Freeview intermittent interference
Brian Butterworth published on UK Free TV There are several different types of interference that cause problems. This page deals with the situation where:
- Freeview reception is perfect or near-perfect most of the time
- The audio on TV and radio channels mutes momentarily a few times each minute
- The picture on a Freeview channel freezes a few times each minute
There are two main causes of this type of intermittent interference:
- 'Induction' interference
- Mobile phone interference
Induction interference
Induction interference is caused by mains-powered household devices that contain a large motor, such as:- Washing machine;
- Tumble dryer;
- Central heating pump or combination boiler;
- Fridge;
- Freezer;
- Power tools (drills, jigsaws etc)
- Vacuum cleaners;
- Water pumps;
- Automatic doors
You can identify if one or more of these devices is causing the Freeview reception problem by powering off the devices.
If one of these devices is causing the problem, then the reception problem can usually be solved by using a mains filter device and use it on the Freeview boxes mains connection.
Such as device is this: Maplin: 6-Way Flat Screen and HDTV Surge Protector and Mains Filter.
Mobile phone interference
If you keep a mobile phone by your Freeview box or digital television, keep it further away!This also applies to other transmitters such as baby monitors, video senders, walkie talkies, and portable phones.
Help with Freeview, aerials?
Thursday, 17 March 2011
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katie9:59 PM
Hi when my daughter is upstairs in her bedroom and she is using her mobile phone whether texting or phoning it interferes with all the tv's in the house. apart from throwing her mobile out the window could you please help x
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Friday, 18 March 2011
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Mike Dimmick2:43 PM
Reading
Katie: I'm assuming you're using Freeview, digital TV through an aerial, rather than satellite.
The phone does use frequencies very close to the top end of the range used for TV. You can really only check that the cabling is in good condition, and possibly have it routed differently so the cable doesn't go past her room.
If there is a distribution amplifier, it might need better screening to prevent it picking up noise, or the power supply might be failing. If you're using wall-plate sockets, they might need to be replaced with screened ones if you haven't already done this.
Finally, older aerials were often not matched properly with the cable, because it didn't matter as much with analogue. You might need to replace the aerial with one of a similar size that has a 'balun', a device that matches the aerial properly to the cable.
If you haven't replaced the aerial or cables within about the last ten years, it may be time. Aerials and cables deteriorate with weather and sun exposure and this problem could just be a sign that they're no longer getting enough signal to where it's needed.
Has your region switched over to entirely digital yet? If not, it may be worth waiting until it does. For more specific advice, we'd need your postcode to see which transmitter you'd be using and how strong a signal you should expect.
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Mike's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
Monday, 21 March 2011
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LSB13024:20 PM
Driffield
I don't know if this could be classed as an intermittent interference problem but I am only able to receive the BBC channels with my box but not the other channels. The other channels are pixelated and the box say's the signal strength is poor. My mum and dad and brother have no problems they can receive all channels. Could this problem be down to the box or the fact that I have 2 aerial cables joined together? I hope you can help.
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LSB1302's: mapL's Freeview map terrainL's terrain plot wavesL's frequency data L's Freeview Detailed Coverage
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Mike Dimmick5:56 PM
Reading
LSB1302: I believe it's most likely that your aerial is pointing to Belmont, and it's probably a 'Group A' type designed for RF channels 21-35. The first four analogue transmissions are between channel 22 and 32, so aerials installed before Channel 5 started will usually be Group A. Channel 5 is on C56. Most of the digital multiplexes are at higher frequencies, channels 48-66. You need a wideband aerial, which covers C21 to C68, to get all the channels.
At switchover, the public-service multiplexes move down into Group A, but some of the commercial channels will still be at higher frequencies, and you'll still need a wideband to get all of them.
When joining aerial cables, you should always use a proper coaxial cable connector. You can't just twist the conductors together. If you're trying to feed two TVs from one aerial you should use a proper splitter rather than connecting the two cables directly to the aerial.
