TV antennas

Carlo123 · Member

TV antennas

PeterD · Guru

Firstly, there is no difference between an analogue and a digital TV antenna. They all simply conduct electrical signals. They are simple devices and don't know what the signals they are receiving are.

You could start on these threads.

http://www.activeboard.com/forum.spark?aBID=51933&p=3&topicID=32298180

http://www.activeboard.com/forum.spark?aBID=51933&p=3&topicID=24653271

jimricho · Guru

Hi Peter,

Non-techies just talk amongst yourselves for a few minutes wink

I don't wish to get into a pedantic argument here as what you say is in essence correct however there are "external" factors that could easily be (mis)interpreted as implying that some aerials are more suited to digital than others. For example where the analogue signals are on VHF and the digital on UHF. Another situation I have come across at a couple of places is where the VHF (read "analogue") signals are vertically polarised and the UHF (digital but including some analogue as well) are horizontally polarised. I've also been led to believe that the feedline (co-ax) from the antenna can be more critical. I don't know whether this is due to losses or mis-match being more evident on UHF. Perhaps susceptibility of the antenna to multi-path distortion (ghosting on analogue) may be a factor.

At this stage of the digital "roll-out" and the pending closure of analogue I think I'd be looking for an antenna setup that has good UHF performance and has a built in "booster" amplifier and not worrying too much about VHF.

Ok non-techies you can come back now..... I have an "Explorer" antenna that performs quite well on digital. Analogue can be iffy for reasons covered above.

Re the situation at Cervantes, I have no local knowledge of that area but it may be that the signal strength is such that asking any caravan antenna to pick up any signal is a big ask.

Jim

-- Edited by jimricho on Wednesday 12th of May 2010 06:24:25 PM

PeterD · Guru

There is a lot of mystique regarding antennas. A lot of this comes from unscrupulous firms advertising in such a way as to make people think their existing antennas are unsuitable for digital TV. The fact is that the new digital channels are being located on adjacent channels to the existing analogue. This is done so the networks can use their existing transmitting antennas.

The only time this does not apply is where the analogue TV is located in bands 1 & 2, (those channels below CH 6.) In those instances, the new transmitters are generally located in bands 4 & 5 (UHF channels.)

When travelling around you will find areas where there is band 3 channels and this will still apply for digital. Discount the need for a high band VHF antenna at your peril.

You are on the ball when you talk about co-axial cable. If you have long runs of poorly shielded cable your signals will be degraded by interference picked up by the cable. This leads to pixelation and picture drop out. It also caused problems on analogue TV but viewers put up with this when the installers told them it was because they were in remote locations. In the short runs we use this is of less consequence. However, I would recommend you do not purchase cheap cable.

jimricho · Guru

I certainly agree with PeterD's comment re unscrupulous sales people falsly implying that unless you have a "digital" antenna you can't get digital TV.

The "Explorer" antenna I use is primarily designed for UHF but does have an "element" (passive open dipole in techie talk) for high band (band III in techie talk again) VHF reception. It's performance on low band VHF is next to useless but as I have a digital TV I don't find this a problem (for reasons PeterD has outlined above). The Explorer also has the advantage that it comes as a complete kit. Note however that there would be other antennas on the market that are probably just as good.

A quick perusal of the channel allocations reveals that the allocation of VHF channels for digital applies mainly to (State) capital cities although there may be odd instances where this does apply in regional areas.

I do notice however that some of the antennas I see around the caravan parks would appear to be primarily designed for VHF rather than UHF. I still feel that one should give priority to UHF performance over VHF performance if looking for a simple "one size fits (nearly) all" solution to the antenna issue as I would think that most members of this forum would spend more of their time on the road away from the capital cities.

Before jumping to conclusions about the reason for non reception of digital, one should also check that digital TV is available in the area concerned.

Re Cervantes, the only TV transmitters listed are analogue SBS, ABC, and one commercial station, with the only digital being the ABC (in adition to ABC analogue). These are very low power (10 watts and 3.5 watts). The nearest "main" TV transmitters I think would be at Perth and Geraldton, too far away for a caravan antenna. Without local knowledge I could stand to be corrected on this.

Digressing slightly, I recently purchased a "Happy Wanderer TV Signal Finder" which I have found very helpful for correctly pointing the antenna in the right direction and this too can make a difference to the reception quality.

PeterD · Guru

jimricho wrote:
The "Explorer" antenna I use is primarily designed for UHF but does have an "element" (passive open dipole in techie talk) for high band (band III in techie talk again) VHF reception. It's performance on low band VHF is next to useless but as I have a digital TV I don't find this a problem (for reasons PeterD has outlined above). The Explorer also has the advantage that it comes as a complete kit. Note however that there would be other antennas on the market that are probably just as good.

Jim - I think you will find that the Explorer you have will cover the same channels as the DSE one with an added amplifier that other forumites promote. However it does have a performance advantage over the DSE one. I know the performance of it as I carried the Phaselink UHF only antenna and had a separate VHF antenna which was fed through its amplifier (the Explorer antennas use the Phaselink antennas as part of their kits.)

The only reason I ditched the Phaselink was because of its bulk that provided storage problems in my rig. I replaced it with the Happy Wanderer DX Active 1. The performance is similar to the Explorer/Phaselink models with the built in amplifier. I think you will get the best available performance with any of these antennas I have mentioned in this posting. Forget those stick, dome or non-directional antennas.

Carlo123 · Member

Thanks for your advice guys. At the moment I am tending towards buying an amplifier rather than changing my antenna. Any thoughts? Also I was reading in "the nitty gritty of caravanning" that I might have needed to retune the TV. The bloke at Harvey Normans didn't think I would need to retune as I travelled around the country but who knows. I need to get this sorted before we set off to Broome in a few weeks as my wife won't be happy if she has no TV for the next few months.

jimricho · Guru

Carlo123 wrote:

Also I was reading in "the nitty gritty of caravanning" that I might have needed to retune the TV. The bloke at Harvey Normans didn't think I would need to retune as I travelled around the country but who knows.

Sounds like another piece of crap advice from some pimply faced ex-MBF (Maccas Burger Flipper) at Harvey Norman. (I wonder how long it takes HNs and Dick Smiths to untrain these nerds from asking "would you like fries with that?")

Yes you (most likely) will need to "retune" or re-program your TV when you move to another location. This is usually just a case of "drilling down" through the menu options and setting the TV to do a "channel scan". The TV will then automatically "retune itself". This can take up to a few minutes (about half to one stubby while you're waiting, depending on how thirsty you are). Check with the TV's instruction book to see how this is done (after first translating it into English from Chinglish or Japlish)

Note also my comments above about having the antenna pointing in the right direction.

re new antenna/new ampilifier, sorry can't help much without checking out your existing set-up (not easy as I live in Newcastle and you're in Perth), so it might be a good idea to have someone knowlegeable in these matters (NOT a DSE or HN ex-MBF) have a look at it for you.

PeterD · Guru

The less efficient stick type antennas benefit greatly with an amplifier. Their performance may not be as good as the ones I have talked about earlier, but many have been satisfied with their performance.

Having said that, you will still find a few spots where my choice of antenna will romp home while the lesser amplified antennas are really struggling. The other thing when comparing these antennas is changing positions in the park can have a significant effect on the signal. I hav had times when I have shifted the antenna from one end of the van to the other and have gone from an extremely bad picture or nothing to something that is watchable.