Some tech questions about the LimeSDR XTRX ecosystem

General Discussion
1

Dear All,
I have some technical questions about the LimeSDR XTRX HW:

  1. 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?

  2. What are the physical dimensions of the LimeFEA mPCIe Full carrier card ?

  3. The document: [LimeSDR XTRX v1.2 Board — LimeSDR XTRX Boards 23.01 documentation] (LimeSDR XTRX v1.2 Board — LimeSDR XTRX Boards 23.01 documentation) shows that the system does not have a continuous RF coverage. There are gaps in the RF band due to the matching networks. The frequency ranges for the Rx channels in Fig.6 and Table 3 do not match. Which one is correct?

Thanks for your help.

Regards,

Darek

2

@ricardas could you clarify please.

Both versions use the same PCB and this measures 100x65mm excluding the PCIe connector.

There are no gaps this will just be where the matching networks are optimised for.

3

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.