Dropouts using Smartlink

Rick N0VT

This time of year I travel around on vacation and use my laptop and my cellphone to connect to the home station via Smartlink. There are frequent audio dropouts on my end, but stations on the receiving end tell me my signal is solid, and despite the dropouts I'm able to transmit and copy digital messages 100%. Is there anything I can adjust to get rid of the dropouts I'm hearing in my headphones?

Mike-VA3MW

The dropouts are usually a loss of network communications.

Where I would first look is your upload speed from the radio. What is your upstream bandwidth?

And, it is possible that your router is part of the bottle neck. It could also be your ISP or any other technology in the middle that is dropping the data (called UDP packets). These are the first items dropped in a congested network.

A quick test is to find the settings for the Panadapter Rate and the Waterfall FPS (Frames/second) and reduce those to zero. Since the panadapter and waterfall are essentially a movie being sent from the radio, it can consume a bunch of upload data. By reducing this number, you also reduce the amount of data being sent. You don’t say if you are using MAC or Windows software, but, regardless, the impact is the same.

Reducing these items will not impact the audio stream, but the audio stream too will be impacted by possible network congestions along the way.

This can be a hard problem to isolate to the root cause since there are so many parts to the communication path and most of them out of your control. That leaves us with the Router and the Data Rates controlled by the FRS and RATE settings which are part of the display.

What I have seen in the past his reducing these variables has a huge improvement. You can also try turning on a low data rate connection when you do your first connection to the radio if this is SmartSDR on Windows.

You do also want to make sure that you are on the latest version of SmartSDR as there have been huge improvements in latency since Version 3.3 or before.

Let us know what you find out as others are watching as well.

73

Rick N0VT

Thanks Mike. I'm using the latest version of SSDR on my laptop, which connects to the internet via my hotspot (my android phone) via the low bandwidth option. Since the dropouts I'm hearing are only in my ears and not happening over the air, I believe it must be happening somewhere inside the laptop. (i5 processor with W10 Pro) Does that make any sense?

John KB4DU

Yes.

Mike-VA3MW

Those dropout could be happening anywhere along the line, not just the laptop.

UDP packets are designed that way. It is not uncommon for them to be dropped once they are sent. This is the way that all streaming works and if any switch along the way (and there are many) might find itself briefly overloaded, it will stop servicing UDP packets and then then send a message back to the sender computer to throttle back.

It might be as simple as a questionable cable between the radio and your network switch. Yes, cables do go back. Both @Ken Wells and I had cables actually die recently. This is my discussion on my recent findings. What I did learn that not all network ‘boxes’ are created equal. And, the only way to tell is by doing tests and keeping notes.

It might also be the iPhone. I know on my Macbook Pro that I get much better SmartLink audio if I turn off Location Services on the MBP. It makes no sense, but there has to be a correlation and I just have not yet found out why. With location services on, it is almost unusable.

It is just like Ham Radio and antennas. :) Yes, it should work the way the Handbook says. But, we have all learned that there are always many variables.

https://community.flexradio.com/discussion/comment/20603359#Comment_20603359

You might try running a bufferbloat test on your router at the radio end. You do this by running it from a PC/MAC - Browser within the same network.

I hope that helps a bit. 73

www.waveform.com/tools/bufferbloat

Rick N0VT

The bufferbloat test gave me a grade of "A". Unloaded latency was 9ms, download active was +6 and upload active was +0.

Mike-VA3MW

Good to know. So, that isn’t the issue with the drop outs.

Something else is impacting the communications, but it is very hard to figure out just what.