Freeview: Crystal Palace (Greater London, England) transmitter
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Full Freeview on the Crystal Palace (Greater London, England) transmitter

Google StreetviewGoogle mapBing mapGoogle Earth51.424,-0.076 or 51°25'26"N 0°4'32"WSE19 1UE

4G at 800MHz (at800) Freeview reception issues

When 800MHz 4G mobile broadband services start there will be 3 multiplexes in the higher risk range (C21-23, C30, C59-60): C22: ArqA, C23: BBCA, C30: BBCB
See How do I know if the 4G broadband will overload my Freeview? and Full UK map of 4G issue areas for details.

This transmitter has no current reported problems

The BBC and Digital UK report there are no faults or engineering work on the Crystal Palace (Greater London, England) transmitter. Click to recheck

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The symbol shows the location of the Crystal Palace (Greater London, England) transmitter which serves 4,490,000 homes.

Other maps:Crystal Palace DABCrystal Palace AM/FMCrystal Palace regionBBC LondonLondon

Radiation patterns

Radiation patterns withheld

Map key

The bright green areas shown where the signal from this transmitter is strong, dark green areas are poorer signals. Those parts shown in yellow may have interference on the same frequency from other masts.

Crystal Palace transmitter Freeview broadcasts

If you have any kind of Freeview fault, follow this Freeview reset procedure first.

Digital television services are broadcast on a multiplexes (or Mux) where many stations occupy a single broadcast frequency, as shown below. The rating shown takes in account the output power level and the various Freeview transmission modes and do not indicate an ongoing fault.

MuxEffective power level, aerial positionRatingModeWatts
PSB1
BBCA
 horizontal
Maximum64QAM 8K 2/3
24.1Mb/s
DVB-T MPEG2		200,000
Channel icons
1 BBC One London, 2 BBC Two England, 7 BBC Three, 9 BBC Four, 70 CBBC Channel, 71 CBeebies, 80 BBC News, 81 BBC Parliament, 301 301, plus 12 others
• as a digital multiplex transmitted on frequency C23 (490.0MHz) from 324m datum.
PSB2
D3+4
 horizontal
Maximum64QAM 8K 2/3
24.1Mb/s
DVB-T MPEG2		200,000
Channel icons
3 ITV (London), 4 Channel 4 London ads, 5 Channel 5 London ads, 6 ITV 2, 13 Channel 4+1 London ads, 14 More 4, 28 E4, 33 ITV +1 (London),
• as a digital multiplex transmitted on frequency C26 (514.0MHz) from 324m datum.
PSB3
BBCB
 horizontal
Maximum256QAM 32KE 2/3
40.2Mb/s
DVB-T2 MPEG4		200,000
Channel icons
101 BBC One HD (England no regional news), 102 BBC Two HD (England), 103 ITV HD (ITV London), 104 Channel 4 HD London ads, plus 1 others
• as a digital multiplex transmitted on frequency C30- (545.8MHz) from 324m datum.
COM4
SDN
 horizontal
Maximum64QAM 8K 3/4
27.1Mb/s
DVB-T MPEG2		200,000
Channel icons
10 ITV 3, 20 G.O.L.D. (not free), 25 Dave ja vu, 26 Home (not free), 27 ITV 2 +1, 30 5*, 31 5USA, 34 ESPN UK (not free), 38 Quest, 39 The Zone, 44 Channel 5 +1, 72 CITV, plus 22 others
• as a digital multiplex transmitted on frequency C25 (506.0MHz) from 314m datum.
COM5
ArqA
 horizontal
Maximum64QAM 8K 3/4
27.1Mb/s
DVB-T MPEG2		200,000
Channel icons
 TV News,  TV Stars, 11 PICK TV, 12 Dave, 17 Really, 29 E4+1, 32 Movie Mix, 46 Challenge, 48 Food Network, 82 Sky News, 87 Community Channel, plus 9 others
• as a digital multiplex transmitted on frequency C22 (482.0MHz) from 321m datum.
COM6
ArqB
 horizontal
Maximum64QAM 8K 3/4
27.1Mb/s
DVB-T MPEG2		200,000
Channel icons
15 Film 4, 18 4Music, 19 Yesterday, 21 VIVA, 24 ITV 4, 41 Sky Sports 1 (not free), 42 Sky Sports 2 (not free), 47 4seven, 83 Al Jazeera English, 85 RT English , plus 21 others
• as a digital multiplex transmitted on frequency C28- (529.8MHz) from 321m datum.


Regional news from the Crystal Palace transmitter


BBC London 4.9m homes 18.4%
from London W1A 1AA, 11km north-northwest
to BBC London region - 55 masts.

ITV London News 4.9m homes 18.4%
from London WC1X 8XZ, 11km north-northwest
to ITV London region - 55 masts.

