“Why is My Internet Slow?” (Packet Loss)

You’re playing a game. Suddenly, your character teleports back 5 feet. “LAG!” you scream. What actually happened? Packet Loss. The internet sends data in tiny envelopes called “Packets.” Sometimes, the mailman drops an envelope.

TCP vs. UDP: The Protocols

• TCP (Transmission Control Protocol): The Reliable One.
  • “I sent Packet 1. Did you get it?”
  • “Yes.”
  • “Okay, sending Packet 2.”
  • Used for: Webbrowsing, Email, Text. Accuracy > Speed.
• UDP (User Datagram Protocol): The Fast One.
  • “Sending Packet 1, 2, 3, 4, 5! Catch them if you can! I don’t care!”
  • Used for: Video Games, Voice Chat, Robots. Speed > Accuracy.

The Robot Heartbeat

FTC Robots communicate via Wi-Fi Direct using UDP. Every 20 milliseconds, the gamepad sends a packet: “Joystick X = 1.0”. If a packet is lost due to interference (too many Wi-Fi signals in the stadium):

1. Packet 1 (“Drive Forward”) arrives. Robot drives.
2. Packet 2 (“Stop!”) is Dropped.
3. Packet 3 is delayed. Result: The robot keeps driving forward for an extra 100ms and smashes into the wall. This is a “Lag Spike.”

The Spectrum War

In a robotics competition, there are 200 phones and hotspots. The 2.4GHz and 5GHz airwaves are a battlefield. This is why we teach teams to:

• Use 5GHz channels (Less crowded).
• Avoid metal shielding around the antenna (Faraday Cage).
• Keep the Driver Station close to the robot.

Lag isn’t just annoying; in robotics, it’s dangerous.