All posts by jb38
Below are all of jb38's postings, with the most recent are at the bottom of the page.
Rod: Yes! as analogue has always been capable of very good quality when direct cable links are used because low powered RF signals of the analogue variety can be very vulnerable to all sorts of interference or instability that degrades the picture quality, that said though I did mean to add that when you were carrying out the Sky box scart to 2nd TV scart in test to also do similar with the RF connection between both, as this would then verify the quality (or not as the case may be) of your RF cable distribution system plus the analogue picture quality of your second set, as if its a freeview set with also an analogue reception capability (as most are) then in my experience the analogue performance in some of these sets isn't always quite as good as a purely analogue TV.
The route Briantist has mentioned of using an HDMI extender is obviously a lot more complex to arrange and which might make it not so practical a proposition in many households, but however its virtually a guaranteed performance way of doing things, whereas when dealing with wireless senders this cannot always be said to apply, basically because they are also vulnerable to picking up various forms of interference from things like microwave ovens, broadband lines, Wi-Fi devices etc, however many people do have great results from them with the quality obtained being virtually the same as though taken directly from the Sky boxes (or TV's) scart output.
If you do go along the Digisender line chose a 5.8Ghz operating frequency type "to try out" and not a 2.4Ghz one, as the latter type operates at only a stones throw off frequencies used by M/V ovens etc, "try out" really meaning that Argos although having less choice of devices is possibly a more flexible source of supply rather than Curry's.
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Rod: CAT5 cable is a quality multi stranded cable comprising of four twisted pairs of wires and is the type of cable commonly used for Ethernet as well as HDMI extensions, with it basically being used for the latter because its considerably less expensive for long cable runs over using HDMI cable, however unless a person is acquaint with fitting plugs to multi-stranded cables the job can be a bit daunting to some.
When I mentioned Argos what I was really subtly meaning was that although I don't necessarily approve of this type action, but its much easier to return a faulty item (or at least alleged to be!) to them over than doing same at Curry's, as its almost guaranteed that they will not be near so co-operative in this respect.
Before you purchase anything though I would carry out the direct RF coupling test between the Sky box and your second TV's input as was mentioned in my earlier posting, this just to verify that your secondary TV's are OK on a direct analogue RF input and that the picture quality problem is definitely connected with your cabling, as I do have elements of doubt about this.
To clarify another point I was thinking about, what station do you receive your Freeview signal from?
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Rod: Thanks for carrying out that test as it somewhat confirmed my suspicion that the cabling wasn't causing the problem, what I would like you to do though is to change the Sky box RF output channel to anywhere in the 30's and try a second set test again after having retuned the 2nd (or 3rd) TV, no need to try it beside the Sky box though now that you know it isn't the cabling.
By the way the RF output level on the Sky box is impervious to being affected by anything received by the box, but what I would like to know is whether or not you can see any speckles on the analogue picture in the back ground of the wavy lines? as that would indicate a weak signal, but so as not to be influenced by picture content try the tests whilst the Sky box is on anything in the service menu with the blue background, as that shows up speckles better.
If however speckles are not observed on the 2nd TV's analogue picture then that is inclined to indicate that the RF output strength is OK on the Sky box, this then leaving the possibility that either (1) the actual box has an instability defect in its modulator or (2)its output is too strong for the particular TV you are feeding it into to, this being verified one way or another by trying a third TV, but only if its of a different brand to the second.
Re: the signal strengths mentioned, I assume that you referring to the signal strength indicators on the Sky box inputs?
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Rod: Really pleased to hear the good news that all seems to be OK now as I was beginning to suspect that something was being missed along the line, the reason being that wavy lines on an analogue picture are always an indication of either instability within the system or that another source of RF is intruding either on, or is close to the channel being received, and the fact of you mentioning about how good your freeview picture was, the complete reversal of the usual complaint heard!, made me think that you must have a very strong DTT signal at your location and the reason I enquired as to what station you receive from, you obviously having sussed out my line of thought!
