6 replies to this topic

[ashisb]

Hi,

I live in the SE suburbs of Melbourne, having built a house 3.5 years ago. The builder installed 4 TV points and coiled the antenna cable in the roof space for later connection to an aerial by me.

As it turned out, I never installed an aerial because we installed foxtel cable on our main TV and the one TV we used elsewhere worked fine with a set of rabbit ears I had.

In recent times, I've got fed up with the analogue retransmission of 7 and 10 on foxtel, particularly with regard to AFL footy and decided to get myself a set top box for that purpose, realising I was going to need to get an aerial installed as well.

I picked up a Topfield TF7000HT for $194 from Retravision yesterday and plugged it in, pretty much just to see how to set it up. I ran the auto tune, and lo and behold, it found all digital channels and with perfect, uninterrupted reception.

My TV only accepts a maximum of 576P, but both SD and HD channels work fine. My question is, is this to be reasonably expected, or am I just very lucky?

[charlesc]

You are just very lucky it seems.  However, maybe that is in some ways, but not others though...

From what you are saying, the cabling is in place, and presumably runs from a splitter to the four outlets, with a length going upstream from the splitter to where an antenna would mount, this last cable just being coiled.

It does seem very surprising that whatever is being picked up by the cabling is of sufficient level and quality to give 100% reception.  In particular as it probably goes through a 4 way splitter, which would then divide that signal four ways.

Your cabling seems to be acting like an antenna, which maybe doesn't say much for its shielding qualities. That could be the downside.  Are you really receiving no pixellation or sound drop-outs?  Are you close to the transmitters in your area maybe?

[ashisb]

charlesc, on Jun 15 2007, 10:28 AM, said:

You are just very lucky it seems.  However, maybe that is in some ways, but not others though...

From what you are saying, the cabling is in place, and presumably runs from a splitter to the four outlets, with a length going upstream from the splitter to where an antenna would mount, this last cable just being coiled.

It does seem very surprising that whatever is being picked up by the cabling is of sufficient level and quality to give 100% reception.  In particular as it probably goes through a 4 way splitter, which would then divide that signal four ways.

Your cabling seems to be acting like an antenna, which maybe doesn't say much for its shielding qualities. That could be the downside.  Are you really receiving no pixellation or sound drop-outs?  Are you close to the transmitters in your area maybe?

Yeah ... I've got line of sight to Mt Dandenong Transmitters, which are probably 10-12km away as the crow flys.

And although I've only tested it last night and this morning, there is absolutely no pixelation or sound issues.

Oh, and one other thing, our house is double story, on the side of a small hill, above the tree line. Between the house and the transmitters there is very little else but grassed plains and some small hills.

[charlesc]

ashisb, on Jun 15 2007, 10:36 AM, said:

...And although I've only tested it last night and this morning, there is absolutely no pixelation or sound issues.

That is pretty amazing, especially as the transmitters are 10 -12 kms away, not excatly under your nose.  The clear line-of-sight has got to be a plus.  

If you disconnect the fly-lead to the STB from the wall plate, do you still receive an OK signal?  Maybe the fly lead is acting as the aerial, rather than the in-house cabling..

In any case, I'd be getting  a few Lotto tickets...  It must be your lucky time.

[ashisb]

charlesc, on Jun 15 2007, 10:46 AM, said:

That is pretty amazing, especially as the transmitters are 10 -12 kms away, not excatly under your nose.  The clear line-of-sight has got to be a plus.  

If you disconnect the fly-lead to the STB from the wall plate, do you still receive an OK signal?  Maybe the fly lead is acting as the aerial, rather than the in-house cabling..

In any case, I'd be getting  a few Lotto tickets...  It must be your lucky time.

I'll try the lead tonight out of interest. I'm guessing the signal would be pretty good. To put it in context, here is the Melbourne reception area with the transmitters and my house identified:

Picture

[pgdownload]

Definately lucky but not totally unheard of. I sometimes plug my PVR (Toppy) into a TV with no aerial attached at all. Most channels no signal but a couple I get a static sequence of frames. You've got a 10m cable plugged into the back of yours so I'd anticiapate much better. But as mentioned the majority of people trying to get away with no aerial would have major problems.

Regards

Peter Gillespie

[charlesc]

ashisb, on Jun 15 2007, 10:36 AM, said:

...there is absolutely no pixelation or sound issues.

Just a further point on this.

As you may well be aware, digital reception is characterised by three main 'states', unlike analog reception.  Two of these states are frustrating, one more than the other, and even when you are in the third state, you don't always know for how long .

'No reception' is pretty self-explanatory, 'perfect' reception is at the other end of the scale, and in between is the very frustrating area of picture and sound 'breakups'.  Unlike analogue where the degradation is more graceful, digital is basically non-snowy and non-ghosty and there perfectly, breaking up, or not there at all.

The trouble is you might be getting 'perfect' pictures at the moment, but be very close to the 'Digital Cliff' where pixellation and sound glitches start to occur.  These occur because the quality of the signal is getting worse, and there are more errors in the digital signal received than the Forward Error Correction (a key part of the whole DVB-T transmission/reception system) can cope with.

It would be strange that without an antenna on your system, and with the signal already split 4 ways (unless your fly lead is really the antenna in this case) that you would not, on occasion, be dipping into the breakup zone.