Self-help relays

Charlton AthleticTransposerRedeveloped north stand Charlton Athletic Football Club130 homes
DeptfordTransposersouth-east London100 homes
GreenfordTransposer12 km N Heathrow Airport203 homes
HendonTransposerGraham Park estate50 homes
White CityTransposer9 km W central London80 homes

How the transmission frequencies change over time

years1950s~851984-971997-981998-20122012-132013-182013-18
aerial groupVHFA KA KA KA KA KA K
C1BBCtv
C22-2ArqAArqAArqA
C23ITVITVITVBBCABBCABBCA
C25-1SDNSDNSDN
C26BBC1BBC1BBC1D3+4D3+4D3+4
C28-B-ArqB-ArqB-ArqB
C29-Dlocal
C30C4C4C4-BBCB-BBCB-BBCB
600C32-A
C33BBC2BBC2BBC2com7
C34+C
C35com8

orange background for multiplexes names moregreen background for transmission frequencieslilac background for power levels in watts800MHz band: 4G mobile to start in 2013700MHz band: possible 4G in 2019 more600MHz band: new or moved digital TV services more
Notes: + and - denote 166kHz offset; aerial group are shown as A B C/D E K W
Italics for analogue, digital switchover was Wednesdays 4th April and 18th April 2012.

  • Ofcom have projected that a local television service for London including Greater London area could use an Interleaved Frequency on the Crystal Palace transmitter using C29
  • COM7, COM8 projected for 2013-16. COM7 and COM8 to operate as Crystal Palace,Guildford, Reigate SFN.

Comparison of old analogue and current digital signal levels

Analogue 1-4 1000kW
SDN, ARQA, ARQB, com7, com8, BBCA, D3+4, BBCB(-7dB) 200kW
Mux 1*, Mux 2*, Mux A*, Mux B*, Mux C*, Mux D*(-17dB) 20kW
PreDSO-BBCB*(-20dB) 10kW

History of Channel 3 in the Crystal Palace transmitter area

Sep 1955-Jul 1968Associated-Rediffusion†
Sep 1955-Jul 1968Associated TeleVision◊
Jul 1968-Dec 1992Thames†
Jul 1968-Feb 2004London Weekend Television♦
Jan 1993-Feb 2004Carlton†
Feb 2004-Dec 2014ITV plc♦
Feb 2004-Dec 2014ITV plc†
• Breakfast ◊ Weekends ♦ Friday night and weekends † Weekdays only. Crystal Palace was not an original Channel 3 VHF 405-line mast: the historical information shown is the details of the company responsible for the transmitter when it began transmitting Channel 3.


Your comments: most recent posts are at the bottom

firstFirst comments prevEarlier comments  ◊  Later commentsnext Latest commentslast

Your comments are always welcome. Please use the form below to add your thoughts or questions to this page. We will get back to you as soon as we can.

Pamela
Thursday 26 July 2012 8:28AM
I live in Felixstowe,and since June I have to keep doing a new search sometimes several times a day as I keep losing the signal. Sometimes BBC is perfect and there are no ITV programmes and sometimes the ITV programmes are very clear and no BBC. Then other times I turn on the TV and there is nothing at all but a scan brings them all back. What is the problem here? After June 2011 my reception was perfect but now it is a mess.
Graham
Thursday 26 July 2012 10:31PM
Pamela,

It's happened to our Pansonic DVD recorder freeview signal tonight too.I'd set it up to record Channel 4 from 8pm - 9pm and all we have is the first 3 minutes then it froze, went blank with the message at the bottom - 'no signal' and it's still the same now at 10.25pm. I've lost the ITV channels as well. Interestingly those channels are working on our two Tv's and all three devices run off the same aerial. I receive my signal from the Talcolneston transmitter. I've had problems like this before and it always and only affects the DVD. By the way, I live in Suffolk too, at Ingham just north of Bury St Edmyunds and would love someone knowlegable to explain what the problem is - should I throw away the DVD recorder and get a different one??
Mike
Thursday 26 July 2012 11:14PM Haywards Heath
Since Monday this week we have very low signal, if any, on all channels and have completely lost HD. Post code is RH16 1HW (Haywards Heath). I believe we get service from Crystsl Palace. Signal has been very good up until then. The only thing that has been different is the hot weather!

