[Solved] Crap ! I seem to have a USB buffering issue.

Take a look at this video:

Because of the bad propagation i was trying to make some QSOs on JT65 and i was not able to get any response from anyone. So, because i don’t use WSJT-X a lot and because its CAT always interferes with RUMlog and CubicSDR who also want a CAT connection, i just went over the initial setup again.

At some point in the manual it says: “Click the Tune button on the main screen to switch the radio into transmit mode and generate a steady audio tone. Listen to the generated audio tone using your radio’s Monitor facility. The transmitted tone should be perfectly smooth, with no clicks or glitches.” So that’s what i did and the above video showed. So what’s next? How do i solve this?

I tried with FLdigi to send a long PSK31 signal and the same behaviour shows. I tried with my old MacBook Pro and that one works fine. Crap! Can i not use any digital modes anymore now??

So i sent the following message to the Apple forums and to the Silicon Labs Community:

USB buffering MBP 2001 vs 2015?

I am a HAM and i am using my Early 2015 MBP for data communications. I seem to have a problem where the USB ports are not able to handle the traffic going from my software to the radio.

I am using a USB cable running at 115200 between my radio and the MBP. You can see the behaviour in this video: https://www.youtube.com/watch?v=-cxr5axl_60

In this video i first put a continuous tone on the USB port. The effect should be that the radio sends out this continuous tone on the air. However, as you can see in the video, the audio is interrupted and gets worse over time up to the point that the USB port is not receiving any data anymore and the transmit signal gets interrupted.

I tried this with various USB cables and various different programs and the behaviour is the same with all.

In the video you can also see that i am sending out a CW signal not using the MBP and that signal is clean.

Why do i think it’s the MBP? Because i tried a Late 2011 MBP running the same OS as my 2015 one (Sierra) this morning and that MBP doesn’t have the issue.


Any idea what has changed in the USB handling between 2011 and 2015?

Any idea how i can manipulate the buffering if the USB port on the 2015 MBP?


Thanks for your input,



No answers yet…


When i set the audio preferences in WSJT-X like this i don’t have the issue:


I opened a ticket with Silicon Labs explaining the issue and they have sent me a previous version of the driver. This version doesn’t show the above behaviour. So i’m a happy camper again.

CubicSDR has progressed into a great piece of software

It’s been a while since i wrote on this blog, but that doesn’t mean nothing has happened in the mean time. Things have progressed a lot on the panadapter front.

In my last post i wrote about the SDRPlay only supporting Windows, well that has changed, SDRPlay now also supports OSX. that makes that i can now use CubicSDR on my Mac and specifically CubicSDR has come a long way in it’s development:

  • I wrote about CubicSDR supporting osmosdr, that has changed. CubicSDR has now moved to SoapySDR. SoapySDR is an open-source platform for interfacing with SDR devices and supports the most common SDR devices under which the SDRPlay. More about SoapySDR on https://github.com/pothosware/SoapySDR/wiki


  • CubicSDR now also supports Hamlib. Hamlib is a library to control radio receivers and transceivers and one of the transceivers supported is my TS-590. More about Hamlib on http://sourceforge.net/p/hamlib/wiki/Hamlib/


  • CubicSDR is going to support more modulations, specifically the digital ones. So we will be able to decode digital signals without the need for Windows decoding software. This is not finished yet, but it’s looking good so far.

Screen shot 2016-01-06 at 14.06.16

  • then there are many small new features like multiple SDR support, RTL-TCP, audio device support, automatic and manual gain control, many UI improvements and many, many more enhancements to come. The developer Charles J. Cliffe is really putting a great effort in building a superb SDR program that is going to give HDSDR a run for its money.

So when i add all these new developments up as of now i will use CubicSDR as my panadapter for my TS-590 without the need of having to use Windows. I removed my RTL adapter from my radio and am only using the SDRPlay from now.

The final setup (or DXLab Suite, HDSDR, RTL-SDR, TS-590 How-To)


So this is my current setup. Step by step:

  1. Hook up CN303 of the TS-590 to the antenna input of the RTL-SDR.
  2. Hook up the TS-590 to the laptop for CAT control. In my case i am using COM3.
  3. Configure DXLabSuite to use COM3 for CAT control.
  4. Install VSP Manager and configure a COM pair. These are two virtual COM ports connected to each other. I use COM4 and COM5.
  5. Configure DXLabSuite to use COM4 as second CAT interface using the Kenwood protocol.
  6. Install Omni-Rig and configure Rig1 to use COM5 (remember that this is the one connected to DXLab) for the TS-590.
  7. Install HDSDR and add the correct RTL-SDR drivers. How-to can be found on the HDSDR website.
  8. Configure HDSDR to use the RTL-SDR USB.
  9. Configure HDSDR to use Omni-Rig and select Rig1.
  10. Switch everything on and enjoy.