Hi all,

Mods please feel free to move this thread into correct section.

I have had SD on my CRT for well over 3 years now and am very happy.

however, occasionally when someone opens fridge door or turns lights on the screen will pixelise.

I have quad shield on the antennae aerial so that is eliminated and also a surge filter EMI/RFI on power board for SD set top box.

Anyone have a quick an easy solution for removing this interference with switches and their frequency interfering with SD top box?

Any suppressors from jaycar/recommendations???

Thnx all

I experienced this same problem some years ago and it often relates to the STB you are using.
Just a suggestion...don't open the fridge so much and keep the lights on or off!
It's really not that serious is it?
Up-grade to a HDSTB and this problem may well go away...it has for us!

you can minimise/stop this if you amplify the signal by a few more dB's at the antenna and then using an attenuator of equivalent value at the outlets, this will increase the SNR between the Antenna signals and the Impulse Noise created when you turn on lights, open fridge Door, etc.

No problem really but just curious of an supressors available on the power supply to block this high frequency on the mains line.

It seems my power-surge RFI/EMI is not enough.

I think I may do some mods and install this

http://www.jaycar.com.au/productView.asp?I...=&SUBCATID=

Worked on my DVD player to stop interference from mains noise.

Thanks all for your replies.

To get reliable digital reception you need to have a good quality signal, of adequate signal strength. And this is as measured at the antenna, essentially off-air.

Impulse interference can get into the system through a number of usual mechanisms.
One such mechanism is certainly through the distribution cabling, poor quality connectors/splitters/devices not shielding correctly, even the flylead to the receiver from the outlet.
Another mechanism can be through airborne interference getting in to the antenna itself, essentially as received signal.
Interference on the mains power system is another one, although probably not directly, especially if the devices being used are of good quality. I think it is more likely that interference coupled to the power line may re-radiate and be picked up by poorly shielded devices, or by the antenna itself.

If the antenna is in poor condition, or not of particularly good design, this may make the problem worse.

The OP indicated that quad shield cabling was being used. Hopefully if there are any other connectors/splitters/wall plates etc in the system, they also provide good shielding. If the shielding of this part of the system is good, adding extra boosting at the antenna wouldn't really help, as the impulse would be likely IMO to be coming in via the antenna. A booster would boost this as well.

If at the antenna there is sufficient margin of signal strength, and more importantly, signal quality, interference is much less likely.

And to achieve this may mean trying a better antenna for that particular situation, and locating it in a better spot to minimise interference pickup and optimise received signal reception. And the best spot can often only be found with digital field strength meters.

These are all good points . Personally I would run it strait from the wall with a quad shield flylead bypassing your surge board. Apart from the obvious place for interference to get in (the antenna) flyleads are often a weak point in a system. Get a rg59 quad shield flylead the good ones can have 100% interference protection.

Cheap solution

XLR8,
The signal received by the antenna is considerably less than the voltage producing the spike on the mains.

If you antenna is designed for any channels below channel 6 it is good at picking up the spike from the mains wiring in the house.

There is no point in filtering the power mains for the above reason.

Go to the Geographic Viewers’ Forum, which is near the bottom of the main forum’s home page. Select your region and read the pinned post “Get the Best Reception”. Please post any further correspondence in that strand for all in your region to see. I will see it anyway. You could also search your location in that strand for others in your area.

The answers depend on what transmitters you are trying to receive and what you are using now to receive the signal.
So on the appropriate forum state your location and whether you are using a roof antenna, indoor antenna or from an antenna system in a block of apartments.


AlanH

Haven't seen that so much with the older RG-59...

RG-6 quad shielded are good.

To stiff! so stiff that they can spread your pal plugs quad is quad and has the same interference shielding. RG6 just has less losses than RG59 but that would be pretty hard to spot over a 1m flylead.

I have seen this too. If you're using quad-shield the EMI won't be conducting through the shield and in any case the RF filters in the STB should remove EMI spikes coming in from the antenna. More than likely the EMI pulse is being conducted in through your mains and mixing in further down the RF chain inside the STB, especially since you have different mains sources all causing the same symptom. This is more prevailent (but not necessarily limited to) cheaper STBs where the power supplies do not have a lot of RF filtering.

RF shielding is a bit of a black art but I suggest sticking Ferrite RF chokes on things to see the result:

Ferrite chokes on the STB mains lead (at the STB end)
Ferrite chokes on your fridge lead (thereby removing it at the source)
Ferrite chokes on your (A/V leads in case it is being conducted through the TV)

So head down to Jaycar and pickup a few chokes and see how you go.

Good luck!

This could help, but it is an expensive option to try. If you have a good signal I would steer clear of masthead amps as they pickup and amplify all sorts of crud and before you know it your neighbors kids and their UHF walkie-talkies are overloading the masthead front-end and killing your reception totally.

Just my 2c...