menuMENU    UK Free TV logo Maps

 

 

Click to see updates

Current Freeview changes make it a little less reliable

Over the next three years, Freeview is shuffling the frequencies it uses to make room for more mobile broadband. Will this mean risking missing a few TV shows?

Please do not blame Freeview.   They are pumping out all the usual signals if this happens to you.      Photograph: UK Free TV
Please do not blame Freeview. They are pumping out all the usual signals if this happens to you. Photograph: UK Free TV
published on UK Free TV

Freeview is reliable

If you enjoy watching TV using Freeview, this means that there is a wire going from the back of your TV set to an aerial on the roof of your home, flat or office.    In the air. the Freeview TV signals travel in straight lines, like light, so the aerial needs to be able to “see” the top of a Freeview transmitter tower. 

From the top of one of these towers is mounted a cylinder that is covered in transmission panels.   This allows the Freeview signals to be sent out in a controlled pattern, for several reasons:

  • It is wasteful to send the signals out into space;
  • It is unhelpful to send signals over a country borders;
  • It is unnecessary to send signals into mountains where no-one can get them;
  • To limit the possibility of interference in a very flat area;
  • Sometimes to synchronise a signal in a single frequency network area.

 

Tropospheric Ducting

It is quite reasonable to think that all the above conditions would remain constant over time.

It was discovered that all TV signals sent horizontally do not always just zoom off into space.   From time to time, changes to air pressure cause “Inversion” and the signals can reflect down as if there were a mirror at cloud level.  Sometimes the signals can be found 800 miles beyond their expected locations.

 

The way the digital TV signals are encoded incorporates ways to reject these unplanned, unexpected interference.    There is a limit to what can be done in all instances.

Whilst it is possible to predict where the “mirrors” can occur in the atmosphere – see http://www.dxinfocentre.com/tropo_nwe.html - the loss of Freeview channels from your box can then depend upon:

  • The Freeview multiplex you are watching (the ones in DVB-T2 mode are safer);
  • The direction your aerial points because which TV transmitters are in a line projecting from your roof to your normal transmitter AND which transmitters are in line 180 degrees from the above one;
  • If your aerial system has an amplifier (that might get overloaded and stop working);

This means that moving a few streets away can make the difference between no Freeview at these times and normal service during a time of Tropospheric Ducting.

People who watch satellite TV can have a similar, random problem caused by heavy rain and snowfall. 

Generally, these Tropospheric Ducting events happen in the UK about the times the clocks go forward and go back, and sometimes when there is a very still, cold winter. 

 

Why the 700MHz changes might be an extra problem

 In simple terms the 700MHz changes will reduce the number of transmission frequencies for Freeview from 40 (C21 to C37, C39 to C48) to just 30 (C21 to C48, C55 and C56).  This is being done in a way that keeps all the channels you can watch.

It does mean, however, that during those times of random Tropospheric Ducting it will be slightly more likely that an interfering signal might occur at any given location.

 

Do not adjust your set

So, please don’t blame Freeview.   They are pumping out all the usual signals if this happens to you.    

If it does happen, please don’t retune your equipment.    It is unlikely that the problem will continue for more than a few hours at the most, and you will most likely be able to watch most other Freeview channels.

 

Do we need an “Inversion Effect” predictor?

Would it be useful to develop a tool to work out how bad a potential Tropospheric Ducting event might be for a given location? 

 

See also https://ukfree.tv/article/1107052352/What_is_the_Inversion_Effect_and_why_does_it_effec



All questions
Would I be able to Get Sky Freeview on Kos? If Yes what size dish would I need?1
Is there any way i can use my Sky service in Pakistan?2
I use a UK sky card to receive Uk TV in Australia?3
Can I buy a free to view card for 4 and 5 to watch via my Nokia satellite box in4
Can i use my freeview box in Stavanger Norway and what channels will i be able t5
In this section
Will I need a filter when the 5G mobile broadband services start in 2020?1

Comments
Wednesday, 21 March 2018
R
Roger
10:23 AM
Maidenhead

I am now having to purchase a Wideband aerial to receive the new frequencies (UHF channels 55 & 56) from Crystal Palace as my existing aerial is Group A only. Does anyone know if you can claim back from Digital UK the cost of replacing the aerial?

link to this comment
Roger's 3 posts GB
S
StevensOnln1
sentiment_very_satisfiedPlatinum

10:51 AM

Roger: You can't reclaim any costs that you've paid yourself, however you may be eligible for a free replacement wideband aerial if you don't have satellite or cable (this is arranged via the Freeview Advice Line - see link below).

