4.9 FLIPFLOP - Pulse Width and Phase Transient Calibration
01-999162-00 C0402
VNMR 6.1C User Guide: Solid-State NMR
68
4.9 FLIPFLOP - Pulse Width and Phase Transient
Calibration
The flipflop.c pulse sequence (
) is the standard sequence for multiple-pulse tune
up. It is applicable for UNITYplus and
UNITY
INOVA as well as UNITY and VXR-S with
a Sync Module. It is used for measurement of the pulse width and removal of phase
transient.
Macro
The macro
flipflop
calls the sequence and a parameter set.
Parameters
pw
is the 90
o
pulse length, in microseconds.
phase1
is the phase of the first 90-degree pulse, and is set to 0 (x).
phase2
is the phase of the second 90 degree pulse. It is set to 0 (x) for FLIPFLIP and 2 (-x)
for FLIPFLOP.
trig='y'
for UNITY and VXR-S with a Sync Module. Otherwise
trig='n'
.
np
is the number points and
np=128
or
256
.
tau
is interpulse delay, in microseconds, including
pw
. The minimum tau is about 7.0
µ
s
when
pw=1.5
µ
s
. See
rof1
and
rof2
.
rof1
is the amplifier unblanking time before each pulse. The receiver is also immediately
blanked and a T/R switch if present is placed in transmit mode. Set
rof1=1.5
µ
s
.
rof2
is the receiver unblanking time after each pulse. A T/R switch is placed in receive
mode immediately. For
1
H the receiver comes on after about 2.0
µ
s
. For lowband nuclei
the receiver is set to come on after 8.0 ms. these two times are controlled by hardware
adjustment in the magnet leg. Set
rof2=0.2
µ
s
for a High-Power preamp. Set
rof2=0.5
µ
s
for a Solids
1
H/
19
F preamp.
dtau
rof1
rof2
acq
dtau
rof1
rof2
acq
tau
tau
d1
pw
pw
[phase1]
[phase2]
'np'/4 times
Figure 22. Pulse Sequence for flipflop.c