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#1 Canuck Eh!

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Posted 24 February 2012 - 04:57 AM

Hello all, this being my first post on this board I hope this is the correct place for this topic.

As near as I can see from the info I've collected from this board your reception problems are somewhat less than ours in Canada. It appears you are lucky enough to have your transmitters located on a single tower whereas our transmitters in any one city can be spread around the compass making antenna beam width a major problem.

I am coming over for a visit & will be touring NSW by campervan & joined this forum for ideas on TV reception on the road. I'll be using a usb stick DVB-T tuner & homebrew antenna (s) cut for your channels 27 -51 & it literally folds into a pocket (folding version of SBGH without a reflector). I may bring something for channels 10 - 12 but it doesn't appear they are really necessary (I think). All I need to pickup is a "pal to F connector adaptor" for my cable lead attachment to the tuner. Also a plug adaptor for my laptop charger to fit your mains plugin .... any sources easily available in Sydney would be appreciated.

The real point of this post is to introduce those who wish to build, experiment or design your antenna for your specific requirements to a web site dedicated to this purpose. There are some VERY knowledgeable people available to help. The bonus is that these builds area fraction of the cost of purchased "Box" antennas and in some cases are proven to have higher gains than those available commercially.

Enjoy this excellent site
http://www.digitalho...splay.php?f=186

Regards

#2 mtv

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Posted 24 February 2012 - 05:05 AM

If you are intending to watch TV in the major Australian cites, most channels are VHF channels 6-12.

#3 Canuck Eh!

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Posted 24 February 2012 - 06:07 AM

If you are intending to watch TV in the major Australian cites, most channels are VHF channels 6-12.


Ouch! Thanks for the heads up. After going back to the "MySwitch" site I realised I wasn't interpreting the channel numbers correctly. The real channel numbers are only found under the transmitter details. Looking at the available channels list it "Appears" they are mostly UHF channels. VHF antennas are a whole new ball game size wise. Darn, this makes it tougher for a portable unit.

Regards

#4 Canuck Eh!

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Posted 24 February 2012 - 07:41 AM

Found what would work well for your channels 6-12, essentially equivalent to our VHF Hi. Could be made from metalised foil tape and sewed to fabric or unsupported 10awg wire with or without reflector. Small size of 23inch diameter and with reflector has possible 6-7.5 dBi gain. There is also a modification to use this up to about 700 Mhz (channel 51).
VHF only antenna http://www.digitalho...ircular antenna
VHF (3.3 - 40 dBi) + UHF (6-9 dBi) antenna reflectorless http://imageevent.co...ps/dreamcatcher

I hope these links are useful for other "Travelers". Note they can also be roofmounted, or indoors as a wall mount.

Regards

#5 mtv

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Posted 24 February 2012 - 11:01 AM

Australia uses channels 6-12 and 28-69 both horizontal and vertical polarisation, sometimes a mix of VHF and UHF and even a mix of polarisation in various locations, so it can be quite a challenge receiving them all in some places with a single antenna.

#6 alanh

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Posted 24 February 2012 - 08:12 PM

Canuck,
Not only do we have all the transmitters on the same site, we are using DVB-T. The digital standard in Canada is ATSC which is much more affected by reflected signals causing unreliable reception which is much less of a problem for us. Infact the Central Coast of NSW, Newcastle have single frequency networks. This is were a number of transmitters in a region are on the same channel but the polarisation is vertical on one and horizontal on the next closest one.

I suggest you read http://www.dtvforum....showtopic=14026 You should particularly read the transmitter list (listed in geographic order of region) There is separate lists for each state. You may also be interested in reading the antenna basics+ link as well.

AlanH

#7 alanh

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Posted 24 February 2012 - 08:22 PM

Canuck,
I have just looked at your antenna links.
Loops are not popular here. They have much less gain than many of our antennas. Look at the antenna links in the above link. Remember that most antenna gains here are referenced to a dipole. So if you add about 2 dB it will equal dBi.

AlanH

#8 Canuck Eh!

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Posted 25 February 2012 - 09:02 AM

Australia uses channels 6-12 and 28-69 both horizontal and vertical polarisation, sometimes a mix of VHF and UHF and even a mix of polarisation in various locations, so it can be quite a challenge receiving them all in some places with a single antenna.


