Category Archives: Multimedia

Antenna saga

As part of the ongoing antenna saga, the weekend before last I acquired some coax from Bunnings (I thought 20m would be plenty – wrong! Just enough), and a mast. I mounted the mast on the facia and strung the coax up in the roofspace, and left it at that.

This weekend it rained cats and dogs Saturday and I was out of the house until mid-afternoon Sunday, so I wasn’t left with much time to finish the job before sunset Sunday. But, like a fairly well oiled machine I managed to disconnect the antenna, loosen all the bolts that needed loosening, cut it down, fold it up, drag it to the manhole, try putting it through, pull it back out again, fold it up better, put it through the manhole, drag it outside and up to the roof, mount it (very cool that the mounting bolts were still hanging on the antenna even though it had originally been hung in the roof space), realise there wasn’t a hope in hell I was going to hook up the coax with the antenna floating out in the air like that, dismount it, hook up the coax (noticing of course how easy it is to slice through the braiding when slicing through the plastic sheath and having to do it again), discover that the weather sheild for the connector was knackered and ‘repaired’ it with a metre of electrical tape, remount it, discover the mounting bracket was on back-to-front, remount it, tighten up all the bolts, tape down the coax to the mast and return to ground level just as the sun set.

A very tidy piece of work, which only required me to attach the other end of the coax to the splitter and away we’d go. My figuring was, hook what we’ve got into the splitter and I’d see how the picture was and make adjustments later; worst case scenario was that our TV reception for a week would consist of bunny ears. Except the modern coax differs from what’s already in the house in two ways: firstly, it’s aluminium shielded instead of copper; secondly it’s smaller and thus the mounting clamp in the splitter wouldn’t actually grip the de-sheathed coax. I ended up creating a solid mechanical connection by restoring the sheath on the top half of the coax.

Testing revealed a miraculously improved analogue picture quality, including rock-solid SBS reception and Channel 31 visibility. Some negative ghosting was evident, and the Channel 31 picture could improve a little more, so perhaps there will be some fine tuning of the direction next weekend utilising the advanced technolgoy of our radio phone. The splitter doesn’t seem to be detracting too greatly from the signal, so it could be staying. I ought to get some 75 ohm resisters ‘tho. I think there are only two active leads from the four-way splitter.

Signal strength reported by the HDTV cards on all channels has improved to the 95-98% range.

HDTV PVR: heartbeat

I tried hooking the cards up to the included antenna. Far worse than the bunny ears. Hooking the cards up to the house antenna made things a lot better. Channels nine and seven are 98% strength, two and ten are passable at ~80% strength, and SBS, with just 60%, is unwatchable.

My house antenna is a funny beast. I can’t find it. It doesn’t have a presence on my roofline. I have to go up into the roofspace this weekend to see if its one of those magical in-roofspace antennas, but I don’t think so. There used to be an antenna mount on the back of the house, which you can tell by the holes and lack of paint at that particular spot. I’m thinking a better antennna (or maybe even having an antenna) will improve the reception.

I’ve also got it doing output via the video card to the TV, but it’s not ideal as it stands. The TV software wants to put a grey boarder around the picture, which is fine if you’re watching a monitor, but bites arse if you’re watching a TV. And, not surprisingly, 16:9 doesn’t look that big on my 4:3 TV. Hopefully switching to PVR software like MythTV will help with this.

As for noise, the plan is to have the box in the next room and run cabling through the walls. Quieter. But it will make loading a DVD a pain in the butt.

So, more problem fixing, but given the hardware seems to work, I’m going to start fiddling with the OS next.

HDTV PVR: intial impressions

I use my video purely for timeshifting – watching a show that screens at midnight at a more socialable hour. But the quality leaves a lot to be desired.

My grand plan is to retire the VHS recorder, replacing it with a shiney new digital thingy – a PVR, Personal Video Recorder. Which you can buy off the shelf, one or two grand (AUD). And I would. But, then again, I’m a geek, and that means why buy something when you can build it yourself for twice the price and with the enormous expenditure of your own time?

For example, it would be nice to be able to burn TV onto DVD. And most PVRs have a single tuner – while we all know that TV stations schedule the show you want to watch at the same time as at least one other you want to watch; you can only record one; and, incidentally, you can’t watch the other unless you have another digital receiver like a settop box (I’ve seen ’em for $80 at Safeway). Sure, you could tape one and watch the other, but that doesn’t work so great at midnight when it’s a schoolnight. And most PVRs are Standard Definition, not High Def – and if you’ve had the misforturne of trying to watch a SD signal, you know it doesn’t hold a candle to analogue (I’m not going to take a step back here). The biggest hard drive you’ll find in a PVR is 120Gig, and that’s the super-top-end-gee-whiz unit; most come with 40Gig – which might be fine with SD, but bites when recording HD at 15Gig/hour.

So in general, PVRs suck arse. I’m gonna build my own.

I got the bits last night – bottom end PC, two tuner cards (different brands – for reasons that will become apparent), 200Gig HDD (I figure I’ll upgrade to a decent sized RAID array later). Loaded up Windows (I’m using it to prove the concept, then swapping to Fedora 3 once I know the hardware’s good), dropped in drivers (God, what a nightmare; it seems like it eventually loaded) and hooked the whole setup to a bunny ear antenna.

One card can show me Channel 9. That card isn’t happy about the other channels it found, which was nowhere near what’s out there. They’re called things like “Ch@&&el T#n”.

The other card doesn’t show anything, but found all the channels. I think it found Channel 7 twice.

From the bunny ears I’m getting 75% signal strength.

So, now I can play around with recording SuperNanny and Enterprise, but I don’t think there’s much of a future with the current setup. I’ve got to try slightly more sophisticated antenna technologies. And I’ve got to see if I sucessfully can hook my creaky old TV up to the video card – there are a number of adapters that look promising.

I’ll keep you posted.

Josh’s freaky Compaq PC

I’m using a Compaq D5S/P1.7/20j/p/128c/6 AUST

I’m getting whitenoise in the soundcard at work. It’s there all the
time, but drowned out by music. It stops when I have the left mouse button
depressed to select cells in Excel, but releasing it resumes the whitenoise.
Clicking on or selecting stuff outside of Excel doesn’t affect it. Outlook
selections don’t stop it, but selecting stuff in Word stops the whitenoise –
but again, only while the mouse button is held down. Another thing to stop
the whitenoise is dragging splitter bars around in Visual Studio 6. So it’s
not the mouse per se. And just recently, these “fixes” have stopped
working. Stopping a particularly long build restored the fix. Popping up
task manager shows that it seems that the white noise goes away when the CPU
goes to 100%, unless there’s disk activity. Got any suggestions how I can
fix this? And, preemptively, I don’t intend to load the CPU at 100%
permanently for my listening pleasure.