If you live from the broadcast source, it is normal for you to have problems with the digital signal. In very bad weather, the digital signal can disappear as well. If you live close to the broadcast source, there is no bad weather, and yet you still have problems with the signal, then you should consider the options for improving your TV signal.
The problems with the digital TV signal are often caused by the antenna that is used. You should be using an antenna that is able to receive ultra high frequency signals. UHF is the frequency in which the digital signals are broadcasted and the analog signals are broadcasted in very high frequency - VHF. This is why if you want to receive the digital signal perfectly you need an antenna that will receive the UHF signals from the digital broadcast perfectly. The distance for your home and the broadcast source is important. IF you live close to the broadcast you will be able to receive TV signal with a small indoor antenna, and if you live far from the source you will need a larger outdoor antenna. Make sure that you place your antenna at a high place, so that trees, mountains or power lines won't interrupt the digital TV signal.
If the problem is not with the antenna, then you should expect your coaxial cables. Make sure that your coaxial cables are connected properly with your TV set or your digital receiver box. The coaxial cables that are most suitable for transmitting digital TV signals are those marked as RG-6. You can also consider placing a signal amplifier. This device increases the strength of the digital TV signal; you should place the amplifier close to the antenna, so that it can amplify the signal as it travels through the coaxial cable. Solving these problems will surely improve the quality of the signal and thus you will be able to receive the digital TV signal in perfect quality.