Wednesday, April 30, 2008

Fibre Channel - don't go far!

Graham asked me for some thoughts on a customer who wants to site Avid Unity SANs in several buildings and have clients connected over multi-mode -> single mode (and back) media translators. It sounded a bit dodgy so I went digging;

Clarion seem to be the most upfront about cable lengths for one and two gig fibre channel on their storage and they quote 500m and 300m respectively. In all the scenarios it isn't signal loss that's the issue (decent grade multi-mode cable degrades at about 0.5 dB /100m which makes the 500m for multi-mode eminently achievable by even modest splicing). The problem is all down to latency and since Avid expects so much housekeeping of a Unity to happen at the client (mirroring etc) you can see why all the Unity documentation quotes 150-180m (depending on which switch/HBA combo) for client-Unity connection. This (assuming C=2.5 x 10^8 m/s in gallium-doped OM1 glass) means the tolerable latency is around 600nS. This would not be achievable once single-mode media-translators are involved.

In a sense fibre channel is the worst thing to either send a long way and/or run through translation stacks (between it's native multi-mode to single mode and back again). It's Asynchronous but doesn't enjoy IP's fault tolerance and it's handshake'd but doesn't have TCP's dropped packed abilities. Worst of all it's time-dependent because it's video! It's a situation where playing fast'n'loose will end in tears.

Tuesday, April 29, 2008

It's business time - The Flight of the Conchords

Coming soon to BBC4 this is the most original sitcom in years - I'd list Pheonix Nights (and the subsequent Max & Paddy), The Office, Lead Balloon, Outnumbered, and Curb Your Enthusiasm and the best things so far this century. My friend Kevin Cade (who we're visiting next weekend - looking forward to seeing Lucy and the boys for a sleep-over) made me aware of these guys last year with a clip on his podcast;

Sarah and I have been enjoying the HBO series which (as mentioned) will be on Freeview soon;

Monday, April 28, 2008

Nimbus Data Systems, 10GigE press release

With 10 Gigabit Ethernet now available for less than half the cost per gigabit of even traditional Gigabit Ethernet, all of the necessary elements are in place for immediate enterprise deployments.

Thursday, April 24, 2008

Astrologers fail to predict proof they are wrong

Researchers at the Sorbonne did a similair analysis in the eighties when they got their shiny new Cray XMP. I love it when honest old maths shows up dishonesty!

Good news for rational, level-headed Virgoans everywhere: just as you might have predicted, scientists have found astrology to be rubbish.
Its central claim - that our human characteristics are moulded by the influence of the Sun, Moon and planets at the time of our birth - appears to have been debunked once and for all and beyond doubt by the most thorough scientific study ever made into it.
For several decades, researchers tracked more than 2,000 people - most of them born within minutes of each other. According to astrology, the subject should have had very similar traits.
The babies were originally recruited as part of a medical study begun in London in 1958 into how the circumstances of birth can affect future health. More than 2,000 babies born in early March that year were registered and their development monitored at regular intervals.
Researchers looked at more than 100 different characteristics, including occupation, anxiety levels, marital status, aggressiveness, sociability, IQ levels and ability in art, sport, mathematics and reading - all of which astrologers claim can be gauged from birth charts.
The scientists failed to find any evidence of similarities between the "time twins", however. They reported in the current issue of the Journal of Consciousness Studies: "The test conditions could hardly have been more conducive to success . . . but the results are uniformly negative."

Wednesday, April 23, 2008

Duct tape saved Apollo 17 moonbuggy, while on the moon.

I spotted this on BoingBoing - everyone knows that the world is held together with cable ties and duct tape. Little did I realise that it's used off world as well!

Friday, April 18, 2008

Memories of Lime Grove

I was recently supervising a job in White City and took a lunch-break to wander around the market and down to Lime Grove (the first studios I worked at when I joined the Beeb in the eighties). Of course it's all been redeveloped as housing but it was nice to see the fashion college and primary school across the road.

Martin Kempton's site is excellent and will easily kill an hour of work-time! See his pages on Television Centre.

The move of the VT department to stage 5 did not take place immediately. They had to wait for a new tape format to be established before equipping all the suites. This format was the D3 cassette. Developed by Panasonic, the BBC was its first major customer. A few suites were opened in 1991 and used for training but the big move to stage 5 happened in January 1992.

The BBC's post production department had been created in 1989 - combining film editing with VT editing and sound dubbing. This new department was, as its name suggests, more concerned with what happens to the programme after it has been made rather than during it. From 1991, the new D3 cassette enabled each of the studios to be equipped with its own machines which were (and are) operated by the studio resource manager.

Thursday, April 17, 2008

Tin Whiskers

Tin whiskers caused the failure of the Galaxy IV satellite in 1998. At frequencies above 6 GHz or in fast digital circuits, tin whiskers can act like miniature antennas, affecting the circuit impedance and causing reflections. In computer disk drives they can break off and cause head crashes or bearing failures. Tin whiskers often cause failures in relays, and have been found upon examination of failed relays in nuclear power facilities. Pacemakers have been recalled due to tin whiskers

Wednesday, April 16, 2008

Five invests in Signiant

Along with all the SI work we've done recently (building their edit suites, machine room and graphics) Root 6 has sold a Signiant digital media distribution and workflow automation system to Five.

