First comments 
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RobertSaturday 2 June 2012 9:19PM
JB38: You make some very interesting observations. All my poratble TV's use a straight radio type aerial so a loop aerial is not to hand. My main TV is in the living room which has large windows from which I can see the trasnmitter mast at the top of the hill. I have had a decade of perfect Freeview reception and made he last change to the coniguration of my AV equipemnt in Oct 2011. Everthing worked and was 'rock solid' until April 4th. I will follow your suggestions when I have some 'I/O' time or 'downtime' with he system as I watch TV in timeslip with the HDR set to record everything I might want to watch days ahead. I've manage to get though 2 of the 3 Lord of the Rings films on CH4 HD without error. My professional background is trouble shooting Mini computer errors especially disc drives. Although I later switched to Oracle databases. Your help is appreciated. Stephen PSunday 3 June 2012 1:41AM
My professional background is trouble shooting Mini computer errors especially disc drives.
Does that mean you can mend my PVR ?RobertSunday 3 June 2012 8:52AM
I did repair a friend's Thompson DHD4000 is was not booting up and giving no video o/p. Once cracked open, I heard a tell tail click click from the hard drive. Power supply! so I powered the disc from another supply and the thing burst back into life. According to the internet weak PSUs are a known problem and i found a capacitor kit for the PSU which I then fitted. But it took months to do the final physical repair. I also have my own Thompson DHD4000 and Lite-on LVW-5045 which are both sick and need repair waitting for me.
So what's the problem?
and can you fix 'my' transmitter for me?Stephen PSunday 3 June 2012 10:30AM
Its a Wharfdale something. Seems to work OK; then shuts down. I have unplugged the HD and still same.
I give up on your problem, which I presume is related to proximity. Did you try nothing at all in the aerial input? Or just a fly lead?Tony KendrickSunday 3 June 2012 10:34AM
I live in Littlehampton and have a 52 element roof mounted aerial installed six years ago. In spite of living a mile from the coast and receiving Rowridge mostly over open water reception was fine. But after the 18 April switchover when the COM5 mux moved to Ch21 signal quality dropped to between 5% and 25% while signal strength is high so often drops out altogether. The other commercial muxes have 90+% signal quality and strength.
Is this an inversion problem or could the 200k signal on Ch 21 be causing cross channel interference (I haven't got a T2 tuner yet so dont get the HD mux)?Tony Kendrick: I think that the most likely solution is to change your aerial to vertical.
Other people have posted on this site saying that they have changed their aerials and that it has rectified the problem.
That may be a costly exercise if you can't do it yourself.
"Maybe" some attenuation to reduce the level of signals might help. Whether it will work will depend on whether you can find a sweet spot where the higher power signals are reduced enough but the lower ones are reduced too much.
This is probably exacerbated by the fact that the powers that be decided to put the low power (50kW) horizontal signals on adjacent channels to the relatively high power (200kW) horizontal signals. RobertMonday 4 June 2012 10:06AM
There were 3 big films on Saturday on HD the Mux. I got about 2 hrs into Lord of the Ring, just after Brian Blessed did some shouting in the advert break and it started raining in Crystal Palace. Un watchable TV.
It's been raining and dull so I have nothing but dammaged video since.
I found my Fringe electronics PRO TV & Sat Signal Finder. The aerial into the HDR is 62 dBuV, Aerial into TV 74 dBuV and the 12" Wire 71 dBuV at TV aerial socket. They say 59-78 dBuV is OK.
HDR is more sensitive and susceptible that the TV but produces a much better picture across the board. The TV indicates the RF is producing bad video. I’ve only just discovered were the signal condition monitor is on the TV menus so I can measure a bit rate error. Other times I’ve seen signal Quality Red (1) and perfect vision and sound. When TV & HDR shared aerial, perfect Video on TV and HDR unable to find the Mux.
Dave Lindsay: Attenuation was an early theory and I have posted about reducing attenuation. Measuring the actual signal at 0dB attenuation show it to be at lower end of optimal.
Mazbar: I do have access to an outdoor aerial via a communal aerial system (74 dBuV). The problem is that ever since the days of three channel TV, I have always got a better picture by using an indoor aerial. Analogue Cable TV offered no advantage, despite claims. I have checked since but I still think the indoor aerial is superior although not as neat. I know that in my block and the next block the communal aerial systems have exactly the same problem. Both were considered working before but not after DSO. Set up for HD (Oct 2011) was no problem at all and has been rock solid until DSO1.
