All posts by jb38
Below are all of jb38's postings, with the most recent are at the bottom of the page.
Briantist: Many thanks! much appreciated, as "some" people might possibly interpret this as some technical abbreviation rather than simply being a glitch, it also appearing on pound signs.
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Idris Martin: Well, although the signal path from both Stockland Hill and Rowridge is obstructed the terrain indicator shows that the severity of the obstruction is far greater in the case of the latter, this somewhat tallying up with your findings insomuch that Stockland's C26 was received but not Rowridges C24, albeit that Rowridge's "vertically" polarised PSB transmissions "are" indicated as providing a superior signal to that from Stockland H.
Of course if (as expected) your aerial is mounted horizontally then this could account for nothing being received.
That said, although it does have to be admitted that anything seen on a reception predictor has to treated with an element of caution, but a point to note is that when carrying out a manual tune test for the purpose of signal assessment its always advisable to enter the "C" number into the box but "not" follow this by immediately pressing search or scan, because on most devices hesitating before pressing same will cause the tuner to act like a proper signal strength meter whereby it will indicate signals down to very low levels underneath that necessary to resolve a picture, but which are ignored during a scan.
By the way, the info seen by opening the undermentioned link (copy and paste into your browser) provides details of the what's expected in your area, the two following being that indicated on the terrain predictor from both the stations in question.
Coverage Checker - Detailed View
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
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Iain Davies: In addition to that said by MikeP but still relating to, although nothing is seen on C51 it does not necessarily indicate that zero signal exists, and so you should try a test by going into your TV (or boxes) tuning menu / manual tune then entering C51 into the box but "not" followed by pressing search or scan, as this procedure on most devices will result in the tuner acting like a form of signal meter free of threshold limits, albeit that overload conditions can affect this test.
This procedure should be tried both with, and without, the distribution amplifier connected in line, if the signal still vanishes with the amp in-line then try the same test on Mendips COM6 C52 and see what the result is.
Of course, another way of testing is to insert one of these cheap (around £4.00) variable attenuators in-line with the amplifiers aerial input socket, then check to see if C51 appears whilst you adjust the level of attenuation.
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Iain Davies : Provided that you are within the coverage area of the directional C51 transmission then nothing of a technical nature can be done at the transmitter to stop anyone from receiving it, however could you please confirm (or not) that when you fed the signal into your Blue-ray recorder for the purpose of looping through into your TV that it was coming directly from your newly installed aerial? and that you can actually view the programme "content" (not just signal) on C51 without the amplifier in circuit.
It would also be of assistance as far as signal level assessment at your location is concerned if you could provide a post code from somewhere located nearby, plus it would also help to have knowledge of the distribution amplifiers model number and is this a newly acquired item? because apart from that said in your update the problem could be suggestive of either the amplifiers input being overloaded or even a fault in the devices input circuitry, especially when more than one device is seemingly being affected.
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Christopher Pugh: Provided that can put up with the inconvenience of having to use the TV / AV button to select your Freeview box as the input, then your problem might be rectified by opening up the scart lead socket and snipping the wire connected to pin8.
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Iain Davies: Although I still feel that its a bit unusual for signal overload symptoms to suddenly appear on all of your devices by simply changing the aerial, that is unless the one you were using was grossly inefficient!, however now its known that all of your devices are of the same Panasonic brand (my main TV being same) then its likely that their level of susceptibility to signal overload conditions (swamping) will be roughly the same on them all, whereas not the case with different brands.
As far as the Blue-ray recorder is concerned, passing the signal through its loop-through facility does not usually result in any amplification of the signal (or very low if it does!) although it would have been of interest to know if the C51 signal could be picked up by the Blue-ray recorders tuner before being fed into the TV via the HDMI connection rather than just using the device as a loop- through facility.
Although still being unable to assess the signal level expected at your location, but dependant on where your distribution amplifier is sited you should try a test using either a set top aerial or a short length (about 6' or so) of wire connected into its aerial input socket to see if this results in C51 appearing, if it does then you will have to purchase an attenuator such as that seen on the link and use it in line with the splitters aerial input socket, or alternatively purchase another splitter but of the passive (non-powered) type.
Just a little point about Panasonic's, the strength level indicators on these devices are inclined to be over lively compared to the reality of the situation, Humax being more in line with the actual, but should the Humax also indicate a strength of 100% then the signal level "is" excessively high.
TV Aerial Attenuator Variable 0-20Db Freeview Digital | eBay
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Iain Davies : Fully appreciating how frustrating this type of problem must be, but though it does have to be said that faults of this nature are seldom ever cured except by trial and error and with the person suffering from usually having to make some minor purchase, and if your signal is as strong as what your report would suggest then its either a variable attenuator to place in-line with the input to the distribution amplifier, or alternatively to do away with the powered splitter and replace it with a passive version which also gives an element of attenuation to the signal.
But though, and as mentioned on a couple of occasions, its not possible to estimate the level of signal expected in a particular area with any degree of accuracy without having knowledge of a post code from somewhere nearby, as this then gives access to the reception predictor plus more importantly (in some cases) the terrain indicator.
Anyway, purely for information purposes the undermentioned link is for a relatively inexpensive 4 way passive (non-electronic) splitter of the coaxial connector type, screw "F" connectors being the norm for this type of device.
Wellco 4 Way Aerial Splitter Allows 4 TV's or other: Amazon.co.uk: Electronics
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Iain Davies: Yes, but its not the low powered 10Kw LBS that is overloading the tuner, but the swamping / desensitizing effect caused by the 100Kw main transmitters resulting the tuners auto gain circuit coming into play to avoid instability, the side effect of this being that it makes the tuner less sensitive to weaker signals whereby causing them to drop under the threshold level required for reception, hence they vanish!
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Iain Davies: Thanks for the update!, pleased to see that you have now managed to rectify this problem.
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Monday 31 March 2014 9:36PM
Idris Martin : Just in case you are wondering, please ignore the A after the degree angle number, as this is something that has automatically appeared in recent times ever since Briantists site came back on after having been off for a day due to a fault having occurred.