All posts by jb38
Below are all of jb38's postings, with the most recent are at the bottom of the page.
rob: Thanks for the update on the situation, and although the aerials you have chosen for use are not of the type I would recommend for reception in situations such as yours, basically on the grounds that any deviations in the angle of the signal being received by a high gain aerial, generally results in the signal output levels fluctuating to a much higher degree than would be experienced from such as a Log periodic.
Of course that said, it all depends on how good the tuner in the receiver is, as some are much better than others at coping with this sort of thing based on the effectiveness (speed) of the auto-gain circuitry as well as the quality of the decoder.
However, as your aerial installation is in the loft, this makes things much easier as far as "trial and error" is concerned, insomuch that if you do experience periods of picture glitching etc, you could try temporarily (if) replacing the DMX10 with a log and see if this improves the situation, if though it doesn't, then the problem is being caused by factors outwith your control and which there is basically no cure for.
Yes, maybe you could post update once the installation is completed, making a note of the strength / quality levels received from the various multiplexes and keeping it away for future reference, likewise carrying out a further check at a later date after the season has changed purely to see if anything has altered.
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Colin Swan: If by "full service" you are meaning the range of commercial programmes, e.g: ITV3, Pick TV, Sky news etc?, then they are already being transmitted from Knockmore, but though your location is not indicated as being able to receive them due to the signal path from the transmitter suffering from multiple line-of-sight obstructions, even the BBC and ITV which is transmitted at a higher power, comes under the status of poor as far as reception is concerned.
Freesat is about the only way you will ever be able to view the full range of programmes, that is if the satellite dish can get a clear unobstructed view of a Southern facing skyline at (approximately) 152 degrees.
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Colin Swan : As an afterthought, should you be referring to the Grantown Freeview light relay of Knockmore, located @ 5.5 miles, then it (like dozens more) will not be getting upgraded, as anything other than BBC1 and ITV1 are not connected with the licence fee and as such having to be paid for purely by commercial interests, most of these interests (advertisers) having considered that the costs involved of providing and running the service would not be justified by the returns expected from areas of low population.
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Broneirion transmitter was listed as operating on reduced quality (from 07.03 - 07.47) whereby reception would only be affected if you were viewing these programmes on EPG101 & 102, however, reception should "not" have been affected if you were viewing either on normal (SD quality) EPG1 & 2.
As far as reception from the Broneirion transmitter is concerned, although you would appear to reside in a predominately tree lined area and which can be very detrimental where Freeview reception is involved, but was reception from the far more powerful Llandinam transmitter ever checked out? this station located at roughly the same distance away (or maybe a little closer) than you are from Broneirion.
By the way, the Llandinam transmitter is located at nearly 180 degrees in the opposite direction to Broneirion, the three multiplexes used by that station being BBC 41 - ITV 47 - HD 44.
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Jennifer Milborrow : During copying and pasting from another screen I accidentally cut off part of the above reply, it having started with "The HD service from the" etc, etc.
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Louise: It would be of considerable assistance if the model numbers of the Samsungs were known, but though the main thing is that "if" you still have the cable box connected into the TV via a jumper lead, completely remove it followed by switching the TV off for about 10 seconds before switching it on again and checking if anything has changed.
However, minus the model number info, have a look in the set up menu and make sure "air" then "aerial" is selected as the signal source, as I feel that it will still be set on cable thereby cutting out the Freeview tuner.
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Ian Glover: Re C46, if your aerial is facing towards the Hastings transmitter, (@ 5miles / 82 degrees) then its not surprising that you are having difficulties when trying to tune in C46, as apart from the aerial facing in the wrong direction its also mounted on the wrong polarity, transmissions from Hastings being on vertical polarity (elements up and down) whereas Bexhill (0.6 miles / 167 degrees) is horizontal.
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Ian Glover : If your aerial is vertically mounted and is facing towards the Hastings transmitter, then there was / is no logical reason for you not being able to receive any signal on C25, that is unless a glitch (albeit unreported) had occurred at Hastings last Thursday whilst work was being carried out on the National DAB radio transmitter on that day.
Its assumed that you did refrain from carrying out a retune on finding that the BBC had vanished? as all retuning achieves if the transmitter is still down is to wipe out the channels already stored in tuner, making it necessary to carry out further retunes to recover them.
The main point being, is C25 reception back to normal?
As far as C46 is concerned, although you have made reference to strength, the more important factor by far is what the quality is indicated at, because a receivers decoder will not resolve a picture on signals indicating low quality, and that is irrespective of strength! your reference to the signal being 72% and yet no channels were downloaded, being a classic example of low or no quality.
The other thing that I meant to add to my comment on aerial polarity being, that not only is your aerial on the wrong polarity for the Bexhill transmitter, but worse, that the signal is being picked up on the aerials dead spot, that is when an aerial is positioned at 90 degrees to the signal being received.
On the subject of signal checking, I am unaware as to the brand of receivers you are using, but the best way to check a signal is by going into the manual tune screen, entering the mux channel number you wish to check, but "not" followed by pressing search or scan after having entered the number, as on most equipment the strength and quality will appear nomatter how low they may be without being affected by the threshold cut off levels, this only kicking in if search or scan is pressed, threshold levels (particularly quality) being the reason why someone might see a signal being indicated and yet nothing has been stored after the scan.
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Colin Swan: What I had mentioned regarding Knockmore not being receivable at your location was based on that seen using Digital UK's postal code based reception predictor, and although information from these sources always has to taken with the proverbial pinch of salt with regards to accuracy, in your particular case the negative predictions given as far as reception from Knockmore is somewhat backed up by the terrain indicator, (not predictor) which as mentioned in my previous reply indicates multiple obstructions to the signal path from that station.
Although you mentioned as having seen a number of horizontally mounted aerials in your area appearing to point towards Knockmore, this station being on a bearing of 56 degrees whereas the Grantown relay is 68 degrees, I carried out a Google Earth rooftop tour in the Carrbridge area (starting at Packhorse Bridge) and could only find one horizontally mounted aerial, all being vertically mounted and pointing towards Grantown.
That said, it might be the case that a few choice spots for reception from the station desired is possible in your particular location, as any horizontally polarised aerial you see has to be pointing towards Knockmore as no other transmitters exist, however its really a case of just how reliable the reception is from that station, this being where it would be prudent to try and make one or two enquiries in the area where you have seen these aerials.
By the way, the aerial required to cover reception from Knockmore would have to be a wide band type, as the channels span from 23 - 60, a Log periodic type aerial used in conjunction with about a 15db (minimum) booster being an ideal choice, the SLX brand 20db variable gain boosters sold by Argos being excellent for this purpose.
Terrain indicator.
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
Reception predictor.
Coverage Checker - Detailed View
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Friday 6 February 2015 9:23PM
Austin Grant: Further to that said by Dave Lindsay, Buncranna is indicated as being covered by the Londonderry transmitter, the BBC being on C44 and ITV on C41, transmissions from Londonderry being vertically polarised, i.e the aerial elements facing up and down.