Important changes to Freeview TV signals | Freeview

link to this comment
StevensOnln1's 2,678 posts GB
Thursday, 22 March 2018
G
Gary
9:49 PM

Hi there I have had to rescan my channels as they had all disappeared and my Samsung tv prompted me to rescan but now all my channels are unwatchable NOt happy can any one help as I am now going to have to get sky instead . Ps all channels were perfect before up date to rescan thanks Gary

link to this comment
Gary's 1 post GB
Gary's: mapG's Freeview map terrainG's terrain plot wavesG's frequency data wifiG's R&TI Service businessG's digitaluk trade radioG's DAB coverage
S
StevensOnln1
sentiment_very_satisfiedPlatinum

11:55 PM

Gary: Why would you have to get Sky if your Freeview has stopped working when none of the channels on Freeview require a subscription to watch on satellite? You are predicted to get a good signal from either Reigate or Crystal Palace, however you are also predicted to get weaker signals from various other transmitters so it may be that your TV has tuned to another transmitter in error. Try unplugging the aerial, then retune your TV to clear all the stored channels, the reconnect the aerial and retune again. If that doesn't restore your channels, please let us know which direction your aerial is pointing and whether it is mounted horizontally (with the little rods going side to side) or vertically (with the little rods going up and down).

link to this comment
StevensOnln1's 2,678 posts GB
Saturday, 24 March 2018
P
Psohlavec
10:31 AM

Why didn't Freeview make more of an effort to announce the shift to 700Mhz frequencies in London? Whilst a routine retune is no problem, it is not very customer-friendly for people to discover, on the day, that they need to change their Group A aerial to a wideband aerial if they want to retain certain channels like BBC News 24 HD on Channel 107. Surely leaflets could have been mailed to houses. Also, whilst Freeview will in some cases have a new aerial fitted free of charge, many people do not want someone clip-clopping around their property and would rather do the job themselves!

link to this comment
Psohlavec's 6 posts GB
Thursday, 29 March 2018
A
Algynon
9:17 PM

Psohlavec: I agree entirely with you and I don't like the sound of the .

The changeover has been a shambles, there's been no advanced warnings as in the case of previous re-tuning alerts but this time it's not a simple case of re-tuning either. My current (Group A) aerial can't get a signal from UHF 56 mux at all. BBC Four HD (TV Ch 106) and some other HD channels are on the COM8 multiplex which has moved to UHF channel 56 from 21st March onwards.

I complained to Freeview who offered to send an engineer to instal a wideband aerial free of charge but refused to reimburse me if I bought and fitted my own. They've been inundated with calls and the soonest they could send an engineer to me is in two weeks time (April 11th) so I'm going to do it myself anyway.

The more people who complain the better; I've also complained directly to matt.hancock.mp@parliament.uk; Head of the Department of Digital, Culture, Media and Sport, the department ultimately responsible for this badly handled and inept 700Mhz clearance policy.



link to this comment
Algynon's 2 posts GB
A
Algynon
9:21 PM

Psohlavec: I agree entirely with you.

The changeover has been a shambles, there's been no advanced warnings as in the case of previous re-tuning alerts but this time it's not a simple case of re-tuning either. My current (Group A) aerial can't get a signal from UHF 56 at all. BBC Four HD (Ch 106) and some other HD channels are on the COM8 multiplex which has moved to UHF channel 56 from 21st March onwards.

I complained to Freeview who offered to send an engineer to instal a wideband aerial free of charge but refused to reimburse me if I bought and fitted my own. They've been inundated with calls and the soonest they could send an engineer to me is in two weeks time (April 11th) so I'm going to do it myself anyway.

The more people who complain the better; I've also complained directly to matt.hancock.mp@parliament.uk; Head of the Department of Digital, Culture, Media and Sport, the department ultimately responsible for this badly handled and inept 700Mhz clearance policy.

link to this comment
Algynon's 2 posts GB
Thursday, 5 April 2018
G
Gordon Hayes
5:52 PM

Even with a mast head amplifier I am still unable to access BBC 4HD though the other BBc channels show signal strength at 100%. So what is the reason or solution

link to this comment
Gordon Hayes's 2 posts GB
S
StevensOnln1
sentiment_very_satisfiedPlatinum

7:14 PM

Gordon Hayes: As per my reply to your post a few days ago, we need a full postcode.

link to this comment
StevensOnln1's 2,678 posts GB
Friday, 6 April 2018
P
Psohlavec
10:21 AM

Gordon Hayes: If your aerial is a band A aerial it will not provide a signal for the new frequencies in the 700Mhz band and the channels 55 & 56, which Crystal Palace now uses for some of the channels, including BBC News 24 HD. An amplifier will only turn a small poor quality signal into a large poor quality signal. Get a wideband aerial, but preferable a band T aerial, so that it is less likely to pick up interference from mobile phone networks. If the aerial is on the roof it is difficult to get to as a DIY job. Luckily I was able to change my group A aerial as it was on a 6 foot off-set pole mounted just below the guttering. If you have a weak (good quality) signal the amplifier will help.

link to this comment
Psohlavec's 6 posts GB
Select more comments
Page 4

Your comment please
Please post a question, answer or commentUK Free TV is here to help people. If you are rude or disrespectful all of your posts will be deleted and you will be banned.







Privacy policy: UK Free Privacy policy.