fpga bandwidth

[bc2007]

I am using the PCI-5640R transceiver board and have modified one of the examples that came with the installation. The example VI is the Input and Output VI which I have configured for QPSK modulation at 70Mhz IF.

This seems to work fine when viewing the 70Mhz output with a spectrum analyzer and also viewing the Eye pattern for the QPSK. Trouble is I can't control the bandwidth of the I.F. at 70Mhz. 

Is it possible to set the bandwidth and how?

Tks

[JerryAL]

Hi jlgnasa

The bandwidth of the generated signals are typically about 0.8 times the IQ rate of the signal.  This is due to the filters in the DAC’s digital upconversion.  If you require smaller bandwidths for a given IQ sample rate, a filter would have to be created to filter the data prior to sending it to the DAC.

The LabVIEW Digital Filter Design Toolkit supports created fixed point filters for LV FPGA.

Jerry

[Mauricio Capistran-Garza]

Hi jlgnasa,

The bandwidht of the signal will depend directly on the symbol rate, the samples per symbol, and the pulse shape filter coefficient that you are using (if any). What Jerry mentions is the maximum possible signal bandwidth for a given IQ rate, which he is right, it is 0.8 times the IQ rate. But your signal bandwith migh be lower, depending on the previously mentioned parameters.

- Mauricio