How TV signals work - Why we use a TV signal Meter
TV Signals are - Invisible.
TV signals are beamed out from your local TV Transmission Tower. They arrive at your TV antenna or reception device. As the signal is collected from your TV antenna it travels done the cable to your splitter (if you have one) which then is distributed down more coaxial cable to the TV point (or wallplate on the wall) where further coax cable (your TV cord) Sends the signal to the jack on the back of your TV or Set Top Box. This is a simple system. Even in a simple system there are many points of termination that can cause signal to break down or signal to fail. The materials themselves like the splitter, wallplate, coax cable, antenna cord can cause signal breakdown if they are old or faulty. Generally speaking, materials start to lose performance over time (old age) and this is a major culprit of bad TV Reception.
Knowing or fault finding under-performing components cannot be done by simple looking at or inspecting the material with the naked eye. (Sometimes old and worn cable looks like it would be failing but can be working perfectly just the same as brand new, shiny TV antenna looks to be in perfect tact can in fact - actually be faulty). This is where our Digital TV signal reader comes into play and allows us to do the job we do cost effectively. Without this instrument you just do not get the full story. You have no idea without it to make accurate decisions about how to fix TV reception problems - you would be essentially implementing the 'trial and error' method.
Digital TV SIGNALS - the way they behave with obstacles
TV Signals are no different from every other RF frequency ie. your garage remote or radio waves that travel through the air. Just like your garage remote you don't have to point it directly at the garage door - you can be coming around the corner and you can get your garage door to start opening. TV Signals do permeate the atmosphere (travel outward like gas) but do travel in a straight line. When they hit an obstacle is it only then they they change directions. Now think of the spoon in a glass of water - that looks bent. There are thousands of tiny obstacles in the air that allow the signal to change direction.
With trees, buildings, mountains and other large natural or built obstacles TV signal 'refracts' or bends around this obstacles just like the spoon in water that looks bent. The light in the glass of water is slowed down by the water giving off the illusion that the spoon is not straight.
If you have a mountain or a tree that blocks the direct path between a house and the transmission tower - the TV signal has to 'bend' over the mountain to hit the TV antenna. The distance that you are behind the obstacles plays an important part. If you are right behind it - this is hard for the TV signal to refract that much. Where as if you are back a bit - it's quite common for us to find that the signal does not have to 'bend' over/around etc the mountain as much to hit a customer's TV antenna.
Also the frequency of the channel (All TV channels are on a different frequency) - determines how much the TV signal will refract. The higher the frequency the less refaction. This use to mean that SBS and was the reason why SBS was very hard to get if you had a poor SBS reading. Nowadays in metro areas SBS has been changed to a lower frequency.
In Rural Australian Areas, TV signals are on the UHF band ( a higher frequency ). This means less refraction and is bad if there are a lot of hills and obstacles in the way. The good news for higher frequencies and rural areas is that there is a lower entry requirement for the signal to be amplified and get good results. It's not a 1:1 ratio for amplifcation vs. line of sight but it is good to know that low and high frequencies both have their pros and cons - just as the old analogue vs. digital signals have their pros and cons.
Either way all TV signals are invisible and this requires a TV signal meters to measure what is really going on. Would you stick your tongue in the power socket to measure how many volts are coming through? I know! I'll test it now! A Deathly amount.