Tuesday, February 26, 2008

Single mode fibre

Last week we did our first single-mode ('mono-mode') fibre job at Molinare. They are doing a job for the Beeb at Pinewood where they have to extend a dozen circuits provided by SohoNet for KVM and HD-SDi extension (the DS-Nitris editing station lives in Soho but the editor sits in Pinewood).
Anyhow - some things we discovered about single-mode over our usual multi-mode are;

  • For loose tube cable you really can't tell the difference between the skinny 9-micron and the relatively fat 62.5 micron fibres because the cladding on the glass is the same width - 125 microns (see the diagram). In fact, when you prepare the ends and get them into the fusion splicer you are hard-pushed to see the difference.
  • For testing you need to use a mono-mode light source and detector and the appropriate test leads. Thankfully Darren at DIS sorted me out with his tester. I'm going to look into buying one if we do more single-mode.
  • The Tritec Fase-2 splicers that we use have a mono-mode config that runs the laser cooler so that the little centre-core isn't blown away by a beam intended for the bigger cores.
For a quick explanation of mono-mode fibre see the Wikipedia article (link in the title).

Saturday, February 23, 2008

My Wiki

I've been wanting to implement a Wiki for ages. Here is a first stab using TiddlyWiki as a starting point. I'm not sure what I'll do with it - if I can write a script to move this blog there I will.

Wednesday, February 20, 2008

Hamachi for OS-X

My life is complete!

Monday, February 18, 2008

I wish I was this funky!

I'm too white.

Sunday, February 17, 2008

Jeans, t-shirt and not shaving!

Pretty much every job decision I have ever made has had (if not the primary concern!) appearance as an important factor. When I started at the Beeb it was a revelation that you could do a graduate technical job and get paid a decent wage wearing jeans and t-shirt. Since then I've enjoyed the fact that in our industry doesn't judge by appearance. I regularly don't bother to shave from Monday to Friday and nobody assumes I'm an ineffective engineer/project manager as a result. In that way (and not many others!) maybe television is the most egalitarian of workplaces. My qualifications and record are all that matter and the cut of my clothes is irrelevant. I suppose that makes entire sense - why should your apparel have any bearing on how honest or competent you are?
One final thought - you know that the guys who masterminded the Enron scam (and in fact any other incident of massive business fraud) were wearing suites costing many thousands of dollars. Perhaps your personal integrity is in inverse proportion to the value of the clothes you wear - or perhaps there is no relationship!

Friday, February 15, 2008

A trip down misery lane

Here are a few pictures from the original install of Oasis Television's building on Great Pulteney Street. Remember when edit suites cost £500k and had many pieces of equipment that all had to talk to each other! I'm the fresh-faced chap on the right of the sofa and the other chap is my old mucker Chris Clegg. The other reprebates were my wiring team - Amos and Jim are still in the industry and Tony (on the right) is sitting behind me in the workshop today! Both of us have more grey hair now.

Thursday, February 14, 2008

My Friend the Chocolate Cake

My Friend The Chocolate Cake's music can be seen to straddle the worlds of ambient and world music, with an emphasis on piano and violin-led acoustic music. My chum Keith Gibbons got me into them sometime in the mid-nineties and I've enjoyed picking up CDs ever since - a good starting point would be 2002's album Curious. Anyhow - I bought his (their debut) online last night and have been enjoying it since. The version of A Midlife's Tale I had on a sampler CD is totally different and this whole album (origionally from 1991) sounds as fresh as anything released in the last year.

Tuesday, February 12, 2008

Installing an OS on a Toshiba Portege M200

I've spent a day or so puzzling how I was going to install Windows on one of these machine that had a corrupt boot-sector (and so couldn't boot). The manual says you have to use an official Toshiba CD-drive and hunting around the web suggested you could boot off the SD card slot. Both of these were impossible (my USB CD drive was a no-name one that the BIOS didn't recognise and the boot image I wrote onto the SD card couldn't load a DOS-mode USB optical driver).
However - all credit to Brian and Simon who discovered that by using one of these they could boot it off a regular IDE CD-Rom drive.
Job done!

Monday, February 11, 2008

Jack Johnson on BBC Radio 2's Music Club

Radio stations taking space on the tele! Whatever next? I culled this from the BBC Freeview interactive service a few weeks ago.

