All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Jason: The answer probably has more to do with the way in which things work these days. Channels 21 to 37 were ringfenced at switchover to be "sold" to three licencees for them to create their own network.
If there were plans for them to use particular channels at particular transmitters than this would be in effect telling them what transmitters they had to use.
The ringfencing of 31 to 37 is complete nonsense that has resulted in some areas have clashing channels as well as others with out of group channels when they otherwise wouldn't have been.
I agree that from a practical engineering point of view that channels within group should have been allocated where possible, but that isn't the way things are done these days.
A "free market" approach must be taken which means sacrifices. In a free market, providers have choices as to where they serve and consumers have the choice whether to consume. If it means that the latter have to fork out for a new aerial, then so be it.
| link to this comment |
Mark: There is an issue with Goodmans GDB3 models whereby they will not receive post-switchover signals that have a negative offset on their UHF channel number. This is the subject of a Digital UK bulletin:
http://www.digitaluk.co.u….pdf
Post-switchover, one out of six of Crystal Palace's multiplexes have a negative offset and it is the one which carries ITV4, Film 4, Yesterday and others.
It is on UHF channel 28-, thus it has a negative offset. UHF channel 28 is at a frequency of 530.0MHz whereas 28- is a little bit lower, it being at 529.8MHz. The negative offset therefore means that it is a frequency slightly lower than the "centre" of the channel, but above a positive offset of the channel below.
There are some unofficial firmware upgrades for some Vestel boxes (of which this is one) and I'm not sure if one may be suitable for the GDB3. The process requires connection of the box to a computer via a RS232 (serial) connection. This may fix the problem, but if you do it, then you take the chance that it might never work again.
| link to this comment |
Mark: Put something like goodmands gdb3 firmware or vestel gdb3 firmware into Google.
I read that the firmware for GDB2 is NOT compatible with GDB3 and vice versa.
As I say, upgrade at your own risk.
| link to this comment |
Linda Dale: You asked a similar question the week before last which got two responses:
Will there ever be more services on the Freeview Light transmitters? | ukfree.tv - 10 years of independent, free digital TV advice
| link to this comment |
Bob: I think that it is doubtful. Your best bet is probably to focus on reception from Darvel.
** After writing the text below, I looked at Ofcom's multiplex licences document and each of Darvel's COMs have a note by them saying that they are using the reserve antenna until 24th October 2012, which is when Northern Ireland switches to digital. This will be to protect against interference there and suggests that reception of Darvel COMs may improve on that date. **
-----
The Digital UK predictor suggests that reception of the PSBs from Rosneath are "good", but it is all "poor" for the COMs. Also, Rosneath uses Group C/D channels whereas Darvel's are all Group A. This is likely to require a different aerial (see below).
The Commercial multiplexes (COM) don't have as good a coverage as the Public Service Broadcaster (PSB) ones. C29 from Darvel is COM6 (or "ArqB") multiplex.
This difference in coverage is due to the small relay transmitters such as Milburn Muir not carrying the COMs, and due to some which do radiating them at lower powers than their PSBs.
The COMs from Darvel and Rosneath are at half the transmission power of respective PSBs. So this probably accounts for the marked difference of Rosneath PSBs vs COMs in the prediction by Digital UK. This doesn't mean that you will definately not pick them up, but as a gauge of "likelihood of success" would tend to suggest that it is unlikely.
The difficulty with reception from Rosneath is due to the high ground somewhere in the area of High Milndovan.
As I say, Darvel uses exclusively channels within Group A and Rosneath uses only Group C/D ones. Wideband yagi aerials are a compromise. There is a sacrifice of gain on individual channels for the benefit of being more sensitive over the whole band. For this reason, it is best to use a Group aerial for the respective transmitter. This is particularly so for Darvel as the gain of yagi aerials is lower at lower channels. So a wideband yagi has less gain on Group A channels. Manufacturers tend to quote gain figures on channels where their products are most sensitive, which is likely to be channels above Group A.
For an explanation of Groups, see:
Aerials, TV Aerial and Digital Aerial
Then refer to this page for some example gain curves:
Gain (curves), Again
If you look at the curves in the bottom-most graph on that page (Wideband curves), you will see that sensitivity of wideband yagis is lower on Group A channels.
| link to this comment |
Noel White: The Rowridge transmitter has been broadcasting all six multiplexes horizontally and vertically since 18th April. However, whilst PSBs are at 200kW horizontally and vertically, the COMs are 50kW horizontally and 200kW vertically.
If your aerial is still horizontal, then it might be that the higher power PSB signals are acting to make your receivers less sensitive to the (relatively) lower power COMs.
| link to this comment |
Mike: Unfortunately the likely answer is "never".
The Bampton transmitter only carries Public Service Broadcaster (PSB) multiplexes, just like 1,000 or so similar small relay transmitters. The Commercial (COM) multiplex operators achieve a coverage of 90% of the population from 81 of the largest transmitters (largest by viewer population).
For them to transmit from the relays would roughly double their cost of transmission whilst only adding 8.5% of the population to their potential viewer bases. As they operate for profit and have no "Public Service" obligation, they opted not to invest in the relays.
| link to this comment |
Mike O'H: I don't believe so. Perhaps there is something that is reflecting (more) signal to your location and which wasn't present before.
| link to this comment |
Sunday 15 July 2012 5:46PM
Mark: A more accurate location would be useful, or at least knowledge of which transmitter you are receiving from.
If you are receiving from any of the small relay transmitters such as World's End, then it doesn't broadcast the Commercial multiplexes which carry ITV4 and others.
There are three Commercial multiplexes; each being a single signal that carries multiple services.
Do you get ITV3 and Pick TV? These are each carried on the other two Commercial multiplexes.
If you have your aerial directed to Crystal Palace, then what is the make and model of your receiver? There is a known issue with some that means that the multiplex that carries ITV4 will not be able to be received from Crystal Palace.