In car TV

[Casper]

A while ago a mate showed me his in car TV set up for his kids on trips and when I put a new Stereo in Cleo (98 Disco( Kenwood head unit with all the fancy extras that you rarely use)) it is able to act like a DVD player just plug in a screen and with an appropriate arial is meant to be a DTV tuner as well.

My question is, where do you find an appropriate antenna, the one on my mates car is a different plug and being an older unit is analogue and I would need one suitable for Digital.

Is it worth getting the screen?

How good are they on the go?

e.g. sitting in traffic not in the middle of the bush obviously.

Cheers Casper

[VladTepes]

I've seen in car TV's that work fine. Analog ones I;ve seen do sometimes have problems in town though as no direct line of sight to the transmission towers, so signal quality can be degraded.
No idea at all what issues there would be with digital.

Is it worth it? Who knows. Will it shut the kids up? There's your answer.

[RangieBit]

Yep,

I'm with Vlad on this one. The real answer on this is ...... it depends. The best performing mobile DTV installations I have seen have been very carefully researched and set up. The most recent one I came across used an omnidirectional (and amplified) dome antenna in the spot usually reserved for the GPS antenna on the roof of the car.

Good results have been obtained with discriminating antennas (two antennas and electronic smarts to figure out where the strongest signal is coming from) and a high quality DTV tuner.

Around the big cities (not right inside the concrete canyons) you might get good reception from a simple on-glass antenna (or even the existing glass mounted radio antenna) and the included tuner. You might also get absolutely crap results.

FWIW the factory supplied DTV systems all seem to provide more than adequate results. These tend to use the two discriminating antenna setup. If your ride didn't come fitted with one of these systems then the next para applies.

If you really want and need good digital TV in your ride, be prepared to spend lots of time and oxford's to get a good result. Experimentation is the key here because no two cars or systems are alike.

That's my 5c worth.

Cheers,
Iain

[101RRS]

My GPS has DTV as a function - works OK near the transmitter but it is only standard definition. Are there car systems that that can receive Hd stations as well. If so what is the techo name for it - sd is DVt - mpeg4.

I have been looking at some double din dvd/gps systems and while I do not really want tv they seem to come with it but is all sd rather than HD.

Garry

[RangieBit]

Hey there Garry (and others),

I could be mistaken here but the only DVB units for in-car use that I have seen have all been SD only. I think this is to ensure reasonable picture quality. The data stream necessary for SD (bits/sec) is between 1/10 and 1/4 of what must be maintained to get a HD picture. By going with SD this ensures that you will get reasonable reception somewhere near a major centre.

An example of this can be seen by anyone living on the fringes of a major city. They can get terrific reception of the SD channels rain, hail and shine but as soon as the weather turns bleak they lose the HD stations. This is because their installation is sitting close to the cliff edge of reception.

Just like digital mobile phone technology, DVB is either there, or it's not. Analogue signals just get progressively worse until they become unwatchable. DVB has great picture until it falls over that cliff and then it disappears. You might get a bit of pixellation or sound dropout just before it happens but overall picture quality is pretty good, right up to the point where it's lost. The more bits in the datastream you have to decode, or more importantly have to recover, the harder it is to maintain picture and sound.

SD reception means that the DTV tuner doesn't have to work so hard at decoding and recovering bits to produce an acceptable signal. HD means you need a much faster processor to decode and recover, and you've got LOTS more bits of TV data to deal with each second. SD can still look OK with errors in the vicinity of 1 per 1000, HD needs less than 1 per 10,000 to be barely acceptable. Much harder to do this consistently unless you're sitting in direct line of sight to the transmitter.

None of this is to say that you couldn't get HD reception in your car, just that you'd have to work VERY hard to get it to an acceptable level.

Normal HD DTV reception can be pretty hard to achieve in the home where everything from the antenna to the set is fixed in place, let alone in a vehicle that's moving around with an antenna more generic in it's reception characteristics!! I know, I have done home DTV installs - many times!! Moving the antenna on the roof half a metre can make the difference between great reception and no reception.

Hope that helps some.

Cheers,
Iain