Two of the Freeview multiplexes (collections of channels) broadcast in one mode known as "64QAM mode, FEC=2/3,", and the other three broadcast in another mode called "64QAM mode, FEC=3/4".
The " FEC=2/3" mode provide a more reliable signal than a "FEC=3/4" mode signal at the same power level, but there is a trade-off that means less digital data can be carried.
This diagram shows the current channels carried on the Freeview system. The wider the box, the more bandwidth is used to carry the pictures. The more bandwidth used for a service, the better the picturequality.
Boxes split horizontally denote channels that occupy the bandwidth at different times of the day.
The third line shows the configuration of the BBC "B" multiplexswitchover which is used for HD and is in another mode DVB-T2 256QAM.
64 QAM (3/4) mode
In this mode, the digital TV signal is transmitted in groups of 64 symbols. The "forward error correction" is 2/3, and this results in a bitrate of 24M.1b/s (megabits per second). This can be used to carry up to eight simultaneous television channels.
64 QAM (2/3) mode
In this mode, the digital TV signal is transmitted in groups of 16 symbols. The "forward error correction" is 3/4, and this results in a bitrate of 27.1Mb/s. This can be used to carry ten simultaneous television channels.
Model Code - PS43F4500.
Did aerialtest and no shut down whatsoever.
However, checking signal fascinating. When we measure the signal strength, the TV does not shut down when on the problem channels. We had the signal measured on e4 for 5mins. As soon as we closed it, the TV restarted.
Also, don't know if it's relevant but when changing to these channels the bit error rate spikes to 2000 for a second or two.
We actually had the TV replaced for this reason originally, so I guess this is the aerial?
We are Ne3 1bj, in Gosforth.
Your help is so much appreciated!
Jackson G: The aspect of your problem that's still inclined to suggest its being caused by software defect is the fact of the TV shutting down when certain channels containing a 4 are selected, as virtually nothing you might try should result in this happening except when possibly connected with software updating, a TV shutting down / restarting on completion of same being the norm, but which in this particular instance is not applicable.
On the issue of the software, although the full model number of your TV is really required (that is including five letters after 4500) it would appear that the software version on your model should be 1027.2 issued on December 14th 2013 to replace the older 1027.1, maybe you could go into the software updating screen and check the number that's listed!, if though by any chance you do have version 1 (or older) then the snag is that the update can only be achieved via a download from Samsung's site into a USB memory stick, this then downloaded into the TV via its USB socket.
On the subject of the error rate spiking during channel changing onto the problem channels, if this is only observed when those channels are involved then its symptomatic of a problem being detected with same, although I wouldn't attach too much importance to this as its liable to occur on other devices that are not suffering from any problems.
However, as far as signal strengths are concerned, could you confirm that your aerial is horizontally mounted and that you are receiving Freeview from the Pontop Pike transmitter (@ 11.5 miles / 213 degrees? and its not vertically mounted to suit Fenham @ 2.9 miles / 225 degrees? this station indicated (in theory anyway!) as providing a good signal at your location.
The only reason for enquiring being by you having mentioned e4+1 as being 22, which if referring to strength then OK, other wise Mux C22 is the channel used by Fenham for e4+1.
Hi, Some of our Freeview has completely gone (Yesterday, Dave, Challenge etc.) and the rest is quite pixilated. The same is happening on both our two televisions and I'm worried the whole lot might give up on us soon.
We have just had one of our two freeview DVD/VHS recorders recently repaired. II wonder if that's anything to do with it? Our postcode is NG32 1LP, if that helps.