WXforum.net
Weather Station Hardware => Blitzortung => Topic started by: Nova on November 01, 2014, 05:33:57 PM
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Image 1543 shows 1000 Hz 1mV peak-peak interference caused the the system display dimmer. This noise goes away when the display brightness is set to 100%.
Has anyone been able to eliminate this noise without increasing display brightness to maximum?
Will full brightness shorten the display lifetime?
Thanks,
Joe
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Joe,
This is a known issue with the LCD used in the Blitzortung RED systems. The recommendation from the developers is to set up your display settings so the display is at full-brightness and/or so it shuts-off after some period of time. I have mine set as shown below:
(http://carsonvalleyweather.com/images/wxmisc/2014-11-01_1439-LCD-Settings.png)
It shuts off after 60 seconds. There is a noticeable difference in signal noise between it being on and off.
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Has anyone been able to eliminate this noise without increasing display brightness to maximum?
Will full brightness shorten the display lifetime?
I have mine set to 100% full time. The controller is out in the garage, and I have a Raspberry Pi cam aimed at it, so I want it on all the time. It is an LED backlight, so I expect a long life out of it.
(http://www.miraculon.net/garagepi.jpg)
I have not dug into the issue, but I suspect that some combination of a lower frequency and slower rise/fall times on the PWM might help. Also, if the grounding was poor for the return path of the PWM there might be a common-impedance cause for the noise. (ground ripple getting into the ADCs)
Greg H.
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It's the PWM that is the cause of the hash noise. From what I have seen on my station, it's really not that much but, in an effort to keep all noise at the lowest possible level, I simply have it set to time-out after 60 seconds. I see about 5mv with the LCD backlight on and about 2mv with it off. That is looking at the Signals page with the 5v sampling Enabled.