Flexradio 6700 Popping Crackling sounds while operating remote

Paul Christy · February 24

I have a crackling sound in my SmartSDR audio stream while operating remote. It's usually just annoying but it is a major concern in CW contesting; it's preventing accurate copying of exchanges and severely limiting my ability to compete. It is not atmospheric noise. I have high quality internet connections on both ends. I have gone through extensive network troubleshooting with the HelpDesk.

It does NOT occur with Maestro A using the same exact networks. It also does NOT occur if I listen to the DAX stream. I only hear it on PC Audio. I think this means it must somehow be related to audio processing on the computer that is accessing the remote station.

It DOES consistently occur on all three PC's I have tried it on.

Please, has anyone had a successful resolution to this problem by changing PC or SmartSDR settings or by any other means??? This has become a severe limitation to my "Dream" station (Flex 6700, PGXL, TGXL, AG, plus extremely quiet remote rural QTH).

Thank you,

Paul Christy

N0GN

Keywords crackle crackles crackling crackles pop pops popping

Mike-VA3MW · February 24

The pops is the UDP audio stream packets being dropped on the path from the radio to the end users.

UDP packets are dropped first in congested networks because UDP is a connectionless, best-effort protocol without retransmission, acknowledgments, or congestion control. Unlike TCP, which ensures reliable delivery through retransmissions and flow control, UDP lacks these mechanisms, making it more expendable when routers and switches need to free up bandwidth. Many networks prioritize TCP traffic for applications requiring reliability, while UDP is often used for real-time applications like VoIP and gaming, which can tolerate some packet loss. As a result, when network congestion occurs, routers typically discard UDP packets first to maintain overall network stability.

If the PC has high DPC values, then the network gets services less often and the UDP packets are dropped by design.

Often it is in the WiFi part of the end user. It can also be at the radio network end if the upstream router isn't beefy enough or the upstream bandwidth isn't high enough.

The display settings of SmartSDR, try reducing the RATE and FPS to minimum and see if the problem goes away (all the way to the left). That will reduce the amount of data being sent.

73

Ha Gei · February 24

Paul,

unfortunately this is usually a Problem with onboard Graphic Cards. I have some laptops/miniPC which do work, others are not usable…even though they where no cheapo´s and have a lot of power.

If possible, swap the graphic Card..maybe install the vendors drivers..not the MS Default Stuff. and try again.

Harry

DL9NDW

Paul Christy · February 24

Thank you. That is very helpful and very disappointing

WX7Y · February 24

As Mike said there may be a work around.

From SmarSDR click on "Display" on the Right side of the Slice and slow down the FPS, and Rate you may need to increase the AVG if it is down a bit to far, I have found these three settings have a lot to do with the Graphic's noise problem on Laptops and tablets that have limited Video Memory, A lot of times if my Network connection is SLOW it really helps as well.

Personally I do not like a busy Panadapter and Waterfall, it's not like your watching for a Heart anomaly or something so my defaults are always down to about 50 to 60% on the sliders for FPS and Rate and seems to work even on a **** Cell phone network.

73

Bret WX7Y

Paul Christy · February 24

It happens both on wired and wireless connections.

Upstream router is brand new Verizon Business InCloud 5G with about 100 Mbps Down and 30 or more Up with Cat 6 to the 6700.

Downstream is wired Cox Business with similar specs.

Display settings are pretty conservative. Rate Is 55, fps is 15, Average is 90.

Mike-VA3MW · February 25

Thanks Paul

I am not familiar with, but it does sound like a cellular connection. It isn't a speed issue but more of a jitter issue. Cellular data connections will have more jitter than a terrestrial connection. It might be possible that this is what you are hearing.

We have learned that not all devices are made equal, even new ones sadly. The other thing we have seen is that not all gigabit switches work as well as others when connecting to the 100mb NIC card in the radio.

I only mention these items to give you something to have a look into. You can always open a support ticket as well for some other ideas.

The reason we mention the link.local test is to help isolate and narrow down the root cause.

73

Paul Christy · February 25

I turned down display rate and fps to 0 and average to 100 and it's still happening. I have used a wired connection at the upstream end and it's still happening. I have gone through the HelpDesk. I have spent a huge amount of time fiddling with router, computer, and SmartSDR settings. I just really still cannot understand why or how the root cause could possibly be the router connections when the signal is PRISTINE on Maestro and when I listen to the DAX stream on the computer using the same exact networks. Obviously, an acceptable signal is reaching the computer.

