December 4, 2018 11:01

# Looking for resources for TV RF delay line?

Hi

I haven't done any construction since school days but really loved doing it.

I have an idea for a project which will solve an AV issue I have at home.

I use the powered RF2 output on my Sky+HD box to to distribute my Digital TV aerial signal and my Sky output to 3 TV's in my house.

I've just bought a new (4th) main TV and that receives the HDMI output from the Sky Box.

The decryption of the HDMI in the TV leads to a delay in this main TV which causes an echo around the house. It's a fraction of a second of about 100 to 300ms. The analogue signal getting to the 3 peripheral TV's first!

I imagine that I can put a simple resistance/capacitance circuit in the RF2 output, inline, but don't know quite where to start looking for resources.

Would any one be prepared to guide me?

So I need to learn a bit about the AV RF signal and I'll need some maths to calculate component values?

Phil

December 7, 2018 08:45

Hi Phil,
I've written a long comment, but having problems posting it directly, so I'm putting it in a text file attached to this message. (I'll replace with a direct comment when the system lets me do so without error message.)

December 5, 2018 13:08

Hi Phil, I confess to no experience in this area and will be interested to hear any expert opinions, however from memory communications with geostationary satellites cause a delay of about 250mS. I mention this as coaxial delay line will need to be about 0.6 of this distance! So way out from any LC delay line possibility.
Regarding an RC delay you will probably require a gain element to restore the signal between delays, this will obviously introduce noise as the signal is restored, what is required is beyond my knowledge but you could start investigating this area.
My initial thought was a digital delay, but the buffer will have to be huge (and fast) and require video ADC's and DAC's which will be expensive.
The above is not very useful regarding a solution, but my thoughts are this is a non-trivial issue you are trying to resolve. I look forward to any other answers on this topic.