Any ideas?
andy
Friday 27 July 2012 9:22AM Benfleet
hi cystsl palace signal is go up the wall at some pint of the day is the hot weather what doing 1am get 100% all channels at all time please repl soon cheers andboy
Terry Carter
Friday 27 July 2012 11:42PM Colchester
Since the start of the O/Games i have awful sinal strength and BBC 1/2 do not exist, any ideas please.
Mark Fletcher
Saturday 28 July 2012 12:31AM Halifax
Terry Carter.Colchester,CO5 8BL.
Having checked with the BBC Reception Test via your postcode given,there are no problems with any of the possible transmissions in your locality.
I would look up inversion effect as a likely cause !
Mark Fletcher
Saturday 28 July 2012 12:35AM Halifax
Terry Carter.Colchester.What i forgot to add are you receiving from Crystal Palace or either from Sudbury or Dover main transmitters ?
What local news bulletins do you normally receive on BBC1/ITV1 channels ?
Michael
Tuesday 31 July 2012 12:03AM London
Michael: Awful again today. The recorder had decided Crystal Palace was too weak. Even after manually retuning everything in sight, the BBC channels (from Crystal Palace) are poor and Sky News isn't there at all this evening. The digital TV is fine so it must come down to the tuner of the recorder ...

... except this had been fine for some years before the digital switchover and for a couple of months afterwards.

Now, we were sold the digital switchover on the basis that the digital signal would be better once analog was out of the way. Quite clearly at the moment it is worse than pre-switchover. Yet this site says there are no problems (at least on BBC) at Crystal Palace. Have we all been sold a pup? If I have to replace equipment that worked perfectly well pre-changeover because someone somewhere decides to weaken the signal for a couple of weeks when they feel like it, who do I sue?

Well, OK, not sue perhaps (and I'm not going to panic buy) but someone must be responsible for this mess. Are they even aware there is a problem, and who do we contatc to complain about what to my mind is a breach of trust on the digital switchover?
jb38
Tuesday 31 July 2012 8:22AM
Michael: Even although you have reported the digital TV (also Freeview?) as being fine this could simply be because of it having a more sensitive tuner coupled to it also having slightly better circuitry, (e.g: Panasonic TV's / Humax if a box) or alternatively that its aerial feed might be supplying it with a slightly higher level of signal, this totally dependant on whatever method you use feed the aerial into both devices and that both devices are definitely tuned to the same transmitter.

As far as Digital TV is concerned, its inevitable that if a TV system is changed from one like analogue than can produce a picture of sorts right down to an almost zero signal with one than "has" to have a certain level of signal before anything can be heard or seen, that the latter is bound not to cope with serious fluctuations in signal levels caused by seasonal atmospheric changes and such likes which can allow signals to be received from far off places that can clash with local transmissions, this being something that has always happened albeit that analogue can cope with this in a much better way.
Chris
Tuesday 31 July 2012 12:11PM London
One last query, security is security but Olympic games would you know if there would be any external interference of any kind that would disrupt the freeview signal that would be attributed to extra pressure on let's say bandwith due to the Olympics. In other words would you be informed of any external factors that would block my London signal that is not entirely due to the transmitters.
Michael
Wednesday 1 August 2012 12:12AM London
Michael: Chris's point had also occurred to me. I know red button services have been amended but if the standard signal has been degraded, that's been kept quiet. I can't think of anything more likely to hack off Londoners than making it difficult for loads of us to view what our extra council tax is paying for (yes, I know general taxation funds a lot of it too).

Yes, the digital TV is Freeview too. I have moved that to the location of the HD recorder and it performs fine .. unless of course I feed it the signal from the HD recorder! Similarly, I moved our stone age Freeview box upstairs to the location of the digital TV. Didn't change its performance.

I think the difference has to be the quality of the tuner. The digital TV seems able to cope with lower signal quality and - perhaps just as importantly - substantial variation in signal quality that we are experiencing. Typically, the signal strength is solid at 70-75% but the quality is either down at 30-40% or constantly shifting sharply within the range 10 to 70%. The exception is when the box decides it fancies Heathfield or Bluebell Hill for BBC and/or ITV, when signal strength also drops to 40-50%.

One last point is that some of the similar complaints from people in other parts of London have come when our signal is OK.
Thomas
Saturday 4 August 2012 10:31AM
Overnight we have lost all channels associated with multiplex A & D. I am at a complete loss for what to do as this a large chunk of Freeview now gone. Any advice greatly appreciated. We have until this happened always had great reception.
Michael
Saturday 4 August 2012 11:40PM London
Michael: We have usually ended up deleting all channels on our HDD recorder (by retuning with the aerial disconnected) and then manual tuning the five multiplexes we are supposed to get from Crystal Palace. This usually gets back the BBC and ITV muxes but does not improve the other three - however deleting everything first does semms to prevent channels being numbered 800+.

It looks as if the Crystal Palace signal is weak at 8am when our HDD recorder auto retunes, so you may have to pick your time.

Even so, tonight's Olympic joy was slightly diluted by watching pixellated atheletes, even on the BBC signal from Crystal Palace. I expect they will get well pixellated in the next few hours though...

