All posts by Robert
Below are all of Robert's postings, with the most recent are at the bottom of the page.
Was any engineering work logged against the Crystal Palace transmitter on 29th May 2012. Ariva Spend the day removing and rebuilding the Digital Pods from the top down. I will continue to watch with interest. Since 4th April 2012 my pervously 'Digitally perfect' Freeview reception stopped. It can become unwatchable when it rains (In Crystal Palace) with 20-30 error pixels splatters and the sound chopping half words. Boosting from 20MW to 200MW did not work. I bougth a new 'HD' indoor aerial and run it though a 6dB attenuator. But got no improvement over the original indoor UHF aerial which served me well for years. My last changed was Oct 2011 when I went HD and have recorded over 700 hours of perfect freeview up until 10th April when a BBC4 program demonstrated error bursts of 20-30 pixels every few seconds. Unwatchable TV the sound cuts out on half words and you get a digital kiss every so often. I have been monitoring at the quality and power indicators on the muxes and channels and this was a first clue that Arqiva were adjusting the transmitter (some days before). The pods going up and down attached to a guide wire and a man in a cage was a bit of a clue. My Freeview is 'digitally perfect' at the moment the problem is intermittant and linked to rain at Crystal Palace. I also bought a UHF signal finder and was looking for an alternative signal but no luck. The pattern of errors suggest it is co-channel interfence and the corruption to the data is so massive that the built in error correction is totally overwhelmed yet the quality signal can stay in the green. I have enough spare equipment to confirm my belief it is the transmitter at fault. I did a local survey and no one who uses broadcast Freeview had not noticed a decline in reception quality. 
JB38 I'm not sure if your comments were aimed at my question about what Arqiva were doing to the Crystal Place transmitter or not but let me clarify. The transmitter has, at the very top the aerials which were used to transmit the 4 channel analogue TV service below are the array of ‘digital pods’, These are aerials which transmit the Freeview digital TV signals. These were taken off the mast (not all at once as Freeview did not go off the air). The array was then rebuilt. In the Victorian age, a lot of devices were described as ‘electric’ despite NOT using electrical power. ‘Digital’ has the same fait in marketing speak today. My Electro Magnetic Transmission Theory dates back to 1981 but am reasonably confident that a UHF modulated wave for analogue TV would look very different to a UHF modulated wave for digital TV even if both wave are analogue is nature. ‘Optimised for the reception of UHF modulated waves used for digital TV’ would be a better description. Although I don’t know enough to be sure such optimisation is possible. DigitalUK say any outdoor TV aerial over 30 years old probably will need to be replaced for Freeview but it is hidden in the section about communal aerial systems used in flats. In my quest to get my ‘digitally’ perfect reception (Interference and nose within the ability of error correction to correct ) post 4th April (BBC) and18th April (all the rest) I bought a new indoor aerial (made no difference). It was ‘HD compatible’ and ‘3x Noise Filter’ which I cannot check on the accuracy of those statements. However I can shot holes in ‘Amplifies terrestrial HD TV signals’ and ‘active triple noise reduction filters’ because to amplify you need active electronic components like transistors (unlike passive electronic components like capacitors and resistors) and active devices need electrical power to work. As this aerial does not have batteries or plug into the mains it cannot have active components inside. Trading standards might have a go on this one. I’m having a go at ‘Total tripe’ I fail to see where cows stomachs come into this. Braintist & Stephen P.
Thanks very much for comments and it's a good case in point of trusting the web for information. The Radio & Televison Interfence Service will not touch this one with a barge pole as it is an indoor aerial. Since the 4th of April I have been clutching at straws trying to cure an intermitent reception problem. The signal quality and strength monitor is too much of a blunt tool, I've had quality of 1 (Red) and perfect picture & Sound and unwatchable TV on 10 Green both times the reading was constant. The 29th looks like a red herring coupled with what you have said above about the transmitter configuration, I've still got an intermitent probelm that can degrade into unwatchable TV. Logan's Run on CH4 HD had 2 small glitches until the last segment when the action climax became unwatchable, 2 hrs into the flim! I upgraded in October 2011 and the system ran for well over 700 hours of perfect glitch free video until 4th April. It has got thought some very long records glitch free since but it is still too unstable and unreliable. I stopped moving the aerial about two weeks ago and had concluded it was a transmitter problem. After a decade of perfect reception I might have to move to cable. I have not found anyone yet around here who has not thought Freeview reception had degraded since DSO. I have a degree in Physical Electronic and in 1981 knew the theory of how Yagi aerials worked, the cleaning up of digital signal down fiber optics cables and Electro Magnetic wave transmission theory. Unlike 405/625 changeover, I thought Freeview was all about using the same UHF aerial configurations but diggin deep into the DigitalUK website paints a much darker picture. Does anyone else consider that Crystal Place now has an ‘insidious’ intermittent transmitter problem for people very local to the transmitter? Their Freeview reception can go totally to pot when the transmitter mast gets wet. And this is a new phenomenon post 4th April BBC and 18th April the rest. How much does anyone, world wide know about the behaviour of the multiplexers run at higher power. What changes were made to the configuration? How well is the science understood? How much field testing