I suppose I could really have shortened your suffering somewhat by just asking you to carry out the test of taking out the Sky boxes "normal" aerial input whilst viewing the offending image, because if the problem disappeared by doing that then it was being caused by the presence of another strong RF signal close to (or even on) the Sky boxes output, but however if it didn't clear up then it was likely caused a modulator problem and to try setting it to a lower channel, because speaking in general terms RF generators lose their power efficiency the higher up the channels they go and a faltering modulator can cause various types of patterns on a screen.
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Briantist: Yes! that facility you provide is very convenient as it saves people looking up lists, although so long as anyone using this info as a guide realises that its always best policy to keep a FEW channels of separation between whatever they set the Sky box RF output to and the actual channels seen used by the multiplex transmitters they receive their freeview from, as if they set it only about one or two channels away either side they can still have a problem dependant on the signal strength of the freeview signal they receive and how good their TV's tuner is at rejecting adjacent channel interference.
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KI Moore: No, they will always work independently in the sense that Briantist has mentioned, but as you will likely have your Bush freesat box connected into your TV's HDMI socket when you take the said box out of standby to view something it should automatically switch your TV over to it from whatever it might be showing, likewise back to freeview or whatever again when the Bush is placed back in standby.
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J
How do I change the RF output channel on a Sky Digibox? | Help!Friday 11 February 2011 4:23PM
Newark
Rod: That's certainly the best policy! and pleased to have been of assistance.
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Briantist: Maybe I am not fully tuned in today so please excuse this query if it appears a bit odd to you, but when you say the best free channels are you referring to aspects concerning reception or is it viewing quality of the programmes?
I personally feel that the site already contains such an absolute wealth of information that navigational skills are increasingly required to find what has been last replied to, the "my settings" - "latest postings" box being something I find myself frequently using.
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Braintist: Ah! now I realise what you are referring to that would be quite a useful addition to the various station listings and a facility which could be pointed to in cases where people experiencing difficulties with their Sky box RF output feeds to other rooms are suspected of suffering from a possible channel (or near) clash with another source of RF, as whoever could then just refer to the spare channel list appropriate to the station they receive their signals from and likewise set their Sky boxes RF output accordingly.
Regarding the suggested channel separation, although I very much agree with "two" being used where adjacent analogue is concerned I do still feel that for guaranteed "lasting" results two should be used as a standard no matter what mode of adjacent transmission is in existence, this because that many of the tuners used in the more mediocre (and unfortunately some not so!) brands of dual standard TV's aren't particularly good and their RF input circuitry is liable to be somewhat swamped (desensitized) by the presence of "any" powerful RF signal on an adjacent channel to the one they were using to pick up the analogue feed from a Sky box, and with the inevitable reduction of the input signal strength that would occur resulting in a deterioration in quality of the analogue picture being viewed.
I feel that this is a type of problem that might well start to show in some peoples installations who use Sky box feeds after the multiplex transmitters in their area's have switched over to high power operation, with this especially so amongst the people who have went slightly over the top in the upgrading of their aerial systems in an attempt to get perfect reception from a multiplex that's only temporarily operating at a very much reduced power, a foolish move in my opinion albeit that I understand their frustration!
On the subject of switchover, I do realise that you have set a very big task for yourself but wouldn't it be prudent to wait until the main part of the switchover process has taken place? of course that is unless you intend to cater for pre as well as actual switchover dates meaning that you provide two sets of channel numbers for each station?
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Tuesday 8 February 2011 9:27PM
Rod: Well I would estimate that the quality via a wireless sender would be roughly nearly halfway between what's obtained using the RF and viewing Sky directly, although a good way you could verify with reasonable accuracy what it would be like is to place one of your secondary TV's beside the Sky box and couple both together with a scart lead, then whatever result you get will be very nearly the same (or should be!) if you use a wireless sender.