JB38: Did the wire test yesterday while it was raining. In the TV it gave a very similar picture and measured 80 compared 73 on a wedge type indoor aerial, the one I was using on the HDR (shared) since Oct. The lowest reading was 63 for BBC1 and 90 for ITV1.
Swapping to the HDR The wire gave a predominantly yellow signal quality against a Green quality for the aerial, the Picture was bordering on unwatchable for the aerial but being give a steady full marks (10) for quality for that channel. The Sky’s clear so I cannot check at the Mux level. I have fired an email asking for an advanced user guide to explain what this diagnostic is supposed to indicate as I not getting consistent results. Other times the quality signal bounces around all over the place all.
Both the TV and HDR crash out with no signal if nothing is plugged in.
Thanks for all your help. Suggestion always welcome.
jb38Monday 4 June 2012 4:45PM
Robert: Thanks for your latest update, and all said noted.
PSB1/BBCA started at 200Kw on Ch23 and if anyone situated relatively close to the station could not receive it on an indoor aerial then it was most likely because that the signal strength received was still too high for the tuner in the receiver to cope with, this being very dependant on the brand of device used as well as its screening ability as far as resisting high powered RF signals being picked up directly by its internal circuitry, PVR's usually being better in this respect because of them being contained in a metal casing.
Of course in these type of situations other peculiar effects such as apparent null points can be observed if one wanders around in decreasing circles with a signal meter strung around their neck, but every situation is different for a variety of reasons making it whereby no one single answer is ever possible, and with this being why RF engineering gets classed as a "black art", as problems are generally sorted out as they are found, as its impossible to forecast every eventuality in advance.
Regarding your wire aerial test, what you have reported roughly tally's up with what I expected, but the only downside of that type of test is, that although the signal strength is at a more acceptable level for the receiving equipment it is however very susceptible to fluctuations from movement close by, and this does not necessarily mean in your own apartment but those adjoining it.
To be able to get a better idea of the situation you could try a much more reliable test, and for which you will require a short length of coax enough to stretch between the TV's aerial socket and your window ledge, the coax braid and core at the window ledge end being connected into an electrical (5amp) terminal strip. You then require a stiff piece of wire to construct a small loop having a maximum diameter of about 6" or so and connect this into the terminal strip, thereby in effect constructing a small loop aerial.
Temporarily fix this just inside the window ledge so that the signal received has the very best chance of NOT being affected by movements from within the room nor suffer if the walls of the property are wet should it have happened to rain, but leave the TV on its signal checking screen (channel you watch most) whilst you are fixing the loop with the best orientation for reception.
jb38Monday 4 June 2012 8:37PM
Robert: Just in case you were wondering, the first two paragraphs of this reply is in answer to the question you asked under the other thread heading of: "Freeview on the Crystal Palace transmitter".
RobertThursday 7 June 2012 9:55PM
jb38: Loop under construction but I have done some back to back testing. I was getting problem on PVR but in bedroom a indoor Yagi, spare digibox and 9" monitor video was good. I then connect PVR to yagi. and moved digibox + monitor and connected to 'suspect' aerial in living room. My hope was that I would get a workaround by using a 'remote' aerial but this afternoon during rain, PVR was having problem yet monior was error free. Therefore it appears up-scalling via HDMI is now an issue post DSO and PVR records up-scalled version to hard drive. jb38Friday 8 June 2012 4:58PM
Robert: What model of PVR are you using? but with regards to your suspicion about a possible post DSO issue having cropped up connected with the HDMI cable link, have you actually verified this as applying or not? obviously done by just temporarily coupling the two devices together via a scart lead, although it does have to be said that the superior HF characteristics of HDMI make it more vulnerable to being interfered with, so the cables used should be as short as possible as well as being of reasonable quality, this of course excluding cables seen with fanciful claims being made for them as well as being sold at inflated prices.
Another point I meant mention before concerning you having stated that your reception gets worse when it rains, a possible reason for this could be caused by the combination of the height of the mast in relation to your proximity to it, insomuch that the signal level received could be even more intense by the moisture in the air conducting the energy from the masts radiators more efficiently than if would be directly through air, this having the effect of making you appear as being even closer to the mast than you are, as indeed just like happens in any circuit where high voltages exist irrespective of whether it be 50Hz or 500Mhz.
