 |
 DIGITAL
SIGNALS REQUIRE A SET AMOUNT OF SIGNAL IN ORDER FOR IT TO WORK THE GAIN
SHOULD BE BETWEEN 45-70db IF THE SIGNAL IS OUTSIDE THESE PARAMETERS THEN
YOUR PICTURE WILL BREAK UP.
WHY DOES MY PICTURE KEEP STOPPING AND BREAKING UP?
A digital signal is made up of bits of information.
Even with a good signal and quality installation, there will always be
errors in the signal. If an installation has 2 errors in 10,000 bits of
information, the system is defined as error free!!
The best way to explain this is if someone sent you a message with
one or two letters missing, you would still be able to read it as
below:
Be at th restaurant at six pm to
nigt.
If more letters were missing, you would still be able to read the
message, but you would pause and faulter, just the same as your
freeview box does when it breaks up into little squares and freezes.
Be at h retaurnt at sx pm t nght.
If more information was missing, you just simply wouldn’t be able to
understand the message in the same way as your freeview box would
not be able to.
Be a h reauant a sx m to ngt.
|
IF I BUY A DIGIBOX, WILL IT WORK?
As the digital signal can be affected by many
different forms of interference and weather conditions, an installer testing
the signal for you can only say the signal is ok at the time of testing. To
save you the cost of a site survey, the best solution for the customer is to
firstly follow these simple steps:-
1. Set up the freeview box which will automatically scan for all available
TV programs.
Channel 5 is one of the more difficult signals to receive. If your freeview
box has not detected channel 5 at all, this means that your box has missed a
whole group of programs and you do have a problem with your reception.
2. If your freeview box has detected channel 5, watch it for a few minutes
to see whether the picture stops or freezes into small blocks. If this
happens, you do have a problem with your reception.
3. If your are receiving channel 5 perfectly, the next time the weather is
wet or windy, check channel 5 to see if you are still maintaining a good
picture. If not, this indicates that you have a problem with water ingress
on the cable or aerial.
4. During a period of viewing, if the TV picture freezes and blocks into
small squares for a few seconds, this also could be an indication that
unscreened cable and amplifiers etc.. could be picking up interference from
passing vehicles or other sources.
If you do incur any of the above problems,
then a site survey may be required.
CABLE JOINTS
On many occasions, cable joints like this are found
in lofts tucked under the loft insulation and even under the roof tiles.
Sometimes many cable are joined together in this way. This is a joint that
will cause you problems with digital reception. It was never an ideal way of
joining cables although it would usually work with normal analogue TV
reception.
The cable joint seen right uses a method that screws together, providing a
good tight joint and eliminates the possibility of the cables pulling apart.
This is the high standard that digital installation now requires, to give
you long term reliability.
 This cable (left)
was removed from a customer's roof and is the sort of problems that made the
normal picture go a bit snowy when it rained. With digital, the picture went
totally and the customer was confused as to why they only lost their digital
picture when it rained. This is the sort of problem that affects long term
reliability of your digital TV.
Top of page |
Aerials explained | Selecting an
aerial | Freeview boxes
|