Coleby Digital TV

  New Technology - Old Fashioned Service

Freeview Problems                                                                

Sometimes upgrading to Digital Freeview is as simple as plugging in a Freeview receiver.

However, in many areas, Freeview Digital Terrestrial signals are transmitted on slightly different frequencies from the old analogue signals, so you may need a new aerial.

In addition, the digital signals are weaker than analogue and more susceptible to interference coming from motor vehicles and electrical wiring, so the aerial cable ought to be a fully shielded type. Most TV aerial cable is not fully shielded and needs to be replaced in order to minimise the risk of "picture freeze" and "audio glitches". It may also need to be routed differently to keep it away from sources of interference.

The "weakest link" is often the lead that connects your Freeview box to the wall plate. If you pull it hard or trip over it, you can damage it internally. People are quite happy to pay hundreds of pounds on an aerial system then spend 50p on a "clothes line" patch lead behind the TV. As this position is one that is susceptible to lots of interference from the TV, Video, DVD and Freeview box itself, any cables here must be high-quality double-screened. You can make them yourself with left-over cable or you can buy them ready-made.

Here is a totally unscreened wall plate (rear view). You can see around 20mm of the coaxial centre core is unshielded and, therefore, able to receive and transmit interference like a small aerial.

The braided copper screen of the cable is clamped so tightly that the air-core plastic dielectric has been crushed. This will cause an impedance discontinuity that can cause serious problems such as "some channels missing" or simply poor quality pictures or digital pictures "breaking up".

The Freeview box should be connected to the aerial with a continuous run of double-screened coaxial cable (as used for satellite TV). Any joints or wall plates must also by fully shielded.

If you need to split the signal to more than one Freeview box or TV then an     ordinary splitter will lose around 60% of the signal! The correct way to do it is with a "masthead amplifier" which we can install for you.

If you have "lines on the picture" or "ghosting" then this is caused by something after the Freeview box (or a faulty box). Try connecting the box to your TV with a new fully-screened Scart lead.

DO NOT STACK EQUIPMENT!

Freeview boxes, in particular, are very susceptible to the effects of heat and interference from other equipment. They should be installed on a cool shelf (not metal) away from other equipment. The proximity of metal can interfere with correct operation. If you do experience problems, move your Freeview box at least a metre away from your TV and from other electronic equipment and see if that helps.

Another common problem:

You've got a video recorder (or similar) connected in line and you've left it switched on. Its RF output is blocking a Freeview multiplex.

Other problems

Typically "no signal" or "picture breaks up into squares" are caused by the VCR or by insufficient signal or by interference getting into the aerial system (which includes the downlead and anything connected in it).

Note: indoor aerials are notorious for causing problems because the signals can be reflected by nearby walls, roof tiles, pipes, wiring and even human bodies! The result can be signal cancellation, causing complete or partial loss of some channels. The positioning of the aerial can, therefore, be extremely critical.

Because of signal reflections and interference, the positioning of an indoor aerial is absolutely critical. An inch can make the difference between receiving all channels perfectly or none. (Each time you move the aerial you must rescan the digital channels!) I'd start by keeping the aerial as far from sources of interference as possible. The major source of interference is the TV set itself. (How many times have you seen an aerial perched on top of the TV and "wavy lines" on the picture?) Other sources of interference include electrical wiring and electrical equipment - especially equipment fitted with a thermostat. So don't do the ironing next to the aerial!

Placing the aerial on top of (or above) a metal structure can sometimes help. Try a metal CD rack or a (cold) radiator. Try varying the height. In a bedroom, on top of a wardrobe is often a good choice.

Let us install a     
high quality aerial   

[ Home ] [ Up ]