RF synthesizer or an NMR instrument
First Claim
Patent Images
1. A frequency synthesizer for an NMR instrument which comprises:
- look-up table storage means for storing at successive addressable locations a digital representation of a carrier signal;
digital-to-analog converter means connected to receive the digital representation of the carrier signal read-out of the look-up table storage means and convert it to an analog carrier signal;
a digital adder having an output which produces a digital number that is the arithmetic sum of digital numbers applied to its first and second inputs, the output of the digital adder being coupled to the look-up table storage means to address the locations therein;
a phase latch for storing a digital phase number and for applying the digital phase number to one of the digital adder inputs; and
a digital accumulator for continuously adding a digital carrier frequency number which is applied to its input and generating the accumulated digital number at its output, the output of the digital accumulator being coupled to the other of the digital adder inputs;
wherein the addresses applied to the look-up table storage means are advanced at a rate determined by the digital carrier frequency number to thereby produce an analog carrier signal at the output of the digital-to-analog converter which has a frequency that is determined by the digital carrier frequency number, and wherein the phase of the analog carrier signal is determined by the digital phase number.
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Abstract
The transceiver of an NRM instrument includes a digital synthesizer that produces an analog carrier signal which can be controlled in both frequency and phase and which can be frequency and phase modulated. The analog carrier signal is mixed with reference signals to boost its frequency to the Larmor frequency of the instrument.
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Citations
6 Claims
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1. A frequency synthesizer for an NMR instrument which comprises:
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look-up table storage means for storing at successive addressable locations a digital representation of a carrier signal; digital-to-analog converter means connected to receive the digital representation of the carrier signal read-out of the look-up table storage means and convert it to an analog carrier signal; a digital adder having an output which produces a digital number that is the arithmetic sum of digital numbers applied to its first and second inputs, the output of the digital adder being coupled to the look-up table storage means to address the locations therein; a phase latch for storing a digital phase number and for applying the digital phase number to one of the digital adder inputs; and a digital accumulator for continuously adding a digital carrier frequency number which is applied to its input and generating the accumulated digital number at its output, the output of the digital accumulator being coupled to the other of the digital adder inputs; wherein the addresses applied to the look-up table storage means are advanced at a rate determined by the digital carrier frequency number to thereby produce an analog carrier signal at the output of the digital-to-analog converter which has a frequency that is determined by the digital carrier frequency number, and wherein the phase of the analog carrier signal is determined by the digital phase number. - View Dependent Claims (2, 3)
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4. A frequency synthesizer for an NMR instrument which comprises:
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look-up table storage means for storing at successive addressable locations a digital representation of a carrier signal; digital-to-analog converter means connected to receive the digital representation of the carrier signal read-out of the look-up table storage means and convert it to an analog carrier signal; a digital adder having an output which produces a digital number that is the arithmetic sum of digital numbers applied to its first and second inputs, the output of the digital adder being coupled to the look-up table storage means to address the locations therein; a first digital accumulator for continuously adding a digital carrier frequency number which is applied to its input and generating the accumulated digital number at its output, the output of the digital accumulator being coupled to one of the digital adder inputs; and a second digital accumulator for continuously adding a digital frequency number which is applied to its input and generating the accumulated digital number at its output, the output of the second digital accumulator being coupled to the other of the digital adder inputs; wherein the addresses applied to the look-up table storage means are advanced at a rate determined by the sum of said digital carrier frequency number and the digital frequency number to thereby produce an analog carrier signal at the output of the digital-to-analog converter which has a frequency that is determined by the sum of the digital carrier frequency number and the digital frequency number. - View Dependent Claims (5, 6)
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Specification