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Mike's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
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Mike7:47 PM
Hi Can you pease help me with digital reception in York.I assume i get my signal from Emily moor transmitter.Digi bow is quite new and has been working fine until the past few days.Now most channels nice and sharp but BBC channels break up or freeze with a noisy click. Will it be interference from weather and will it improve after switch over.Dont really want to buy another box or new tv before its sorted.Thamls very much. Mike
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katie10:58 PM
Hi mike, thanxs for all thatv advice. I am in Lincolnshire and postcode is pe22, if that helps x x
katie
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Thomas11:19 PM
Bradford
Be aware that the weather can affect Freeview reception worse than analog. If it's windy, and you have a rooftop aerial, you may get intermittent picture freezes or pixellation as it blows around.
Also if it has been very fine and dry recently, you may get signals from other transmitters reflecting off the ionosphere; ones that are normally out of range. This can cause co-channel interference and loss of your Freeview service.
You may need a new plug putting on the end of the antenna cable that plugs into your Freeview box. Move the cable around while it's still plugged in and see if heavy picture distortions occur when moving it. If so, the cable is probably broken inside and will need a new plug fitting.
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Thomas's: mapT's Freeview map terrainT's terrain plot wavesT's frequency data T's Freeview Detailed Coverage
Tuesday, 22 March 2011
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Mike Chandler9:31 AM
Gosport
I have just sent this question to Glomex and the UK distributor for these aerials about an ongoing saga with reception on a boat and wonder if you have any ideas.
Just a quick follow-up on this, the signal breakup occurs only on the channels which use 64QAM all the 16QAM channels work fine, any ideas?
Regards
Mike Chandler
We have consistently had a problem with TV reception on a catamaran using first the v9125 and subsequently the V9112, in both cases we are using your aerial cable and the supplied line amplifier, we have tried different cable and amp and aerial location. Both units do not seem to be omnidirectional but vary between good signal to no signal when swinging at anchor and we have almost given up trying to remedy this but recently we installed a new TV which tested and works fine on a standard terrestrial aerial but when installed on the boat there are continual signal breakups on most channels except BBC although I have not done an extensive test. The new TV has a menu item that displays signal quality as well as strength and I have noted that where we have breakup the signal quality is low and variable although the signal strength is consistently high(90%+), currently the boat is in Gosport using I suspect the Rowridge transmitter the aerial is mounted on a mast about 6 metres above the waterline, I am reluctant to fix this unit to the masthead in an attempt to resolve this problem bearing in mind these problems. Varying the amplifier gives no change to the signal strength until about 2 circles from the stop when it cuts out with no signal and bypassing the amplifier seems to have no effect.
Please can you help with this, either Glomex or Marathon?
Regards
Mike Chandler
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Mike's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
Hi Mike,
I cant see this type of aerial being of any use at anywhere other than a strong signal area, using a inline amp even (a low noise one) will add noise making the signal to noise ratio worse, I cant see how this aerial has any signifcant gain due to its design. The only advantage this has over a indoor aerial is that it is outside.
A better & cheaper alternative would be the televes digi nova aerial which when powered (by a psu)has its amp built into the aerial which better maintains the signal to noise ratio, It also has the benefit of being made by a well known & respected manufacturer with apropriate back up.
Mark Aberfan Aerials
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Mike Dimmick4:18 PM
Reading
katie: We really need a full postcode to give complete detail in most cases, but Lincolnshire is pretty flat so it's quite likely that you're using the Belmont main transmitter. Alternatively, you could be using the Waltham main transmitter, though this is less likely. Do you get Look North from the BBC and Calendar from ITV, or BBC East Midlands Today and ITV Central Tonight?
Looking at the frequencies, it's much more likely to be Belmont, as that uses high frequencies for most of the digital multiplexes - up to C68 for Mux A, which is right next to the mobile phone frequencies.
Belmont switches over at the beginning of August this year, and Waltham at the end. You could just see how well it works once switchover is complete - some channels will be moving to lower frequencies, and all will increase in power substantially.
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Mike's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
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