A first yesterday was to find one of the muxes claiming to be 698KHz, which appears to be "Waltham" - is that Walthamstow North? Previous "wrong""ansmitters have been Bluebell Hill and Heathfield.

I want to know whom I should be complaining to. The whole thing seems to be secretive and accountable to nobody.
Dave Taylor
Wednesday 8 August 2012 1:19PM
David Taylor:
Hi Guys,
When Freeview Digital was first started I
purchased a box but got "no signal" message
(see original posts)
After full switch over all worked ok, except I had to buy two new TV's.
My house is in a dead spot and analogue
reception was never very good.
Yesterday I turned on TV and we were back to
the state we were in before, with no signal
messages and frozen picture etc.
Nothing has changed with my aerial etc.
Have they reduced the signal strength?
Dave Lindsay
Wednesday 8 August 2012 2:37PM
Dave Taylor: I have read back your postings.

I have observed that the White Oak Leisure Centre could be in the (or under the) signal path at 850m away (just over half a mile). I mention this because it appears to have a large metalic content.

This terrain plot shows that you could have line-of-sight, assuming no obstructions:


Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location

Perhaps the poor reception at your location is caused reflections that are acting to reduce the quality or signal strength.
Dave Taylor
Wednesday 8 August 2012 3:27PM
Thanks for reply
What I can't understand is why I've suddenly
lost the signal unless the power from the transmitter has fallen.
Could well be White Oak Centre causing a
dead spot.
Don't have line of sight to transmitter as
I'm down a dip.

Dave
Transmitter engineering
Friday 10 August 2012 5:00AM
CRYSTAL PALACE transmitter - Freeview BBC Digital TV Off Air from 23:18 yesterday to 23:19 yesterday [BBC]
Transmitter engineering
Saturday 11 August 2012 5:00AM
CRYSTAL PALACE transmitter - Freeview BBC Digital TV Off Air from 23:18 on 09 Aug to 23:19 on 09 Aug [BBC]
Bonnie
Sunday 12 August 2012 12:01PM Feltham
I have had "no signal" coming up for the last three days, I can not get any channels at all, my aerial is brand new as is my freeview box, it says on the websites that the crystal palace transmitter is off air, but only on the 9th of August, please could someone tell me if I am doing something wrong or if it is a fault that I can not fix myself and if so, when will this be fixed
jb38
Sunday 12 August 2012 4:32PM
Bonnie: Where is your aerial located? my only reason for asking being that "if" (as I realise you might not) you reside in the beige brick properties then the aerials mounted at each end of them appear to be of a communal nature serving the apartments within each block, and as such obviously out with your control as far as doing anything is concerned.

However the reception predictor indicates Crystal Palace as being able to provide a good signal at your location, but though the aerials referred to appear to be pointing towards Guildford and likewise mounted vertically, and although Guildford is also indicated as receivable at your location its not quite at Crystal Palace levels.

That said, if your box has a manual tuning facility then for a test go into the tuning menu - "manual tune" and enter Ch23 (BBC from Crystal Palace) then press search or scan and see if anything comes up, if not change to number to Ch43 (BBC Guildford) and carry out the same test, giving an update on results.

It would also be of assistance to know the brand / model of box you are using.

Dave Taylor
Sunday 12 August 2012 8:19PM
Hi Guys,
Just to update you about my problem.
Having had no signal for some days I was going to get out my three piece ladder on Saturday to check the aerial.
I turned on TV to try it and lo and behold
the signal had returned and all was back to
normal.Still don't know what the cause was,
Just another of lifes mysteries I guess

