From time to time people find that theirFreeview box, integrated set (idTV) orPersonal Video Recorder (PVR) has lost many channels without any apparent changes.
There are a number of factors to consider
Freeview is broadcast ondigital 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 thatreception is of themultiplex first if this is lost it affects all the channels in the multiplex in the same way.
Thesignal strength received bythe box or TV for a particular multiplex from a giventransmitter 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-fashionedanalogue 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 channels
First disconnect theaerial lead from the Freeview box or TV set and reconnect it and then followthis reset procedure toscan for channels again. If this does not result inservices being restored, check theFreeview transmitters page to see if there are anyengineering problems with your local transmitter.
How to check all cables, connectors and aerials
The 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 newcable. 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.
Cables
Make 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.
Aerial
For reliable and effective Freeview reception, arooftop 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 abooster, thepower may have failed. Check the fuse to the power to thebooster.
Weather problems
There are two main weather problems that effect Freeview reception.
This indicates whichmultiplex (mux) each is carried on. The six main multiplexes are:
PSB1 = BBC A (BBCstandard definition TV and BBC radio) PSB2 = D3&4 (ITV1,Channel 4,Channel 5 and others) PSB3 = BBC B (all HD channels) COM4 = SDN COM5 = Arq A COM6 = Arq B
How is COM4reception? Is thequality down on this channel? What about the three PSB channels?
I have a Panasonic HDD Recorder and LG TV both nearly 10 years old to receive myFreeviewSignal via an externalAerial using theRowridgeTransmitter. Thereception has been perfect and on Friday the Panasonic recorded a BBC1 HD programme , but come Saturday 21st September the HDchannels BBcB had disappeared from both EPGs . I have not altered the wiring and have rescanned twice now . Any help please.
AJ Southam: There is currently plannedengineering work taking place atRowridge. Rescanning causes most TVs to delete their existingchannel list before scanning again and listing thechannels that are found at the time of thescan (some TVs do this automatically overnight), so any channels which aren't found won't be listed. Check for any loose cables or connections then rescan again periodically and the missing channels aren't being affected by engineering work.
If you continue to have problems, post back with the details of theSignal Strength andQuality % figures for eachmultiplex's UHFchannel as found in your LG TV's Tuning Section under SignalTest. A full postcode would also help as we can then check predictedreception and check for possibleinterference from new/upgraded mobile phone masts. Are theaerial rods (or squashed Xs) horizontal or vertical?
Hi I would like some help I have lost somechannels,D3+4 and SDN, for over aweek, I have got 2 tvs and abooster for the airal. The tvs are a LG and BUSH and I have returned them and checked the booster, I live in NN10 9SN. Can I get some help please
reception from hythe, kenyt,transmitter stopped for all but BBC since February. All stationas returned March 1 until about midnight when allchannels failed. On Sunday it was back to just BBC. I have done all the checks and retuning to no avail. We are in the town so should i moveaerial toDover direction andhope it can get over the hill or is something going to be done about it
Shirley: We need a full postcode to be able to see the predictedsignal strengths of eachtransmitter at your exact location before anyone can offer any specific advice.
Ourapologies, we seem to have missed your post until now. TheSandy Heathtransmitter has been undergoing PlannedEngineering which may have affected your signal. Also despite the fact that you should get a good signal from Sandy Heath, you aren't in the best of locations as you don't have line-of-sight to the transmitter. I'm afraid Retuning is the last thing to be contemplated when you haveNo signal or badly pixelated pictures. You cannot tune to signals that aren't there or can't be decoded, the usual result is to clear the correct tuning.
Do check that youraerial is still pointing correctly for Sandy Heath, compass bearing 124 degrees - that's in-between ESE and SE, and its rods (or squashed Xs) should be horizontal. Check your downlead isn't flapping about in the wind. It's also possible that retuning when there was missing/weak signals from Sandy Heath may have got you tuned to weak/poor signals from another transmitter.
Assuming your aerial system is ok, it'll probably be best to try manual retuning for the missing multiplexes (ie. not an auto retune), by going into your TV Tuning section. Check in your TV Tuning section that you are correctly tuned to Sandy Heath's UHFchannels. They areC27,C24,C21,C33,C36, &C48 - that's inmultiplex order - BBCA/PSB1, D3&4/PSB2, BBCB HD/PSB3, SDN/COM4, ArqA/COM5, ArqB/COM6 (If you can normally get the Local multiplex fromMadingley which I very much doubt, it's onC35). If any of those are missing (or any different ones are incorrectly present) then manually tune the UHF channel for the particular multiplex.
Another possibility is someinterference issues. You are surrounded by Mobile Phone masts and there could be a new/upgraded one now operating in the700MHz band. You should have received a postcard from Restore TV.. See -https://restoretv.uk/post…ure/ I'd contact Restore TV and request a Free filter. Now as you have an aerial pre-amp/booster/splitter the Filter must be fitted before that. If the booster is fitted to yourmast, you need to advise Restore TV and they should send an engineer Free of charge toinstall a waterproof one on the mast.
Whilst Steve is correct about the PlannedEngineering atDover, it should not have caused the Hytherelay to lose signal for any lengthy period, but I'm afraid retuning when you haveNo signal or badly pixelated pictures is a bad idea. You cannot tune to signals that aren't there or can't be decoded, the usual result is to clear the correct tuning. Check in your TV Tuning section to be sure you are tuned to UHFchannelsC26,C23 &C30 for Hythe multiples BBCA/PSB1, D3&4/PSB2, BBCB HD/PSB3.
Brian Butterworth published onUK Free TV