All posts by jb38
Below are all of jb38's postings, with the most recent are at the bottom of the page.
Emily: Advice on difficulties with reception cannot really be given in cases where a persons location is unknown, this preferably given in the form of a post code or one from somewhere nearby, e.g: a shop / Post Office, however as the programme channels mentioned are all on the SDN transmitter you should go into your TV or boxes tuning menu / manual tune then enter and scan C29.
By the way, on most equipment the level that a signal is being received at can be checked "before" actually scanning it by pausing after entering the mux channel number required, as even although a signal level might be seen in some instances its possibly sitting at a level under that required for the receiver to capture and store it.
It should also be noted that as engineering work is being carried out at the Waltham transmitter breaks in transmission or alternatively periods of reduced power can be expected to occur at any time.
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Rob: Being located at only 4.7 miles away from the Oxford transmitter and with a clear line-of-sight from same then I would be inclined to carry out a test on the ITV1 mux using either a non-powered set top aerial or alternatively a short length of wire (about 6 feet or so) connected into the TV's aerial socket, because if the signal received on C60 is indeed grossly excessive then it should be possible to obtain a reasonable picture of sorts using an improvised aerial, this of course being done purely for test purposes.
As far as your main aerial is concerned, something such as a Log 36 would be ideal for your situation as this has an element of protection against 4G transmissions, that is should you ever be affected by same.
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Rob : I would also follow David Pinfold's advice as far as temporarily bypassing any powered splitters should you be using same? although before doing so I would try a test by connecting the attenuator between the aerial and the input to the distribution amplifier just in case the high signal level being received is triggering instability in the amplifiers circuitry.
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rob: I suspected that might be the case! and which could suggest that your problem is possibly down to other than a grossly excessive signal level but more one caused by RF instability occurring in the system, and going by what you have reported possibly even occurring from within the Sony's tuner! .
I would therefore like you to try another few tests but purely concentrating on C60, as I have a feeling that the excessive level being indicated using the set top aerial is not fully from the transmitter but possibly from some source of localised interference, and so I would like to know the answers to the following.
Is your Sony TV positioned next to a wall of an adjoining property? and if it is and the set top aerial is similarly positioned then move it (the aerial) away from the wall as far as you can manage, also try positioning the set top aerial near to (or on) the floor level.
If that said does not apply or has not made any difference, then try a short piece of wire (about 12") connected into the TV's aerial socket whilst on C60, if nothing is seen then hold the end of the wire and see if this makes any difference?
If your Sony TV is free standing and is not mounted on a wall, then if at all possible I would like you to try it out on your daughters aerial socket
You should also try carrying out a factory reset on the TV followed by retuning it via a "first time installation".
The tests requested might all appear to be unconnected but they all help to build up a picture as to the possible reason for your problem, as I have my doubts that its purely being caused by an excessive signal level being received, because if it was the set top aerial test should have partially resolved the problem.
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rob: If indeed your problem is being caused by some form of localised interference then its likely to be a harmonic of whatever is causing the problems fundamental operating frequency and not something actually transmitting on C60, as harmonics (especially from a transmitter device located nearby) can in many instances be just as bad, although harmonic signal interference usually falls off rapidly as you move away from the source, this being why I suggested moving the set top aerial away from the TV and also trying a test by connecting the Sony TV into your daughters aerial socket which I believe to be upstairs?
Another possible source of interference is from "some" types of broadband powerline adaptors, as they can introduce harmonics into the ring mains wiring system.
Tetra interference is another possible source, as the first harmonic from a Tetra base station (on high 395 Mhz) as used by the Police / Fire services etc is close enough to C60 to cause problems.
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rob: Some brands of Freeview receivers are more prone than others as far as reacting in an adverse way to any forms of localised interference that may happen to be around, and especially if the source of the interference is located nearby such as possibly from something sited on the other side of a properties separation wall, this being my reason for suggesting that if at all feasible to try the Sony TV up in your daughters bedroom, as you really do have to eliminate the possibility that the problem is associated with where the TV is presently located.
You could of course try your daughters TV on the aerial connection used by the Sony and see how it performs, but as aforementioned, interference affects some TV's more than others when operating "close" to a source of interference and so the test is more valid if the Sony is tested out using daughters aerial outlet point.