Dave
Mark Fletcher
Sunday 12 August 2012 9:26PM Halifax
Dave Taylor.One possible cause was the inversion effect !
Transmitter engineering
Monday 13 August 2012 12:11PM
CRYSTAL PALACE transmitter - Freeview BBC Digital TV Off Air from 23:18 on 09 Aug to 23:19 on 09 Aug [BBC] Over the next week Crystal Palace main transmitter: TV (digital) Liable to interruption, Radio (analogue) working normally, Radio (digital) working normally. [DUK]
Lorry
Wednesday 15 August 2012 12:06AM
All bbc channels on freeview are currently down and have been for at least an hour. (Tues 14/8 11pm on). Why can I find no information on this, ie is it planned or is it a fault and when is it expected to return?. (crystal palace).
Mark Fletcher
Wednesday 15 August 2012 12:45AM Halifax
Lorry.One indicator is the transmitter engineering text immediately above your text.Crystal Palace main transmitter TV digital liable to interruption.
Yes sometimes the transmitter engineering texts should be more transparent as such in advance of any ongoing works or interruptions so we are well prepared as such.
Mags
Saturday 18 August 2012 7:09PM
I had no signal at all for 4 days, now only very blocky and unwatchable signal, with still no BBC for 3 days...in the E3 area. Any clues what I can do or when normal service will be resumed?
Mark Fletcher
Saturday 18 August 2012 8:36PM Barnsley
Mags.As you did not leave a full postcode preferably to ascertain reception possibilities in your area,i would look up inversion effect as a likely culprit !
jb38
Saturday 18 August 2012 8:45PM
Mark Fletcher: Digital UK's post code reception predictor (only this side of it) appears to have been down since yesterday evening, have you seen anything mentioned about this anywhere?
Mark Fletcher
Sunday 19 August 2012 12:00AM Lytham St. Annes
JB38.Not particularly aware of the postcode reception predictor being faulty last night,but i was certainly aware of gremlins elsewhere on this site as i was unable to respond to any texters yesterday as well as unable to click on any other link without the associated gobbledegook cropping up.
It appears that the postcode predictor on this site is functioning again as i am staying in Barnsley this week and hopefully by typing in the postcode of my recent holiday in St Annes (end of June 2012),Lytham St Annes crops up instead it for now (postcode predictor) should be working normally once again,fingers crossed !
jb38
Sunday 19 August 2012 12:28AM
Mark Fletcher: Thanks Mark, yes I also noticed a few odd things cropping up yesterday, but I would be obliged if you could try a test by clicking on the "Digital UK tradeview" link at the right hand side of your posting, as I have just tried it and DUK states "Error - we seem to be having difficulties etc".
Mark Fletcher
Sunday 19 August 2012 1:54AM Barnsley
JB38:Just typed in your request and exactly the same scenario here,"Error we seem to be having difficulties" even typed in the postcode and house number same "Error" message displayed !
So there are some technical difficulties still ongoing as i text !
jb38
Sunday 19 August 2012 7:22AM
Mark Fletcher: Thanks for your confirmation on that, as when I didn't seen the problem being referred anywhere else I was starting to get a bit concerned in case the problem was at my end, and so when I noticed that you were on I thought I would take my chance and enquire.

Michael
Sunday 19 August 2012 11:49AM London
My digibox and HD recorder are still messing around. Tne Toshiba HD recorder retuned itself to a different transmitter this morning.

Main development: I took the digibox to my father's house half a mile away, where reception used to be worse pre-switchover, and where he used a loft aerial. Sure enough, signal strength on the digibox was about 49%. but signal quality was rock solid at 98%, pretty consistently over the muxes. I checked by phone that the HD recorder was still playing up at home at the same time.

This contrasts with the same digibox at out house showing signal strength of 85-90% and signal quality varying (and I mean varying, as you watch it) of 70-85% on UHF Ch 23 and 26 and 45-65% on the others. The corresponding readings on the HD recorder are 70-75% strength and 48-63% and 25-60% quality. These readings are for when there is a problem. When there isn't (typically in the afternoons) quality is consistent at around 75 or 70%.

So, it's not the digibox (or presumably the recorder) gone wrong. It is the signal quality, or the variation in the signal quality. The digital TV can cope with this but the digibox and recorder cannot.

I intend to do the same test next door when the neighbours are back, which should indicate whether it is the signal coming into the aerial or something between aerial and equipment. That "something" might be a powered signal splitter (and presumably amplifier) in the loft, given that could simply be amplifying errors, but the same setup has been working fine for years, and for several months post-switchover. And the signal strength reported by the HD recorder (and the digibox?) does not seem excessive on the face of it. I'm reluctant to mess around when I still think the incoming signal may be at fault, to the extent that the HD recorder thinks a dodgy signal from elsehwere is better. I have already had engineers round checking that the signal coming from the aerial is OK. They reported that it was fine at around 70% BUT when they came the setup seemed to be behaving I don't know for sure that they also looked at signal quality.

I was surprised that everything functioned with only 49% signal strength but I was even more surprised at the very high signal quality. What should I expect for quality? Should it work on a nice consistent 70% quality, say?

I have a horrible feeling that the answer to this one is "it depends", but would my Toshiba recorder base its retuning decision on strength, quality or a mixture of both?

Annoyingly, none of the televisions we have appear to indicate strength and quality separately, simply giving an overall measure.

