Digital tv reception problem?
Can anyone tell me why is my digital tv reception very poor at times?
I have a set top box as well as digital on our tv, we have serious problems with it, at times it breaks up so badly that we can barely watch it. I have re-set it numerous times, to no avail. Could living in front of a train line have anything to do with it, or could it simply be the outside Ariel. We live in a flat so access to check Ariel hampered.
Thank you!
The digital TV requires a good signal input from the antenna. Signal intensity is not the only condition, the signal must also be free from reflections, etc. You will have to try move the antenna, to achieve a good picture.
With analog TV, this was an easy task. The digital TV settop box nor the TV set gives any indication of signal quality. Relocating and repointing the antenna is the only way to go. Check with your neighbors in the house, maybe you would need another antenna.
Just place in front of your set top box a dedicated preamplifier and the problem will be solved.
It is recommended the preamplifier to be placed outside, near the antenna, but at the beginning you can try placing it near the window where the cable enter into the room.
Search the net for different models and prices.
Antenna Preamplifier: APL-103 (10/12 dB, shielded) - TV & SAT TV
TGNonlineshop - DVB-T Preamplifier 470-862 MHz UHF MegaAmp ULNA3018 90100125
Hate to disagree but I think vfone is wrong.
Digital signals are prone to multipath problems and cable reflections far more than analog TV signals. What used to look like an almost inperceptable picture ghost in the past is now a collision of ones and zeroes in the signal stream. It is far more important that the signal is 'clean' than it is strong and in real terms that means a good cable and an uninterrupted signal path. If the passing train interrupts the signal it could well be the cause of your problem and the only solution would be to reposition the antenna so it sees over the top of the train. Before doing anything else, see if your TV/Set top box has a signal strength indicator, often this is in the tuning or information menu. The strength may well be adequate already in which case no amount of extra signal boosting will help, in fact it would probably make matters worse. It may also have a signal quality indicator, technically this is a BER (Bit Error Rate) measurment and is more likely to indicate a good solid picture than the signal strength alone. It is possible to have a low signal strength but high quality at the same time, in fact digital works perfectly at much lower signal levels than analog in most cases.
If you do decide to buy a signal booster (preamplifier) take no notice of advetising hype like "specially for digital" or "DVB compatible", it makes no difference whether it's for analog or digital, it works the same for both.
Brian.
I think 90% of cases of bad TV reception (especially digital) is due to low input signal at the receiver input.
If you don't have to much RF experience, before thinking to anything else, go to the first electronic store and buy a TV preamplifier.
You will be surprised by the results, especially if you have the possibility to place it near the antenna.
Think after to a better solution if doesn't work.
No, vfone is correct and betwixt is wrong about ghosting due to cable reflections or multipath propagation. In your location you have DVB-t and maybe also DVB-t2. Multipath propagation, causing analog PAL ghosting, can in many cases actually improve c/n for DVB-t and even more for DVB-t2 due to that DVB-t2 also implemented FEC (forward error correction).
A minor time difference between main and echo signal which had resulted in a very visible ghosting in an analog TV should not cause any problem at all for DVB-t due to its coding.
One specialty with DVB-t is that it can handle SFN mode. In a Single Frequency Network do several transmitters transmit same content at same channel and synchronized in time, which allows for bigger area coverage and better frequency planning. At receiver end can several stations be received with almost same signal strength, same frequency and limited relative delay without interfering. That had caused extreme ghosting in a PAL-TV.
Bronhood's problem, I assume he also receives DVB-signal in his antenna jack and not any DVB converted to analog TV.
Good reception starts with a good antenna. If living in a flat, best is to let someone measure if signal is good enough in the antenna jack.
Older DVB receiver had both rather poor sensitivity, and low dynamic RF gain. As this gain was set to not cause too strong system gain, did it cause problem when signal was weak as it not was enough system gain. A preamplifier could then improve reception from zero to 100% picture quality.
All DVB-receiver have a receiving quality menu were two important thing can be read:
1. Signal strength. If indication low, verify anything is faulty in the antenna signal path, such as connectors, old coax-cables with high attenuation and losses, faulty antenna filters...
1. Signal quality. If this one is low while signal strength is ok, there is too much noise compared to signal. Check if it is weak signal from the transmitter, if antenna is best possible with high gain and pointing in correct direction, if low loss cable and that a high sensitive DVB receiver is used.
A different DVB receivers can make whole difference as much junk FTA-receivers have been sold and these as well as old receivers do often work less well if signal level is low.
I still argue that amplifying a weak signal will improve matters but amplifying a bad one won't.
Brian.
Agree with "amplifying a weak signal will improve matters but amplifying a bad one won't" except for that we seems to have different opinions about definition "bad".
Reflections of type "collision of ones and zeroes in the signal stream" is one of the things DVB-t is almost immune against due to its type of coding as long as coaxial cable is less then 5000 meter long for 64-QAM and 7uS guard interval. If I remember correctly have also 14uS guard interval been tested in Australia, allowing up to 100 km between each transmitter in a single frequency network. In worst case can you then have rather heavy multipath-delay reception somewhere in between two-three of these transmitters. Due to how DVB-t is coded is a such received signal still possible to fully decode and is not a bad or unclean signal.
DVB - Digital Video Broadcasting - Home, EBU.CH :: Home Page and BBC - Homepage have tons of free material in this matter as they did very intense investigations before DVB was implemented.