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All posts by Graham

Below are all of Graham's postings, with the most recent are at the bottom of the page.

G
Crystal Palace (Greater London, England) Full Freeview transmit
Saturday 18 February 2012 2:55PM
Camberley

Postcode GU15 1ER, aerial pointed at Crystal Palace, with high gain roof aerial and booster amp, feeding 2 Sony TVs. Previously received 104 channels on Freeview. Now receive 42 channels on Muxes 1, B and C only with signal good and additionally Mux 2 on the other TV with high signal. To me this looks like a signal level issue from Xtal Palace. I've obviously done all the checks suggested. Any other thoughts?

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GB

Briantist, have you seen there is a common thread to a number of recent posts regarding loss of signal level from Crystal Palace? In my case I now have only Muxes 1, B, and C, with zero signal levels on the others, having had until recently very good signals on all muxes. Is there a statement somewhere which says that the Crystal Palace signal level has reduced and will only be increased to full power on the final swithchover day? I can see from the publicised signal strengths that this is the case, but a statement from the Transmitter Engineering posts might be useful.

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GB

An aerial company makes this statement on their website with regard to Crystal Palace Transmitter: "Note, as work takes place on various digital transmitters (to prepare for the DSO) you may experience problems, e.g. with certain MUXES disappearing." So, the output power may not be reduced, but this issue of missing Muxes is recognised by a professional aerial company.

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GB

David, as I have said before, it seems there is a common thread to a number of recent posts regarding loss of signal level from Crystal Palace? I now have only Muxes 1, B, and C, with zero signal levels on the others, having enjoyed 104 channels on Freeview before. Nothing has changed at my end, so it must be either the Tx or the transmission path. I have suggested as others have that the engineering works are affecting the output, but as you have seen before - the answer is apparently interference. I can only agree with you that denying something is being affected at the transmitter is not helpful. Ironically I now have to use the analogue rx to get an ITV/Ch4/5 signal. Progress!

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GB

I've just used the new Reception Prediction System and for reception at my postcode from the Crystal Palace transmitter, the model is predicting low signals for Muxes 1, B, and C (which I can still receive) and lower signal strengths for Muxes 2 and A (which I cannot receive). So the model predicts the relative levels correctly, although of course it doesn't provide the propagation model algorithms, so actual receiver levels cannot be tested or compared to the receiver equipment figures (the TV reception signal levels are probably only guides anyway and I don't know the aerial gain). Therefore, simple propagation loss seems to be the answer and not interference, which cannot be calculated without knowing my aerial characteristics. I hope this model is available post switchover, so I can confirm the situation then.

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GB

Thanks for all the comments.
FJC, I live on the Crystal Palace side of a ridge at the Bagshot end of Camberley at 100m with 20m above me protecting me from Hannington.
Mike, the predictor under the "Full Details tab" claims to provide receiver signal strengths, see Find out how to receive Freeview and Freeview HD | ukfree.tv - independent free digital TV advice The predictor also claims that my best solution is Crystal Palace today and also shows the best signal strengths after switchover.
(GU151ER)

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GB

Angrybird, I asked in a local TV dealer in Surrey if they were also experiencing poor digital reception at the moment. Answer was "of course we are and we've been told by a rep that the reason is the transmitter power output has been reduced whilst they are making modifications prior to DSO (our transmitter is Crystal Place). We've had high pressure and inversions many times over the last 5 years but always maintained a good signal. This time it is coupled with low power outputs, hence no reception.

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GB

I've made this comment elsewhere, but it's probably worth repeating. I asked in a local TV dealer in Surrey if they were also experiencing poor digital reception at the moment. Their answer was "of course we are and we've been told by a rep that the reason is the Crystal Palace transmitter power output has been reduced whilst they are making modifications prior to DSO". I guess if you are working on an aerial with 20kW of RF, then so would you. We've had high pressure and inversions many times over the last 5 years but we have always maintained a good signal. Since early February, whilst they have been working on the transmitter, poor atmospherics have combined with lower signals, hence loss of reception on several multiplexes. Here's to the 4th April and 200kW.

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GB