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  • FTC5110
    started a topic <G26> Match Replay discussion

    <G26> Match Replay discussion

    Our team posted an official Q&A about <G26> Match Replay due to verified Wi-Fi interference. There's no clear definition of what constitutes verified Wi-Fi interference and we're really keen to learn what other teams think about this as we head towards World Championship events shortly. This year in Houston FTC is on the same floor as FRC so yet more WiFi signals and people with phones floating around!


    Here's the text of our Q&A post:

    What constitutes verified Wi-Fi interference? There's no viable way of verifying Wi-Fi interference with a team's peer to peer WiFi direct sessions within rule <T3> timeframe. The only indication available to teams is "Ping Time" along with an unusable robot of course!

    Q: If an FTA views a team's Driver Station phone screen during a match which shows a ludicrous "Ping Time" of several seconds is this considered verified Wi-Fi interference?

    Q: Assuming the above answer is NO then please provide a definition of what "verified Wi-Fi interference" actually is.

    Looking back to earlier seasons with Samantha modules run through an Access Point there were log files on the match control computer which could be analysed where necessary and matches were replayed when excessive lag was noted by multiple teams. Heading into the 2018 FTC World Championship events it would be great to know how <G26> will be applied.

  • FTC5110
    replied
    Originally posted by JoAnn View Post

    This post has been answered in the Tournament section of the Game Q&A forum, but I've copied that response and posted it here:

    A1: No, not necessarily. Ping times are a measure of the wireless connection quality and the availability of the Robot Controller to respond to messages from the Driver Station. High ping times can be caused by multiple factors, such as an incorrectly written op mode, an improperly configured Wi-Fi adapter (for example, if the Wi-Fi adapter is also connected to a Wi-Fi infrastructure network), or even a poorly places Robot Controller (if it is embedded in the metal frame of the robot, for example, then the Wi-Fi radios might have a difficult time transmitting reliably to each other). If multiple robots operating on the same Wi-Fi channel are experiencing high ping times, then without additional monitoring tools in place it would be difficult to prove that there is significant or verified interference in the venue.[
    So where a team is confident their op-mode is written correctly, isn't connected to an infrastructure AP, and has mounted their phone is a sensible location then Ping Time seems to be a pretty good indicator of Wi-Fi Interference. Good to know! My understanding is the USB communications was decoupled from the RC-DS communications thread some number of SDK versions ago so there should be no claims of loose cables causing Wi-Fi issues anymore.

    Can we have the WTA and/or FTA at Houston and Detroit World Championship events explain to teams, perhaps during the driver meeting, what they should do during and after a match where they suspect Wi-Fi Interference so it can be either Verified or otherwise pinned to team specific problems. Fully understand the tools in use however we're dealing with something that happened "last match" making analysis more difficult especially during a schedule sensitive event.

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  • JoAnn
    replied
    Originally posted by FTC5110 View Post
    Our team posted an official Q&A about <G26> Match Replay due to verified Wi-Fi interference. There's no clear definition of what constitutes verified Wi-Fi interference and we're really keen to learn what other teams think about this as we head towards World Championship events shortly. This year in Houston FTC is on the same floor as FRC so yet more WiFi signals and people with phones floating around!


    Here's the text of our Q&A post:

    What constitutes verified Wi-Fi interference? There's no viable way of verifying Wi-Fi interference with a team's peer to peer WiFi direct sessions within rule <T3> timeframe. The only indication available to teams is "Ping Time" along with an unusable robot of course!

    Q: If an FTA views a team's Driver Station phone screen during a match which shows a ludicrous "Ping Time" of several seconds is this considered verified Wi-Fi interference?

    Q: Assuming the above answer is NO then please provide a definition of what "verified Wi-Fi interference" actually is.

    Looking back to earlier seasons with Samantha modules run through an Access Point there were log files on the match control computer which could be analysed where necessary and matches were replayed when excessive lag was noted by multiple teams. Heading into the 2018 FTC World Championship events it would be great to know how <G26> will be applied.


