UHF harder to get than VHF?

Forums › Freeview (DVB-T/DVB-S) › UHF harder to get than VHF?

rayonline

1489 posts

Uber Geek
+1 received by user: 37

Topic # 85282 16-Jun-2011 12:41

I am just wondering if UHF is more picky to get a decent signal than VHF?
Any people or people you know who are in a main city and cannot get UHF and need to resort to a dish instead?

I did a bit of research. Most houses around us only have a round dish and/or VHF. One house across from us has a Phased Array UHF aerial and two up the road has a 91 element. We are also in a valley with hills around us.

Thanks

TechSol

258 posts

Ultimate Geek
+1 received by user: 8

Technical Solutions Aust

Reply # 481823 16-Jun-2011 12:52

By it's very nature, higher frequencies are harder to transmit over distances and through/around objects. UHF are higher frequencies than VHF.

However in my experience this seems to be somewhat offset by how forgiving freeview is.... put it this way, Sydney had far greater difficulty with their digital TV transmission in 2000 than Auckland has. Yes, Sydney is more hilly however.

I used to live in a deep valley in Mellons bay in Auckland.... I managed to get freeview using the a 91 element aerial and a masthead amplifier (about 25db)

illicit

553 posts

Ultimate Geek
+1 received by user: 15

Reply # 481832 16-Jun-2011 13:07

Lots of installers will do free quotes, ring around they will come and test the signal and provide a quote - FREE.

Brunzy

657 posts

Ultimate Geek
+1 received by user: 56

Trusted

Reply # 481833 16-Jun-2011 13:11

As a general rule , yes.
The higher the frequency , the less it follows the curvature of the earth.
If you are down the bottom of Middleton / Halswater it may take a bit of searching

Behodar

6220 posts

Uber Geek
+1 received by user: 1037

Trusted

Lifetime subscriber

Reply # 481840 16-Jun-2011 13:36

This might be a good place to ask: I'm in a "mini valley" with a couple of metres worth of hill in the way, and at present I can *almost* get Freeview HD. For example it may work for two minutes, drop out for 10 seconds, work for a couple of minutes again, drop out again, etc.

When the frequencies have been changed down to the new bands (whenever that happens), is that likely to have a noticeable improvement in a case like mine? Or is the change of 112 MHz not really large enough to do anything?

Brunzy

657 posts

Ultimate Geek
+1 received by user: 56

Trusted

Reply # 481844 16-Jun-2011 13:52

Possibly , but with three muxes difficult to say if they all would.
If you are shaded ,not always the lowest freq is the strongest.
Best bet would be to get someone with a Spectrum analyser to walk round your roof and find the optimum position.

rayonline

1489 posts

Uber Geek
+1 received by user: 37

Reply # 481892 16-Jun-2011 14:53

Yeah we are smacked right on one of the many corners of Halswaters and Middleton.

B1GGLZ

1927 posts

Uber Geek
+1 received by user: 128

Reply # 481928 16-Jun-2011 16:05

rayonline: I am just wondering if UHF is more picky to get a decent signal than VHF?
Thanks

Not really. VHF antennae are very prone to ghosting from surrounding terrain which doesn't happen on digital. The antenna for UHF is much more compact but can be significantly affected by its surroundings such as trees in front of the antenna and in the signal path particularly if they are wet.
I've just been setting up a new TV in a 'mini-valley' in Glenfield with trees and a reasonably high ridge in the signal path. Last weekend we put an old antenna (47 el) with old co-ax on the roof and signal varied from no signal to getting 2 of 3 multiplexes to around 66 strength and 50+ quality. The best signal was actually when it was sitting on bxes and a balcony rail and very subject to placement. move it just a few inches and no signal. We were able to achieve a useable signal.
Today I installed a brand new 47 el antenna with new co-ax (albeit rg59 and not rg6) on a j-pole mounted on the balcony barge board pointing through a gap in the trees. The signal is now 93 on all multplexes and quality is 100. Much better than I expected and just shows what a new antenna and co-ax can do.

Brunzy

657 posts

Ultimate Geek
+1 received by user: 56

Trusted

Reply # 481948 16-Jun-2011 17:01

rayonline: Yeah we are smacked right on one of the many corners of Halswaters and Middleton.

In that case refer to line 3 of the post before yours.
PM me if you need any more info

TechSol

258 posts

Ultimate Geek
+1 received by user: 8

Technical Solutions Aust

Reply # 482127 17-Jun-2011 09:38

Behodar: This might be a good place to ask: I'm in a "mini valley" with a couple of metres worth of hill in the way, and at present I can *almost* get Freeview HD. For example it may work for two minutes, drop out for 10 seconds, work for a couple of minutes again, drop out again, etc.

When the frequencies have been changed down to the new bands (whenever that happens), is that likely to have a noticeable improvement in a case like mine? Or is the change of 112 MHz not really large enough to do anything?

112mhz wont really help much TBH. Have you tried amplification? Also a site survey would probably help get you a little bit above the digital cliff.