All posts by KMJ, Derby
Below are all of KMJ, Derby's postings, with the most recent are at the bottom of the page.
Steve Flynn: The poor quality on some muxes is indicative of the signal either being subject to interference from another transmitter (including an RF modulator) or the signal is corrupted due to multiple reflections or partial obstructions such as trees in the signal path. The Digital UK postcode checker does not make a prediction for the Hannington COM muxes at your location and significantly shows the PSB mux on C42 as being less reliable than the other two. This makes me wonder if Heathfield signals could be present at a very low level, but sufficient to cause problems to reception from Hannington. Heathfield shares C41, C42, C44 and C47 with Hannington. If this is the case careful positioning of the aerial to find a null for the Heathfield signals will be required.
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Elaine Hitchcock: Without additional information with regard to the transmitter that you intend to receive from it is not really possible to give any information, except that I am aware that the Glossop relay transmitter in Derbyshire has been off air since 12.45 today 18th February 2013. There is no information regarding a time for restoration of service.
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Tony Putner: ITV3 is carried on the SDN mux which is only transmitted from main transmitters and a number of former relay sites which serve relatively large numbers of viewers. The reason for this is based on economics, as additionally serving all the other relays would double the transmission costs whilst only adding about 8% more viewers. The owners of the COM muxes therefore declined when invited to consider serving additional sites. Crystal Palace is your nearest main station for reception of the full six mux service.
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Roy Barton: If the problem, at least in part, is interference from Stockland Hill, it is quite likely that better results could be obtained from an aerial pointed out of the window compared with one mounted on the chimney, which although capable of receiving a stronger signal from the desired transmitter could also be subject to a stronger signal from the interfering transmitter. It is the nature of digital reception that the interference at a very low level could be ignored, but when it increases slightly to the critical level that is able to block the required signal there will suddenly be no reception. This is in contrast to analogue reception when an interfering transmission was displayed as slight patterning on the normal picture. Increases in the strength of the interference simply degraded the picture further, until in extreme cases it replaced the normal reception with the out of area signal. Your observations with the grouped aerial out performing a wideband are quite usual. In fact some of the cheaper wideband aerials appear to be a group A dipole coupled to a set of group c/d directors. Even with more scientifically constructed arrays the directors must be short enough to work at higher frequencies, making them inefficient on group A channels.
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Steve: It might be worth checking if there is any interaction with the HDMI cable and/or aerial fly lead by changing their positions relative to the Freeview+ box and the TV. Also check that the Freeview+ box has not tuned in ArqA from Midhurst on C59 rather than the correct C22+
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Roy Barton: The mention of 45 degrees polarisation reminded me that some local radio FM transmitters used to use slant polarisation in order to offer reception on both horizontal and vertical aerials. This was before FM transmissions were standardised to have horizontal and vertical components, now refered to as mixed polarisation.
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Nedbod: Freeview will migrate to DVB-T2 over time, possibly 2018 for the COM muxes if the plan for a C22/25/28 SFN is implemented that soon. It is reasonable to assume that shopping channels, for example would continue to use SD whilst in DVB-T2, likewise the popularity of the radio channels would no doubt ensure that they continue on Freeview.As for logos disappearing- no chance, even itv has one now. The problem is too many TVs and STBs do not display the channel being received on the front panel. I have always thought that this should have been a basic requirement, like manual tuning, scart sockets and RF modulators, but sadly some receivers have none of these features.
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Mr P Watmough: C38 is now allocated to special events usage, to replace C69 which has been withdrawn for 4G use.
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Liam : Further to Dave Lindsay's comment, remember that the Sky signal is analogue, so you will need to switch between analogue and DTV (assuming each TV has a built in Freeview tuner) to access both services. An analogue only TV would require the use of a Freeview box with RF loop-through facility to allow the Sky signal to be received by the TV. The Freeview box would then be connected by a scart lead for viewing when the A/V input is selected on the TV.
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Monday 11 February 2013 7:36PM
Iain Davies: There is currently no spare capacity for HD transmission on Freeview as this requires muxes to be DVB-T2. The proposed temporary muxes might accommodate some or all of the additional commercial channels mentioned, however there could still be a shortage of capacity in the event of these muxes being closed, and the existing SDN, ArqA and ArqB becoming DVB-T2.