All posts by KMJ, Derby
Below are all of KMJ, Derby's postings, with the most recent are at the bottom of the page.
Sharon Arnott: The current weather conditions are causing transmissions from other areas to travel further than normal, with the result that those signals which share frequencies with your nornal services are causing interference which shows up as a rather unhelpful "no signal" message on digital tv. This situation might last for only a few seconds, but can also be present for hours or several days in exceptional circumstances. The frequencies for the PSB muxes from Emley Moor are also used at Wenvoe and The Wrekin, Waltham shares frequencies with Mendip, while Sutton Coldfield's PSB frequencies are used by COM muxes at Bilsdale. If you leave the receiver tuned to your local frequencies reception will resume when conditions revert to normal. However if you have attempted to re-tune by scanning for channels you could have lost your normal channels if they were blocked by interference or replaced them with useless long distance alternatives. In that case you will need to re-tune when the interference subsides.
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Liam: Sandy Heath is predicted to give variable reception at your location. Waltham, at least as far as the predictor goes, appears to be far more reliable.
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P S Billingham: The problem is out of area signals travelling further than normal blocking reception of the normal service from Ridge Hill. Since Sunday (22nd September 2013) high pressure has resulted in tropospheric ducting affecting an area including West Midlands, South Wales, West country through Devon and Dorset extending across the English Channel. It is unusual for the effects to be so strong in the current locations, but normality should return by the end of the week!
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MRS J Johns: The problem regarding interuptions to reception resulting in glitching or "no signal" messages being displayed is caused by the weather conditions. High pressure over the area has created conditions whereby out of area signals are travelling further than normal. If these signals are on the same frequencies as your local service it results in reception of the local service being blocked. Reception is expected to return to normal by the end of this week.
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Maria: Whilst it might appear that this is the case, the phenomenom of tropospheric ducting is more noticeable at nightfall than during the day because it occurs when the air on the ground is cooling at a different rate to the air in the upper atmosphere. The resulting temperature inversion causes UHF TV and VHF radio signals to be defracted back to earth instead of them continuing into space upon reaching the horizon. The result is the signals are received beyond the normal coverage area, if they are on the same frequencies as used by your local transmitter it results in the local signal being corrupted, giving viewers intermittant reception or "no signal" messages. A similar situation can apply at sunrise, or in the middle of the night when fog on the ground is accompanied by clear air above but there are less people watching TV at these times, so it might go unnoticed, unlike during peak viewing time.
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MikeG: Sometimes the culprits are UK transmitters in adjacent regions! A look at the William Hepburn's Tropospheric ducting forecast charts will give some indication of which transmitters could be sending signals way beyond the normal coverage area. The Rowridge transmitter is co-channel with the Sandy Heath PSB muxes and Emley Moor is co-channel for the COM muxes.
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Merliin: Channels which on Freeview but are part of a subscription package on satellite will not become free to air via satellite because if they did they would lose subscription revenue. The minimal amount of extra viewers would not give rise to a worthwhile increase in advertising revenue.
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michael : Technical superiority is really only important to professional users and enthusiasts. Look how VHS was adpoted as the system of choice for domestic VCRs despite superior alternatives being available. Most people, it would appear are not bothered by grainy TV pictures or hiss in the background on FM radio. As long as DAB transmitters can deliver a signal that is robust enough to avoid drop-outs, (which most people would find intolerable) the majority of listeners will be happy. I suspect that the "large number of filler relays" will duly be built in order to prove that the decision to switch off FM was right and proper. The transmitters for the local muxes in Scotland and Wales will no doubt mirror those for the BBC national network - good news for fans of Capital Radio! despite the fact that coverage via DRM on medium wave, or DRM+ for four networks on a single FM frequency could have been a more efficient way of covering the area. I have doubts about 4G ever being much use as a provider of radio services in remote parts, considering how 3G is non-existant outside built up areas.
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David: The DAB transmitters at Fishpond Hill are shown as off-air since 06.31 this morning, 3rd October 2013.
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Monday 23 September 2013 7:45PM
naomi dure: The William Hepburn tropospheric ducting forecast predicts strong ducting affecting an area including South Wales, Devon, Dorset and across the English Channel. taking place from this afternoon (23rd September 2013) and into tomorrow. It is likely that during these conditions signals from out of area transmitters could cause interference to your normal reception. Mendip, for example shares frequencies with Huntshaw Cross on the COM muxes.