So much for CE markings

By   18 December 2024 22:23

For some time, I suffer from tremendous interference from various sources. The worst one is LED lighting which generates very strong interference in the 50 MHz band.

I wanted to see the effect of the interference in case we still had analogue television. There was one low band VHF transmitter in The Netherlands, transmitting on system B channel 4, picture carrier 62.25 MHz, from the TV tower in the centre of the country.

Follow this link for a page with photos of the dismantling of the channel 4 antennas in 2007.

A Grundig VG1000 test pattern generator was used. It has a modulator to generate TV signal on the low VHF band. I tuned the modulator to 49 MHz to get the interference into the centre of the TV channel. A test receiver was tuned to the Grundig signal.

A directional coupler was used to feed the test pattern emission and the interference from the 6 m antenna simultaneously to the TV test receiver. The test pattern signal level was adjusted so that it was 6 dB above the minimum required level for a good picture quality, at the input of the test receiver.

The connector from the 6 m antenna was disconnected and reconnected a few times to show the difference.

6m_TV-QRM-test

 

The LED lighting interference is so strong, that the TV picture becomes very bad and colour is no longer received, presumably because the 4.43 MHz PAL subcarrier PLL unlocks, overwhelmed by the interfering signal.

The distance to the source is about 30 m, so if this was the house next door, it would effectively wipe out the TV signal.

The video was recorded from the screen with an iPhone and some aliasing is visible. A video will be grabbed later on.

Here is the video, which speaks for itself. Thank you, European Commission.