All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Tracy: The purpose of the incoming aerial being connected into the Sky box is to allow Freeview broadcasts to be viewed. If you do not watch Freeview on the upstairs TV, and you have no other TVs connected to the output of the Sky box, then the incoming aerial is surplus to requirements.
If the TV adjacent to the Sky box is connected to the Sky box and you only wish to have Freeview available on it (and not on the upstairs TV), then you could feed the incoming aerial directly into that TV.
Since 27th June 2012 the Sudbury transmitter which serves your area has been broadcasting on C60. If you change it, you will need to retune the TV. If it has manual tuning where a UHF channel can be entered, then you can enter the same channel number, else you will have to scan.
C51 might be available. You can use somewhere from C61 to C68 because it isn't used at the moment, but the 4G mobile networks are likely to use those channels so you would probably have to change it when they come on air.
Once you have changed the output of the Sky box to C51 and retuned the TV, if the picture is a bit grainy, unplug the incoming aerial lead to see if it is interference from something that is being broadcast.
If this proves to be the case, then 54 may be a possibility.
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M. Partington: These are "offsets" and indicate plus or minus 0.2MHz from the centre of the channel.
For example C49 is at 698.0MHz whereas C49- is 697.8MHz and C49+ is 698.2MHz. And C50 is at 706.0MHz whereas C50- is 705.8MHz and C50+ is at 706.2MHz.
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Su: There is a large overlap of signals from two transmitters in your general area, these being Waltham and Sutton Coldfield.
You may be able to manually tune in the channels for Waltham, having "blanked" what's already stored, probably by running the scan through with the aerial unplugged.
Waltham uses channel numbers BBC One (C61), ITV1 (C54), BBC One HD (C58), ITV3 (C29), Pick TV (C56), Film4(C57).
If you run the scan through and unplug the aerial at 25% and then plug in again about 58% it should miss out 39 and the 40s which are those used by Sutton Coldfield.
Once you have done this, check that it is tuned to Waltham for all channels. Do this by viewing the signal strength screen on each of the six services above (five if it isn't a HD set). Then observe that it is tuned to the UHF channel given above.
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John B: Being in the dark as to your location, it is impossible to have any idea as to what sort of signal area you reside in.
However, it could be the case that you have too much amplification, although this usually affects HD signals before the SD ones.
Whilst signal strength meters on receivers are in no way scientific, 100% strength could be an indication that the signal level is too high. The result is much the same as too low a signal level. As the signal level increases over that which the receiver can tolerate, the strength and quality will start to fluctuate and jump up and down.
At switchover the power of digital signals increased. In some cases, installations fitted for reception of the pre-switchover low power signals is OTT after switchover.
The strength of Hannington before switchover was restricted generally to the east so as to protect against interference with the Guildford transmitter. Consequently the difference between the strength of the pre-switchover signals and the current signals in that area is very big and an installation fitted to receive the pre-switchover signals could be boosting the current signals too much.
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frank: Wait until Wednesday.
This list of Saorview transmitters says that the Moville digital signal is on low power until switchover:
http://www.rtenl.ie/wp-co….pdf
You may be able to receive digital from Limavady and Moville using a single aerial as they are only 10 degrees apart from your location. I suggest that you wait until both transmitters are running on their full final power on Wednesday.
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Briantist: Going back to what devices will receive the NIMM, what about Full HD TVs that don't have a DVB-T2 tuner in?
Will these be able to decode the MPEG4 using DVB-T?
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Briantist: Sorry, I confused NIMM and Saorview!
The question should be will Full HD TVs that don't have DVB-T2 built in be able to receive Saorview? I guess that they might be able to do as they will have MPEG4 decoders in. Is this correct?
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les: There is no ITV4 HD channel.
Where does your aerial point?
The Westwood Ho! transmitter broadcasts only PSB channels which don't carry ITV4.
Refer to this page that show the six multiplexes and the services carried on each:
DTG :: DTT Services by Multiplex
ITV4 is on COM6. You may be able to receive the COM channels from Preseli.
If you have a TV that has ITV4 tuned, then go to it and bring up the signal strength screen and observe the UHF channel number that it is tuned to. I expect that it will be C49 which is Preseli. Then go to the HD PVR manual tune function and tune to the same UHF channel.
As your local transmitter does not broadcast COM channels (see the link above) and therefore if you are receiving them and only have an aerial on your local transmitter then you are picking them up off-beam of your aerial (and probably opposite polarity) so you may have intermittant/poor reception.
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Saturday 20 October 2012 2:52PM
Tracy: This could be caused by the UHF channel (frequency) that you are using to output the analogue picture to your upstairs TV now being used for digital in your area.
The Sky box puts out a signal on your aerial lead on a UHF channel (frequency). You need to use one that is not used by a Freeview transmitter that is being picked up by your aerial else the digital (Freeview) signal will interfere with the analogue picture from the Sky box, the effect on the analogue picture being that it will be more grainy.
You need to establish whether this is the likely cause. If you power on the Sky box and turn on the upstairs TV and select the Sky channel. Then remove the aerial lead going into the Sky box (the one that comes from the aerial). If the level of interference on the Sky picture on the upstairs TV reduces as a result, then this tends to suggest that it is interference from a digital signal.
Find out what RF channel number your Sky box is using by following the instructions here:
How do I change the RF output channel on a Sky Digibox? | ukfree.tv - 10 years of independent, free digital TV advice
If this appears to be the problem, then let us know which RF channel it is using and we can suggest which one(s) you might be able to use at your location.