All posts by KMJ, Derby
Below are all of KMJ, Derby's postings, with the most recent are at the bottom of the page.
S Rogers: The problem is the low power Freeview service shares a frequency with high power French (and English) transmissions which are not normally receivable at your location. When the weather conditions are such that these high power signals travel further than normal, due to the inversion effect,your local signal is swamped by the out of area signal resulting in your receiver finding French channels, as you have observed.
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BW: I suspect that due to the inversion effect during the present weather conditions you are receiving signals from Tacolneston and Sandy Heath which are blocking reception of the lower powered Freeview service from Bluebell Hill. C39, which still works for ITV4 etc is not used by either of these transmitters.
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Nick R: Does your Mum's TV lose reception of all channels, or just those which are carried on one or two of the muxes? If it is a total loss it would suggest that possibly the power supply to the communal aerial is interrupted (unplugged while Hoovering takes place?) or a source of interference is switched on at the time mentioned, a faulty security light for example, as this is around nightfall. If it is only one or two muxes affected it is worth checking which frequencies have been stored by the TV. Until 27th June 2012 Sudbury uses C44, C41, C49+, C54, C63 plus C47(HD), whereas Clacton relay uses C48+ and C52 plus C42(HD). If Clacton frequencies have been selected the aerial will be 40 degrees off beam, so they might not be as reliable as the Sudbury alternative.
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Paul Foster: ArqB will remain temporarily on C33 @20kW until 18th April 2012 when it will change frequency to C28 and the power will be increased to 50kW on the horizontally polarised signal. Additionally it will be transmitted at 200kW with vertical polarisation from that date. SDN and ArqA change frequency and mode at the same time and will also transmit at 50kW horizontal and 200kW vertical.Note that in order to transmit Sky Sports ArqB has already changed to 8k mode, this will account for the signal appearing weaker for some viewers.
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karen: If you are receiving from Crystal Palace, after switchover the PSB muxes will use the frequencies vacated by the current analogue services. If you have good analogue reception now you should have good digital reception on those muxes after switchover. The COM muxes however will share frequencies with Rowridge, which could make them more susceptible to reception problems in overlap areas between the two transmitters. You ask why some frequencies are affected more than others by the weather conditions causing the inversion effect. Lets suppose that the conditions are causing signals from, for example, Belmont to travel further than normal into the London area. These signals will only cause problems on the frequencies that are common to both transmitters, which at present are Mux1, Mux2 and MuxB which are low power at CP and high power at Belmont, so these muxes at CP get swamped and give "No signal" The other common frequency is C30, which is at lower power from Belmont competing with high power analogue Channel 4, this would possibly cause slight "grain" on the CP picture. After switchover CP would probably be strong enough in its main service area to drown out the unwanted weaker signal on most occasions.
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Melvin Rainbow: If I could add to what jb38 said above, it seems likely that Mux BBCA from Midhurst is coming in that little bit stronger with the result that your local signal drops out. Did the problem begin on 29th February, by any chance?
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Carol Galloway: The current weather conditions are causing out of area signals to travel further than normal, and block reception of those normally received. If you are using Bluebell Hill the official prediction is for variable reception of Mux2. Another post has mentioned loss of signal on the high power transmission for Sandy Heath which uses the same frequency (C24), so it would appear likely that the high power Rowridge signal or one of the continental transmissions is currently swamping the regular service in Kent and parts of East Anglia. If you no longer have ITV1 etc in your channel list keep trying to input the Mux2 frequency manually until you are successful in finding and storing the required channels.
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a: At Pontop Pike Digital TV this week is liable to interruption for engineering work in preparation for switchover. There is also the possibility of weather related interference from out of area transmissions, however I'm not sure if there are any transmitters remaining on air on C65 that could interfere with MuxC.
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G Davies: Reception of Mux2 from Bluebell Hill, even without weather related problems is currently predicted to be poor and deteriorates to no prediction at all up to switchover. At this time Dover is predicted to give good reception, betwean 18th April and 27th June 2012 Crystal Palace is shown as good reception for MuxD3+4 on C26, then after 27th June 2012 (DSO stage 2) you should again have good reception from Bluebell Hill.
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Sunday 25 March 2012 11:16AM
tia c: If you are using the Bluebell Hill transmitter Mux2, which carries ITV1, is currently using a frequency which is more susceptible to interference from other transmitters. After switchover on 27th June 2012 it will change to the frequency currently used by analogue ITV1, with power increased to 20kW, up from the present 4kW.