Understanding RSSI and LQ in ExpressLRS
If you’re into RC flying or building your own gear with ExpressLRS, you’ve probably seen terms like RSSI and LQ pop up in your radio or OSD. But what do these numbers really mean, and how do they affect your flight experience? Let’s break it down in simple terms.
What is RSSI?
RSSI stands for Received Signal Strength Indicator. In ExpressLRS, it tells you how strong the radio signal is that your receiver is picking up from the transmitter. Think of it like the volume of a radio station — the louder (or stronger) the signal, the better your receiver can hear it.
ExpressLRS measures RSSI as a raw value, often scaled between 0 and 100 or 0 and 255, depending on your setup. A higher RSSI means a stronger signal, which usually means more reliable control.
How ExpressLRS Measures RSSI
ExpressLRS uses the radio chip’s built-in hardware to monitor the signal power. It constantly checks the strength of the incoming packets and updates the RSSI value. This is done on the receiver side, so it represents the actual signal your model is getting.
What is LQ (Link Quality)?
LQ, or Link Quality, is a bit different. Instead of measuring just how strong the signal is, LQ shows how good that signal actually is in terms of data integrity.
In ExpressLRS, LQ is calculated based on how many packets are received correctly without errors. If the signal is strong but noisy, you might have a high RSSI but a low LQ because some data is corrupted or lost.
Why LQ Matters More for Flying
While RSSI tells you about signal strength, LQ gives a more practical indication of how well your RC link is performing. High LQ means your commands are getting through reliably, which is critical for safety and control responsiveness.
Quick Summary: RSSI vs LQ
- RSSI: Measures signal strength (how loud the signal is).
- LQ: Measures signal quality (how clean and error-free the data is).
- You can have high RSSI but low LQ if there’s interference or noise.
- LQ is usually a better indicator of real-world link performance during flight.
Checking RSSI and LQ on Your Setup
Most ExpressLRS receivers send RSSI and LQ info back to your radio or OSD. You can usually see these values in real time, helping you make decisions like when to return home or adjust your antenna.
For example, if your RSSI is dropping but LQ stays high, you might still have a good link. But if LQ starts to fall, it’s a warning that your control link might be about to break.
Tips for Better RSSI and LQ
- Use quality antennas and position them properly.
- Avoid obstructions like metal or thick walls between transmitter and receiver.
- Keep your firmware updated — ExpressLRS improvements often include better signal handling.
- Fly within recommended ranges to maintain strong and clean signals.
Wrapping Up
Understanding RSSI and LQ on ExpressLRS helps you get the most out of your RC gear, whether you’re flying a racing drone or building a custom plane. Monitor both values to stay safe and enjoy a smooth flying experience.
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