    This post has been answered in the Tournament section of the Game Q&A forum, but I've copied that response and posted it here:

    A1: No, not necessarily. Ping times are a measure of the wireless connection quality and the availability of the Robot Controller to respond to messages from the Driver Station. High ping times can be caused by multiple factors, such as an incorrectly written op mode, an improperly configured Wi-Fi adapter (for example, if the Wi-Fi adapter is also connected to a Wi-Fi infrastructure network), or even a poorly places Robot Controller (if it is embedded in the metal frame of the robot, for example, then the Wi-Fi radios might have a difficult time transmitting reliably to each other). If multiple robots operating on the same Wi-Fi channel are experiencing high ping times, then without additional monitoring tools in place it would be difficult to prove that there is significant or verified interference in the venue.

    A2: Ping times can be used to make a determination if wireless interference. For example, if multiple robots operating on the same Wi-Fi channel experience high ping times and poor control, then the WTA/FTA might suspect that there is significant interference in the venue for that operating channel. This is a simple and cost effective approach for monitoring for wireless interference.

    At higher profile events (such as Regional and World Championships) WTA's and FTA's often also use more sophisticated tools (such as Fluke Aircheck spectrum analyzer, a MetaGeek WiSpy analyzer, and other specialized tools) to monitor the wireless spectrum at the venue. These tools can alert the operator when there is significant interference on a Wi-Fi channel. Unfortunately, these tools are relatively expensive, so they are not used at every event. However, if these tools are present and are being used to monitor the spectrum, then a WTA or an FTA can use them to determine if interference is an issue.

    If an FTA or WTA suspects Wi-Fi interference, they will report this suspicion to the Head Referee. The FTA and Head Referee will further explore the potential violation of this rule. The Head Referee will work with FIRST Headquarters staff to determine if rule <T4> has been violated, and determine appropriate next steps (for example, match replay if the interference altered the outcome of a match, or potential disqualification of a team).

    As a reminder to all teams, when an event assigns a specific Wi-Fi channel, teams should also make sure to stay on that channel for the duration of the event unless otherwise asked by the event to switch channels. Technical staff only monitors the channels that are assigned by the event director, and therefore can only review the logs from the channels that are actively being monitored throughout the event.

    JoAnn

    Leave a comment:


  • FTC5110
    replied
    Originally posted by CoachZM View Post
    In the Control System Troubleshooting Guide it discusses the use of Wireshark to look for specific wireless issues including DEAUTH packets. I am sure they are using this software to scan the network throughout the event to look for anyone or anything that could be interfering with the wi-fi connections. If an FTA would see a large spike in DEAUTH packets at the same time there were communication issues with a team then this in my opinion is something they use to look at match reruns. It is possible for someone to intentionally send DEAUTH packets to a specific teams phone which would cause the DS and RC to lose connection from each other. We run Wireshark at our tournament to look for things just like this.
    Did you see any correlation between teams reporting excessive lag and DEAUTH packets? Ultimately I'm looking for a clear definition of what data FTA's will use to determine "verified Wi-Fi interference" and realistically just how much analysis can be done within the space of a few qualification matches without holding up proceedings?

    Leave a comment:


  • CoachZM
    replied
    In the Control System Troubleshooting Guide it discusses the use of Wireshark to look for specific wireless issues including DEAUTH packets. I am sure they are using this software to scan the network throughout the event to look for anyone or anything that could be interfering with the wi-fi connections. If an FTA would see a large spike in DEAUTH packets at the same time there were communication issues with a team then this in my opinion is something they use to look at match reruns. It is possible for someone to intentionally send DEAUTH packets to a specific teams phone which would cause the DS and RC to lose connection from each other. We run Wireshark at our tournament to look for things just like this.

    Leave a comment:

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