A somewhat crude way to tell if this is happening is to place a metal rod on your window ledge and connect one end of a FET (high impedance) input voltmeter on to it, the other meter lead not being connected to anything unless the reading is very low, then clip it onto another piece of metal.
By the way older analogue pointer types are generally better for tests of this sort.
The test being, that provided the meter doesn't have any RF blocking measures in it like a capacitor having been placed across its input terminals then note the reading obtained in dry weather, then compare this to the indication seen when it rains, even better if the rain is on the rod.
Of course this "closer effect" when it rains referred to can completely reverse over long distances, where a signal can in many cases be reduced rather than enhanced for a variety of reasons.
RobertSunday 10 June 2012 12:13PM
jb38: Thank you for your invalueable help but Sorry you are getting too focused on my equipment.I used indoor aerials but I have data from 3 three seperate communial aerial systems. All that appear to suffer in same way and conformation that this is new problem, linked to DSO and when it rains.
Everyone I've talked too in my block (who uses CP) has seen intermittent reception problems. That is seven households. Two people in two different blocks to mine have a 'carbon copy' of my problem.
Arqiva made a large number of changes all at the same time any one of which could have introduced an intermittent problem. Each one increases the technical risk of the project which I think were huge the more I read, the more I would panic.
Even if I was sucessful following your advice, digital TV in this area could only be described as unbelievably flaky.
I've got a meeting on Monday which might put this one on a professional footing.
My PVR is a Panasonic DMR-BW780 but My TV Samsung LE40C530F1N agrees even if it does not get so upset at the bad RF it decodes fom its own aerial. The remote aerial test are inconclusive at the moment.
I recorded 700 hrs of perfect video between Oct 2011 when PVR/Aerial configuration was setup and 3 April 2012.
I begining to think there are two different intermittent problems. I need to 'white box' a digital tuner, I can only black box test at the moment.RobertSunday 10 June 2012 12:50PM
Stephen P: It could be it is doing an automatic standby but why now? Have a look around the menus see if it has such a feature and if that could be the cause. Bad PSUs are a fact of life because everything built to a price, lots devices share the same electronic units inside, like power supplies. Is it getting hot and needs better ventilation? might have thermal shutdown built in.
Your best way forward is to google the Wharfdale model number and see if you pick up on a discussion thread. Treat the information it witn a bit of caution an expert can be caught out because of a querk in design of that model may invidates he general 'good' advice.
Google the problem, prehaps try with 'Wharfdale' added
If you can discover a 'firmware revision' google just that code. See what you get.
If you nifty with a screew driver and careful with mains electricity, have a look inside and see if you can find any code numbers and google them.
This is all about detective work and tapping into people who know more (maybe)or can show a path to solution.
It all about how many hits come back to any interenet search, too many or too few and relevance to the problem.
Use the internet and read with caution. jb38Sunday 10 June 2012 8:36PM
Robert: My comments were purely based on you having stated (7th @ 9.55pm) that it now appears that up-scaling via HDMI is now an issue post DSO, and also you having referred to reception deteriorating when it rains with of course me having explained a possible reason for this occurring.
That said though, the reason I explained would affect a communal aerial system much more than an indoor one by the fact that the communal aerial will also capture the high level of EMF that's in the rain by having direct contact with it, whereas you wont with an indoor aerial and why I mentioned the rod on window ledge test as being the only way to verify this.
So when you say that you now think that there are two different intermittent problems, yes! I feel that as well, but in my opinion one concerns the communal aerial system, and the possibility that its distribution amplifier "inputs" are being overloaded by an excessively high level of signal and is causing slight instability in the amplification / distribution system, and with this being reflected in the quality of the signal from the other end that's being fed to the various apartments.
The second being that your indoor aerial is suffering from an element of capacitive type problems, i.e: movements from within the room or from an adjacent apartment, the only way to eliminate (or near anyway!) this being to have the aerial placed as near to the window as you can.
I honestly do feel that you are looking (or maybe hoping?) for some highly technical reason for your problems that possibly involve the construction of the radiating elements on the mast, whereas the real reason is far simpler, that of being located in area where a permanently high level of RF is circulating around it from all angles.
Stephen PSunday 10 June 2012 8:50PM
Robert - thanks.
Now where was it put when we tidied?Wullie BMonday 11 June 2012 10:17AM
Clydebank I cant get any the BBC channels on my freeview box
I used to get all the channels but now I get every channel except the BBC one's.