Thursday, February 07, 2008

Common problems with ethernet networks

The ugly face of the overdraft is stalking me and so I'm back onto freelancing in the evenings. I was at an interesting place last night - a film effects company who were having big trouble with their network. Windows shares that would sporadically not mount, name resolution that sometimes didn't work and file transfer speeds that often dropped to just a few kbits-1. They are running a mixed Linux/Windows/Mac network and so it seemed like the problems would be due to some underlying infrastructure issues. They have a Windows server running Active Directory with DHCP, DNS and WINS resolution - the reason for both WINS and DNS is that their render manager only talks NetBIOS names and won't resolve via DNS. Here are the problems I found;

  • Sharepoints is an OS-X app that makes sharing directories over Samba as easy as under Windows - it seems to add little extra value compared to using the Sharing control panel. One little gotcha is that there is a check box marked 'announce as master browser' which on all the machine I found was selected. Looking in the Windows server system error log showed numerous entries (many every minute) where the server was complaining about all the Macs trying to assume master-browse status. Unchecking sorted this and name resolution for the Windows machines improved markedly.
    Now, there is a well-established order for Windows browse master allocation - server, workstations etc. There will be at least one Master Browser on a workgroup/domain and one Backup Browser for every 32 systems in that workgroup/domain. This means that in a domain/workgroup with fewer than 32 systems, there will be one Master and one Backup Browser. One more Backup Browser will be added for every 32 systems. This is accomplished by the Master Browser telling a Potential Browser to become a Backup Browser. The browse service maintains an up-to-date list of domains, workgroups, and computers and provides this list to applications when requested. For example, a W2K user might see this list when they select a workgroup to which the user's computer does not belong from within the "My Network Places" application. "Browse lists" can also be displayed by using the "net view" command. The list can contain the names of domains, workgroups, and computers that run file and printer sharing services. These computers can be Windows for Workgroups (WFW) through XP machines, including both workstations and server, or any Samba shares that are in that subnet as well. Both domain and workgroup (if present) resources will be shown in these browse lists. So, having numberous Macs trying to bum-rush the show as browse masters is not a great idea!

  • The network seemed to have a good beginning - a couple of HP ProCurve 2800 and an 1800 all uplinked over 2gig fibre via SFPs. I discovered that one of the uplink ports was dead and so someone had 'got it going' with a cat6 between them. However - the failing port was intermitent and so periodically you'd get connectivity via two routes and a packet storm would ensue! I switched the SFP to a working port, re-established the fibre and removed the cat6 interconnect and it suddenly got a lot more solid! The HP ProCurve manager software is very good for identifying this kind of trouble.

  • This network had grown 'organically' (sic!) which means that where they needed more ports (an extra render-farm, for example) they had thrown in a Tottenham Court Road special - Netgear/DLink/etc. This had happened one time too often and so there were several pieces of equipment that were separated by four (or even five) ethernet switches - you run into the problem of the protocol retry period being less than the propigation delay through that many nodes. I nominated one of the ProCurves and made sure that all the switches in the place hung off that (and hence no two machines had more than three switches between them) and the servers all hung off that ProCurve.

So - there you go - I got home tired but really happy that I'd managed to sort some things out. I don't know how some of these little effects houses manage without engineers. I really like getting back to trouble-shooting and maintenance (and hopefully clearing down some debt!).

Wednesday, February 06, 2008

Do non-integer frame-rates confuse you?

It's something that people ask me about all the time - 23.976fps seems particularly perplexing. It all related back to NTSC being 59.94 fields and the need to transfer film (and now HD 'electronic film') back to 29.97fps (the 3:2 pulldown equates 29.97 to 23.976). So why didn't they stay with 60 fields when NTSC came in? Apparently it is all down to someone at the SMPTE thinking that the cross-talk between colour sub-carrier and the audio carrier causing in-vision intereference. Subsequent experimentation showed that this wasn't the case but by that point in 1956 29.97fps and hence drop-frame timecode (and the four-field sequence) were with us.
Anyhow - the most coherent explanation of all this and how it relates to HD frame rates can be heard in this week's Schubin Report.

Tuesday, February 05, 2008

Pirated by iTunes, Artist Turns to BitTorrent

The Flashbulb, aka Benn Jordan, became so outraged when he discovered that iTunes was effectively pirating his music, that he uploaded copies of his latest album to BitTorrent. TorrentFreak caught up with Benn to learn more about the decision to stop distributors and ‘coked-up label reps’ from getting all the cash.

Sunday, February 03, 2008

You know you're getting old when.....

You take your nine year-old to the Science Museum for the day and you see half a dozen bits of software and equipment in glass cabinets that you used to work on or fix during your career!

Here is an Ampex AVR1 2" video recorder - although we didn't have this model at the Beeb we did have AVR1000s. You can also see an Apple 2, a ZX80 and a copy of Windows 3.11

They also have Technics 1210s and a Phillips 1700 series VCR. On the right is a Cray-1 which looks like a masterpiece of engineering. It is well worth a visit and the have a whole gallery dedicated to telecomunications. I would have spent the day in there but for two nine year-old who wanted to see the rocket show!