Wednesday, April 29, 2009

Telcos and dark fibre

My institute's magazine is superb - unlike most industry/free rags it is readable and reminds me of how good Scientific American was in the eighties. One of the best articles last week was on the amount of dark fibre there is in the world. The link (above) is to the article;

The telecommunications industry built too much fibre-optic network capacity during the 1990s. Companies such as KPNQwest, FLAG, Global Crossing and Tyco borrowed too much money and laid too much fibre, and suffered the consequences. Is that over-capacity still present? It’s not clear.

This diagram is missed out of the HTML version of the article.

Friday, April 24, 2009

Balanced to unbalanced audio - wiring?

Simon, one of our wiremen asked me the following question;
...why do we always cut-back the black core when wiring FST into RCA (phono) connectors?

Back when all broadcast gear drove balanced lines with a proper rep-coil (a 1:1 audio transformer) you could safely bodge-unbalance a balanced line by shorting the cold to the screen and you get full signal across half of the sending rep-coil and everything worked. Nowadays not all equipment drives a balanced line this way - may bits of gear use op-amps to derived the +ve and -ve going halves of the balanced pair (via the inverting and non-inverting inputs - think 741 Op-amp). If you pull one of the signal cores to ground you effectively short one bit of silicon and it sits there warming up. That may not be a problem, but in the case of Avitel distribution amplifiers (well, after 1995) they driver stage burns out after a few months (long after the SI engineers have left!). This exact problem bit my backside when I worked at Oasis TV and all the monitoring switchers in the machine room had unbalanced inputs.
The only downside of using my method is that you loose 6dBs of level, but probably into a piece of equipment that wasn't calibrated (like a DVD recorder or TV). I think that's a worthwhile compromise to avoid the possibility of frying the backplane on audio distribution amps (or suchlike).

Wednesday, April 22, 2009

How can you soar like an eagle when you're surrounded by turkeys?

Graham made that observation!

Saturday, April 18, 2009

Channels Four and Five

I must have made a subconscious connection last week when I saw Al Gore's An Inconvenient Truth film on Channel Four. I made that entry about incandescent bulbs. Although I was glad they showed it I wish Channel Four would be true to their climate change denying past - remember The Great Global Warming Swindle which Channel Four commissioned, transmitted, released on DVD and stood by when Ofcom found it to have misled the public? I made a rather excellent (in my opinion!) blog post here where I also mentioned bulbs(?!)
Anyway - I used to watch Channel Four a lot ten years ago and Channel Five never - the situation today has almost entirely changed with me watching Five a bit and Four rarely (I did rant on about it after Christmas).
Now then, we do a lot of work for Five and their engineering department are a really nice bunch of guys. I was in their main transmission suite last Wednesday and was surprised to see that although promos, stings, ads and other interstitials come off server main programme segments still come off tape. I did my heart good to see a stack of DVW-500s!

Thursday, April 16, 2009

Best Ringtone

I like a good comedy ringtone - something that is distinctive and makes other people smile. Here are my most recent ones - feel free to download and use them;

So much better than some dime-a-dozen R&B hit!

Tuesday, April 14, 2009

VNC on the Mac

I've been bugging my colleagues for a better VNC client than Chicken of the VNC but nobody knew of one! It turns out that Remote Desktop (which has VNC as a subset protocol) also includes a lightweight client (in Leopard). From Finder do;

Go > Connect to Server and enter VNC://machine-name-or-IP

and enjoy the love - it is a lot more responsive than Chicken as well.

Tuesday, April 07, 2009

Planned Obsolescence and the end of tungsten bulbs

Planned Obsolescence is a terrible thing not only from a consumer's point of view but also it's terrible for the environment. I have an uncle who worked for Osram and he always felt uneasy about the practice (that was very common in the manufacture of incandescent light bulbs) of pumping a transient high current through the bulbs as they came off the production line to ensure they failed after an average of 1000 hours. Without that final conditioning (sic!) a tungsten filament bulb will last tens of thousands of hours. In fact some companies sold those bulbs for many times the price in industrial quantities to users for whom sending a person down the sewer (for example) to replace a bulb hugely outweighed the price of the lamp.
I'm glad the compact fluorescent has put pay to the tungsten lamp, and hopefully LEDs will be the next evolution - they consume a tiny fraction of the current for the same light output.
Let's hear it for the rainforests!

Wednesday, April 01, 2009

Established standards Apple play fast 'n' loose with

  • RS422 - Of only minimal interest to the average user but RS422 is used extensively in television equipment. It is THE remote control protocol for driving VTRs/Telecines/effects machines etc. When Avid, Media 100 and IMmix VideoCube started delivering offline editing machines based on Macs in the early nineties they use the onboard RS422 serial ports to control the VTR and it works (just!). RS422 is a balanced serial standard where the Tx and Rx lines of an RS232 ports are balanced (either in a rep-coil or op-amp driving the line). Merely by providing a Tx pair and strapping one side of the pair to GND isn't good enough!
  • USB - I know the iMac was the first machine to popularise this now-ubiquitous interface but why do Apple provide USB cables with that little lump on the inner edge of the socket? I have to reach for a set of pliers every time I use an Apple USB extension!
  • SCSI - Apple have NEVER used the approved connector - from the very first Mac they used a 25-pin D type and when SCSI reached the v.3 spec (40MBytes per sec) with 50 or 68 pins for balanced working Apple pulled the same stunt as RS422 - balanced with one side of each pair tied to GND!
  • PCI - it's why you have to buy an Apple-specific version of any card more complicated than a USB card!
  • DVI - What was all that stuff with the Apple Cinema Display connector? It was just DVI in a different (more expensive) form.
  • EIDE CD/DVD drives - I lost count of the number of times I had to buy an Apple replacement optical drive that was a standard Sony/LG part but with APPLE FIRMWARE! A £50 drive that costs £250!