FPV Drone Latency Explained: What It Is and How to Reduce It

FPV drone flying is all about precision and control. One of the key factors that can affect your flying experience is latency—specifically, how quickly the drone responds to pilot controls. Whether you’re racing, flying freestyle, or capturing cinematic footage, reducing latency can make a huge difference in your drone’s performance and how connected you feel to it. In this guide, we’ll break down what FPV drone latency is, why it matters, and how you can reduce it to enhance your flying experience.

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What is Latency?

Latency in FPV drone flying refers to the delay between when you move the control sticks on your transmitter and when you see the drone responding in your FPV goggles. This delay results from various components in the control loop, including the transmitter, receiver, flight controller, motors, and FPV system.

Typically, latency in FPV drones can range from 10ms to over 100ms, with higher latencies making it difficult to control the drone. Lower latency is critical for faster response times and better control.

Why Latency Matters

Every millisecond counts when flying an FPV drone. Here’s why keeping latency minimal is important:

• Precision and Responsiveness: Lower latency means the drone reacts faster to your inputs, allowing for more precise control. This is crucial in FPV racing and freestyle flying, where split-second decisions can make a big difference.
• Smooth Flight Experience: Higher latency can make your drone feel sluggish or unresponsive, negatively affecting the smoothness of your flight. This can impact the quality of your footage and overall flying experience.
• Pilot Reaction Time: The faster your drone responds to your inputs, the better you can avoid obstacles or react to sudden changes in your surroundings. For example, if your drone is traveling at 100MPH (~45m/s), even a 10ms delay means your drone would have traveled 0.45 meter before responding to your input—this can be the difference between avoiding an obstacle and crashing.

Breaking Down FPV Drone Latency

To understand how latency works, imagine you’re sending a package through the mail. First, you drop it off at the post office, then it’s sorted at a distribution center, passed onto a delivery truck, and finally arrives at your doorstep. Each step in this process adds a bit of time, just like each component in the FPV control loop contributes to overall latency.

• Visual Input: You see your drone’s movements through the goggles.
• Cognitive Processing: Your brain processes the visual information.
• Physical Response: You move the control sticks based on what you see.
• Transmitter Sending Commands: The transmitter processes your inputs and sends them to the drone.
• Flight Controller Processing: The drone’s radio receiver forwards the signal to the flight controller, which processes it and adjusts motor speeds.
• Motor Response: The motors react, changing the drone’s movement.
• Visual Feedback: The camera captures the drone’s new position and sends the updated video feed to your goggles.

The total control latency is the sum of the delays from each of these events. Factors that affect latency include:

• Human reaction time
• Gimbal input encoding speed (e.g., EdgeTX’s 500Hz polling)
• Radio link speed (e.g., Crossfire’s 150Hz vs. ExpressLRS’s 1000Hz)
• Receiver protocol speed (e.g., CRSF vs. SBUS)
• PID loop frequency (e.g., 4K vs. 8K)
• ESC protocol speed (e.g., DShot300 vs. DShot600)
• Motor acceleration time
• FPV system latency
• FPV goggles’ screen refresh rate

Reducing Control Latency

To minimize control latency in FPV drones, focus on optimizing each component in the control loop:

• RC Link: Invest in a low-latency radio control system, such as ExpressLRS, which offers some of the lowest delays available. All of my radio recommendations support ExpressLRS: https://oscarliang.com/radio-transmitter/
• Flight Controllers: While most Betaflight flight controllers today use 4KHz and 8KHz PID loop frequencies, you can still fine-tune settings. Properly tune PID and use less filtering and RC smoothing to reduce latency, depending on your build.
• Motors: Choose motors with enough torque to spin the propellers of your choice. For example, on a typical 5″ drone, a motor might take up to 50ms or more to go from 0% to 100% throttle, it’s a substantial amount of latency. A motor that is too weak will take much longer to accelerate to the desired velocity, hence resulting in more latency. FPV motor recommendations: https://oscarliang.com/motors/#Recommendations
• FPV System: FPV system latency—often called “glass-to-glass” latency (from camera lens to goggles screen)—is critical. Analog and HDZero systems offer lower latency than HD systems like DJI and Walksnail, but that’s the price we must pay to enjoy the superior image quality and more robust connection. But with DJI and Walksnail, you can still reduce latency by using higher frame rates. Keep in mind that with digital systems, latency can fluctuate with signal quality, so maintaining a strong signal is essential – for example using the maximum output power and appropriate antenna setup.
• Improving Reaction Time: Beyond the equipment, improving your reaction time through practice—especially in FPV simulators—will help reduce the impact of latency. Building muscle memory is key to becoming a more skilled pilot.

Conclusion

FPV drone latency plays a crucial role in your flying experience, especially when precise control is needed. By understanding the factors that contribute to latency and making targeted upgrades to your gear—whether it’s upgrading to a high refresh rate RC system or choosing a low-latency FPV system—you can significantly reduce delays. This results in smoother flights, better handling, and a more enjoyable FPV experience. For pilots looking to take their flying skills to the next level, reducing latency is a critical step in mastering FPV drones.