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USB Underflow: Trouble recording 245 MHz RTBW on both channels (RX1 and RX2)


We have an application that requires us to utilize the full 245 MHz Real Time BandWidth (RTBW) for both channels simultaneously. We are achieving this by checking the full spectrum option of the Spectran block. We are using the block diagram shown below with a trigger option to control recording.

The issue we are having is a USB underflow warning. Our application is of high importance and we cannot afford to miss data points. Could someone please help us configure our diagram such that we can record 245 MHz of bandwidth on both channels simultaneously?

Please note the top image shows our block diagram and the bottom image shows the error we are receiving and the settings for the Spectran and IQ Power Spectrum blocks. Please also note that both IQ Power Spectrum blocks have identical settings.

Thank you in advance!


This isn't possible unfortunately at the moment.

With IQ data, the 5 GBit/s USB bandwidth per port is enough for 1x122 MHz RTBW, so with both USB ports you can get either 2x122 MHz or 1x245 MHz RTBW.

With Spectra data, for safety reasons the options are limited to either 2x92 MHz or 1x245 MHz in current versions of the RTSA to keep device temperatures in check. This restriction will be lifted in upcoming versions of the RTSA.

Note that you also get a DSP overflow warning as the IQ Power Spectrum block is quite taxing to the CPU of the PC.

Since you don't seem to need IQs better use SPECTRA, which highly reduces USB bandwidth and processing power and also offers real 2x245MHz bandwidth.


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