The only other possibility I can think of which is unrelated to what is emerging from Crystal Palace, is the Shard. I dismissed this in my mind as the building was essentially there for some time before its opening a few weeks back, but is it possible that some cladding was added late in the day? I know that a small area of Ponders End had issues with Canary Wharf, for example, so a very localised effect is not impossible.

jb38
Sunday 19 August 2012 12:35PM
Mark Fletcher / Dave Lindsay: Just tested out DUK's post code reception checker and pleased to be able to say that the problem appears to have been rectified.
Dave Lindsay
Sunday 19 August 2012 12:45PM
jb38: Thanks for posting about DUK Postcode Checker working now. I tried it an hour or so back and it was still off. It is now working for me.
Mark Fletcher
Sunday 19 August 2012 1:51PM Barnsley
JB38:Just clicked the digital UK tradeview link to the side of my last text and now working normally again !
jb38
Sunday 19 August 2012 4:49PM
Dave Lindsay / Mark Fletcher: Yes thanks, and long may it continue to do so, as it's an essential aid into providing assistance to anyone with problems of a reception nature, as without it anyone providing assistance is (up to a point anyway!) just about as much in the dark as the person seeking help, and in many cases with that even applying when the person seeking assistance has provided non-post code info on their location.
Michael
Monday 20 August 2012 11:13AM London
Michael: To add to my last night's post, I found the HD recorder getting BBC1 etc off 698K this morning. After wiping all chanells as usual, for a change I let it do an auto retune. I found that while it did pick up Ch23 successfully it then went on to pick up the same mux on other UHF channels, evidently overwriting the Ch23-generated ones (i e not storing them as 801+). This was despite the Crystal Palace signal being stronger and of higher quality than the alternatives. However, it does dispose of the theory that Crystal Palace must somehow be next to non-existent at 8am. Hard to know why the HD recorder is doing this. But if the signal as received by the tuner was as it was six weeks ago, presumably it would not be!
Peter Suthers
Tuesday 21 August 2012 10:22AM
Several times since Chrystal Palace Digital Switch Over, messages appear informing that new TV Channels are available & suggest a re-scan.
Does anyone know where one can find information regarding what the changes are each time?
Due to the height of my block I have to manually tune all 5 of my receivers (TV, DVD, PC & 2 x PVR) to prevent reception from other transmitters.
This is only worth it if the changes are relevant to me. I'm not interested in data & chat channels (& most of the TV channels to be honest, the guy who sang "57 channels & nothing on" was a prophet for our times).
Michael
Tuesday 21 August 2012 11:42AM London
Michael: Peter - I am probably wrong but I have a suspicion that the "new services" detected may be the same old services coming from a different transmitter.
Michael
Thursday 30 August 2012 2:48PM London
Michael: Finally tried our digibox next door. Same result as at my father's house - reduced signal strength, steady 98% quality, fine picture.

So we have:
- digital TVs that work fine on our signal;
- a digibox and a HD recorder which do not work on our signal, producing a lot of pixellation and breakup, but the digibox does work next door and (in a dip) at my father's house. I haven't moved the HD recorder but I am assuming it would also work elsewhere;
- one older digital TV (not mentioned before) which is a bit iffy;
- results similar whichever TV points I use, and whatever configurations of equipment and cabling I use.
- it was worse in mornings and evenings, but more recently yhe problem seems to there all day.
- an aerial engineer confirmed some weeks a go that the signal as received at the TV point was OK, but (a) I'm not sure he looked at quality as wella s strength and (b) it was behaving when they called.

So it appears that the digibox, HD recorder and (to some extent) older digital TV cannot cope with the low (and highly variable) signal quality, but the newer digital TVs can.

There are four TV points in the house, fed from a rooftop aerial with a distribution amplifier/splitter in the loft. As far as I know there is no masthead amplifier (not sure how I can tell, though).

If I switch off the amplifier, the signal goes, as I would expect. So to test if it is the problem I would have to mess around up in the loft playing around with what I have found in the past to be rather awkward connections.

With this setup, is it possible that I could have too much signal strength, and that quality problems not apparent next door are being amplified into something which is upsetting half my equipment?

Is there anything else I can try?

jb38
Friday 31 August 2012 12:39AM
Michael: I was having a look back through your various earlier postings for purposes of checking the history of your problems, but though whilst doing so came across a statement that appeared somewhat contradictory and which I couldn't quite fathom out, and so I would be obliged if you could clarify the following as far as the devices you are using to receive Freeview is concerned.

The statements referred to being:
>> Our main TV is analogue so has to be fed by either out Toshiba RDXV59DTJB2 HDD recorder or our (very) old Sagem Freeview box. <<

>> Is it plausible that the recorder and Freeview boxes are unable to cope with quality variations that are no problem to the TV? <<

What TV is being referred to in the latter statement?

However no matter what is being referred to it should be appreciated that no two Freeview devices have the same sensitivity tuners unless they are identical models to each other, this being the cause of the differences in performance that you have noticed, Panasonic TV's and Humax boxes being devices fitted with two of the best tuners around, and capable of giving reasonably glitch free reception in circumstances where other devices would be glitching every 30 secs or so.

