I had an expensive digital TV aerial fitted a few mths ago, I have seen recently that the sound and picture breaks up (pic goes blocky and sound goes scratchy) when a motorcycle goes past the house, the bike concerned is one of them Bee stuck in a jam jar engined ones…and it has only just lately arrived on our estate does this happen to anyone else or do I have a technical issue with the aerial ? Can the interference be 'trimmed out' ?

dunno but it sounds like this guy has the same problem:
http://www.digitalspy.co.uk/forums/showthread.php?t=214308

Did the installer use screened cable from the aerial to the telly or just bog-standard co-ax ? My place has ye-olde 20yr old co-ax and picks up chavmobile interference if they pass. I would have thought that screened cable should block the interference ?

Did the installer use screened cable

I am not sure, the aerial is a full digital one and not digital ready type, I could ask the installer what he used, or, check myself a shielded co ax should be easy enough to spot. Thanks.

Yep me and my neighbours have the same problem. So much so a posse of the old codgers went round to the potential lung donors house and he now rides a different way through the village……really annoying 👿

The installer will be a bit of a donut if he's used co-ax for a digital setup but you can still buy the stuff and it is cheaper than screened so…….

It's impulse jamming caused by the spark plugs.

The spark causes a EM spike that is of the order of nano seconds in duration, and as bandwidth is equal to the inverse of the the time function, you end up with noise over a very wide bandwidth, almost from DC to daylight.

As this noise is wideband (ultra wideband maybe?), it leaks around all the screening that you can probably put in place, and raises the noise floor in your receiver,

Digital TV works on some kind of packet data system with error checking algorithms, but the spikes still manage to blat out enough of the bits so that your picture breaks up.

It's impulse jamming caused by the spark plugs.

I am thinking now that when we all go digital during the big switchover some law must be brought in to inhibit these destructive impulses ?

I dont get it with bigger engined motorbikes as I have had a near neighbours going past for a long time, its probably the cheaper end of the market for 50cc heroes ?

Hmmm,

I think it's the screening on the offending bikes that is the main problem, as if you can screen enough of it the power at the source, it quickly falls (as a one over range-squared function, for an isotropic emitter) to levels that the receiver can deal with. Hence big stuff and cars are less of a problem.

It's not just chicken chasers though – One of my neighbours has some noisy Harley V-Twin thing, that as well as waking me up every Sunday morning, makes my TV unwatchable. In fact it's out side now, throbbing away. grrrrr.

Not sure about legislation to sort the matter out any time soon.