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Freeview reception has changed?
Brian Butterworth published on UK Free TV
There are a number of factors to considerFreeview is broadcast on digital multiplexes. This means that, once broken down into a stream of bits, each television channel is combined into a single transmission of 1s and 0s. This means that reception is of the multiplex first if this is lost it affects all the channels in the multiplex in the same way.
The signal strength received by the box or TV for a particular multiplex from a given transmitter determines if the data can be received or not. So, a poor signal results in no data, an adequate signal in perfect data and a low signal in either none or all.
Poor digital signal levels do not result, as they do with old-fashioned analogue television, in a sub-standard picture or sound. Poor signals often result in a perfect data-stream, but are prone to periods of no reception. Sometimes this will be for hours, but can also be several times a minute when caused by induction from fridges, freezers, central heating systems, two-stroke scooters, baby monitors and so on.
If you have lost ALL your Freeview channelsFirst disconnect the aerial lead from the Freeview box or TV set and reconnect it and then follow this reset procedure to scan for channels again. If this does not result in services being restored, check the Freeview transmitters page to see if there are any engineering problems with your local transmitter.
How to check all cables, connectors and aerialsThe RF connectors need to be in very good condition to work. There are two general types:
Factory-fitted connectors are very reliable as they cannot easily be taken apart, but they can be damaged by wear and tear. On the female-type the central section is often composed of two parts which can often be forced apart, resulting in a poor connection you can push them back together if this has happened with a pair of tweezers. On male connectors if the central pin is damaged, you will need a new cable. If there are any loose partials in the connector, remove them.
Another problem with these cables is that quite easy to sprain the connector at the back which causes little obvious external damage, but disconnects the internal connection. This happens often when a set-top box is pushed backwards into a cabinet.
Hand made cables can also suffer from similar problems to factory made ones and they are also prone to accidental damage from a cable being pulled. If such a connector is not firmly attached to the cable, the connector may need refitting.
CablesMake a visual check of the cables. There are a few basic checks:
If the cable has been slashed or cut, it will not be very effective or reliable. If such a cable is fitted externally, this can allow rainwater to enter the cable and this will reduce the signal levels.
You can easily damage an RF cable by crushing it, for example in a door. If the outside of the cable has a permanent kink in the cable or has been very tightly looped, this could be the site of damage.
AerialFor reliable and effective Freeview reception, a rooftop aerial is required. It is hard to make a visual check of such an aerial without putting yourself in potential danger.
You can make a visual check of the route between the aerial and the transmitter. Any form of obstruction will damage the digital signals. In particular trees coming into leaf, as these will leech the signal before it reaches your aerial. This applies to both trees adjacent to the aerial and at a distance.
Another common problem in cities is building work. A large crane will often change position many times during the day, and if this is between your aerial and the transmitter this can reduce the signal levels in an unpredictable way.
If your system uses a booster, the power may have failed. Check the fuse to the power to the booster.
Weather problemsThere are two main weather problems that effect Freeview reception.
The Inversion Effect: please see What is the Inversion Effect and why does it effect my Freeview TV reception?
Wind: high winds sometime can dislodge the aerial this results in a poor signal.
Rain: poor or old cables can fill with water and this results in a poor signal. If this happens, the cables will require replacement.
Help with Freeview, aerials?
Sunday, 31 December 2017
Paul Davies: Your DVD is just a player, and netflix etc are via the web, so they have no connection with your TV signal.
'Resetting Freeview' is just retuning the TV, or returninng the TV to its 'factory/initial setup' state which can be done via the menu. However, you need to discover why your TV signal is breaking up, since Mendip should give you a perfectly fine signal.
Check which transmitter the TV is tuned into, and then note signal strength - it could have locked onto a transmitter much further away. You should be able to manually tune from the setup menu, and you should look for Channel 45, etc on that to use Mendip.
If the signal is weak and your looking at the correct transmitter, check your cabling, because that a primae reason for a problem.
Use Mendip - Digital UK reckons you should get a good signal, and you'll get the full range of channels. Wenvoe seems even better, but there seems to be something on the signal path pretty close to you. Look at which way your aerial and everyone else's is pointing - which one is it?
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Friday, 9 February 2018
I wonder if you can offer advice. After months of perfect clarity, our freeview HD channels have started getting small black outs and pixelation out of the blue. This has been going on for about a month. We have a standard YouView box purchased from John Lewis. We have a very high signal (Strength 91% / Quality 100%) which I believe we get from Crystal Palace (we're near Epping). After googling the issues I purchased a variable attentuator and have tried various strengths which hasn't fixed the issue (what is optimum for a YV box?). I've swapped cables, checked connections and re-tuned with no luck. We are in a shared block so we can't access the building's aerial, but I haven't heard anything from the neighbours about anyone else having any issues. I also don't think it is 4G as the 4G signal in our area is pretty poor - unless poor 4G can affect freeview HD? I've discounted the weather as it's been going on for a while and the disruption is now constant on all the HD channels.
Does anyone know of any changes to Crystal Palace which may have affected this? Or is anyone having recent, similar issues? Or has any other possible causes? I'm loathed to do a factory reset as we'll lose all of our recordings, but I guess this would be a last resort before returning the box. After endless googling I'm kind of out of ideas so any advice or help would be great!
Thanks very much, J
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JL: We could do with a postcode, but yes, 91% on a Humax Youview PVR will cause the signal to break up.
Nothing particularly will have changed at the transmitter - its more likely that the PVR was pretty much on the threshold of being overloaded, and just a very slight rise in signal strength has pushed it over the edge. They are known to have sensitive tuners, as my collegues at Oxford Street would probably agree (our techincal support guys certainly have), and thus people do think there is something wrong with them sometimes. Actually they are just working a little too well.
Attenutaors are the way to go, but I know what you mean about variable ones - they didn't work for me either. I bought a number of these: 6dB Coax Plug Inline ATTENUATOR: Amazon.co.uk: Electronics
I bought them from that seller, and got a 3db, a 6db, 9db, etc. They can be used by themselves (just get another aerial cable so that you can put a cable from the wall, then the attentuator, and then a cable to the back of the box, so that there is no weight on any socket), but if the signal is still too high, then you can either use a more powerful one, or fit one to another, putting them in series. So if a 6 isn't enough, you can add a 3db, etc.
If you look at the page 'too much of a good thing' on this site, it will tell you the optimal signal strength, but 75% is pretty much perfect.
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Saturday, 17 March 2018
3 mux's have stopped working, LB, com 7 and com 8 and so cannot view the channels. The channels appear in the guide.
They have zero strength, not only on my Humax PVR, but on Hitachi HD ready and on a neighbours Bush HD tv.
They worked before the last re-tune on March7th.
Anyone else have this problem or know the reason please?
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Sunday, 18 March 2018
To get any meaningful response or help you need to provide a full post code so that we and others can see what transmitter you are using and what the reception conditions are like. In some areas, the change of channels used for COMs 7 & 8 require a change of aerial, but that depends on where you are.
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