Some tech questions about the LimeSDR XTRX ecosystem

[ricardas]

@darek_m

The data sheet says that the maximum RF bandwidth is more than 100 MHz. However, the user gasparka asked about the filtering that limits the bandwidth to 75MHz. Can I get 100MHz BW out of the device or is there any filtering that limits it?

You can get 100MHz bandwidth, it’s not limited by filtering. The limit depends on channels count, so in SISO you can have sampling rate up to 122.88MHz, but in MIMO only 61.44MHz.
That’s a dependency on PCIe connection. XTRX uses PCIe Gen2x2 lanes which mean the maximum data rate could be 1 GB/s, but most mPCIe adapters provide only x1 lane, so the maximum data rate drops to 500 MB/s.

SISO: 122.88MHz * 3 bytes (IQ pair) = 368.64 MB/s
MIMO: 122.88MHz * 6 bytes (2xIQ pair) = 737.28 MB/s : too much for x1 PCIe lane.