The other point to remember being, that if when observing a signal its strength and quality is seen to be continually fluctuating (especially quality) when its known that your aerial is electrically sound as far as bad connections are concerned, then the problem is in effect out with your control, as its liable to be caused by either atmospheric reasons allowing distant stations to be picked up thereby blocking local reception, or that the problem is due to the intermittent effect of tree foliage blowing about, worse obviously if wet.

In both cases about the only thing a person can do is make sure that the signal being received is at a high enough level above their receivers cut off threshold whereby when the signal drifts downwards its still above the cut off point and not constantly dipping under it.

Occasionally moving the aerial a few feet either way (left or right) can help the situation, but frequently its at the expense of some other mux, so its really a hit and miss situation.
Michael
Friday 31 August 2012 7:22PM London
Michael: Ah yes. The main TV is an old analogue one so has to be fed via SCART from a box with a digital tuner.

The other TVs in the house are digital, an LG, a Mikomi (Argos own brand?) and a Samsung borrowed from my father. The Mikomi was a bit iffy on Ch 22/23/28 muxes at times but the others were working fine.

I said "were", you may have noticed. The LG got really bad on those muxes a couple of nights ago, and the digibox has also started playing up. The Mikomi also got much worse. No footie for me last night!

Then today I switched off the distribution amplifier in the loft, expecting this to lose nearly all the signal. But no, the HD recorder worked fine. So too the Samsung and the LG, though later that started to be really bad on the Ch 26 mux. The Mikomi in the kitchen seemed to lose signal altogether, but at the main TV point it worked better than usual. So, for the first time, I was onserving differences between different TV points in the house.

The signal strength shown on the kit that can show it was a lot lower. Quality seemed more settled (and sometimes consistently high) - except where a tuner was having problems. The digibox is better, but not by much.

This does seem to suggest that the problem for the HD recorder was too strong a signal. But reducing the overall signal by switching off the amp seems to cause other kit problems, at least in some locations. Trying to amplify it at some points and attenuate it in others would surely be a complex trial and error exercise.

Every time I write this stuff up, something else occurs which does not seem to fit the pattern. I'm starting to think that the distribution amp is malfunctioning, particularly as the problems were not there until a few weeks ago. Deterioration of internal cable, perhaps?

Outside foliage seems an unlikely culprit, as next door, with a similar aerial (and similar Freeview via a box) setup shows nice level quality. The main change in the immediate locality has actually been the removal of a large pine!

The whole think s starting to make my head hurt!
jb38
Friday 31 August 2012 11:11PM
Michael: One particular thing you have said is extremely interesting, this being the results you obtained with the distribution amplifier switched off, because although distribution amplifiers boost the signal to varying degrees dependant on the spec of the model used, on the other hand when they (all types) are switched off they act like an attenuator having been placed in line with the aerial, this being why if done on an analogue signal it always resulted in a grainy picture.

The point about this situation being, that you must be receiving a reasonably good level of signal at your location for it to overcome the attenuation effect of an unpowered amplifier being in line, and so although I realise that you obviously require the distribution amplifier for purposes of feeding the signal to other locations its possible that the overall signal level created by this is slightly too high (for some devices) whereby an attenuator being placed in-line with the amplifiers "input" could help the situation, as an excessive level of signal displays exactly the same symptoms to one that's on the weak side, including "false" low signal indications caused by instability in the tuner.

I would therefore suggest that you try a test on one of the TV's by connecting its feed directly onto the aerial lead that feeds into the distribution amplifier albeit I do realise that in most cases this is a bit inconvenient to arrange, but though its the type of test that is necessary to evaluate what's happening.

Another point to note is, and although very unlikely to be applicable in your situation, but on "some" occasions when the signal quality is observed to be continually fluctuating this can also be due to a signal being on the verges of being excessively high, because signals in non line-of-sight situations tend to drift up and downwards in strength throughout a 24 hour period, and if they are hovering at the top end of high (with good quality) and they drift slightly further upwards then as soon as that happens the quality drops, this resulting in the fluctuations referred to.

jb38
Saturday 1 September 2012 7:33AM
Michael: Just a small addition to that said, its not exactly unknown for a distribution amplifiers internal power supply to fail and especially during the warm weather, and so although what was mentioned about the amplifier still applies in every way its best to check that its still working.

The procedure is to have the amplifier switched on and carry out a signal strength / quality on a reasonably stable channel noting the readings, then connect the TV' aerial feed straight into the aerial and carry out a second check noting what the difference is, and provided an excessive level of signal is not upsetting the readings what's indicated with the direct aerial connection should be "slightly" lower than before.

If though its higher, then either the amp is defective or the signal level is excessive.

