usrp
The usrp sampled a combination of the rf
signal (coming from the 430 receiver upstairs.. about
3.5 usecs transit time) and the tx samples (coming from the
waveguide probes in the tx room .. negligible delay).
The receiver signal is blanked
(upstairs in the dome ) and down stairs in the receiver room.
- LO and Rf blanking
- This is done upstairs in the dome.
- If the signal is blanked upstairs at T0 secs, the
blanking will appear downstairs around T0 + 3.5 usecs
- Downstairs blanking.
- Dana's blanker is used to blank the receiver
signal during the tx pulse.
- It uses the test output next to the blanking thumb
- I think it is triggered with the protect pulse. It stays
active for the tx pulse plus the extra delay added in the
Problems with the data.
The usrp data for t3150 was analyzed for
- 17jan18 (about 4 hours then the tx broke)
- the processing went normally
- 18jan18 (15:30 to 7:30 the next day).
- The program could not synchronize (in software) with the
- The program uses the blanking region before and after
the tx pulse to synchronize with the ipp.
Looking at the 17,18th data, the blanking region at the start of
the txIpp was about 10usecs shorter than normal.
The plots show a single tx pulse
for 17 and 18 jan18 (.ps)
- Page 1: tx pulse voltages for 17th and 18th jan18
- Black is the I voltage, red is the Q voltage
- Top plot 17jan18
- Bottom plot 18jan18.
- the blanking region before the tx pulse is much shorter
- Page 2: Blowup around Tx start showing power.
- Vertical lines are drawn for events the occur
(downstairs in the receiver room)
- green: rf on pulse
- blue: beam on
signal. (this occurs 10 usecs before the rf on
- purple: tx ipp (
or protect pulse). this occurs 2 usecs before the beam
- moving forward in time:
- 0 usecs: txipp/protect pulse.
- 2 usecs: beam on request
- 12usecs: rf on
- Top: 40 ns resolution power vs time.
- black is 17jan18 power, red is 18jan18 power.
- The vertical scale is logarithmic.
- Bottom: power smoothed to 1 usec resolution.
What is happening:
- -12 usecs:
- downstairs protect pulse is generated.
- 17jan18. Dana's blanker receives this and immediately
drops the rcvr power by about 25db
- 18jan18. the receiver power does not change. So dana's
blanker did not blank the receiver signal
- the beam on request goes upstairs.
- -4.5 usecs
- 18jan18 rcvr signal shoots up.
- this level is much higher than the tx on power level
(look at the page 1 voltages).
- The 6.5 usecs is about the time it would take a signal
to go up to the platform and then come back down.
- this could be the monoplexor switching into the rf
signal (or maybe some shot noise from the beam turning
- It stays high for about 1 usec
- -3. usecs:
- 18jan18 data gets blanked.
On 22jan18 we checked the test blanking output signal that
went to dana's blanker.
- We found a 1 usec jitter in the blanking signal turning
- The protect signal from the 430 tx into this box, did not
have this jitter (but is was less than 2Volts).
- When routing the test blanking signal to dana's blanker:
- dana's blanker worked correctly. it even followed the 1
- So we don't have an explanation where the 10 usec delay
01oct15: 440 and 1000 usec rf pulse:
Data taken on 01oct15 was used to examine two
different rf pulses:
- 1000 usec rf pulse with 2 usec baud
- The power was about 1 MWatt (measured upstairs) in the
- 440 usec rf pulse with 1 usec baud.
- This was split upstairs into dome and ch. The combined
pulse power (measured upstairs) was about 1.2 MWattts
Both of these pulses were modulated by the coded long pulse
random pn code.
The plots show the different rf pulses
- page 1: Voltage vs time.
- black in real, red is imaginary voltage
- top: 1000 usec pulse, 2 usec baud
- 2nd: blowup 1000Usec pulse .You can see the overshoots
at the baud transitions
- 3rd: 440 usec pulse, 1 usec baud
- bottom: blowup 440 usec pulse.
- Page 2: power, phase vs time
- Top: total power in rfi pulse vs time.
