Help please, signal worse when antenna outside on pole (WLG)

[Ser Olmy]

Hi, new to the forums, had a trawl but couldn't find anything similar so am posting for help. Afraid I'm not really that knowledgeable about radio, more a software and computing geek.

I purchased a Freeview HD UHF outdoor antenna (http://www.dse.co.nz/dse.shop/4c207417006e70da2742c0a87f3b06db/Product/View/L4735) and hooked it up to a Samsung TV with built in digital and analog receivers. After a few minutes waving the antenna around in the lounge and running auto-program-scans on the TV it eventually picked up 16 digital channels (and plenty of analog but not really interested in that). All digital channels absolutely rock solid except for Maori TV which was pretty sketchy. Analog channels mostly fuzzy/snowy but just about watchable. (Before purchasing the outdoor antenna I did try an indoor boosted antenna but without success, awful analog and no digital channels found with that device).

"Great" I thought. Today I put the antenna up on the roof, it's pointing in the same direction in the same orientation, it's using the same cable, and now only half the digital channels are picked up, and they're all pretty unwatchable with pixellations/discolourations/audio corruption sometimes total signal loss. Analog TV is ghosting quite badly which it wasn't doing when the antenna was in the lounge.

What have I done wrong? :( I just spent half an hour on the roof with a buddy watching the TV for signal improvements while I s-l-o-w-l-y rotated the antenna through 180' and just cannot get any channel to come in reliably. I really don't want to have to put the outdoor antenna indoors and balance it on a chair again - I thought putting the antenna up higher would help things!?

Does anyone have any suggestions? Or a decent map of transmitter locations so I can be sure it's pointing directly at one? The maps I found weren't much help and could find no info on the actual physical transmitter locations - just generic place names. Is there a googlemaps overlay with the transmitter locations marked precisely somewhere?!? If someone could list GPS co-ords of all transmitters I'd be happy to knock up and host an overlay.

Here's a pic of the pole on the house if that helps. Would the existing antenna cause any problems? Is there a way I can test the cable with a digital multimeter perhaps I screwed up one of the ends?

Thanks for any help. Hope to get this fixed by the time NZ play their next WC game! BTW I live on Balfour St in Wellington almost at the end that connects with Farnham Street.

http://stormhold.bsnet.co.uk/~ser_olmy/pics/temp/ant1.jpg

[Geekster]

I'm not familiar with transmitter locations outside canterbury, so the only advice I can offer is to look up the transmitter names on google maps, that might pop up something useful (it does for the local sugarloaf transmitter). If I was you, I'd align the new antenna to the old one (assuming you were using it before), you might be picking up a bounced/ghosted signal off of a nearby building.

The existing antenna shouldn't interfere with the new one at all, assuming that it's connected to the same cable. As for the cable itself, you can't really test the quality of it with a multimeter, only continuity. You could, however, disconnect both ends, and bridge the core to the shield on one end, then measure the resistance on the other. If it seems a little low/high for the type of cable you've got installed, that might offer a few clues.

Hope it helps.

[Ser Olmy]

Tried googlemaps but wasn't able to find precise locations. Ideally I'd like to see the transmitter in satellite view. Maybe someone who knows can find them and post some links :)

The existing antenna has it's own cable, both existing and new cables run to the lounge next to each other. Only the new antenna is plugged into anything, the existing cable is unplugged. The new cable is RG6. What the old cable is I've no idea but it's way way thinner than the RG6.

Would it be right to say with the cable currently plugged into the antenna there should be absolutely no connection between shield and core if I connect a test meter to the shield and core at the TV end of the cable?

Thx for the reply :)

[Ser Olmy]

Tried googlemaps but wasn't able to find precise locations. Ideally I'd like to see the transmitter in satellite view. Maybe someone who knows can find them and post some links :)

The existing antenna has it's own cable, both existing and new cables run to the lounge next to each other. Only the new antenna is plugged into anything, the existing cable is unplugged. The new cable is RG6. What the old cable is I've no idea but it's way way thinner than the RG6.

Would it be right to say with the cable currently plugged into the antenna there should be absolutely no connection between shield and core if I connect a test meter to the shield and core at the TV end of the cable?

Thx for the reply :)

[Stu M]

I 'think' your VHF is pointing at a repeater that dose not have digital transmission. A site survey with a proper spectrum analyser would be the way to go. Being that you live in Wellington, there is no guarantee that you will be able to pick a digital signal, as a hill may be blocking the signal path, so a satellite dish may be the only way to go!

