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8 Pulse Programming
8.1 General Principle
The complete pulse programmer of the Fourier is implemented in the FPGA of the main
board. This imposes some restriction on the variability and size of the pulse programs for
this system. For example, there are no possibilities for branching in the pulse program.
The pulse program can start due to an external trigger but once it started, it is not possi-
ble to halt/resume the program by to external triggers like the MAS signal. Another
restriction is that RF phases can only be switched by 90° in a running experiment. This
limits the phase cycles to the values, 0, 1, 2 and 3.
Unfortunately, it was not possible to use the output of the Topspin Avance compiler as an
input for the Fourier pulse programmer due to a completely different topology. Therefore
a different approach had to be used.
In addition to that, the console must also work with the miniSpec software because the
same hardware is used as a high end miniSpec.
The solution is that the pulse program language for the Fourier is XML based. Instead of
using the output of the Avance pulse program, only the pulse program parameters are
extracted and an internal pulse program on the Fourier main board is started. As a con-
sequence, for each Avance pulse program there must be a Fourier XML pulse program
which generates exactly the same RF output. Both programs must have the same name.
Starting the Avance pulse program loads the respective Fourier pulse program into the
Fourier pulse programmer, sends the parameters like delays, pulse lengths and ampli-
tudes, spectrum width, etc., to it and finally starts the experiment. The FIDs are sent to
the workstation via Ethernet using the same CORBA protocol as the DRU on the Avance
system.
The advantage is that the complete infrastructure of TopSpin can be used like ased,
NMRSIM, graphical pulse program display, the complete parameter handler, Cortab and
PowerCheck. The operator works in the TopSpin environment only.
The disadvantage is that two pulse programs have to be written which must be perfectly
synchronized. Any change on the Avance pulse program only takes effect on the experi-
ment if the Fourier pulse program is changed as well. Bruker delivers a set of well tested
pulse programs for the Fourier to cover the intended use of the Fourier spectrometer.
8.2 Structure of Pulse Programs
The Avance pulse program is written in a sequential form. Each delay or pulse on one
channel influences the timing on the other channels. To illustrate this, the first pulses of
an HMBC pulse program are used as an example.
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