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Unread 02-20-2018, 02:55 AM
tMOE tMOE is offline
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Dropping Radio Comms from Wifi

Hi,

Our team has been persistently dropping communication between our radio and our driver station laptop across Wifi.
Our connection is stable across direct connections between RIO and laptop (USB), from RIO to radio the radio to laptop (using only ethernet), but as soon as we try wifi connection, we have stable comms for a minute or two and then we immediately start dropping most of our packets.

We have the 1-26-18 NI Update Suite which was supposed to help resolve this issue (along with the new driver station and new roboRIO image). As of 2-18-18 we reinstalled the radio configuration utility and reflashed firmware and configured our radio, and updated our Eclipse (Java) plugins and the PDP firmware v14.
We also did make sure to disable RIOLog in case it was overflowing the radio with too many packets.
Much of this testing was also done with a blank Robot java program, and we have swapped out many electrical components and re-imaged / re-configured our radio and roboRIO.

At this point we are near out of ideas.
If anyone has insights on what we should try next, that would be greatly appreciated.
Thanks!
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Unread 02-20-2018, 07:54 AM
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Re: Dropping Radio Comms from Wifi

Have you tried a different laptop as the driver station?
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Unread 02-20-2018, 11:28 AM
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Re: Dropping Radio Comms from Wifi

Run a WiFi scanner to be sure you are not getting interference from another source. I use "inSSIDer". This will show you the signal strength of all WiFi signals in range.
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Unread 02-20-2018, 11:51 AM
Greg McKaskle Greg McKaskle is offline
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Re: Dropping Radio Comms from Wifi

The Driver Station chart shows amber bars and a green line that can help characterize communication quality.

The green line is the average latency for 1/2 second of packets. The orange bars show a percentage of dropped packets for 1/2 second of packets.

All medium can have the occasional delay or drop, but wifi is obviously more susceptible due to it being a shared medium.

This information is also logged and can be viewed on the DS by opening the Log File Viewer from the Gear icon in the DS. This is logged every time your robot is connected.

See if the log agrees with your perception of comms quality, and see if you can use this to narrow down the culprit.

In our shop, the 2.4 wifi is congested and sometimes unacceptable for driving a robot. Students show up after school and videos and other heavy content uses up the bandwidth pretty quickly. The 5GHz channel is rather quiet, but many of the laptops don't even have 5G. As mentioned, wifi tools are going to help along with some experiments with good feedback.

If you find a definite cause, please post.
Greg McKaskle
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Unread 02-21-2018, 02:32 PM
tMOE tMOE is offline
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Re: Dropping Radio Comms from Wifi

Hi,

We've been trying on both 2.4GHz and 5GHz settings with our radio's configuration, and we have noticed that both settings do drop comms at some point. After analyzing wifi congestion, comms generally seem to last longer when less people / wifi traffic is going around, and comms drops more frequently when there are more people / wifi traffic. Not to mention we were testing recently in a concrete building as our workspace.

We have taken a look at different laptops as driverstation, and all of them with the updated software still drop comms at some point. Some do work generally better than others, but even then there is still a comms drop.

We looked at the driverstation chart with the communications graph, and it does seem very predictable that comms will be perfectly fine with not much packet loss and quick reply times from radio, but suddenly after a certain amount of time it will jump to 100% loss and radio will try really hard to reconnect, but will still consistently drop packets after that.

We can still test with some of our other radios, so we will see what else shows up, but for now we are thinking the comms drops were a result of wifi congestion or interference from the building. We'll try taking our radio to some better conditions and see what comes up there.

Thanks again!
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