Yes after looking at the info from "Myswitch" more closely I realised you use both vertical & horizontal polarization,which differs from our broadcasters who only use horizontal (AFAIK). Most of our broadcasters have mostly gone to UHF (our channels 14-51, 470 - 698 MHz), a few still use VHF hi (174 - 216 MHz) and there is the very occasional very low power repeater on VHF lo (54 - 88 MHz) The web site in my first post has a wealth of information that addresses all frequencies (with an emphasis on UHF) and various antenna designs for different applications, some of which have been derived by posters and are not available anywhere commercially .... complete with all measurements, computer analysis and various methods of builds ... some very inventive people .... fantastically rewarding & CHEAP vs commercial stuff. One based on an old design (Gray Hoverman) has been modified to successfully cover both VHF hi & UHF (14-51) is compact & AFAIK has superior gain figures to anything on the market and can be built with many variations dependent on gain & F/B rejection requirements and materials.

Also much used is free software called "4NEC2" used for design, modification & evaluation of antennas. It can easily rescale a proven antenna for one set of frequencies to another .... for example from our UHF (14-51) to your 28-69 and then analyse the build for gain, swr, f/b ratio etc.

As for vert vs hor hopefully I can just rotate what I bring & live with the results, after all I'm looking for portable as a prime concern.
This is a very basic gray hoverman configured with NARODS for UHF & the top of VHF hi. Foil tape sewed to fabic & rolled up when not needed...a couple of dowels to hold the shape & good to go. If I need more gain I can add 2-3 db using a tin foil, mesh screen or ?? reflector mounted about 4 inches behind the fabric.

FYI if interested in some of the work done. Really interesting stuff if it floats your boat & people want an alternative to generic "off the shelf" and wish to build something specific for their location & requirements. There are MANY other types of antennas & applications presented on this forum
.
Portable Foldable Version
http://www.digitalho...t=portable sbgh
post 35 for gain figures with reflector
post 70 is similar to what I'm bringing with an extra strip above & below the driven elements for added vhf hi reception

This thread shows the development for additional VHF gain & these antennas can easily stacked called (DBGH) for really serious gain.
http://www.digitalho...ead.php?t=99907
Note that since they are home brewed they can modified as conditions require. They can't do both hor & vert polarization but how often would that be required at one site? There, as here, each site will have specific requirements.

Thanks for the feedback. This whole exercise will be a fun & learning experience. After NSW we're off to camp around the North Island of New Zealand. I understand they still use VHF lo frequencies so that will be a challenge for portability. Other than a folded dipole, I can't think of something simple, light & small.

Regards
Warren

#9 nbound

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Posted 25 February 2012 - 09:43 AM

Be aware in some places some or all the channels will be above CH51. Until we restack* in a few years time, we'll continue using channels upto a little over 800MHz.

* - We are moving all our tv channels into contiguous blocks so one transmitter would be Channel A,B,C,D,E,F and a nearby one would be G,H,I,J,K,L. Amongst the benefits is that antennas would only need to cover a single group of stations, and you would only require 1 aerial to receive all your stations in most areas.

After the restack we'll no longer be using above roughly 700mhz. Enabling mobile phones and other technologies to use the newly freed space,

Edited by nbound, 25 February 2012 - 09:49 AM.


#10 Canuck Eh!

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Posted 25 February 2012 - 09:56 AM

Thanks Alan
I'm aware of the different standards & am bringing the correct USB tuner.
I have found MySwitch & will access it while on the road for transmitter characteristics in the area I find myself.
Since anything I bring will be light & portable a simple rotation of the antenna should solve the polarisation problem on a station to station basis. I won't be at all concerned to flip it around as required....I'm on the road not in a house.

Since I'm toting what antenna(s) I think I will need in my luggage from Canada they will have to be light, small and still give reasonable performance. The higher frequencies (UHF) are a snap using a SBGH which if you check the specs above is very impressive. I have 2, one of which is the folding version with attachable reflector elements & can reliably pull in stations from 50+ miles away, the other is a fabric mounted version for indoor use without a reflector. The fabric version with NARODS is what I'll be bring for UHF & limited VHF hi. See post above for link & information.

The loop antenna at 23 inch diameter makes a good, small & decent performer for VHF hi, much better than a dipole (rabbits ears) or even a folded dipole. With a reflector mounted for increased gain it's very good for it's size .... that's my main criteria. Plus I can make one anywhere in ony a couple of minutes.

If I was a resident & wanted an antenna for the 174 - 230MHz range I'd probably bite the bullet & fab a small yagi or a modified SBGH as linked in the above post. Build your own types are entertaining & you can design for your own requirements.

