Freeview 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 digitalsignal levels do not result, as they do with old-fashioned analogue television, in a sub-standardpicture 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.
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 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.
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.
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.
I got a free signalbooster from freeview in the post last year,it was a great little thing that worked a treat,i move house and lost it,does anyone know how I can get another,ive looked on their site but cant find anything,,i bought one but it doesn't work.cheers
anita: Are you sure that the device you are referring to isn't a 4G filter?, as these are supplied free by a company called AT800 to households located in areas deemed as being possibly affected by a newly installed mobile phone 4G transmitter, 4G filters restricting the effect that 4G signals can have of Freeviewreception.
I have a rather complex aerial system for reception of digitalchannels. I have a loft-mounted, high gain aerial, which is out-putted through two in-line boosters, the second of which has several output sockets which feed to points in my living room, master bedroom, computer room and dining room. Because I also have satellite boxes, the living room and master bedroom pass through two separate duplex arrangements (one cable through the external wall in each case). I have an 'August DVB-400' box in the living room, so the RF signal reaches my TV through a 'pass-through' arrangement.
Several weeks ago, I found that certain channels (BBC particularly) were no longer received properly (if at all) through my living room TV tuner, but there is no problem with the DVB-400 through which the TV signal passes. I have the same poor reception of these channels on my dining room TV and on my Bedroom TV.
Am I correct in assuming that the DVB-400 reception is OK because it has a superior amplifier? Or is there another explanation?
Eric Brett: According to the spec sheet, the August DVB400 doesn't really amplify anything, but though it does have the ability to supply 5 volts via the aerial input socket to power an aerial amplifier, if your in line boosters are self powered? then make sure that the 5 volts supply on the DVB400 is turned off.
The other thing to check is that the RF loop through on standby is set to "on", instructions for both the aforementioned on page 12 of your manual.
It would also be of assistance if your location was known, post code or one from nearby, e.g: shop / post office, as this would enable access to info on the transmitter that covers your area.
I have two TVs, both had good terrestrialfreeviewreception including SKY News, until recently. Now all other channels I watch are good but SKY News is either good, extremely pixelated or no signal.
I am located in BT22 2NH, my local tx is Divis. I have recently cancelled my expensive SKY on the strength of being able to see SKY News on freeview. Please help.
George Stephenson: At your location you could potentially have difficulty with Divis' COM4/COM5/COM6 channels (which carry, ITV3, Pick, Dave, 4Music, Sky News etc) because these are co-channel (same frequencies) as those of Darvel in Scotland and Caldbeck in Cumbria. The PSB channels (BBC, UTV, Channel 4, Channel 5 etc) are not shared. As you are right against the sea then then it's possible that the unwanted signals could affect your reception at some times.
Has the signal level dropped from what it usually is? There are seven channels you should look at: