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Panasonic EX75 HHD recording skips

AL S

Established Member
Hi,
My first DVD recorder - the Panasonic EX75. My first problem - recordings made on the HDD (LP) skip - by which I mean a few frames stutter or appear not to be recorded. In a five minute test recording it happened several times. This is recording from Freeview input via the tuner, ITV1, strong signal.

Send it back?

See if it settles down?

Weather problem, not HDD?

Test it on other channels?

Any advice or previous experience gratefully accepted.
 

HMHB

Distinguished Member
It's got to be worth trying to record other channels to see if it is a general problem. I would also advise recording in SP and XP mode to see if the problem was caused by recording in LP mode. I have never been happy recording in LP mode for stuff that I want to archive.
 

nialli

Established Member
Was the sound okay during playback? My EX-75 has recorded around 30 hours to HDD so far, and I had a similar problem to the one you describe on Monday, recording Five via Freeview in XP mode. The picture jumped a bit but the sound was fine. Looks like a broadcast problem as Five also jumped on NTL that night.

I wouldn't send it back just yet, but would suggest a number of test recordings in different modes from different channels. I've always found the ITV mux on Freeview the most tempramental, regardless of signal strength. We've got max signal strength, but still occassionaly have blips on ITV's channels.
 

Gavtech

Administrator
It is much more likely to be a broadcast/reception problem, rather than a problem with the machine itself... but keep monitoring.

The two multiplexes that contain the channels mentioned [ ITV1 = Multiplex 2, Five = Multiplex A ] are the two most overdriven multiplexes and often seem to cause problems.
 

Goober11

Standard Member
Gavtech said:
It is much more likely to be a broadcast/reception problem, rather than a problem with the machine itself... but keep monitoring.

The two multiplexes that contain the channels mentioned [ ITV1 = Multiplex 2, Five = Multiplex A ] are the two most overdriven multiplexes and often seem to cause problems.

I tend to agree with Gavtech. Niali and I seemed to have the exact same problem when recording Big Love on Monday night. The chances of this happening at the same time with 2 seperate boxes and being faults with such boxes is remote I would have thought. But perhaps there might be a problem with the software in these new Panny boxes.

Is there any Panny email address to report this incident so if it is a recurring problem they can address it with an OAD?

Cheers

Goobs
 

AL S

Established Member
Thank you all.

I have been monitoring it and it does just seem to be ITV 1. Phew! Otherwise, very happy with the new machine.
 

maldonian

Established Member
The problem multplexes A and 2 both use 64 QAM, which allows more channels to be squeezed in but makes reception less reliable, whereas the other four multiplexes use 16 QAM.

Sadly Ofcom wants all the multiplexes to use 64 QAM after analogue switch-off. If this happens people in fringe areas will be more likely to have reception problems on all multiplexes, and lots of people will be in fringe areas even with increased digital transmitter powers. We should all be lobbying Ofcom to opt for 16 QAM. (I'm not sure if it will do any good though, the government only seem to be interested in making as much money as they can make from a one-off sale of part of the broadcast spectrum, and Ofcom seem to be helping them in this aim rather than protecting the spectrum for more Freeview channels of better quality and enough space for HD on Freeview. So while we're at it, we should also be lobbying the government to keep their hands off the broadcast TV spectrum.)

Err... Excuse me while I climb down off my soap box...

Anyway, I agree it's probably a reception problem. One way to check would be to simultaneously record the EX75 output on another recorder (a VCR for example) and then compare the recordings when you notice stuttering on an EX75 recording.

The stuttering happens when there is a brief reception problem because most Freeview tuners briefly freeze the last good frame rather than show the broken up picture or no picture. You sometimes see the same thing on analogue TV, in which case it's obviously happening in the broadcaster's equipment.
 

Gavtech

Administrator
Goober11 said:
Is there any Panny email address to report this incident so if it is a recurring problem they can address it with an OAD?

There is a contact point for such things but it is not email as such, but a targetting webmail system. If you fill in the appropriate parameters on this page llinked below and send it, a form is returned where you can make your comments / Queries... and then send that.

http://www.panasonic.co.uk/customer-Support/contact-email.asp
 

Gavtech

Administrator
maldonian said:
The problem multplexes A and 2 both use 64 QAM, which allows more channels to be squeezed in but makes reception less reliable, whereas the other four multiplexes use 16 QAM.

....We should all be lobbying Ofcom to opt for 16 QAM. ...

Err... Excuse me while I climb down off my soap box...

Please STAY on it as far as I'm concerned. You have MY backing.:D
 

AL S

Established Member
Maldonian
So are you saying that there won't be space for many HD channels via Freeview in the future? Not good and surely contradictory to the TV companies desires?
 

maldonian

Established Member
So are you saying that there won't be space for many HD channels via Freeview in the future? Not good and surely contradictory to the TV companies desires?
When Bands IV and V were allocated to 625 line TV the broadcaster engineers carefully selected the channel allocations to avoid interference between adjacent transmitters and they managed to fit four national analogue networks into the available space. Since then Channel 5 has been shoehorned in, mainly using channels around 36/38 that were left free for other users (radar and radio astronomy then later used for VCR modulators), but it's coverage is poor in many areas. If they had to, they could probably have allocated the 48 available channels (21 to 68) to more than four networks from the start, but it would have been at the risk of increased interference in fringe areas. It's not just channel clashes in overlapping service areas (causing co-channel interference) that have to be considered, there are other types of interference too, such as adjacent channel.

Now they have managed to fit in 6 multiplexes in addition to the existing 4 or 5 analogue channels, it seems possible that the allocation rules can be relaxed for digital TV. However the mulitiplexes are on low power at the moment to avoid interfering with the analogue transmissions, and only being transmitted by the main transmitters, so the service areas are smaller with much less overlap, so there is less need to worry about the effect of adjacent transmitters.

This will change when analogue is switched off and the digital transmitter powers are increased, making the service areas larger. I suspect they will have to reallocate all the multiplexes from scratch to reduce interference from adjacent transmitters. I haven't seen any mention of this, but that's what I suspect may happen. And that's probably when the government will step in and limit the spectrum available for the reallocation.

I suspect the allocation rules could actually be relaxed a bit for digital, because the effects of interference on digital are different from analogue. It may be possible to fit in, say, eight national multiplexes (don't quote me, I plucked this figure out of thin air) provided the current 48 channels are retained. If that were possible then there would be two extra multiplexes available nationally. They could be used for extra channels and/or to improve the quality of the existing channels. If the government pinches a chunk of the spectrum to sell off to other users then the broadcasters might only be able to fit the existing six multiplexes in the remaining space.

So where does HD fit in? With current compression techniques I think 2 or 3 HD channels can fit in a multiplex, depending on the type of compression and whether 16 or 64 QAM is used. So if we were to finish up with eight national muliplexes, two of these could be allocated to HD, giving a total of 4 to 6 HD channels. That's based on my guess of eight multiplexes, I have no idea how many we will actually finish up with. As compression techniques improve it might be possible to fit more HD channels into a multiplex. In practise, the HD channels would probably be multiplexed with SD channels and spread across the multiplexes. But it seems quite possible that several channels could be transmitted in HD - provided the government doesn't pinch the spectrum they would need.

Different people will have different opionions on how the available space in the multiplexes should be allocated. Some people must watch what I consider to be rubbish channels otherwise they wouldn't survive. I would prefer quality rather than quantity. I rarely watch much outside the main four/five channels anyway, mainly because (a) I prefer programmes made in this country and (b) I can't be bothered to search through all the channel listings to find out what's on. So I would be quite happy if only BBC1, BBC2, ITV, Channel 4 and Channel 5 were available in HD, together with perhaps a sports channel and a film channel.

Sorry, this is a long reply to a short question. I think the main message has to be that the government could severely limit the development of terrestrial TV if they go ahead with their plans to sell part of the spectrum it uses and needs.
 

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