All posts by jb38
Below are all of jb38's postings, with the most recent are at the bottom of the page.
Stewart: Yes very true! but its purely dependant on the signal strength received, as some devices can actually give a slight boost to a signal passing through it whereas others have the opposite effect, and if the latter situation applies in an area where a signal isnt that particularly strong, then any reduction in its strength can cause it drop below the receiving threshold of the TV in use.
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Steph: As you are only 4 miles away from the transmitter a standard log periodic type aerial would be perfectly suffice for your requirements, as well as it being exceedingly easy to position in a loft by it not having any reflector elements, although for ease of purchase the Argos 535-6443 @£12.99 would also be OK albeit being slightly more awkward to mount.
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Robert: Well the cause of this really touches on what I mentioned about reception threshold levels, as anytime the Mux station referred to drops out and you carry out a signal check on the Mux channel concerned (Ch68) you will no doubt see that the signal is actually still there, but at a level obviously below your receiving devices capability of resolving a picture, these levels being something which can vary between different brands of sets, insomuch that one "sensitive" device might well show a picture where another lesser sensitivity type wont, this being where a booster can sometimes help by lifting the signal.
Radio frequency signals (for any purpose) can vary throughout a 24 hour period for numerous reasons including atmospheric conditions, this natural variation being the reason why analogue pictures could at times show slightly more speckles on the picture as normal, this purely because of the TV receiving a lower strength signal, however digital TV pictures aren't affected by varying signal levels so long as this level is always above the cut off threshold, as when it drops under, that is when you do witness the difference!
This said based on the Mux 2 picture just dropping out, and not that any signal check has indicated zero signal.
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Mike Myers: Trade predictor charts only show what is presently known as being possible, and Ch56 isn't mentioned as its only a proposed channel and will not actually be transmitting as such at switchover, likewise knowing whether you will be able to receive it or not cant be forecast until then.
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Peter K: Put as simply (very) as possible, a signal booster is a radio frequency (RF) amplifier and works in exactly the same way as any other type of electronic amplifier, but in this case where a low level RF signal voltage from the aerial goes through one or more stages of amplification (boosting or magnifying) and comes out at the outer end at a much higher level than it entered.
This being the basis of all types of amplification, from Pop group's microphone systems to Hi-Fi's etc,etc.
Cant at this time put my finger on a suitable link without it being over complicated, and you did say that you wanted it in layman's terms.
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Peter K: It depends on your particular location with reference to the distance from the transmitter, which on checking could be as near as 6 miles from Crystal Palace, as where problems are experienced at relatively close distances from a transmitter the use of a high gain aerial does not help the situation, and indeed can make it worse!
This is basically because high gain aerials generally have sharper pick up patterns, this meaning that any obstruction to the signal path will have a much greater effect than a lower gain (and broader pick up) pattern aerial, and to be factually honest about it, sometimes in these type of situations greatly improved results can be obtained with the simplest of aerials (absolute max of 10 elements) when used in conjunction with about a 15db (or even more) amplifier to compensate for the aerials low gain.
High gain multi-element aerials only really come into their own where poor reception is mainly due to sheer distance from the transmitting station, a type of situation that I cannot say is particularly common in the UK, as bad reception is nearly always caused by signal obstructions of one sort or another, that is apart from seasonal atmospheric conditions or engineering works taking place, these generally causing interruptions to the service or periods of weaker signals.
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Tracy Clark: Are you positive that this still applies? as channel 5 is free to view without a Sky card, its only things like 5* (star) etc that requires a card.
You should reset their box by removing the mains plug for about 15 seconds or so before plugging it in again, then after waiting on it responding to the remote let it go through its searching for listing procedure.
If at any time they want to discard the sky box then a standard Freesat type would be ideal for them, because as they may well have mentioned, the local news service on the Sky box without having a card installed is by default London, not really very appropriate!
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Belinda: As you will probably already know you, according to Digital UK's trade predictor, are in a no-go area for Freeview from anywhere, this using "The Pilgrims Rest" in the High street as a marker as you haven't given your exact location.
The reason you will have to wait until the 23rd of November (restricted service starting on 9th) is because the new Freeview service will be using the same frequencies that are presently used by analogue.
By the way, the Freeview starting on the 23rd of November is classed as a "light" service, meaning only three Mux transmitter channels compared to a full services six, the three providing the main BBC & ITV programmes only, that is as well as the HD service.
However there is the possibility that on the 23rd of November that dependant on your particular location, you "might" be able to pick up all six Mux transmitters from Tacolneston, as that would then provide a full Freeview programme service.
Reception predictors, even trade ones, are not by any means 100% accurate in what they show as being possible, and this is why I say "might" when referring to Tacolneston.
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Annoyed viewer: Digital Terrestrial TV reception is, and always will be, far more critical than analogue reception ever has been, however the problems you have been experiencing should in theory be rectified come the 17th of the month.
However, that is with the exception of Mux's ArqA & ArqB, as they will be operating on only 4Kw until final switchover on 23rd of November, this being something that is bound to cause problems for many who cant really boost the signal to receive them without the danger of the 150Kw high power Mux channels overloading the tuners in their TV's / boxes, this having the same effect as a signal that is too weak, that being a blank screen!
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Thursday 11 August 2011 8:53PM
Robert: Speaking from the viewpoint of an engineer I can tell you that a booster "is" very necessary in lots of locations, maybe even more so than in pure analogue days.
This is basically because analogue can be received / viewed right down to where the picture disappears into the speckles, whereas with digital unless the signal is kept at a reasonable level above the cut off threshold, known as the "digital cliff", the picture will be prone to constant glitches, or disappear altogether!
The only time boosters should be used with caution is in higher signal strength areas where some of the multiplexes are transmitting on lower power than the rest, as striking a happy balance between boosting the lower signal but not overdoing the already powerful one is a bit hit and miss, as signals can constantly vary in strength.
In other words, the advisability of using one is totally dependant on the circumstances of each particular situation!