Remote problem

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  • Updated 3 months ago
I am trying to use another owners radio to test SmartSDR 2.3.9 on Windows 7. If I ping the remote radio in a command prompt, I get around 40 ms. When connected with SmartLink, Network Diagnostics show around 300 ms and status shows up as poor. I can hear audio and control the radio, but the spectrum display doesn't work. Dropped packets is around 6%. Any ideas of where to look for the problem?
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Goran SM6PPS

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Posted 3 months ago

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Chris DL5NAM

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Speed of your LAN/WAN ?
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Goran SM6PPS

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Remote site is LTE-service and I don't know exact, local is 100 Mbit/s down/10Mbit/s up. Owner of the radio says it works fine when he tries. What is confusing for me is that if I ping the remote IP outside SmartSDR, I get 10 times lower response time than what SmartSDR reports. Is there maybe something I need to modify in my client side router/firewall?
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Chris DL5NAM

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No, at remote no router changes needed. Your speed is OK but what's the LAN speed at radio side?

Mostly - if waterfall not work - it's a LAN problem.

Maybe Mike from FRS can answer your question

73 Chris
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N8SDR

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LTE Speed - why do folks insist on running remote setups with Cellular services & LTE services, your just asking for issues!. Then they blame SSDR software or the Rigs Ethernet port.
(Edited)
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N8SDR

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I haven't had any issues running the Flex with smart link at any point, But then again I don't try and wouldn't consider to use a cellular internet carrier to host such things. Fiber here with FTTP.  even when I ran the 100/50 connection never had an issue, and that includes 4 servers and a VOIP systems along with 4 kids streaming or playing on-line games, I recently moved to 500/200 services, as I'll be taken on a more servers and clients.  It just surprises me how many folks try and use LTE or 3G cellular services for remote access and then blame Flex that it doesn't work. It's been my experience along with others that Splashtop remote works better then Teamviewer for audio and most other applications, and the cost is much less!, Using it with around 200 clients here and haven't had an issue. 
(Edited)
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Bob - W7KWS -

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You & I live in an Internet world many can only dream about.

Some examples: 

When SmartSDR first came out there was a lot of trouble with some ISPs throwing out "fragmented" packets since they have been a target of some expoits in the past. According to Steve Hicks, he didn't know that when he originally wrote portions of that software.

They fixed that issue with version 2.3.7 a few months ago (summer 2018) by fragmenting the packets & doing the reassembly themselves in SmartSDR instead of relying on a network router for fragmentation. 

It appears that network routers do this automatically when a large packet is encountered.  That is a packet that exceeds the measured path MTU (Maximum Transmission Unit).  The Flex 6xxx radios produce Vita 49 packets as large as 1500 bytes. Articles addressing packet size suggest that a nominal design target for avoiding fragmentation is in the range of 1200 to 1300 bytes. 

I suffered from this when trying to operate from my daughter's home. We are both subscribed to 50-down, 5-up Comcast service. It appears to me that Comcast NW in her city took the easy way out & threw my packets away instead of a more sophisticated method of security that would have let them through.  Interestingly, both AT&T and Verizon cellular passed them through to my laptop when I was connected via that path.

I think UDP coupled with somewhat small audio buffers in SmartLink is another problem getting in the way of some users who have, or are stuck with lesser Internet service exhibiting high jitter.  In other devices I use buffers as large as 200 milliseconds to avoid all but the most difficult paths.  It's a trade off between latency and reasonably usable audio. 

Your success is probably due to the super Internet you subscribe to.

With time, more experience & resources, I'm sure Flex will introduce methods that others have developed to get around more of the Internet's subtleties.

Bob
(Edited)
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Goran SM6PPS

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Hi Bob, thanks for info about the Vita 49 packet sizes. I think this could be the reason then why I don't see any spectrum. Most Vita 49 packets arriving on my side (client), is less than 150 bytes. Some are 1002 and even fewer are 1358 bytes. I do not get any Vita 49 packets larger than 1358 bytes. So if they are sent from the radio, it looks more like this is the issue rather than speed as some people seems to indicate.
Göran
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ka7gzr

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I always find my remote connects through LTE are always reliable and much better than public LANs. I have tried many of them in restaurants, bars etc. They all have issues such as no waterfall, freezing and long drop outs. I have none of these issues with my unlimited cellular service (AT&T).
Jim
ka7gzr 
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Bob - W7KWS -

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Goran,

It's my thinking that, from SSDR 2.3.7 forward, the Vita 49 payload is fragmented by SSDR itself, wrapped and sent without setting the resulting packet's "Fragmentation" bit, thus avoiding some ISPs from throwing these packets away. The payload is then reassembled at the distant end by SSDR.

I think this probably would account for you seeing only smaller Vita 49 packets but I have no inside information on any details of the new algorithms Flex is now using. I'm just putting two & two together as best I can from what little I can see.

With the fragmentation fix implemented I was still experiencing no waterfall or spectrum displays In some places where I was testing my Maestro. It turned out that I was being fooled by a delay of as much as two minutes before those displays would appear. I was giving up thinking the fix wasn't working.

Then I was distracted by a phone call & when I came back to my Maestro, both displays had appeared
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It seems this is a different issue than ISP throw away but summer is here with other activities so I haven't pursued any of this further.

73,
Bob
(Edited)
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Stephen Cook

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I suspect the reason for the difference in times is the size of the packet. When you use the “ping” command with just an IP address the default size of the packet is 128 bytes (if memory serves me correctly). Where as when SSDR is communicating with the radio it will be using much larger packets. Larger packets, longer times.
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Kari Gustafsson SM0HRP, Elmer

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I have been using 4G LTE at my remote Flexradio for two years now. It has worked flawlessly. But I have no alternative. Yet anyway. In rural areas it is still the only way to access broadband internet services. I guess we will have 5G before fiber.
73 Kari SM0HRP
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Kari Gustafsson SM0HRP, Elmer

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I start a new thread to focus "Fragmentation issue w SmartSDR 2.3.9 and not w Smart SDR iOS" on the issuse.