was done? I have had the very sensible suggestion of using attenuation which I have experimented with. But I also have noted a steady drop off signal powered as measured by my hard disc recorder, over the weeks since 4th April 2012. A few days latter after purchasing new aerials and attenuators, I thought the signal power measurement did not work, because it was always 10, even with 18dB of attenuation. It was only when I tried an unterminated VCR RF lead that I got a reading of 6. A few weeks later when I froze my configuration and stopped trying to find a new sweet spot for my new indoor aerial, as I had come to the inescapable conclusion the fault was outside of my equipment, I ran for a while with 12 dB but have reduced to 6 and then 0 in response to the measured power levels and continuing problems. Seven people or 100% of the people I talked too who use broadcast Freeview; in my block have noticed a decline in reception quality. 5 have the same insidious fault where TV can become unwatchable since DSO. Lots of indoor aerials and two independent communal aerial systems now longer are reliable for Freeview. After over 50 years of successful broadcast from Crystal Palace, TV is no longer a wireless device in this area. How can you watch a film error free for 2 hrs and the reception become totally unwatchable just at the climax of the film? Our communal aerials would be condemned in an eye blink because of their age according to DigitalUK. UK TV is not designed to be received by anything but an outdoor aerial here lots of people use a bit of wire, coat hanger or nothing, It gobsmaked the engineer who was doing the pre tune for channel 5 that all these TVs worked and on my post DSO survey I found a lady who uses Freeview and still has no aerial. The advantage of digital transmission is that with error correction, noise and interference can be filtered, Schmitt trigger circuits can clean up a digitally modulated analogue signal before it is converted back into in digital data all this help to make the medium far more tolerant and resilient but there are limits. Whatever is going wrong is far s beyond the scope of the signal processing and error correction circuits to cope with. Professional investigation is required. Any comments? 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. 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? 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.
What power did Multiplex BBCA on C23 start with on 4th April. 20 or 200 MW?
Does anyone, outside Arqiva know the detailed configuration changes to the broadcase antenna and if not being able to find BBCA on C23 was a resonable problem to have on an indoor aerial or not.
NICK ADSL UK : Thanks for your posting. I might explain a bit of a ‘reluctance to engage’ I have felt from certain quarters. There is far far more to a problem of this type than the just technical issues. I was clueless to the scale of DSO and the technical risks taken. I’m very glad I’m not involved with any of the discussions and events that led up to DSO; however as an ex- European Technical Support engineer would love a bash at being part of the solution.
For a decade Freeview sometime took 30 minutes to set up and find a sweet spot for the indoor aerial, then it that was it, stable as a rock until I bought the next bit of AV kit and wanted to move stuff around. rebecca damm: Mike Davision is right with the solution he states but there are two other solutions one high cost, one low cost.
The high cost solution is to buy a hard disc recorder not sometime know as PVR instead of the digi box. If your TV is HD ready, you could by a PVR with one or more HD tuners inside and go HD at the same time. You then will able to record TV onto the hard disc with minimum fuss using the PVR’s EPG. Buying a PVR with an HTMI output would be a good idea as even if you current TV does not have one, your next will and will give you better quality of picture over a SCART connection. You could still can record to tape by connecting the PVR (SCART) on the VCR This does not have to be done at the time of broadcast. I would also give you the flexibility to record all you favourite programs over the week that you are away on holiday. I see at least three clear benefits over Mike’s solution.
The low cost method it to use the TV as the source of the Freeview video signal. TV can be setup to send a video output down the SCART to the VCR which can be told to record it but there are drawbacks getting it setup is one, you would only be able record what you were watching, you would have to leave the TV on, and on the correct channel to record your favourite program to watch later, if you were out at the time of broadcast. Manual programming is a pain and error prone.
cathy: Six visits and you don't buy what your being told. Your can go and buy an new TV but I do not expect that to make any difference either. Neatly, their digibox would no longer be used.
Check out if her friends (espicially if they used the DigitalUK service too) and neighbours (new reception problems since DSO?). Are they seeing similar problems?
How many times have they changed the Digibox?, have they tried a different model?
Go back and talk to the service manager. Post again if you not happy with what you are told or think you have been fogged off. 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. 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. 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. Val Tilley: As a TV/Video amateur with a computer background what I understand is ‘Error’ Pixels or block on the screen start to appear when the block of data which make up the video audio stream come through with uncorrectable (unrecoverable) data errors due to too much noise or interference on the modulated UHF signal from the aerial.
Digital transmission is fault tolerant, you can have a degree of noise or interference but it has to be within the bounds of the error correction circuits. This is its greatest strength. Your tuner not only ‘knows’ the data is damaged but can correct it so the picture and sound generate are perfect so you never know but looking at the TV.