By the way, I will not personally be available to give further assistance until about next weekend as I will be on holiday, although someone else will probably answer any query you might have.
Michael
Saturday 1 September 2012 12:34PM London
Michael: Thanks, jb38. It was my experience with analogue which made me expect little or no picture, rather than a better picture, with the amp off, so what transpired was a major surprise to me.

I had wondered about putting an attenuator in line near the equipement but it would be guesswork as to how much I need.

Carrying TVs or other digital equipment up to the loft is liable to result in not having said digital equipment in working condition any more, which is one reason why I have not tried it yet. (Would a long cable down to floor level be expected to work? Think I've got some spare cable - without connectors - somewhere. I suppose that with a suitable connector - whatever it might be - I could connect each cable directly to the aerial as well.) The other is that the connections look awkward to me, and if there is a way of terminally messing up the cable, I will probably find it!

I think it is clear that the amp was amplifying the signal that the digibox and HD recorder were using, as the signal strength they show is markedly lower without and the signal has either been lost or is seriously degraded at other points. That's not the test you suggest, of course. I've been careful to say "amplifying the signal" rather than "working" because it might be doing so in a highly variable manner. If the PSU is giving a jerky supply, might that cause the behaviour I am observing? PSUs are usually presented as being specific to one device but I think I have a variable one knocking around somewhere, so it might be worth trying that (cue exploding amp in loft...).

Whatever is going on, it is something that has only been going on seriously for about eight weeks. As the aerial signal seems strong enough unamplified, and the kit I have tried elsewhere works fine, a malfuctioning amp does seem to be the fault that best fits the bill.

However, thinking about it, there have been some smaller, easily dismissed, deteriorations before this. In particular, I have a TV card in my computer connected to one point, and 9 times out of 10 I get a green mass of pixellation at the foot of the picture. Yet 1 time out of 10 it is fine! That's been the case since I got the computer a couple of years ago, but of course the cause could be completely, er, unconnected.

As it happens, I have even got the digibox working off the unamplified signal at the main point this morning. It does seem inconsistent, and I do worry that deterioration arising from the constant swapping around of cables might itself be an issue. I think I'll leave well alone for the weekend and see what happens.

Just for the record, there are four outputs from the amp, servicing five TV points. One of the cables must split out of sight; I think this is the one to the points which now seem dead, which makes sense as they would get the least signal at all.

Finally, thanks for all your help, and enjoy your holiday!

Michael
Sunday 2 September 2012 1:43PM London
Michael: Just an update. Tested the power supply and it gives a steady 5 volts DC, as it should do. Suggests to me that it has to be the amplifier/splitter itself.
Michael
Wednesday 5 September 2012 9:04PM London
Michael: Sorted! Aerial technician replaced the splitter/amplifier with a straightforward splitter, and eveything works.

He said that the aerial was actually picking up too much signal. Also that when I unplugged the splitter/amp, the improved (but still variable) signal seen on the main TV was being picked up purely by the cable between the splitter and the aerial point, that cable being high quality and (if it matters) outside the house.

This begs a number of questions (though I am not too worried now everything is fine). If the aerial signal was too strong, how did it work before? My guess is that when it was working properly the amplification was less than the attenuation provided by splitting. At some stage it stopped splitting the signal properly, hence overload on some aerial points and poor or no signal on others. But what do I know?

Anyway, I have to eat humble pie about blaming it all on the Crystal Palace signal.

The other question, I suppose, is why the excessive signal was not diagnosed by the earlier technicians I had in. In their defence, things seemed to be working OK that morning, and the deterioration at other times was less than more recently; they only checked the output at one aerial point as well, rather than the input to the splitter.

So long and thanks for all the fish...
ERnest Cook
Sunday 9 September 2012 10:45AM Billericay
I cannot get HD signal ihave a new aerial and a new tv
Reception of non HD is perfect
Transmitter engineering
Monday 10 September 2012 1:55PM
CRYSTAL PALACE transmitter - Over the next week Crystal Palace main transmitter: TV (digital) Liable to interruption, Radio (analogue) Possible weak signal, Radio (digital) working normally. [DUK]
Susan Lock
Friday 21 September 2012 12:21PM
For the last week (15th-21st September 2012) I have been driven round the bend with my LG TV that loses the EPG after about 3 minutes rendering my TV useless if I want to change the channel or record anything. I have to turn it off then on again to change channel before the EPG is gone again. I have rescanned for the channels loads of times. I have checked the signal strength and it has now dropped from 70 to 67 and today 65. During the cut over I found that under 70 my TV had a mind of its own and just did not function properly since it loses the EPG data which seems to be the main brain of the TV system. How long is this 'tinkering' with the signal going to last since it must be effecting a large section of Freeview customers?
Graham
Friday 21 September 2012 12:32PM
Sort it out you knob jockeys



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