FYI the following is a link to the available UHF digital stations I have on my property on an island off the coast of British Columbia Canada. It shows the direction, distance & strength of each station at my location. I can reliably receive the top 4 stations with the portable folding unit with reflectors mounted 15 ft above ground. Pretty good considering the signal strength available for something like this.

select the bullet "only digital" under the "pending" list. Should list digital real channels 35, 19, 24 & 49 http://www.tvfool.co...d9e7456d5fa66e4

Regards

Edited by Canuck Eh!, 25 February 2012 - 10:31 AM.


#11 Canuck Eh!

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Posted 25 February 2012 - 10:18 AM

Be aware in some places some or all the channels will be above CH51. Until we restack* in a few years time, we'll continue using channels upto a little over 800MHz.

* - We are moving all our tv channels into contiguous blocks so one transmitter would be Channel A,B,C,D,E,F and a nearby one would be G,H,I,J,K,L. Amongst the benefits is that antennas would only need to cover a single group of stations, and you would only require 1 aerial to receive all your stations in most areas.

After the restack we'll no longer be using above roughly 700mhz. Enabling mobile phones and other technologies to use the newly freed space,


Hi nbound

Yes I did note that you have some stations using up to channel 69, but for my purposes the gain loss vs the number of stations I will likely encounter I think I'll be OK. After all this is a vacation on the move not a permament location. Using the available software the SBGH can easily be resized for your upper frequencies .... essentially shifting from 14 - 51 to your 28 - 69. It would be slightly smaller.

If I was a resident & was primarily interested in the restack UHF I think I would seriously take a look at tweaking the SBGH (or even the DBGH) people have developed on the above noted site. Since the frequency range would be smaller (526 - 694 MHz?) than our 470 - 698MHz some additional gain might be realised.

I just love the idea that all your stations are transmitted from a single tower. It sure would make life here easier rather than trying to pull in stations of varying strength and from different directions. Everything becomes a compromise. The fact that it MAY be possible for you to chose which towers you wish to use might make antenna selection easier also. That would depend on what was receiveable reliably from each tower I guess.

Regards
Warren

#12 mtv

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Posted 25 February 2012 - 10:38 AM

Warren,

Just to clear up any misunderstanding.

Most Australian transmitters are on the same 'site'... but not necessarily the same tower/antenna array.

There are also some which are in close proximity, but not on the same site.

Have a read through the locations of transmission sites in the ACMA handbook.

I'm sure you'll find a wealth of information in there.

http://www.acma.gov....DARD/pc=PC_9150

Edited by mtv, 25 February 2012 - 10:40 AM.


#13 nbound

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Posted 25 February 2012 - 10:42 AM

I just love the idea that all your stations are transmitted from a single tower. It sure would make life here easier rather than trying to pull in stations of varying strength and from different directions. Everything becomes a compromise. The fact that it MAY be possible for you to chose which towers you wish to use might make antenna selection easier also. That would depend on what was receiveable reliably from each tower I guess.

Regards
Warren


Yeah, rotors are completely unheard of here outside of satellite dish use. On each transmitter the stations are also equalised in transmission strength. As for choice, most tv markets have a single high powered transmitter, and then smaller ones of varying transmission strength to fill in areas otherwise unfilled. In some areas you can get good reception from stations outside your market area, but usually the only difference is news bulletins. Australian TV channels are highly homogenised, and unless your near a larger state capital (the metro stations which the regional networks largely re-relay do have -some- different scheduling) there is no point at all getting out of area reception if a local alternative is higher strength at your location. The extra community station present in the larger capitals also is broadcast at a much lower power level (except in perth, surprisingly), and is therefore a very poor candidate for out-of-area reception.

Previous to the early 90s we had a situation somewhat similar to yours, where the larger capital cities had 5 networks (3 commercial, 2 government), and each market area had 2 tv stations (one local commercial, one government), Though most places outside of the city fringe markets would struggle to receive 1 if any other transmitters from outside their region, owing to the distances between them, and the topography of the east coast.

Edited by nbound, 25 February 2012 - 10:49 AM.


#14 alanh

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Posted 26 February 2012 - 12:16 AM

Nbound
The only channel groups are A - E in either horizontal or vertical polarisation this means 6 RF channels per site. So there are 30 RF channels available.
The geographic spacing can be closer between a pair of transmitters on the same channel where the polarisation changes from horizontal to vertical or vice versa.

Warren
Remember that in NZ all transmissions are between 520 - 694 MHz. and that DVB-T modulation and MPEG-4 compression is used. Their channels match Europe in being 8 MHz wide.

