All posts by KMJ, Derby
Below are all of KMJ, Derby's postings, with the most recent are at the bottom of the page.
John Crabb: If your HDD recorder is fitted with an RF modulator it will be necessary to change the output frequency to one that does not cause interference. Alternatively an HDMI lead, if one is in use, or even an aerial fly lead might need to be re-routed in relation to the recorder or TV if interaction between them and a tuner is causing the problem. As you rightly say single frequency interference is usually the first thing to check for, along with faulty cables or connectors. If one frequency is abnormally weak compared to the others it is sometimes necessary to reposition the aerial slightly to move it out of a null for the troublesome frequency. It does appear though that an unusually large number of people are experiencing problems over what was expected to be a straight forward change of frequency. This does therefore raise the question over whether there is a problem on C49 (and C48) with the signal being unintentionally weaker than the others.No doubt Arqiva will check that in due course. There is of course the additional problems of communal aerials that have never had to receive C49 before, so lack the necessary channel filter and a larger than usual percentage of viewers who are equipped to receive from two transmitters, who might now find that BBCA on C49 from Mendip is now out of range for the filter on the Mendip aerial, requiring a change of diplexer to restore reception of all services.
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Julian Parker: This will happen in the Bristol Channel area because the Wenvoe transmitter (BBC Wales) uses lower frequencies than the Mendip transmitter (BBC West), this results in the scan finding Wenvoe channels first, which are duly entered into the channel list, then when Mendip channels are found any which carry a variation will be placed at the end of the channel list - usually in the 800s, as the LCN (normal) positions are already occupied. If the Mendip signal is stronger than the Wenvoe signal some tuners will overwrite Wenvoe channels with identical content to store the transmitter with the strongest signal, which sometimes results in an assortment of channels from each of the available transmitters. The direction that her aerial is pointing will usually determine which transmitter offers the strongest signal, but in the first instance channels on lower frequencies are always scanned first.
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Michael Perry: If the suggested plan is implemented all UHF TV transmitters will be either group A or group K, Mendip being the latter if C40/43/46 is adopted for the PSB muxes. Wideband aerials, especially those in use on transmitters that use vertical polarisation might also need replacing as one of the measures to reduce reception of unwanted 4G (or 5G) signals.
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Michael Perry: The odd thing about the reception problems which are mainly in the Taunton direction is the number of cases that report poor reception currently on C48 which did not give problems prior to C49 being adopted for BBCA. Makes one wonder if just maybe there is a problem with the radiation towards the southwest. Among the countless thousands of viewers who have no problems there could still be a significant difference between the strengths of the signals being received. I agree with the other points you make, additionally viewers who have interference on C49 might have always had it but of course not noticed it. Equipment that has the RF modulator set to C49/50 and radiation from poor quality HDMI cables could be factors for some viewers.
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Darrell : What re-tune was that? The Winter Hill transmitter group re-tunes on 10th April 2013. If you have re-tuned recently, and also when you do so on future occasions it is important to check that the receiver has stored channels on the correct frequencies for the direction in which the aerial is pointing. In your location Winter Hill and The Wrekin are almost 180 degrees apart, so it is likely that an aerial set for Winter Hill will also pick up signals from The Wrekin, and as these are on lower frequencies and therefore found first in the scan, could well have been stored in error.
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Nicola Baker: Do the receivers in question have a facility to automatically re-tune, either at regular intervals or when a re-tune prompt is detected? If so, as Hannington uses lower frequencies than Oxford its muxes are found first during the scan. Consequently these muxes will be stored and the EPG slots filled. What happens when the scan reaches the Oxford frequencies depends on the design of the box. Mux BBCA, for example, will be detected as carrying a different region to BBCA from Hannington, so either BBC1 Oxford alone, or all the channels in the Oxford mux will be stored in the 800s. An identical mux, such as SDN will often either be ignored as a duplicate, or because the signal strength or quality is better than the Hannington version already stored, will then be stored instead of the Hannington version in the normal positions in the channel list. You could well find the COM muxes are quite randomly chosen from either Oxford or Hannington after each retune! Some boxes offer an option to turn off the automatic re-tuning facility.
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square eyes: If your tuner has a channel delete option you will need to delete all the channels for Mux BBCA and Mux ArqA from the channel list, then manual tune to C49 and C50 if possible or scan for channels. Otherwise it will be necessary to carry out a "factory reset" or "return to shipping conditions" or "first time installation". This will delete all information stored, including returning any adjustments you may have made to default settings. Then re-tune.
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Martin: Random channel numbers in the channel list on some receivers points to the LCN ordering option in the menu needing to be set to "enabled" If you have channels in the correct places with EPG info randomly absent and/or channels in the 800s this indicates reception from two or more transmitter sites. Usually receivers need to have the full set of channels from the same region stored to enable the channel list to populate correctly although there are a few recognised overlaps where the EPG information will work correctly for the additional services.
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Palmer: MuxBBCA changed frequency to C50 and ArqA to C49, so receivers still tuned to the old frequencies will have lost reception of standard def BBC channels and Sky News etc.You will need to re-tune to the new frequencies to restore reception of these channels.If your tuner does not automatically replace the channel list as it scans you will need to delete the old information first, either by using a channel delete facility if available, or by doing a factory re-set, after which re-tuning should store all channels on the correct frequencies. If there is a problem with channels from Yorkshire or Wales being stored instead of the required Winter Hill channels, it will be necessary to do a manual tune on each of the Winter Hill frequencies after first clearing the channel list.
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Sunday 31 March 2013 10:52PM
Richard Tonkin: The diplexer possibly allows C53 to C69 to pass at full strength from the Mendip aerial and C21 to C51 from the Wenvoe aerial. This would result in the Wenvoe aerial receiving C49, possibly badly due to its orientation added to any leakage of the signal on the Mendip aerial depending on how efficient the diplexer is at blocking frequencies out of its intended range. At this stage, due to the large number of viewers who are having problems with reception of C49, it is not possible to say whether the Mendip signal itself is also suspect.