It's not like I'm not trying. I also replaced my network switch with Brand New Netgear GS308 gigabit switch.

I get the idea from the other comments that it may be more fruitful to try a new computer. Is there a known combination of computer, operating system and graphics card that definitely works? Any other suggestions?

Mike-VA3MW · February 25

Did you try the link.local test?

Paul Christy · February 26

Hi Mike. Thanks for your patience. I did everything in this article:

https://helpdesk.flexradio.com/hc/en-us/articles/27808005218203-How-to-Setup-Smartlink

I'm not finding any specific references to the phrase "link.local". What is that? Happy to try it. Do you mean connect the radio directly to the local computer with just an ethernet cable? I haven't seen any problems on the LAN. Only remote. And only on remote computer. Not on Maestro.

David Decoons, wo2x · February 26

Mike-VA3MW · February 26

Diagnosing Network Issues with a Link-Local Test

A Step-by-Step Guide for FlexRadio Users

Introduction

FlexRadio transceivers rely on stable network connections for optimal performance. If you’re experiencing disconnects, audio dropouts, or other network-related issues, performing a Link-Local Test helps determine whether the problem lies with your radio or your network.

This test directly connects your PC to the radio, bypassing any external network components.

This document outlines how to conduct the test and interpret the results.

Why Perform a Link-Local Test?

Isolates the Problem – Helps determine if the issue is related to your network or the radio itself.
Eliminates Variables – By removing routers, switches, and other network devices, we can focus on potential hardware or software issues.
Simplifies Troubleshooting – If the radio works properly in this test, then the issue is within your network setup.

Step-by-Step Instructions

1. Gather Required Equipment

Your FlexRadio transceiver
A PC or laptop running the latest version of SmartSDR
A single NEW LAN (Ethernet) cable

2. Power Down Your Equipment

Turn off both your PC and your FlexRadio completely.
Unplug any existing network connections to ensure no external devices are affecting the test.

3. Directly Connect the Radio to the PC

Use an Ethernet cable to connect your PC directly to the LAN port on the FlexRadio.
Do not connect the radio or PC to any router, switch, or other network devices.

4. Power Everything Back On

First, turn on your radio and allow it to fully boot.
Then, turn on your PC and let the operating system load completely.

5. Launch SmartSDR

Open SmartSDR on your PC.
In the radio chooser window, check if your radio appears as an available device.

Interpreting the Results

✅ If the radio appears and works correctly:

Try to recreate the same problem. If you are not able to, then this means your radio is functioning properly, and the issue likely stems from your network setup.

The next steps are:

Check for faulty Ethernet cables, switches, or routers.
Ensure your network is properly configured for SmartSDR.
Look for any network congestion or interference.

❌ If the radio does NOT appear or crashes:

This could indicate a hardware or software issue with the radio or PC. In this case:

Restart the test to confirm consistent failure.
If the issue persists, contact FlexRadio Support and report your findings.

Conclusion

The Link-Local Test is a crucial step in troubleshooting network-related issues with your FlexRadio system. By eliminating network components, you can quickly determine whether the problem is internal to your radio or caused by your home network.

If you require further assistance, please reach out to FlexRadio Support with your test results.

🔗 Submit a Support Ticket: https://helpdesk.flexradio.com/hc/en-us/requests/new

Paul Christy · February 26

Thanks Mike. I'll try that next time I'm down at the site which will be around midweek next week. But I would expect that since it is working perfectly on the LAN, it will also function normally on the Link Local test. Anything else I can try remotely in the mean time?

Mike-VA3MW · February 26

If the LAN is perfect that that sort of leans to some other part of the network that is dropping UDP packets. One way to figure out where is to try changing things.

John KB4DU · February 28

Following up on Mikes point, many gigabit switches/routers don’t work as well as 100 Mb devices in this application. I had a similar problem. Replacing the router with an old 100 Mb router (with Wi-Fi disabled) cured the problem for me.

Paul Christy · March 1

I've tried a couple of other older network switches that didn't change anything. I'll see if I can dig up any more switches or old routers. Thanks

Paul Christy · March 6

Arrived at the remote site today. I did the Link-Local test. SmartSDR performed perfectly. I've tried every possible combination of internet access available to me at this remote location. I am still mystified why the Maestro works over the same networks but none of the 4 computers I have tried work, as if encouraging Maestro acquisition.