- I averaged for 1 record (50, or 100 ipps) and then
smoothed over time by 16 usecs
- The plot was normalized to the first 50 usecs of each
- You can see the power droop: about 4 usecs in 1000
- The droop rate is the same for pulse rf pulse lengths.
- Bottom:Phase of code vs time:
- the arctangent of(imaginary/real) voltage samples was
- the green lines are fits to the change of phase
(excluding the transitions).
- There is a .01436 Degrees/usec chirp.
- Page 3: average power over entire rf pulse vs time
- the average power over each rf pulse was computed and
then normalized to the median for 50 (25) seconds.
- Top: 1000 usec rf pulse. ipp = 20 millisecs (so sampling
rate is 50 hz) for 50 seconds.
- 2nd: blowup of 1000 usec rfpulse pwr vs time. You can
see a periodic oscilllation for the 1 second of data
- 3rd: 440 usec rf pulse, ipp=10 millisecs (so sampling
rate is 100 hz) for 25 seconds,.
- bottom: 440 usec rf pulse blowup.
- Page 4: spectrum of total pwr in rf pulse vs time
- i computed abs(fft(rftotpwr)) using the data from page
- Top: spectra of 20 ms ipp. The spike at 10Hz is the
alias of 60 hz sampled with a 25Hz bandwidth
- bottom: spectra of 10ms ipp. The spike at 40 Hz is the
alias of 60 hz in a 50 hz bw.
- The total power droops by 4% in 1000 useconds. This rate
is the same for 440 and 1000 usec pulses.
- There is a chirp across the rf pulse of .01436
- There is a 60 hz component in the total power in rf pulse
The mod anode was not staying completely off
after the rf pulse turrned off. The mod anode output of the
transmitter console is plotted below for various HV settings.
These measurements were taken with a single klystron (klyA)
- The yellow trace is the modAnode. The green trace is the
beam (or rf?).
- hv=60KV (.png)
- hv=70KV (.png)
- hv=80KV (.png)
- The modAnode rises 1.4 divisions in about 800 usecs.
- The modeAnode on to off is 5.8 divisions. This is
about 40 Kv
- So the modAnode is moving 1.5/5.8 - 25% of the modAnode
voltage during this time.. about 10Kv
- This is a lot more than the 5kv supply so this
supply is probably not the problem.
19oct10: scope trace of protect
On 19oct10 we did a test to look at how
quickly the 430 ch receiver could be turned on after the
rf pulse of the transmitter goes off. The setup was:
- High voltage off, ipa off, system on.
- 429 Mhz cw tone transmitted from hilltop antenna
- rf signal ch crr1, 30 MHz IF, to 30 Mhz amplifier, no
filter, and then IF to scope.
- thumbwheel delays set to 1 usec.
- Scope triggered on falling edge of rf pulse.
- The image below shows the signals:
- protect cmd:
- there is a 6 usec
delay in hagens box from rf
falling to protect cmd
- The protect
and is sent upstairs.
monoplexor waits 20 usecs then the diode
current is turned off
- When the
current thru the diode drops to a certain
level, the ack level will drop
- it then comes
back downstairs and shows up on the output
of hagens box.
- Ack drops
(downstairs) 27 usecs after protect cmd
- This is the
7 usec round trip time + the 20 usec
- This is
the 30 Mhz IF voltage.
- There is
a spike 8 usecs after protect falls.
with the thumbwheel
delay.Increaing this delay moves
this to the right.
wheel is labeled IF and LO
the 8 usec delay from protect?
Is this a round trip delay??
8 usecs the noise increases. This
is coming down the cable from
upstairs (but the monoplexor is
still active). I wonder if the
upstairs rf blanking is still
falls (downstairs) we wait 12
usecs before the IF
is this delay coming from?
hagens box, IF
SIGNAL, RF pulse at hagens box, protectCmd
leaving hagens box
- rf Falls
to IF up:
to a minimum range of:
- The -7 is the
3.5 usecs for rf pulse to go
up and the 3.5 usecs for the
IF Signal to come down.
usecs of unknown origin ack falls
07oct10: 430 transmit pulse sequence
The picture below shows the 430 transmiter transmit sequence. a
) is also available)