Pixelated DVB-T Freeview Transmission Signal Strength/Quality At Maximum

Forums › Freeview (DVB-T/DVB-S) › Pixelated DVB-T Freeview Transmission Signal Strength/Quality At Maximum

Damager

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#83488 17-May-2011 19:26

I'm trying to figure out why my signal is pixelated yet the signal strength and quality is almost maximum. Had no issues prior and now getting constant interference from somewhere but no idea what is causing it.

Panasonic Twin Freeview Tuner WR380.

Now looking at it again. Signal Strength is between 8 and 9 out of 10 but the quality is hovering around 3 and 4.

How can the quality be low and the strength be high??

Confused!

Cheers

Steve

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richms

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#470224 17-May-2011 19:32

Are you located somewhere that has had the channels restacked recently? Antenna directly connected to the recorder? House or apartment?

Richard rich.ms

Damager

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#470238 17-May-2011 20:01

Hi Richard

Its just a standard UHF aerial from my sky uhf days with no adjustments made for freeview. The thing i do wonder is that it there is a really old vhf loop aerial which is combined on the roof with the uhf aerial and comes down as a single cable into the house.

Would removing this vhf aerial make a difference? Right now, the signal strength has gone back to 8 out of 10 and the pixelation has disappeared.

I did do a rescan of the channels and the issue still occurs, seems to be no rhyme or reason as to when the quality drops.

im in the waikato region and nawton suburb.

cheers.

webwat

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#470272 17-May-2011 21:23

Is the cable from the aerial going direct to a single TV or is there anything else between the TV and aerial? Sounds like there is some noise in the system somewhere, possibly water got into a connector? Signal strength ? noise margin = signal quality

Time to find a new industry!

hdinsider

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#470326 17-May-2011 22:50

It is possible to have high signal and low quality. The signal may read high but might be picking up an interfering ghost signal that upsets the data. This could be a bounced reflection of the main signal off of other buildings or it could be caused by reflections in the cable if connections or splitters are poor.

If there's any problem in the aerial or cabling you will likely lose some of the Freeview channels but not all. They are transmitted in 3 groups (on 3 different frequencies). One for TVNZ's channels, one for TV3's channels and one for the others that Kordia look after.

Do you have the same low quality on all the channels or just one group?

don't mess with me.... i'm the hd insider....

B1GGLZ

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#470332 17-May-2011 22:55

Might be worthwhile disconnecting the VHF antenna and running coax direct to the UHF antenna. Some tuners don't like multiband antennae or diplexed antennae.

richms

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#470333 17-May-2011 22:59

Some diplexers dont diplex, they just have a filter on one side or the other, so you get all the crap from the side hitting the VHF coming in.

There was a time that they promoted UHF antennas as having an inbuilt diplexer which was basically a second set of terminals for the VHF with a crude PCB trying to filter it.

I have seperate leads in from the 3 antennas (VHF, UHF and FM) and amp them seperately before diplexing as that worked out best to clean up the lower UHF band to put modulators on. 20+ watts of crap running all the time just to get me TV tho :(

Richard rich.ms

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Damager

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#470338 17-May-2011 23:05

webwat: Is the cable from the aerial going direct to a single TV or is there anything else between the TV and aerial? Sounds like there is some noise in the system somewhere, possibly water got into a connector? Signal strength ? noise margin = signal quality

nothing between the aerial and the tv.. well the aerial goes directly into the freeview tuner. think there is a noise issue somewhere

Damager

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#470341 17-May-2011 23:10

hdinsider: It is possible to have high signal and low quality. The signal may read high but might be picking up an interfering ghost signal that upsets the data. This could be a bounced reflection of the main signal off of other buildings or it could be caused by reflections in the cable if connections or splitters are poor.

If there's any problem in the aerial or cabling you will likely lose some of the Freeview channels but not all. They are transmitted in 3 groups (on 3 different frequencies). One for TVNZ's channels, one for TV3's channels and one for the others that Kordia look after.

Do you have the same low quality on all the channels or just one group?

when the quality drops, all channels are affected with quality 3 or 4 out of 10.so the issue remains constant across the 3 groups... as far as im aware.. its a single join on the roof uhf and the vhf with a single cable going into the house and into the tuner.

Damager

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#470342 17-May-2011 23:11

B1GGLZ: Might be worthwhile disconnecting the VHF antenna and running coax direct to the UHF antenna. Some tuners don't like multiband antennae or diplexed antennae.

sounds like the first logical option to try.. okay will look at doing that and report the results

Damager

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#470343 17-May-2011 23:13

richms: Some diplexers dont diplex, they just have a filter on one side or the other, so you get all the crap from the side hitting the VHF coming in.

There was a time that they promoted UHF antennas as having an inbuilt diplexer which was basically a second set of terminals for the VHF with a crude PCB trying to filter it.

I have seperate leads in from the 3 antennas (VHF, UHF and FM) and amp them seperately before diplexing as that worked out best to clean up the lower UHF band to put modulators on. 20+ watts of crap running all the time just to get me TV tho :(

looks like a call to the local tech to get my aerial cleaned up!