All posts by jb38
Below are all of jb38's postings, with the most recent are at the bottom of the page.
Andy: These hubs, or distribution amplifiers, can be obtained with different gain levels starting from around 6dB or so, and so if you do not see this printed on the casing then knowledge of the devices model number would enable it be checked out.
I would like to emphasise though, that when carrying out experiments with alternative aerial positions where digital reception is involved that its really essential to be able to monitor the signal strength & quality levels (especially the latter) whilst you are moving the aerial, as instant feedback on the result of every move made is the key to success, because should (or if!) a good spot be found then its almost guaranteed to be of a critical nature whereby an inch or so either side of the choice position is liable to kill off the most important aspect of the signal, that being its quality.
By the way, should the distribution amplifier only be rated at around 6dB or so then that's not really high enough to make that much difference to the signal, that is unless a somewhat superior position is found during experiments, remember though that should a good spot be found to test the aerial out on all of Mendips six muxes, this done by selecting the following programme guide numbers. (EPG's not TX mux channels)
1 - 3 - 101 (if HD used) - (10) ITV3 - (11) Pick TV - (15) Film 4.
| link to this comment |
pamela dudley: Even although you may well have initially enjoyed reasonably good reception signals can suffer from seasonal climatic changes which alter the levels that they are received at, and what you have reported strongly suggests that the signal you are receiving via the indoor aerial is not really strong enough for reliable reception, this being irrespective of whether its an amplified type or not, the transmitter that covers your area being Rowridge located @ 13 miles away to the S/SW.
Isn't it possible to have some form of outdoor aerial? this not necessarily meaning on the roof.
| link to this comment |
pamela dudley: just to add, that even a loft mounted aerial is preferable to one thats located in the same room as the TV, as indoor types are vulnerable to movements from not only within the same room but even if occurring in adjoining properties.
| link to this comment |
Darren Gray: A satellite signal can safely be taken as always being there whether or not a person can receive it, and with the only "dish connected" reasons for a person not doing so being in situations where either the dish bowl is covered in snow or traces of same are seen to have lodged on the face of the LNB, or in cases where a really heavy thundery downpour is in existence, as this can completely block microwave signals.
An LNB can of course develop a fault, but not usually on more than one of its output ports, although when you say that the Sky boxes feed from the dish runs through a loft box, do you mean in a terminated way or a continuous fashion with no breaks in the cable?
But though, its not exactly unknown for a Sky box to develop a power unit problem of a nature that causes the tuner to be supplied with a low voltage and with this resulting in it cutting out, and so this also has to be brought into the equation as a possible reason for the problem until it can be eliminated as such from suspicion, although unfortunately about the only way of doing this is by temporarily trying another box (any Sky type) on the dish, or by trying your box on someone elses dish.
Maybe you could give an update on the cable question though.
| link to this comment |
Andy: Yes, but I would make sure that whoever you choose is the type of person capable of giving an "instant" response to that seen, as unfortunately many dont!, although if you adopt a slow motion approach to anything done then that helps compensate for the inevitable delay in feedback.
Although the best of all methods is by temporarily taking a small bedroom type Freeview TV (should a person have one!) into the loft and coupling it directly onto the aerial, as this method is by far the most reliable way of doing things, albeit of course I fully appreciate that this is just simply not always possible to arrange in most households.
| link to this comment |
MikeB: Regarding the issue of signal level differences being seen on a TV between when its aerial has been connected directly into it compared to that after having passed via a loop through facility such as on a PVR or HDD recorder, because although obviously some of these thin lower cost jumper leads can lead to odd problems being experienced, however in most cases these differences in levels are not being caused by this but by the circuitry associated with the loop through sockets, and with the reason being as follows.
In most PVR or HDD recorders or indeed any device with a loop through socket facility, the signal path from the aerial input socket does not pass in an electrical fashion directly over to the output socket but goes through a transistor buffer stage located between the input and output sockets, this being the reason why that any device that is being looped through has always to be kept powered (a few exceptions exist) because if it isn't then the signal to the TV or anything else on the end of the loop through will either drop or vanish altogether when the buffer stage transistor loses its power supply, although in real life situations a really strong signal might still partially break through resulting in a somewhat glitchy picture being seen, whereas when feeding an analogue TV all it usually resulted in was to witness the picture fading into a grainy background and not vanishing altogether due to the fact that analogue reception is not subject to minimum threshold cut off levels.
Obviously this loop through problem was thought about in the design of more recent boxes incorporating "power management" or "power save" options, this being the reason for allowing the user the choice of switching the system off, the latter being advisable so as not to miss any software updates that might be in the offering.
By the way, the reason for the buffer stage was basically for purposes of isolating the box or whatever from being interfered with by anything connected into its output socket, such as a lead containing a short circuit.
| link to this comment |
Andy: If its possible to stand at the side or the rear then that's perfectly OK but not at the front for obvious reasons, although if you leave the Humax on its signal check screen where you (or whoever) can see the strength and quality being indicated on the TV, then its easy to determine if any inter-reaction is liable to take place between the aerial and you, because should you move your hand in a critical area this will cause severe fluctuations to be seen in signal "quality" thus indicating where to avoid.
Although in general terms, aerials should always be held on the very rear and NOT in front of the reflector should it have one, e.g: "not" a log periodic type.
| link to this comment |
Jo; Although its assumed that you may well be referring to reception from the Mendip transmitter, but though no one can really offer advice without having knowledge of your location (post code or one from nearby: e.g: a post office) plus info on the aerial you are using, this meaning: communal / indoors / loft or roof mounted.
| link to this comment |
Darren Gray: If you are referring to one of these low cost satellite finders that use either a pointer or an LED bar to indicate when a signal is being received then "yes" provided that its dish connection end is going directly to the LNB.
But though the aspect that somewhat puzzles me is by you having split the outputs so as to feed two separate rooms, because if you are doing this with a twin output LNB then this is OK with the qualification of, so long as a Sky (or Freesat) box is only connected into one pair of sockets at a time, otherwise a quad block is required for purposes of supplying two feeds to each location.
With regards to leaving the sat finder in circuit, the answer is yes! provided that its not seen to be reducing either the strength or quality on that input by any significant amount when the two inputs (LNB1 / LNB2) are compared to each other.
| link to this comment |
Wednesday 3 April 2013 3:14PM
Moira mcregor: Virgin is exactly the same as Sky as far as anyone wishing to view different channels in another room is concerned, that is the only way of achieving this is by having a second box installed.
However where Virgin is involved a person does not really have any choice but to have them carry out the entire work, as the additional box requires registering with their data base as well as being updated as required at the same time, plus as you may already be aware of, that unlike in the case of Sky where the box belongs to the viewer after the initial 12 months contract expires, where Virgin is involved the box is never owned by the viewer no matter how long they may have it and remains Virgins property at all times.
I would therefore advise you to contact Virgin and tell them exactly what you would like to do, but though beware of one thing that many can overlook, and being that the cost of "their" installation is over and above the price per month extra given for the additional box, albeit that the latter can seem to be quite reasonable.