Weak digital terrestrial TV signal - how to deal with it?
There are many areas in Poland that are in quite a difficult situation in terms of proper reception of digital terrestrial television DVB-T signals. And this is despite the increasingly dense network of transmitters and antennas supporting the primary beam.
In locations with good reception of TV signals the situation is simple: just check on publicly available websites (e. g. emitel .pl or dvbtmap.eu) which transmitters are in the vicinity, choose an appropriate antenna for the strength of the transmitted signal and position it exactly in the direction from which the signal is transmitted.
It often happens, however, that due to location, topography and local conditions, the signals reaching individual recipients may be either so weak that their proper reception is practically impossible, or there are too many of them and they are so strong that it generates numerous interferences. In both cases, the head unit in the TV set works unsteadily in the two extreme areas, at the lower or upper limit of reception. All it takes is some additional element in the area, such as a passing car or train, an operating router, or a cell phone conversation, to disrupt this unstable balance.
How to deal with such cases and what to do to improve the comfort and quality of reception?
Unfortunately, there is no ready solution. Each case is specific and requires an individual approach, and bencchmarking by the type and location of your neighbour's antennas can be a very misleading method. Also, adding more amplifying sections is not recommended because in many cases there is not much to amplify or we amplify the whole "bunch" of signals.
So what to do in this situation? To make sure what case we are dealing with, it is necessary to measure carefully the signals from the chosen receiving antenna. Only the knowledge of whether we receive the main beam or a reflected one (maybe several or even many times), which, considering the protective interval, may be treated by the head as a useful signal, will allow us to determine the next steps.
One method is to change the receiving direction of the antenna or its position, or often both. The place of mounting of the antenna is very important for a specific location and not always the one chosen for practical reasons is the right one for the reception itself. Sometimes it is enough to move the antenna mast a metre or two to get a much better quality signal. It is also worth to have at hand a meter that will show us whether the received signal is of good quality and will only require additional amplification, or perhaps the received signal is strong signal but of poor quality.
In the case of a strong signal, deliberately changing the direction of reception or the location of the antenna can weaken it enough, while eliminating other signals from the reflections, that the TV head will begin to work properly in the middle range of its capabilities. Of course, in the case of overlapping strong signals we should choose passive directional antennas, not using any signal amplification stages. Overdriving the preamplifier in the antenna will generate intermodulation, which in turn will cause interference and instability in the operation of the decoder or TV set.
All these procedures are aimed at eliminating irregularities in signal reception by the TV set head, when, due to the quality and strength of the received signal, its operation is unstable and the displayed image does not meet our expectations.
In such cases, every detail is important: from the selection of aforementionedthe antenna, its location and direction, to the selection of the cable and careful installation work. In extreme cases, however, getting a good signal will require a lot of work and trying many different variations before the result meets our expectations.