The following figure shows a simplified block diagram of the NI USRP-2922.
The following lists describe the individual blocks:
Note
The RF switch allows transmit and receive operations to occur on the same shared antenna. On the NI USRP-2922, one antenna is designated receive-only.
Receive Path:
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The low-noise amplifier and drive amplifier amplify the incoming signal.
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The phase-locked loop (PLL) controls the voltage-controlled oscillator (VCO) so that the device clocks and local oscillator (LO) can be frequency-locked to a reference signal.
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The mixer downconverts the signals to the baseband in-phase (I) and quadrature-phase (Q) components.
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The lowpass filter reduces noise and high frequency components in the signal.
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The analog-to-digital converter (ADC) digitizes the I and Q data.
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The digital downconverter (DDC) mixes, filters, and decimates the signal to a user-specified rate.
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The downconverted samples are passed to the host computer over a standard gigabit Ethernet connection.
Transmit Path:
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The host computer synthesizes baseband I/Q signals and transmits the signals to the device over a standard gigabit Ethernet connection.
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The digital upconverter (DUC) mixes, filters, and interpolates the signal to 400 MS/s.
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The digital-to-analog converter (DAC) converts the signal to analog.
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The lowpass filter reduces noise and high frequency components in the signal.
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The mixer upconverts the signals to a user-specified RF frequency.
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The PLL controls the VCO so that the device clocks and LO can be frequency-locked to a reference signal.
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The transmit amplifier amplifies the signal and transmits the signal through the antenna.