Aardappeltaart
Posts: 81
Joined: Wed Mar 02, 2016 11:32 am

Pi4, TV-hat and WIFI AP compatiblilty

Sat Nov 02, 2019 7:02 pm

I'm using the Pi4 for watching DVB-TV and also as a wireless AP.

Both work great separate, but not together. When I'm watching TV, the Pi is losing all connected devices on the AP.

Code: Select all

iw dev wlan0 station dump | grep St
gives nothing

I tried a ribbon extension cable for the TV-Hat, but that doesn't help.

Seems there is interference between the TV-hat and WIFI.

Or can the problem be caused by the an insufficient power supply?

The Pi does not throttle:

Code: Select all

vcgencmd measure_volts;vcgencmd get_throttled;vcgencmd measure_temp
volt=0.8472V
throttled=0x0
temp=51.0'C
AFAICR there was a second batch of TV-hats, because the first hat caused interference, but I can't find any info about it now.
Can someone elaborate on that?

when I disable WIFI completely,

Code: Select all

sudo ifconfig  wlan0 down
I'm seeing higher SNR and less UNC in `femon -H`

The TV-Hat worked fine before on a RPI3+, but I never used Wifi on that device.

Aardappeltaart
Posts: 81
Joined: Wed Mar 02, 2016 11:32 am

Re: Pi4, TV-hat and WIFI AP compatiblilty

Sun Nov 03, 2019 12:23 pm

Ordered an official PSU, could sould the problem.

Still anyone any ideas about TV-hat and WIFI interference (on a PI4), or a slightly patched second TV-Hat batch?

Aardappeltaart
Posts: 81
Joined: Wed Mar 02, 2016 11:32 am

Re: Pi4, TV-hat and WIFI AP compatiblilty

Tue Nov 05, 2019 3:21 pm

Official power supply arrived, but halas no improvements.
So we can rule out insufficient power. It's a nice supply though.

Problem stays: something playing in Kodi, AP is dropping al connections.

But doesn't matter if it's DVB-TV or some h264 content from local disk.

Problem solved it when I force a high WIFI channel in hostapd (11-13) for 2.4GHZ

Channel 3-6; all devices are immediately dropped when playing something in Kodi.

Seems like interference between CPU/GPU and WIFI 2.4GHZ.

Anybody similar WIFI problems with the Pi4?

Aardappeltaart
Posts: 81
Joined: Wed Mar 02, 2016 11:32 am

Re: Pi4, TV-hat and WIFI AP compatiblilty

Mon Nov 25, 2019 5:43 pm

HDMI interference, other cable solved the problems.

https://www.raspberrypi.org/forums/view ... 0#p1571440

Aardappeltaart
Posts: 81
Joined: Wed Mar 02, 2016 11:32 am

Re: Pi4, TV-hat and WIFI AP compatiblilty

Mon Dec 02, 2019 8:51 am

That said other monitor solved the problem.

Strange, but that seems to be the case:
https://www.raspberrypi.org/forums/view ... 5#p1573994

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