DVB-T over 90km

Forums › Freeview (DVB-T/DVB-S) › DVB-T over 90km

Gordy7

1906 posts

Uber Geek

ID Verified

Lifetime subscriber

#145447 18-May-2014 12:03

Hi

Looking at DVB-T from Mt Erin to Wairoa in Hawkes Bay.

What would be the feasibility and reliability be like?

Path is mostly over the sea.
Estimated distance 90km.
Mt Erin height 490m.
Receiver antenna height possibly 5m.
QSL line of sight calc shows approx 100km.

Going Digital report in 2011 says:
Viewers in Wairoa and Mahia whose aerials point south or southwest towards Mt Erin will be included in the Hawke’s Bay region.

Various Yagi gains look to be about 10 to 16dB.
Not sure if a good S/N would be available.

Anyone have experience with DVB-T over such large distances?

Thanks

Cheers

Gordon

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

Behodar

10502 posts

Uber Geek

Trusted

Lifetime subscriber

#1047405 18-May-2014 12:11

Whakatane is ~120 km from the nearest transmitter (Te Aroha) and most people have no problems with Freeview so long as they have a decent aerial (my parents have a 91 element and it works fine). Mt Erin apparently has a similar power output so as long as there is line of sight, I can't imagine that there would be any issues.

Batman

Mad Scientist
29760 posts

Uber Geek

Trusted

Lifetime subscriber

#1047420 18-May-2014 12:57

Might depend on the weather or at least be affected by really bad weather

bfginger

1267 posts

Uber Geek

#1047429 18-May-2014 13:30

Kopukairua next to Tauranga is much closer than Te Aroha but lower powered.

If a 91 element aerial isn't enough there is always something like this
http://www.dtvs.co.nz/index.php?main_page=product_info&cPath=3&products_id=85

Apsattv

2388 posts

Uber Geek

#1048495 20-May-2014 03:59

Most 91 elements out there are Wideband antennas, with the restacking of services recently what is preferable for weak signals is one optimized specifically for high gain in the Band 4

We use to get analogue VHF TV via Wharite over sea path into the Marlbourugh sounds. The signal fluctuated up and down and was pretty much unusable over 140K sea path. It would go from good to nothing within 10 minutes.

a 90k path on UHF might be ok but you might get dropouts!

Try it and see.

Behodar

10502 posts

Uber Geek

Trusted

Lifetime subscriber

#1048524 20-May-2014 07:49

bfginger: Kopukairua next to Tauranga is much closer than Te Aroha but lower powered.

It doesn't appear to work at all from Whakatane. Even with the aerial vertical and pointed at Kopukairua, I still got a stronger signal from Te Aroha (horizontal). I suspect that there is a hill in the way of Kopukairua.

I misspoke when I said "closest" transmitter; I meant the only usable one :)

robjg63

4096 posts

Uber Geek

Subscriber

#1048533 20-May-2014 08:22

Before Timaru got its own local freeview transmission I got it working at my parents house via Sugarloaf in Christchurch.
Thats 160km.
It disappeared in bad weather and wasnt reliable.

Back in the early days of TV2 starting up (the mid 70s) many people in Timaru used to get quite a quite reliable feed from Christchurch.

The VHF analogue signal is a bit more forgiving and digital is either perfect or dead.

I would think 90km unobstructed should be ok - guess you just have to try it.

Nothing is impossible for the man who doesn't have to do it himself - A. H. Weiler

MikeB4

18435 posts

Uber Geek

ID Verified

Trusted

#1048535 20-May-2014 08:28

At 90km over water it is going to be unpredictable and flaky.

Equinox IT

Cloud spending continues to surge globally, but most organisations haven’t made the changes necessary to maximise the value and cost-efficiency benefits of their cloud investments. Download the whitepaper From Overspend to Advantage now.

Gordy7

1906 posts

Uber Geek

ID Verified

Lifetime subscriber

#1048601 20-May-2014 10:08

Thanks for the help so far.

I have seen a few aerials pointing in the direction I am thinking of.
When I get settled in Wairoa I might drop in to one or two of these places and ask what their DTT is like.

This enquiry was started because I am staying at my step son's place.
The satellite video on a 50 inch TV was terrible.
I discovered that he was using an old Sat receiver with composite video output.

Picked up a new el cheapo DishTV Sat receiver with HDMI output from Harvey Norman.
Even though the receiver HDMI is 576i output the picture quality is a vast improvement.

Cheers

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.