All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
P Thomson: Blackburn is vertically polarised whereas Belmont is horizontal, so a horizontal aerial should act to "reject" any unwanted signals to a degree.
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Debbie: Too much signal into your receiver could be a possibility. See here:
Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice
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Tom,Horsham: Not receiving C50 does not necessarily contradict KMJ,Derby as he did not say that you would be able to receive. It is, according to information from the powers that be, a fact that C50 is now up to its full final power of 10kW.
Before switchover, Midhurst's lowest channel was 55. I therefore wonder if your aerial system has a filter in place that is preventing C50 from going through it from the Midhurst aerial.
Below 55, there is only C50, so perhaps there is a filter that cuts off signals somewhere between the two.
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John: Excessive strength of signals coming down aerial leads can be a problem, particularly after switchover.
It is generally expected that where Freeview was available before switchover, that afterwards a full service will be available. In some cases there are exceptions.
At some transmitters, these services are on low power for a period after switchover and this is usually to protect against interference to viewers of other transmitters that haven't switched.
Another thing is that some receivers don't work or don't work in part after switchover, due to various issues.
When the engineer adjusted the amplifier underneath the aerial, did he make any mention of why it is you might not be receiving the missing channels?
As far as satellite services goes, Freesat is available. You can have a Sky+ box without subscription, but you will not be able to use the recording facilities. I understand that you must pay Sky £10 per month for the privilege.
See here for a comparison:
Compare Freeview and Freesat TV | ukfree.tv - independent free digital TV advice
ITV3 is on Freesat; ignore the icon that says that it isn't.
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John: Perhaps with knowledge of your location and maybe transmitter, as well as the make and model of your receiver, we may be able to shed some light on why it may be that you aren't picking up some channels.
If you would like some help, for each of the following, please indicate whether you have it or not: BBC One, ITV1 (or STV if you are in parts of Scotland), ITV3, Pick TV, Yesterday.
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Andrew: The power of the COMs from Midhurst will not increase in power.
I fear that your problem isn't so much low power signal from Midhurst, but the Steyning relay transmitter which is on King's Barn Lane adjacent to Broadfield Stables.
The transmitter doesn't broadcast its signal omnidirectionally. Whilst the powers that be won't release the radiation pattern under FOI, examination of photographs of the transmit antennas on the mast leads me to believe that it beams its signal in your general direction, as well as that of Steyning. (The radiation pattern is the plot of how much signal it throws out in each direction.) Whilst it is vertically polarised, at such close proximity it's probably not surprising that a horizontal aerial picks it up to a degree.
Steyning transmitter broadcasts only the Public Service (PSB) channels (i.e. it doesn't carry the COMs you're having difficulty with). But the three channels that it uses are the same as those used by Midhurst for its COMs. A similar situation exists in Horndean and in some other cases elsewhere that are near to low power relays like Steyning. This is obviously one of the reasons that Midhurst's COMs are restricted in power with respect to the PSBs.
In October of this year the three channels used by Steyning will change and one of Midhurst's COMs will do as well. At this time some of Midhurst's services will cease being co-channel with Steyning's.
I see that there are quite a few aerials on your road that appear to be on Crystal Palace. This may give you the Commercial channels.
I sympathise that you may have a decision to make; to do nothing now and wait until October or spend money making changes to your aerial(s) so as to receive the COMs from another transmitter until October.
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Christopher: You really need a professional installer to answer the question.
However, I will make some observations:
- The three storey block on the opposite side may be an issue.
- This plot shows that you're at the bottom of a drop which is blocking your line of sight of Wenvoe (as well as other terrain that is in the way):
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
If any booster/amplifier is to aid your reception of the Commercial channels from Wenvoe, then it needs professionally fitting on the roof.
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chunkylover57: The channels you do not get are the Commercial ones and the broadcasters have decided not to bother with the Porth transmitter and over 1,000 similar small "filler-in" relays nationwide. They operate on a profit driven basis and cover 90% of the population from 81 of the largest transmitter sites (largest by viewer population). To transmit from the 1,000 plus relays would roughly double their cost of transmission whilst only adding 8.5% of the population to their potential viewer base.
For a more in-depth explanation, see here:
Will there ever be more services on the Freeview Light transmitters? | ukfree.tv - independent free digital TV advice
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Dinna: The answer may be to switch the aerial from horizontal to vertical, as shown in this picture: http://bit.ly/IKM4PE
Prior to switchover, Rowridge transmitted only horizontally, hence your aerial is horizontal. However, after switchover it broadcasts horizontally and vertically.
The Public Service channels, which are BBC, ITV1, Channel 4, Channel 5 and some others, are equally as strong horizontally and vertically and the signals are as powerful as the former analogue and so can cover the same area.
However, the Commercial channels (ITV3, Pick TV, Yesterday, Film 4, Dave etc) are as strong as the Public Service channels vertically only. Consequently your horizontal aerial may not be picking up sufficient signal on one or more of the Commercial channels.
If you have a signal booster that you can remove easily, then try removing it and try again.
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Monday 30 April 2012 11:23AM
P Thomson: It is only 2W to its north west!
I'm not sure whether that might have an affect at 1.4 miles off-beam of the main signal. Just a thought anyway.