NMR measurement apparatus

1 . A Nuclear Magnetic Resonance (NMR) measurement apparatus comprising:

a mixer configured to multiply a transmission signal having a plurality of different frequency components by a local signal to generate a frequency-converted transmission signal under a condition for frequency conversion;

a power amplifier configured to amplify the frequency-converted transmission signal and output an amplified transmission signal;

a demultiplexing circuit including a plurality of filters arranged in parallel with each other, each filter of the plurality of filters having a different frequency characteristic, wherein the plurality of filters is configured to enable the amplified transmission signal to pass simultaneously in parallel through the plurality of filters to generate a plurality of transmission signals corresponding to a plurality of different irradiation frequencies, each of the plurality of transmission signals including a different component of respective irradiation frequencies of the plurality of different irradiation frequencies, and configured to output the plurality of transmission signals to an NMR detection circuit; and

a controller configured to set the condition for frequency conversion, wherein the condition for frequency conversion is a condition for generating the plurality of different irradiation frequencies,

wherein the plurality of transmission signals comprise a first transmission signal having a first irradiation frequency and a second transmission signal having a second irradiation frequency,

wherein one of the first irradiation frequency and the second irradiation frequency is a primary reference frequency and another of the first irradiation frequency and the second irradiation frequency is a sub reference frequency,

wherein a difference method or a summation method is employed as a frequency conversion method for the frequency conversion by the mixer,

wherein the plurality of different frequency components of the transmission signal comprise a first frequency component having a first frequency and a second frequency component having a second frequency,

wherein the condition for frequency conversion comprises the first frequency and the second frequency,

wherein a frequency, among the first frequency and the second frequency, which corresponds to the primary reference frequency, is a designated frequency that is designated within a range of frequencies which the NMR measurement apparatus is configured to generate as an intermediate frequency,

wherein a frequency, among the first frequency and the second frequency, which corresponds to the sub reference frequency, is a calculated frequency that is calculated within the range of frequencies,

wherein the frequency of the local signal is calculated based on the primary reference frequency, the designated frequency, and the frequency conversion method,

wherein the calculated frequency is calculated based on the sub reference frequency, the frequency of the local signal, and the frequency conversion method, and

wherein the designated frequency is designated, such that the calculated frequency is not a negative frequency and does not exceed an upper limit of the range of frequencies.

2 . The NMR measurement apparatus according to claim 1 , wherein

the frequency conversion method is the difference method,

the designated frequency is a frequency exceeding ½ of the range of frequencies which the NMR measurement apparatus is configured to generate as the intermediate frequency, and

the primary reference frequency is a lower frequency among the first irradiation frequency of the first transmission signal of the plurality of transmission signals and the second irradiation frequency of the second transmission signal of the plurality of transmission signals.

3 . The NMR measurement apparatus according to claim 1 , wherein

the frequency conversion method is the difference method,

the designated frequency is a frequency below ½ of the range of frequencies which the NMR measurement apparatus is configured to generate as the intermediate frequency, and

the primary reference frequency is a higher frequency among the first irradiation frequency and the second irradiation frequency.

4 . The NMR measurement apparatus according to claim 1 , wherein

the frequency conversion method is the summation method,

the designated frequency is a frequency below ½ of the range of frequencies which the NMR measurement apparatus is configured to generate as the intermediate frequency, and

the primary reference frequency is a lower frequency among the first irradiation frequency and the second irradiation frequency.

5 . The NMR measurement apparatus according to claim 1 , wherein

the frequency conversion method is the summation method,

the designated frequency is a frequency exceeding ½ of the range of frequencies which the NMR measurement apparatus is configured to generate as the intermediate frequency, and

the primary reference frequency is a higher frequency among the first irradiation frequency and the second irradiation frequency.

6 . The NMR measurement apparatus according to claim 1 , wherein

the plurality of filters comprise a first filter having a first frequency characteristic for generating the first transmission signal, and a second filter having a second frequency characteristic for generating the second transmission signal.

7 . The NMR measurement apparatus according to claim 1 , further comprising:

a probe having the NMR detection circuit;

a filter bank provided between the mixer and the power amplifier; and

a bypassing path provided between the mixer and the power amplifier, and that bypasses the filter bank, wherein

the bypassing path functions when the demultiplexing circuit is to function between the power amplifier and the probe, and

the filter bank functions when the demultiplexing circuit is not to function between the power amplifier and the probe.

8 . The NMR measurement apparatus according to claim 1 , wherein

during reception, the demultiplexing circuit functions as a combining circuit, and

a combined reception signal is extracted from between the power amplifier and the demultiplexing circuit.