Lost channels on Freeview DVB-T Palmerston North

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freebieman

6 posts

Wannabe Geek

#123335 3-Jul-2013 19:46

No signal on Freeview channels previously occupied by Maori TV, Prime and Choice TV.

What's happened? Other channels seem fine, and nothing has been changed at my end. I tried Auto tune on my TV to rescan all channels, but channels such as 10 - Prime and 12 - Choice TV are coming up "invalid channel"
My guess it must have been switched off at the transmitter.

Jaxson

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#848924 3-Jul-2013 19:55

7:55pm.

All channels working well in Palmerston North on my TV.

sultanoswing

814 posts

Ultimate Geek

#848971 3-Jul-2013 22:09

No probs here either.

Jaxson

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#849083 4-Jul-2013 09:22

Time to check your aerial, both orientation and connections quality...

Assuming you are viewing terrestrial/UHF/freeview HD or are you on a satellite version?

mthredgo

80 posts

Master Geek

#849145 4-Jul-2013 11:03

I'm on Wharite too and 2 or 3 weeks back the mux with TV3 and FOUR on it lost power and reception went to custard. The wife gave me some grief asking me what I was to go about it. I was a bit pissed that on the freeview website they don't have service announcements or anywhere to give feedback about transmission problems. After 3 days or so it all came back strong, presumably because it took that long for anyone to work out where to complain

When it happens again any advice on how to get speedier service out of them?

Jaxson

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#849151 4-Jul-2013 11:10

Umm, without being rude, no one else is experiencing these outages, so there may well be nothing for freeview to be announcing.

One of the Mux's is usually a bit harder to receive, due to a range of factors, including the nature of your aerial too.

So, where are you, what sort of aerial do you have, what are you feeding with the aerial (how many TV's/PVR's etc), and do you have UHF only or a combo of UHF and VHF only etc.

With the weather not being so good, if you've normally got borderline reception, it could be enough to drop you below a threshold at times.

mthredgo

80 posts

Master Geek

#849167 4-Jul-2013 11:22

I've the biggest of the UHF antennae, and usually the signal shown for TV3 on a Bravia is High, with the signal strength unfailingly at 100%. Previterbi error correction (or whatever that is) at 5x10-3.

I am kind of tucked up against the Tararuas near SH 57 and when they changed the channels stacks a year or 18 months ago I did upgrade the aerial because the power did drop.

I'd hazard a guess power went down a little, which was noticeable by us on the edge of the signal.

Jaxson

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#849173 4-Jul-2013 11:26

Your TV or freeview box/PVR should have a page that shows the signal strength and quality.

What are you getting across the 3 mux's?

TVNZ include TV1, TV2, U, TV1 Plus 1
Media works (didn't that company just go under) TV3, 4, TV3 Plus 1 and C4
Kordia carry Maori TV, Prime, Trackside etc.

I expect one of the 3 will be clearly the worst of the lot and you'll have to do some work to determine why that is. Connection quality is pretty important, as well as using the right cable and having a suitably good aerial in the first instance too.

Depending on where your cable runs too, you might need a distribution amplifier to help push the signal around. You still need a good original signal though, as amplifying a bad signal just gets you a louder bad signal...

Sharesies

Trade NZ and US shares and funds with Sharesies (affiliate link).

Jaxson

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#849182 4-Jul-2013 11:36

From another website:

pre viterbi is the BER (Bit Error Ratio) of errors in the digital signal prior to correction.

post viterbi is the BER (Bit Error Ratio) of errors in the digital signal after correction.

The figures show the number of errors with a multiplying factor, so 290e - 5 is 290 errors to the power of 5, or 290 errors in 100 thousand.

The aim is to obtain pre viterbi BER readings as low as possible.... at the antenna.

Once you have sufficient signal quality (low BER) then you can add a distribution amp to compensate for losses in signal splitting/distribution.

If you have a poor signal into the amp, it will not increase the quality, only the strength... so you will still have a poor-quality signal at the outlets.

Some tuners handle error correction better than others so what is a BER maximum for one tuner may still be OK on others.

Gererally, readings in the 10K or lower range are best, but sometimes it's not possible to achieve low pre viterbi BER due to terrain, distance, etc, so installers may have to do the best they can with choice of antenna and mounting location to obtain the minimum BER reading.

There are instances where even BER up to 10e -2 will work, but it's a long way from ideal.

All digital tuners can correct errors to a certain point, but when there are too many errors happening too quickly, the error correction can't process them sufficiently and that's when you get pixelation and loss of signal.

If you are getting 0 errors post viterbi, that indicates the error correction in your tuner has corrected all errors and your reception should 'theoretically' be very reliable.

It should be noted that signal measurements in TV's, STB's etc are usually not accurate and you require professional digital signal measuring equipment to obtain accurate readings.

However, the Sony has a reasonable 'guide' with the measurements.