If though the problem still occurs then that could suggest that its down to a fault in the TV's tuner, because if the signal level received was totally over the top then its unlikely that your daughters TV would not be affected in some adverse way.
Another point I was wondering about being, as you are not using any form of powered splitter then what arrangement are you using to feed the aerial into the two outlet points?
Another test that I would like you to try is to carry out a signal strength / quality check on your daughters TV whist its on BBC1and making a note of the indications seen, then carrying out a similar check on the ITV1 channel followed by comparing that seen with the indications obtained from the BBC1 mux.
If for any reason the signal cannot be checked in this way on your daughters TV then go into the TV's tuning menu and select "manual tune" and entering C53 (BBC) into the channel box but with this action NOT being followed by pressing search or scan, as on most devices the level that the signal is being received at will appear in the strength / quality bars, on completion of the BBC1 indications carry out a similar check on the ITV1 mux by entering C60 into the box and giving an update on results.
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d: Purely for your information, all mux channels from the Sandy transmitter are being received perfectly OK up here in the Stamford area, but as Briantist has mentioned a post code is required in order for anyone to be able offer assistance as you might reside in an area known to suffer from reception problems.
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rob : Thanks for the update! I would also appreciate if you could let me have the model number of the Sony in question as I would like to check out the service manual for the set, this being something I should really have requested before now.
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rob: Many apologies for the delay in replying, this purely being down to work commitments in other areas and the time consuming travelling associated with same.
However, your latest reports / tests carried out etc does seem to indicate that the problem is indeed connected with interference being emitted from a device located on the other side of the dividing wall in your neighbours property, but though with the offending device not necessarily always being positioned in exactly the same place hence the erratic nature of the interference.
As far as filters are concerned, these devices will only work "if" the interference is entering the TV via its aerial socket and is not being directly injected into the set via the mains cabling etc, the other point being that your under floor cabling would not appear to come into the equation by the fact of you still experiencing the problem when using the temporary fly lead.
I feel that the only way of finding a solution to the problem is by "subtly" bringing the subject up with your neighbour, because if it is being caused by them having recently started using such as a baby alarm or some other recently acquired device then they could easily move whatever to another position within the same room as interference from these type of devices usually falls off rapidly over short distances.
As far as filters are concerned, these devices will only work "if" the interference is entering the TV via its aerial socket and is not being directly injected into the set, or maybe even via the mains cabling etc.
On the subject of your COFDM query, put in somewhat simplified terms it refers to the type of modulation system used for digital Freeview reception (DVB-T) and with the AGC referred to being the level of automatic gain that's applied by the tuner relative to the strength of the signal being received and likewise with this being subject to wide variations being seen, although the figure being indicated is always higher in strong signal areas due to the tuner levelling the signal out
You might also have seen various other technical info being mentioned such as pre and post viterbi figures etc and which are basically referring to the "before and after" bit error code correction (BER) or quality of the signal, however Sony is one of the few brands that care to provide this type of information and which it has to be said is of no assistance whatsoever to the average viewer, as its something more allied to that seen on professional signal meters as used by aerial installers etc.
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Wednesday 15 January 2014 12:24AM
john: Well, now that its known that you are connected into a communal dish system then that puts a somewhat different complexion on the problem, basically because you are not connected directly into the dish but via a multi-switch distribution system and which can develop a variety of odd problems.
As aforementioned, the quality should never be seen to lag the strength, because if it does on one transponder channel then its possible for it to be worse on another, as unlike in the case of Sky where a signal strength check always indicates that of the default transponder nomatter what channel is being viewed, Freesat devices gives the strength / quality indications of the programme channel being viewed "if" the check is made whilst viewing the channel.
Being unaware as to the model number of your Humax Freesat box, but if that said is the outcome of having carried out a Freesat rescan and NOT a "free to view" (or othersat) setting then this could suggest that the problem is being caused by a defective input feed from the communal distribution system, that is unless some real odd ball fault has developed with your box, something which I very much doubt if it has.
Unfortunately as far as testing is concerned your hands are somewhat tied, although if you were on friendly terms with someone who uses a Sky system then you could instantly have an answer to your problem if they were willing to allow you to carry out a rescan using their dish, as both Freesat and Sky are 100% compatible with each other.
Could you please supply the model number of the Humax device in question.