However, the fact the data had to be corrected is reported in the statistics used for either ‘Signal Quality’ or ‘bit rate error’. This is a feature most tuner have somewhere in their menu structure.
Missing channel 12 (Yesterday) probably means that your tuner failed to find one of the Multiplexers. Crystal Palace transmits all TV and radio over six multiplexers. To check I my tuner has found each one I should have BBC1 (1), ITV1 (3), ITV3 (10), Pick TV(11), Yesterday (12) and BBC1HD(50). Information on what TV station is on what Mux is explained elsewhere on the website but BBC2 shares with BBC1, ITV1 shares with Channel 4 & 5.
My recent experience with automatic scanning suggest that it is not very fault tolerant. The TV's tuner had a perfect picture yet the PVR which I was tuning missed the Mux. I was just manually tuning the Mux with ITV1 on it yet Channel 4 and Channel 5 were not in the list yet worked if I tapped 4 or 5 on the remote. So not very robust either.
Missing muxes are a common problem if you were setting up to watch Freeview via an indoor aerial but prior to DSO finding the sweet spot for the aerial was a 5 or 10 minute task once found it was reliable. I never knew there were seven muxes before DSO because I did not have to be able to diagnose reception problems before.
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
Dholder: I would ask your Freeview box.
You should find somewhere in the menus an option to ‘manual tune’ if you select this option it also displays signal quality and signal power. As you scroll through the frequencies or UHF channels these should react.
Signal power will give you a guide to the strength of the signal and if you get a reaction on signal quality, this shows it is detecting a digital TV Multiplexer (Mux) (where a group of TV stations are) and not just radio frequency background.
The fact you only see 3 radio would suggest your aerial/box is not picking up the BBC mux. So I would expect BBC1,2,3,4 are absent but I think ITV1 would be in your list of TV stations.
If you look at the Multiplexer TAB on this site, It clearly shows which TV stations share the same Mux. In digital TV the Mux has the frequency or UHF channel NOT the TV stations as in analogue TV.
Looking at your channel list, you should be able to work out what Mux or Muxes your NOT picking up. So, lots of digital TV channels have the same frequency, that the way it works (or not sometimes).
The scanning process appears to be a bag of bolts it is not very fault tolerant or robust. I’m testing RF quality in a high signal strength area because my TV works brilliantly until it rains. DSO has forced me to find out what is where after a decade of being able to set up an indoor aerial in about ten minutes with a plonk, scan and a quick scroll, check for favourite channels method.
Assuming that you have an outdoor aerial as per Ofcom, DigitalUK et al think you should, see if it’s pointing in the same direction as most of the other one in the street. It might have been marginal before or have been struck by a low flying duck. If it agrees, then make sure it not wobbling in the wind that could give you problem too. Avoid scanning after rain or a period of wet weather just in case there is a water ingress problem on your aerial, water can cause havoc and might be your original problem.
If you are using an indoor aerial it’s more tricky, time to play the find the missing Mux game.
With the tuner on manual tune set the missing Mux frequency (UHF Channel) take a reading, probably signal quality is more useful to asses if you have a sweet spot or not. Try moving the aerial give it 30 second to settle down then take a reading, any better?
When you think you’ve found the best position or just got bored do another scan.
If you still stuck, then look up your transmitter’s Mux frequencies and take the measurements for each one always wait 30 seconds are they similar results for power and quality? If power is measuring at 100% David’s point above is a good one.
This is the zero cost DIY option of trying to find out what is going on. Why not borrow a digi box and repeat the trial, it might cope better or illuminate the Digi box and suggest more an aerial problem.
Having the numbers on the Muxes might be a good way to find a proper aerial specialist if he says Mux? Then move on.
There are other possible causes but retuning is not as bullet prove as it should be and I think it should be able to tell you ‘your RF sucks’ or ‘Okay Man’ at the end of a scan. It’s a shame that you need to learn how to ask the question.
E&OE Gary: If you’re looking at the signal strength although important, Signal Quality (or bit error rate) is the more important for reception. It is an indication how much work the digital error correction the tuner has to apply to the data stream. Less error correction or better quality is what you are after.
There would have to be very extensive work to support DSO with probably a lot of hardware going live for the first time on the 4th and 18th April 2012. It is described on the Arqiva website as a man turning a big lever from ‘on’ to ‘off’ in one hall of equipment moving to the hall next door and turning another big lever from ‘off’ to ‘on’. Analogue went off on came the new Digital Mux(s). All I can say it must a moved very very slowly between the halls.
Frequent freezing would suggest that in some cases, the data is so badly damaged it gives up trying to produce a picture. The data is no longer correctable; it unrecoverable and we have gone way beyond an error pixel or two.
During these periods of freezing, you have a reception problem. Getting the best signal you can into aerial would a good start. You don’t say how close to CP you are and my own reception problems are documented under the interference section.
Good Luck Brian Butterworth: Get site, very supportive and useful but one article I think is wrong and would like to chat 1 to 1. Could you give a webmaster address or just email me so I can put the case for changing it.
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