Yup.what the actual heck?! Dimmed lights are simply turning on and off really quickly?!
-that is actually really fascinating! I can see why it could cause people to have headaches!
I'm very glad for you, as i remember it was a real issue with your very sensitive hearing at those frequencies.With firmware 2.2.2 on my car it seems to me that this presumed PWM noise is all but gone! Whereas before it was plainly audible in every Lucid I'd sat in (including @RM-S8's shiny new Sapphire) on my car now I can't even tell if it exists.
This was my last remaining real complaint about the car, and I hope I am not just hallucinating that it's resolved
I had mentioned this issue to Zak Edson at the recent Philadelphia area Lucid event. I don't know whether he had a chance to raise my concern internally, but at any rate @mcr16 I hope you can convey my thanks to whoever fixed this.
NerdThe evolution of dimming technology has certainly become more complex than simply reducing the current. LED bulbs, for example, can be dimmed, but there's a catch. If you suffer from migraines, try recording your LED bulbs at home with a slow-motion camera; you might discover that they flicker! Replacing these flickering bulbs with non-flickering alternatives could potentially provide some relief from migraines - it makes a huge difference for one of my best friends.
Here's the science behind it: LEDs powered by a DC source have electrons that remain charged within the diode, continuously emitting light. On the other hand, a typical power source, such as a wall socket, produces alternating current, causing the inverter to switch on and off in each cycle, resulting in a flickering LED light when recorded on video. Because of this, any LED bulb will have a driver that converts AC to DC et voilá, no flicker. But hang on - it still flickers in your home? Well, is it dimmable?
Now, here's where it gets a bit technical. Most LED dimmers utilize a technique called Pulse Width Modulation (PWM). PWM dims LEDs by rapidly blinking them, switching between "on" and "off" states multiple times per second. This reduces the overall brightness as the LEDs are not constantly emitting light. By adjusting the ratio of "on" to "off" time, the brightness can be controlled.
The crucial point to understand is that PWM dimming essentially creates a controlled flickering effect. Even though it might appear seamless to the human eye, the LED is not producing a constant light output with consistent brightness. In essence, all PWM-based LED dimmers will exhibit some level of flicker. Therefore, when we refer to "flicker-free," it's more accurate to say that the LED is free from the negative effects of flicker.
To truly eliminate flicker, a very high-frequency PWM driver is required, operating at something like 25,000 Hz. This high frequency ensures that the power supply can respond quickly to the rapid switching between "on" and "off," preventing any oscillating vibrations that could generate an audible buzzing sound. Frequencies below 25,000 Hz run the risk of creating this unwanted noise, as that sound is going to be *at* the PWM frequency; humans can’t hear 25kHz.
However, high-frequency PWM drivers come at a higher cost, and their availability can be limited, impacting the feasibility of implementation - especially during a pandemic.
I'm curious; who wants to go and record their car's dimmed screen to see if it flickers? I suspect it does, and I'm willing to bet $5 on it!
(Thanks for coming to my TED talk, lol)
I’ve noticed that noise before, it reminds me a bit of what can happen with an unshielded speaker when it is exposed to some nearby magnetic field, and it had two distinct pitches that would cycle in and out periodically. I thought maybe it was some error in cable shielding somewhere in the car where something was causing interference. Interestingly with the latest update, I also no longer notice that noise, although I did need to do a logo reset and during the reboot it did make that noise again, but has not done it since then. Before I wouldn’t notice it unless looking for it as I have some significant tinnitus at baseline I’ve learned to ignore, and the higher of the two frequencies that occurs with that weird interference noise is similar to the pitch of my tinnitus which I’ve trained myself to block out haha.With firmware 2.2.2 on my car it seems to me that this presumed PWM noise is all but gone! Whereas before it was plainly audible in every Lucid I'd sat in (including @RM-S8's shiny new Sapphire) on my car now I can't even tell if it exists.
This was my last remaining real complaint about the car, and I hope I am not just hallucinating that it's resolved
I had mentioned this issue to Zak Edson at the recent Philadelphia area Lucid event. I don't know whether he had a chance to raise my concern internally, but at any rate @mcr16 I hope you can convey my thanks to whoever fixed this.
oh no, they've found me outNerd
(but damn, that is a REALLY good explanation. I just had to further read into it after you gave that info! i was always curious regarding why some screens and car headlights flickered on camera, now I know. Thanks! I thought it had something to do with the refresh rates clashing... thought I read something about that.)
I already knew he was a (hyper) nerd, I'm just joking. That HA API is insane by itself, as you mentioned!
Total speculation: The PWM frequency can be set/synchronized in software, and they fixed some issue where the PWMs for the different screens were out of sync. I've noticed the brightness modulation upon ambient lighting changes seems a lot less aggressive as well, which is another welcome change.