Does anyone know of optimal PC specs that would perform as well as the Maestro?

I do have some bufferbloat which I guess I can work on next. How do people deal with this?

Mike-VA3MW · March 7

Before you toss the PC out, make sure the issue isn’t a bad cable if you have also eliminated the switch as an issue.

Personally, I found 5 bad cables on my remote site one weekend. I tossed them all out for new cables and a lot of problems went away.

Paul Christy · March 7

Thanks! Is there a specific type and brand you recommend?

Paul Christy · March 9

Tonight I connected the radio directly to the router with ethernet cable. Crackles persisted on 3 year old computer. Same results with 5 other cables.

Intel NUC 7 Mainstream Kit NUC7PJYHN2 Mini Business & Home Barebone PC Desktop (Quad-Core Pentium Silver J5005, 16GB DDR4 RAM, 512GB SSD) Bluetooth, RJ-45, Wi-Fi, Windows 10 Pro, IST Power Cable Ordered on Dec 16, 2021.

I have some bufferbloat and I have Passthrough settings on my InHand 5G FWA02 router. Would it help to use a different router? Is there such a router that is known to work with Flexradio Smartlink? Is there anyone who has used this router and made it work?

If this thread is marked as Anwered will fewer people see it and respond?

KD0RC · March 9

Hi Paul, can you try plugging your computer directly into the radio? It is an important step in determining whether the issue is the computer or network. The idea is to eliminate all networking gear other than the radio and computer.

You will need to power off the radio and computer, plug them together, then power them both back on.

Paul Christy · March 9

Thanks Len. I did try that. It works fine locally. Problem is only over Smartlink

KD0RC · March 9

Ok, well at least you know that the issue is not the radio or PC. Have you tried reducing the display frames per second to 5 or so and the waterfall speed to 1? Those are the values that I need when I operate remotely using my cell phone as a WiFi hotspot.

Paul Christy · March 9

Yes. No change even with FPS and Rate 0 and Average 100

Trucker · March 9

I don't think your problem is SmartLink itself. It is most likely something in your remote setup or your internet provider at your remote location.

James

WD5GWY

Paul Christy · March 9

But it remains a total mystery to me why Maestro works fine over the exact same infrastructure and SSDR doesn't.

I've followed every suggestion I've gotten to evaluate for network problems.

To me it seems obvious that there must be some issue in SSDR or computer hardware.

ka9ees · March 9

Have you opened a help desk ticket? If not, you should?

Paul Christy · March 10

I did. We tried lots of things. Just thought I'd check with The Community too.

Paul Christy · March 11

Stuttering is another keyword I have seen. I am attaching two videos. One with Maestro, one with SSDR, on the same exact networks. What are the things in SSDR and the computer that I can fix?

https://www.dropbox.com/scl/fi/1dj5nxarvh1p98rsfys9m/SSDR.mp4?rlkey=64imnb90cik0qrnapgog6j2sy&dl=0

https://www.dropbox.com/scl/fi/lf51wjflk9l1dfebx1vn6/Maestro.mp4?rlkey=i8g4z2og2dl3govsfrwi3exjj&dl=0

Hopfully you can see these. I couldn't figure out any other way to share the videos

Paul

N0GN

m5kvk · March 13

You're not going to like my suggestion, but anyway…

Implement a VPN connection to the remote site and switch to a Mac!! That way you can run SmartSDR for Mac, which allows you to address the radio directly (i.e. by IP address) - something which the Windows version doesn't support.

I have the exact same problem if I access my remote shack using SmartLink from a PC. Luckily, I'm a Mac user anyway, so I implemented a zerotier VPN between the two routers and use the direct addressing of the Mac version. Even though Zerotier uses cloud servers, it does its damndest to establish a P2P connection - only using a cloud relay in extremis.

Gareth - M5KVK

Paul Christy · March 13

Ha! You're right! But thank you very much for the reply. Oh my gosh. So are you saying that Windows SSDR doesn't even work over VPN without Smartlink?? Quite discouraging that they make it so hard to use any remote access setup other than Maestro. They do the same with making CW paddle use remotely almost impossible. Have you heard if it's any better with 8000 series? I would guess it would be the same