digital/Freeview reception peculiarities

  jack 09:25 05 May 2009
Locked

A comment on how not only the lower power transmission of the Channel5/Dave group of channels are received but seemingly different equipment act in diverse ways.

I have a Sony digital TV and a Sony Digital PVR
The TV will receive Ch5/Sky3/Dave - then during the day or at varying times during an hour or so - lose them- putting up messages varying - 'No event info'Not tuned.
Though the channels are there on the display showing the program detail of whats going on.
Then if I retune the set - it will skip those channels entirely and they won't come up at all.
'Dave Deja Vu' however is always there.

Meanwhile the PVR[on the same Aeriel[first item on the loop] gets all the channels all the time
[albeit said digi channels will snap crackle and pixelate from time to time.
I have'rattled all the connections along the aerial line and between units - makes no difference.

So why is the TV so spasmotic and the PVR gets the 'picture'

  john bunyan 09:45 05 May 2009

It is prbobably worth checking that you have a good enough aerial, the cable and connections are ok. If so an aerial signal booster is well worth it -i cured a similar problem I had for about £15. On the Sony tv you can check the individual signal strength if you go through the menu.

  jack 10:34 05 May 2009

Thinking that perhaps a 'digital' Aeriel was needed.
however 'Freeview forums' reckon 'not so' the standard unit doing the job is good enough come the switch over to full power
So decision do the Ariel improvement- go from loft to roof] or simply wait[if I live that long ;-}]

  oresome 12:02 05 May 2009

The signal is marginal and shows up slight differences in tuner performance.

A move to a roof aerial from the loft will fix the problem and is technically the best solution.

I wouldn't rely on an increase in power post switchover fixing the problem. It may well be that to accommodate HD channels, further compression is applied to many existing channels meaning that you will need a better signal to decode them sucessfully. This will negate the effect of increased poweer.

  Stuartli 18:21 05 May 2009

There is no such thing as a digital aerial - it's a wide band aerial (earlier aerials used to be narrow band).

Freeview signals are only a fraction of the strength of analogue signals until your region undergoes the full switchover; moreover, there are two types of transmissions, 16 QAM and 64QAM. See:

click here

for an explanation.

  jack 19:03 05 May 2009

Have printed off Stuartli's link for an in depth read - much good that it will do me.
Think is it worth going to the expense of a roof aerial just for Dave and Sky 3.
Especially as it seems to come and go
at the moment its broken as far as the Tv is concerned and a bit broken for the PVR

  oresome 19:45 05 May 2009

"There is no such thing as a digital aerial - it's a wide band aerial (earlier aerials used to be narrowband)"

I don't agree with the above statement.

Digitally approved aerials will have a balun fitted and have an approved logo on the packaging. The balun improves the noise pickup performance on the downlead.

Wideband and narrowband aerials are available and both are suitable for digital reception dependant on the channel spacing employed at the transmitter. Narrowband will always provide a greater gain for a given size.

Wideband aerials are more common because it simplifies stock holding for retailers and doesn't require technical knowledge to determine suitability.

  john bunyan 21:07 05 May 2009

The others are clearly more technically knowledgable than me, but if you know anyone who could lend you an aerial booster to try out, I still think it is a simple solution. It worked for me.

  Stuartli 22:19 05 May 2009

I first acquired ONDigital very soon after it started in 1998 - I was unable to pick up the middle channels on my then TV aerial because it was (obviously) narrow band.

The aerial specialist I've always used stated I needed a wide band aerial and this cured the problem immediately; the same aerial is still in use today and brings in all the stations available from Winter Hill.

Describing aerials as "digital" is basically a marketing ploy designed to bamboozle those unaware of the reality.

Some of the warehouse TV outlets in my area use a similar sleight of hand by inferring the digital switchover here in November means the purchase of brand new equipment is required.

  oresome 13:58 06 May 2009

"Describing aerials as "digital" is basically a marketing ploy designed to bamboozle those unaware of the reality."

I have already explained that a digital approved aerial will have a balun incorporated in the design. These transformers were rarely if ever fitted prior to digital broadcasts starting.

A balun is a balanced to unbalanced transformer and is now thought desirable because digital signals are more susceptible to certain types of interference.

  oresome 14:25 06 May 2009

"Some of the warehouse TV outlets in my area use a similar sleight of hand by inferring the digital switchover here in November means the purchase of brand new equipment is required."

It's difficult to avoid buying some new equipment, if it's only a STB for the TV!

But then the good old VCR has it's own set of problems and there's the old TV's relegated to the bedrooms that need STB's.

On top of this there are all the flakey aerial systems that aren't up to the job.

Rich pickings for the trade.

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