Any ideas how to solve this problem?RobertTuesday 12 June 2012 12:15PM
JB38: I should avoid writing aloud what I thinking. The TV tuner does better against the interference than the PVR and most of the time agrees that the RF is crap. However the PVR always produces a better quality of picture (when the system works) in the same way as switching on the 5.1 gives better sound.
It was raining when I finished the loop aerial & connected it up to a 9” portable TV placed to I can see it and main TV at the same time. Although the 9” reported steady green for signal quality (80%) and signal strength (80%) on the Mux, the picture was splattered with error pixels. So was it on the PVR, now only connected to TV only via SCART. So was it was on the main TV, as it was on a spare Digi box on AV input to 9”. Four independent indoor aerials/tuners all said the RF was rubbish at that time.
The weather has not cleared so nothing works (error free) at the moment.
Watching the same program comparing two sources at the time I was bugged by a lack of synchronicity of the pixel error patterns until this morning, when I discovered why, the internal tuner of the 9” TV is the fastest, the TV sound echoes behind and the PVR video lags. The Digi box and TV seam in sync and the PVR sentence lags the Digi box. So I’m getting time dilation.
Generally the interference was worse on the loop, then PVR, difficult to judge between main TV and Digi box because of the difference in screen size.
A retune of 9” TV on the loop discovered 3 of the 5 muxes. Mux signal quality/strength look reasonable across the board and are all ‘Green’. I think retuning is too error sensitive and lacks robustness.
I will wait for good weather, restore the tuning in 9” and go hunt for a good picture with loop position. When I get all Muxes found on a retune with the loop, I will consider connection to PVR.
What you be your suggested action plan?
I have noticed weird thing happening to the station number allocation by just switching aerials and I can see typical engineering folklore growing, Disconnect aerial, retune, reconnect and retune again. Does anyone have a handle on what might be going on? I don’t think it is important to this problem, just curious
HodgsonFriday 22 June 2012 5:54PM
Why can I not get Channel 10 when it rains here in Ely Cambridgeshire area. I get a lot of pixellation as well . Any solutions please?Hodgson: In your general area, signals can be received from a number of different transmitters. The first thing is to check that your receiver is tuned to the transmitter to which the aerial faces. To do this, bring up the signal strength screen and whilst on ITV3.
Here are the UHF channel numbers (equivalent to frequency) of the following transmitters:
- Tacolneston C42
- Waltham C29
- Sudbury C49
- Belmont C30
- Sandy Heath C51
If you don't know which transmitter your aerial is directed at, then let us know its rough direction and the UHF channel number that ITV3 is tuned to.
For some transmitters, a new aerial may be necessary, so knowing which transmitter you are using will allow advice as to whether this "may" be necessary. rogerSunday 28 April 2013 7:25PM
Brierley Hill why are my bbc 1 2 3 4 programs having bad interference all other programes ok freeview west midlands dy5 arearogerSunday 28 April 2013 7:41PM
Brierley Hill roger:only bbc stations are effected jb38Sunday 28 April 2013 7:49PM
roger: If only the BBC channels are being affected then carry out a signal check whilst on the BBC and make a note of the mux channel being indicated as BBC from Brierley Hill is on mux Ch60, if though mux Ch43 is indicated then your TV / box has stored the BBC from Sutton Coldfield. DuncanSaturday 18 May 2013 2:20PM
Brighton We live in Worthing (BN11) and in the last couple of weeks have found that we have bad interference (very blocky pixellation and digitally distorted sound) on ALL freeview channels.
Previously we've had occasional problems (which I believe are weather related), but this now seems to be continuous.
We have a roof mounted digital aerial correctly aligned to receive from the Isle of Wight transmitter and only one TV in the house.
I have tried connecting in a booster to the signal, but even when the TV's menu system is telling us that signal quality and strength are both 10/10, we still have interference.
Is it possible that the TV itself has a problem? It is a 5 year old Panasonic TX26LXD600.jb38Saturday 18 May 2013 3:14PM
Duncan: Interference of the nature you describe is nearly always accompanied by fluctuating quality being seen when viewed on the signal check screen, the fact of you having a 10/10 indication suggesting that your signal strength is excessive.
Purely for test purposes, try removing the booster again and allowing the signal to drop under the 10 level thereby allowing you to obtain a more accurate check on the stability of the signal quality, further info dependant on indications seen.
By the way a (1) was missing from the post code entered, this having placed you at only just over 1 mile away from the Whitehawk Hill TX and so I used Worthing Post office as a test code.
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