Limited RX Bandwidth Issue


Reaching out in the hope that someone may be able to provide some ideas as to why, despite many attempts, I can only get very limited bandwidth (15Mhz) from my LimeSDR before all demodulation becomes stuttered. In contacting Lime Micro Jimmy indicated the appropriate way to seek assistance was through this forum so here it goes.

After reading all available forum entries and setup guides (or at lead as best as i can find) i have

1: installed the windows 10x64 drivers Cypres USB3.0:

2: Associated this with the LimeSDR in devcice manager (Windows 10)

3: Installed the latest version of PothosSDR for windows

4: Accessed the LimeSDR with LimeSuiteGUI sucessfully: Connecting with the connection string (recognized as USB3: Limesdr)

However when I run cubic or any other software radio the applications correctly identify the USB:LimeSDR and connect to it. If the sample rate is et in all cases to under 15Mhz all is good perfect scanning and demodulation, however if the sample rate is set to over 15MHz I see the full frequency spectrum being scanned but demodulated signals are extremely chooppy and fragmented (similar to lots of dropped frames on streaming)

After looking at the forums I updated the FPGA and FX3 to the latest levels successfully (now evidenced in the information at the bottom of the LimeSuiteGUI and Modules->deviceinfo)

However the same issue persists;

Thinking it may be an issue with the laptops ability to process the data stream I have installed on two other different laptops with exactly the same effect. Both Windows and Ubuntu.

  • Intel® Core™ i7-3520M CPU @ 2.90GHz 8GB (Windows 10 Home) and (Ubuntu 17.4)

  • Intel Core i5-3317U; Intel HD Graphics 4000, 4GB Memory (Windows10 Home)

  • Intel Core i5-7200U 2.5GHz 2.7GHz 8GB Memory (Windows 10 Pro)

I have double checked that its using USB3 and not USB2
I have run calibration
I have removed the possibility that it was a USB extension cable issue by plugging the board directly into the USB3 port of the PC

I have gained a little more insight from the console output in Ubuntu than was available in windows:

SDRThread::readStream(): 3.1 iqDataOutQueue output queue is full, discard processing of the batch…

SampleSinkFifo: overflow - dropping 9216 samples
SampleSinkFifo: overflow - dropping 7168 samples
SampleSinkFifo: 739 messages dropped

It all points to the laptops having insufficient processor power to process the data stream from teh Lime, but I cant understand why all top out at 15Mhz and the latest i5 machine is not exactly a poorly specked machine. If i use decimation I can get to about 22Mhz but not even close to 60MHz. As I want to receive HF (with the inductor removal) I need go 30Mhz either side of the 30Mhz bottom frequency so at this point FH is a dead duck for me. Does any one have any ideas what may be causing this, I would be most grateful for any pointers.


Hi @Echo,

Share your register setup (ini) file, please.

Hi Zack,

The forum does not permit files to be uploaded other than graphic files I will send these files to your support email address. Thanks for looking at this.

For future reference, using Pastebin or a GitHub Gist etc. is probably best.