Signal Strength vs. Signal Quality

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PANiCnz

625 posts

Ultimate Geek
+1 received by user: 42

Topic # 93703 27-Nov-2011 18:00

Hi all,

Trying to problem solve problematic Freeview reception and was hoping someone with a bit more experience could help.

Went up on the roof today and replace the old VHF antenna with a new UHF antenna. Upon closer inspection the VHF antenna was well past its use by date with a lot of corrosion around the connection.

Sadly after coming down off the room while reception does appear to have improve its not perfect. I'm primarily trying to tune with PC software For The Record and MediaPortal. Both are reporting maximum signal strength but average signal quality.

What could be the problem?? I assume I need to improve my signal quality?

When installing the new antenna we just reused the existing cabling, could this be the issue? Replacing the cabling will be a lot more effort so I'm apprehensive about doing it. I aligned the antenna to match everyone else in the neighborhood so I don't think its an issue with the antenna.

Any ideas?

Thanks

located in Remuera, Auckland. Visually it appear everyone in the neighborhood is pointed at the Sky Tower.

PimpMyMagic

265 posts

Ultimate Geek
+1 received by user: 2

Reply # 550635 27-Nov-2011 18:23

What's the polarization of the Sky Tower xmission? Do I recall hearing it's vertical, in which case you should rotate your aerial 90?. Someone's bound to correct me if I'm wrong.

One possible cause of bad quality is multipath reception where you get multiple signals from different paths through bounces off nearby objects. These multiple signals can cancel each other out at some frequencies and cause phase errors that would degrade signal quality.
Solved by getting a more directional antenna or relocating it - sometimes just a metre or two can suffice.

PANiCnz

625 posts

Ultimate Geek
+1 received by user: 42

Reply # 550647 27-Nov-2011 19:07

PimpMyMagic: What's the polarization of the Sky Tower xmission? Do I recall hearing it's vertical, in which case you should rotate your aerial 90?. Someone's bound to correct me if I'm wrong.

One possible cause of bad quality is multipath reception where you get multiple signals from different paths through bounces off nearby objects. These multiple signals can cancel each other out at some frequencies and cause phase errors that would degrade signal quality.
Solved by getting a more directional antenna or relocating it - sometimes just a metre or two can suffice.

Just did a visual inspection of my antenna vs the rest of the neighbor hood. They are all orientated vertically while I installed mine horizontally. Definitely looks like I made a mistake.

Anything else I need to consider before jumping up on the roof next weekend?

mm1352000

1082 posts

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Reply # 550720 27-Nov-2011 23:13

Generally speaking quality is more important than strength. Unfortunately the absolute values of strength and quality aren't comparable between tuners or set-top-boxes so just try to maximise the quality in MP. Hopefully you'll find that rotating the aerial will make a big difference.

Behodar

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Reply # 550739 28-Nov-2011 06:41

At my old place, rotating 90 degrees changed my reception from "one frame every ten seconds" to "working perfectly" :)

oxnsox

1923 posts

Uber Geek
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Reply # 550758 28-Nov-2011 08:09

Polarisation (horizontal/vertical) is important. Given your proximity to the SkyTower you'll probably be OK then...but ideally you should have replaced the cable.

PANiCnz

625 posts

Ultimate Geek
+1 received by user: 42

Reply # 553542 4-Dec-2011 15:54

Went up on the roof yesterday and rotated the antenna, seemed to make a difference. Everything was coming through nice and clear.

Now this afternoon is raining and I'm getting choppy reception on the TVNZ mux, any idea what might be causing this? Signal seemed pretty good yesterday, strange a little bit of rain could turn things so bad.