[Ser Olmy]

Thx for the suggestions. I have now solved the problem and have 16 channels of rock solid digital TV :D

I did two things, one of which I'm a bit confused about...

1. Moved the antenna below the roofline. I live fairly deep into an enclave in the side of a hill, the enclave could have acted as a big reflector jumbling the signal nicely. That would explain the massive analog ghosting experienced when the antenna went up after it was working in the relative insulation of the lounge. (Wouldn't it??). That sort of makes sense to me.

2. Totally changed the direction the antenna was pointing in. When the antenna was in the lounge it was pointed Northeast (towards a couple of transmitters) and picked up 16 channels almost perfectly, now it's Southeast - not towards any transmitter (not even one on the South Island) - and is 16 channels of perfection. Actually slightly better as even the Maori channel is rock solid. It is totally pointing directly at the side of another building 200 meters away on the next ridge over, could it be reflecting off that?!? If so I may consider dropping round a fruit basket with a thank you note :)

http://stormhold.bsnet.co.uk/~ser_olmy/pics/temp/ant2.jpg

[wiilliiss]

mt kaukau and fitzherbert should be obvious enough.

[Ser Olmy]

Kaukau is behind a wall of rock from here. Fitzherbert is where the antenna was originally pointing in the lounge and on the roof. It just didn't get quite as solid reception as it's current position. Fitzherbert line of sight is blocked by the top of a hill in McAlister Park, can't tell if actual hill is in the way or just the trees on the top.

But, the antenna now points nowhere near any transmitter (unless there's one out Pencarrow Head way which I've not seen on any maps) and gets solid signal. :)

[Apsattv]

If you were pointing at Fitzherbert, then the problem is I think the antenna should be vertically polarised not horizontal! :rolleyes:

please list which frequencys you are loading? then we know which transmitter you are pointing at.


see other thread

http://www.nzdtv.com/forum/showthread.php?t=6

[Ser Olmy]

I can't seem to get the TV to reveal what frequencies the auto-tune picked up. The DTV channels it found and assigned are...

1: TVONE
2: TV2
3: TV3
4: C4
5*: Maori TV
6: TVNZ6
7: TVNZ7
8: TV3+1
9: C42
10*: PRIME
22*: Parliament TV
28*: Chinese TV
50*: Radio NZ
51*: Radio NZ concert
71*: Base FM
100*: Freeview|HD

* denotes bad reception. For video that means perhaps half the screen is viewable the rest discoloured blocks. Audio comes and goes. The other (good) reception channels are rock solid perfect not so much as a glitch.

I checked that other thread but saw no frequencies listed, and freeview.tv's website isn't much help either. The TV will take 'manual' programming but it wants a frequency (in KHz) and a bandwidth (7 or 8 Mhz) if I could find a list of frequencies (and bandwidths wtf is that about?) I'd tap them in :)

When you say vertically polarised do you mean twist the antenna 90' on it's mount or point the whole thing to the floor? (I am such a noob :( ).

[Apsattv]

You are having problems with the Kordia mux

These are the local signal for Kordias mux

Fitzherbert Ch 57 Vertical
Baxters knob Ch 57 Horizontal
Ngara Ch 57 Vertical
KauKau Ch 59 Horizontal

I have looked on my Samsung TV it clearly shows how to manually tune Analogue and Digital channels.

You choose the channel number in the tuning menu e.g channel 57 =762 mhz

Your main antenna is Horizontal, often low power UHF repeaters will transmit in Vertical Polarity.

The antenna needs to match the Polarity of the transmitted signal! crucial or a lot of signal loss will occur.

In other words for Fitzherbert reception you need to put the UHF antenna on its SIDE so the elements are straight up and down. Your existing VHF antenna is Horizontally polarised and from the look of it pointing at MT Kaukau.

[wiilliiss]

wertical means the pieces or elements straight up & down or vertical.

kaukau 48,50,59 horizontal

fitxherbert 51,53,57 vertical

tv will tell you what channel you are on.

[kiwisteve]

its amazing in this area , WTE , Coverage , how many UHF ones are on the wrong polarity
and some recent installs too !!!

[SYS65091]

If a map of NZ DTV Transmitters locations might help, try this Google Map link

http://maps.google.com/maps/ms?msa=0&msid=112196483834929428323.0004513aab7385c70e5f7&cd=2&hl=en&ie=UTF8&z=6

It has the locations, channel numbers, transmitter power, and polarization, so could prove useful for some.

[kiwisteve]

Unfortunately it lists licences from rsm database by the look of it not sites that are actually on air !:mad::mad:

[Apsattv]

There are GoogleEarth DTV pins in some threads here already.