Signals received by the USRP-2954 are amplified, downconverted, filtered, digitized, and decimated before being passed to the host computer. Signals transmitted by the USRP-2954 are upsampled, reconstructed, filtered, upconverted, and amplified before being transmitted.
The area within the dotted line indicates the processing on the FPGA when you use NI-USRP with the default FPGA image. When you use LabVIEW FPGA, you control the processing on the FPGA.
The RF switch allows transmit and receive operations to occur on the same shared antenna. On this device, one antenna is designated receive-only.
The following lists describe the individual blocks:
Either a low-noise amplifier (LNA) or an LNA low-pass filter (LPF) combination amplifies the incoming signal, depending on the incoming frequency.
- The signal travels through either a direct conversion path or an up conversion path, depending on the frequency.
- A final driver amplifier amplifies the signal.
- The phase-locked loop (PLL) controls the voltage-controlled oscillator (VCO) so that the device clocks and local oscillators (LO) can be frequency-locked to a reference signal.
The mixer in the 10 MHz - 500 MHz path upconverts signals to 2.44 GHz.
The bandpass filters limits signals in the 10 MHz - 500 MHz frequency range to 84 MHz of bandwidth.
The quadrature mixers downconvert the signals to the baseband in-phase (I) and quadrature-phase (Q) components.
The lowpass filter reduces noise and high frequency components in the signal.
- The analog-to-digital converter (ADC) digitizes the I and Q data.
- The digital downconverter (DDC) mixes, filters, and decimates the signal to a user-specified rate.
The downconverted samples are transported to the host computer over a standard PCIe connection.
The host computer synthesizes baseband I/Q signals and transmits the signals to the device over a standard PCIe connection.
The digital upconverter (DUC) mixes, filters, and interpolates the signal to 400 MS/s.
- The digital-to-analog converter (DAC) converts the signal to analog.
- The lowpass filter reduces noise and high frequency components in the signal.
- The mixer upconverts the signals to a user-specified RF frequency.
- The PLL controls the VCO so that the device clocks and LO can be frequency-locked to a reference signal.
The signal travels through either a direct conversion path or a down conversion path, depending on the frequency.
The transmit amplifier amplifies the signal and transmits the signal through the antenna.