All posts by Thomas
Below are all of Thomas's postings, with the most recent are at the bottom of the page.
T
What is the Inversion Effect and why does it effect my FreeviewThursday 4 August 2011 11:38PM
Leeds
When Belmont started DSO, I suddenly got the high-power digital signals here in Leeds even though my aerial is pointed at Emley Moor. The weather then took a turn for the worse, and I can no longer pick up Belmont's transmissions. This is probably due to the Inversion Effect no longer reflecting the signals from Belmont.
If your TV keeps prompting you that new channels are available, the best thing to do is disable this warning and do a manual add if possible.
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Since Belmont and Sheffield started DSO stage 1, my analogue reception from Emley Moor has become very poor. On all channels, there is a significant ghost image (not always the same channel) being picked up as well, as if one of the other transmitters is outputting on the same frequencies as Emley's analogue.
Obviously with analogue being turned off next month it's not much of an issue (digital reception has been slightly worse as well but usually ok). It's just a LOT easier to spot problems such as ghosting, pre-echo and co-channel interference on analogue rather than digital.
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On the first day of Belmont's DSO Stage 1, I was getting a its high power BBCA Mux here in Leeds (even though my aerial is pointed at Emley Moor). From the next day, however, I could no longer receive Belmont's transmissions, even now that DSO Stage 2 has completed.
Have they altered the radiation pattern so that it no longer spills into West Yorkshire? Or was I just 'lucky' on that day to pick up Belmont?
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Our aerial system currently has a combined masthead amplifier & splitter, sending the signal to four separate leads.
I know that after switchover the digital transmission power will be raised. Do you think the masthead amplifier will still be beneficial after this? Might I get too much signal from it?
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Mark, if you live only 1 mile from the transmitter and can actually SEE it, you should not need an amplifier at all. A non-powered splitter should do the job. You may be getting too MUCH signal, which can cause problems similar to too little signal.
If you can't change the amplifier/splitter, you may need to install an attenuator to reduce the signal level.
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Not sure if this is the right place to ask, but why are different frequencies more sensitive to the wind blowing the aerial around? Analogue BBC1 and Channel 4 hold up well even when there's wind. ITV1 has variable ghosting in the wind, and BBC2 is the worst - i get a complete loss of picture even with light wind!
After switchover, when the muxes move to the old analogue frequencies, maybe they will also suffer from dropouts? SDN, which gets BBC2's old frequency, might be the worst affected for me...
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For most of the afternoon, BBC1 analogue kept flickering (like a loose connector) and occasionally flipping to a different feed that was 4:3 instead of 16:9, and slightly delayed relative to the 'normal' feed. It happened several times during Total Wipeout.
The flickers could have been caused by my aerial or connectors, but that would NOT cause it to flip to a delayed feed! It's almost as if the Emergency Rebroadcaster kept activating for some reason perhaps they're preparing to switch the transmitter to digital?
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Briantist: Sorry, what I meant was that every so often, it looked like BBC1 was losing its analogue feed and rebroadcasting from another transmitter (perhaps a standby Freeview box tuned to Belmont). This would explain the delay, and also the 4:3 instead of 14:9 picture; Freeview boxes by default are set to pan and scan.
I made a video of it, but I'm reluctant to post on Youtube because of copyright concerns...
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Emma: If the landlord won't move the aerial, there's not much you can do. You could try using an indoor aerial, but that may not give you a good enough signal for Freeview. Could the landlord put a dish on the house so you could get Sky/Freesat? Is cable an option? If all else fails you might be able to get TV through broadband internet.
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Wednesday 3 August 2011 8:19AM
Leeds
DSO is underway in the Belmont region, and I'm receiving some extra channels from the new BBCA Mux it's broadcasting. Don't be surprised if your box or TV says 'new channels found' as it's probably the Belmont signals leaking into your aerial.