Alanh

#15 Canuck Eh!

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Posted 26 February 2012 - 06:33 AM

Warren,

Just to clear up any misunderstanding.

Most Australian transmitters are on the same 'site'... but not necessarily the same tower/antenna array.

There are also some which are in close proximity, but not on the same site.

Have a read through the locations of transmission sites in the ACMA handbook.

I'm sure you'll find a wealth of information in there.

http://www.acma.gov....DARD/pc=PC_9150


Thanks for the clarification re: site vs towers

Weath of information indeed...bit of an understatement...that document pretty much covers it all. Is there a similar one for New Zealand? I haven't found anything that really has any detail.

Regards

#16 Canuck Eh!

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Posted 26 February 2012 - 06:49 AM

Warren Remember that in NZ all transmissions are between 520 - 694 MHz. and that DVB-T modulation and MPEG-4 compression is used. Their channels match Europe in being 8 MHz wide. Alanh


I didn't realize they were actually broadcasting now in digital on UHF. If so, in all areas of the N. Island that makes life golden.

In N.Z. as well as Australia they list all their channels using logical channel designations (or so it appears) and thus the untutored (me) assumes they are still using the VHF analog frequencies. Trying to find the actual broadcast frequencies & what is presently available in various locations is like trying to pull hen's teeth. Why not state in plain language what REAL channels are available in broadcast areas (in Australia that info can be found on Myswitch if you look deep enough). Yes, I know a full scan should work, but knowing what is really there seems to make more sense to me......maybe that's the problem...me.

I'm not sure if the KISS principle should be used or if it is in use & I'm too dull to catch it.

Regards
Warren

#17 nbound

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Posted 26 February 2012 - 07:55 AM

Be aware in some places some or all the channels will be above CH51. Until we restack* in a few years time, we'll continue using channels upto a little over 800MHz.

* - We are moving all our tv channels into contiguous blocks so one transmitter would be Channel A,B,C,D,E,F and a nearby one would be G,H,I,J,K,L. Amongst the benefits is that antennas would only need to cover a single group of stations, and you would only require 1 aerial to receive all your stations in most areas.

After the restack we'll no longer be using above roughly 700mhz. Enabling mobile phones and other technologies to use the newly freed space,

Nbound
The only channel groups are A - E in either horizontal or vertical polarisation this means 6 RF channels per site. So there are 30 RF channels available.
The geographic spacing can be closer between a pair of transmitters on the same channel where the polarisation changes from horizontal to vertical or vice versa.

Alanh


I was using the letters as placeholders for numbers, the exact block channels used are of little importance to this thread. I was not refering to a transmitter using 6 contiguous blocks, which as you are oh so fast to point out would seem a little silly.


In N.Z. as well as Australia they list all their channels using logical channel designations (or so it appears) and thus the untutored (me) assumes they are still using the VHF analog frequencies. Trying to find the actual broadcast frequencies & what is presently available in various locations is like trying to pull hen's teeth. Why not state in plain language what REAL channels are available in broadcast areas (in Australia that info can be found on Myswitch if you look deep enough).


http://www.acma.gov....DARD/pc=PC_9150

Open the PDF (Television by Area Served would be most useful for you), find your location and tada. :)

Edited by nbound, 26 February 2012 - 07:56 AM.


#18 Canuck Eh!

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Posted 26 February 2012 - 09:47 AM

nbound

Thanks but this is the same link that mtv posted above. I still haven't found anything similar for New Zealand. It must be available but I'm just not using the correct search criteria I guess.

Regards
Warren

#19 nbound

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Posted 26 February 2012 - 10:28 AM

nbound

Thanks but this is the same link that mtv posted above. I still haven't found anything similar for New Zealand. It must be available but I'm just not using the correct search criteria I guess.

Regards
Warren


Theres a listing here:
http://en.wikipedia....al_Transmitters (this info is the only channel listing ive seen - appears to cover the digital transmission only)

Good Info here (including coverage maps):
http://www.freeviewnz.tv

Though that wont get you some of the regional still currently analogue stations (some of which I beleive are on VHF, as opposed to the UHF digital services), which you may or may not want to watch anyway. Though these may have started upgrading im not too sure.

Also:
http://www.goingdigital.co.nz/

But seems to be a further simplified version of the Freeview NZ website.


I do love how you can live in Central Auckland, and still they have no issue with you mounting up a dish for free to air channels. Of course thats due to the less regulated state of NZ TV

Edited by nbound, 26 February 2012 - 10:47 AM.