LimeSDR-XTRX max RX bandwidth

Projects LimeSDR
1

Hello,

Im trying to evaluate the LimeSDR-XTRX and I would like to know how to achieve 120 MSPS SISO.
When using LimeSuiteNG I can only get to ~32MSPS before I get some clockgen errors

Regards,

2

Tagging @VytautasB and @Zack for comment, but if you could also provide more details of your hardware configuration. E.g. what have you plugged the board into.

3

Pull latest changes of LimeSuiteNG, and try these commands.
This should configure the board for 122.88 MSPS:
limeConfig -d XTRX --rxen=1 --rxpath=LNAL --rxoversample=1 --samplerate=122.88e6 --rxlo=1e9 --txen=1 --txpath=Band1 --txoversample=1 --txlo=1.1e9 --initialize
This should start samples streaming to confirm the actual sampling rate:

limeTRX -d XTRX --log=debug --linkFormat=I12

Samples received: 16384
Samples received: 61472768
/dev/LimeXTRX0_trx0 Rx: 376.358 MB/s | TS:122886144 pkt:480024 o:0(+0) l:0(+0) dma:14468/14472(4) swFIFO:0
Samples received: 122912768
Samples received: 184352768
/dev/LimeXTRX0_trx0 Rx: 376.320 MB/s | TS:245766144 pkt:960024 o:0(+0) l:0(+0) dma:28932/28936(4) swFIFO:0
Samples received: 245792768
4

Thanks. It seems to work however I can’t see my signal correctly. How do you select A or B?

5

Please describe the setup you are trying to do. The command lines were just an example to set the sampling rate to 122.88 MSPS, there are multiple possible antenna paths for Rx (LNAL, LANH, LANW), and might need gain, LPF, or other parameters to be adjusted according to your setup.

Generally in SISO mode only A channel is used, so the limeGUI or limeTRX currently does not provide arguments to explicitly specify only B channel to be streamed. But in code it’s possible to specify the indexes of which channels’ samples should be in the stream limeTRX.cpp#L483

6

Thank you, that’s very helpful!

7

Wondering how useful this is because it would require Analogue RX LPFH to be bypassed (max filter bandwidth is 75MHz)? Am i correct?

8

@ricardas @andrewback @VytautasB @Zack @vtrudel
I know this is an old thread and it may already be very obvious and clear, but I am new to the Lime XTRX, so please bear with me and please help…
So I am currently evaluating XTRX for a project that I need to use it as a transceiver to convert an L-band signal: 950MHz to 2.0GHz, with a Bandwidth of 50MHz (+/-25MHz at DC) to IQ baseband samples to a computer board (and vice versa for transmission) in a SISO configuration. So my questions are:

  1. In XTRX it says BW ~32MHz and sampling rate ~32MHz; could I push these higher to support my above configuration as a minimum, say ~64MHz and 64MSPS? LMS7002 seems to support this, but not sure if the XTRX board will also support that (have not looked at the codes yet)
  2. What interface can be used for streaming the samples? I am trying to avoid using the FPC connectors (X8, X13) while prefer packet based interfaces such as the mPCIe or the USB. Is this feasible? Personally, had past experience with high speed data transfer via USB2.0 (Cypress FX2) on another board and the performance was not great and had to do a lot optimisation on the FW side and SW side to avoid buffer over run issue. Anyone have any advice here
  3. In the FPGA glue logic , what quantisation level of the samples are set? Is it 12 bits or configurable, say if I want the 8 MSB or the 8 LSB?

Thanks in advance and apologise that I am tagging everyone here.

9

XTRX supports MIMO up to 61.44Msps, SISO up to 122.88Msps.
the board works over mPCIe.
Samples streaming format can be I12 (12bit I + 12bit Q compressed into 3 bytes), or I16 (16bit I + 16bit Q, 4 bytes)

10

Thank you for your response and useful information.