RadioProcessor
The figures on the previous pages demonstrate that the RadioProcessor's A/D can handle frequencies
above Nyquist (37.5MHz) because undersampling performance is comparable to standard sampling. Since
the quadrature detection and filtering components are not even aware of whether aliasing is taking place in the
A/D converter, they will perform exactly the same as for the standard sampling case.
Integration of RadioProcessor into a High-field System
In order to utilize the RadioProcessor as an IF excitation and detection system for high-field NMR
applications above 100 MHz, a phase-coherent up- and down-conversion is required. The diagram in Figure
A1.7, below, presents a simplified system that would utilize the RadioProcessor as a 70 MHz IF system and
maintain the required phase coherence. The RadioProcessor utilizes a 50 MHz on board clock to derive the
75 MHz clock frequency for the A/D section, the 300 MHz clock for the D/A converter and the 10 MHz clock
output. In the proposed system, the 10 MHz clock output of the RadioProcessor board would then drive the
high-frequency synthesizer (e.g., the PTS brand) directly. As the RadioProcessor is broad-band, intermediate
frequencies other than 70 MHz can be selected as well.
2020-10-07
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Figure A1.7:
Simplified block diagram of a complete, phase-coherent high-field
system with the use of RadioProcessor. Mini-Circuits mixers (ZAD-1) can be used for
high-field operation up to 500 MHz. To split the signal from the synthesizer into two mixer
signals, a Mini-Circuits splitter (ZFSC-2-1) can be used. Band-pass filtering is essential
for quality results.
Synthesizer
RF In
RF Out
10 MHz Out
SpinCore
RadioProcessor
BP Filter
BP Filter
Up Conversion
Down Conversion
To Power
Amplifier
From Pre-
Amplifier
RF Splitter
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