Tuesday, April 15, 2008

eCinema FX24 monitor

A couple of years ago I was getting very excited about the DCM-23 monitor. We'd just started carrying it and I'd enjoyed a couple of days of training by Martin Euredjian. I fell in love with the DCM23 - I thought it was the most faithful monitor for HD around at the time - bar none. For progressive, HD work I thought it was a better monitor than the venerable Sony BVM-D24. As Martin had observed there were so many engineers and colourists who were determined not to admit that an LCD could be useful for grading - they weren't going to be impressed! The biggest moan was that the peak white output of the monitor was only 60 Candelas/M-sq. You find that as luminance tends to zero delta-E (the measurement of a 'just-noticeable-difference') gets smaller. The upshot is that if you are serious about grading you will drive your monitor a bit cooler than the average 80 Candelas/M-sq you'd set an edit suite monitor for (that aside I often go to Soho edit suites to calibrate the monitor and find the editor is happily running his display at 160 Candelas/M-sq!).

Small side-note concerning units of luminance - I know a lot of folks quote it in Foot Lamberts but this is a terrible measurement - it assumes monitors are a point-source of light (they aren't) and it is a mix of SI (Lambert) and Imperial (foot) measurements - don't use it! Far better to use the SI unit of the Candela per square metre.

Anyway - we recently got in on demo a new eCinema FX24 - it's their budget range LCD display for HD work and when I first fired it up I thought that it looked pretty good but a bit dim (the 60/80 things already mentioned). Today I had a chance to stick it next to a JVC-tubed monitor that I'd just calibrated (putting the white point at 6500k and 60 Cd/m2) and I was really disappointed. I estimate the peak-white light output to be around 20 Cd/m2 and although the colour in the blacks was OK the whites were somewhat off tending towards red. The monitor seemed to lack dynamic range with subtly graduated objects on the CRT looking very flat on the LCD. I turned the tube off to make sure it wasn't pulling my eye and felt the same way after watching half an hour of real-world cameras footage on the FX24.
Perhaps I was expecting another DCM23 but this was not up to that monitor's high standard. I'd say it is better than a Sony LMD-series LCD broadcast monitor (but that ain't saying much). I shall write a bit more when I have chatted further with Martin at eCinema).

Update: Martin from eCinema sent me some helpful comments;

....BTW, color temperature can be adjusted manually from the "Color Temperature"
menu. There are RGB sliders that can be manipulated to fine-tune the default calibration to your liking.

BTW #2, be sure that you've set the backlight to maximum brightness (hold down MENU button and press the UP or DOWN keys to adjust) and have allowed enough time for the tubes to warm-up (about 15 min).

Yes, FX is a budget monitor. Comparing it to a CRT wouldn't make it shine.

Here's a way to look at it. It is a great monitor for entry-level semi-critical applications. Most Apple FCP/Color users would be very well served by this monitor. It produces an image that is decidedly better than that on a Luma and also better in many respects than that on an expensive BVM-L230.

It if flattering that eCinema product is expected to live up to the highest of expectations. Thank you for that. However, the FX is intended to be what we like to call a "stocking stuffer" here. This means that it is a low cost, relatively non-critical utility monitor that can do well in a wide range of applications where cost is more important than performance.


Monday, April 14, 2008

The Control of Noise at Work Regulations 2005

These came into force for all industry sectors in Great Britain on 6 April 2006 (except for the music and entertainment sectors where they came into force on 6 April 2008).

The aim of the Noise Regulations is to ensure that workers' hearing is protected from excessive noise at their place of work, which could cause them to lose their hearing and/or to suffer from tinnitus (permanent ringing in the ears). Here's an appalling description from the HSE website;

The level at which employers must provide hearing protection and hearing protection zones is now 85 decibels (daily or weekly average exposure) and the level at which employers must assess the risk to workers' health and provide them with information and training is now 80 decibels. There is also an exposure limit value of 87 decibels, taking account of any reduction in exposure provided by hearing protection, above which workers must not be exposed.

85 decibels? 85 decibels-what? Elephants? If they are publishing what is legally-binding material why don't they put in the units properly. The decibel is a ratio, a fraction, not a unit of measurement. I have a feeling they mean 85 dB(a).

PDF of the regulations

Thursday, April 10, 2008

Couple of BBC iPlayer stories

BBC and ISPs clash over iPlayer
ISPs say the on-demand TV service is putting strain on their networks, which need to be upgraded to cope.
This is so rich - ISPs moaning about the fact that they have sold themselves short. Now the Beeb pay Akamai (and other peering partners, I'm sure) for every gigabit of iPlayer data that leaves White City and then I pay my ISP for my 4meg uncapped connection - currently £25 per month which I don't resent. The ISPs have peering arrangements with backbone providers so that they don't actually pay for aggregate bandwidth between those higher echelons of the internet. What it comes down to is that they have sold people on faster-than-they-are-willing-to-provide connectivity and now they have to stand by those promises.

BBC announces Nintendo Wii deal
The video download and streaming service that lets people catch up with BBC programmes will soon be a channel on the hugely popular game console.
Wow - what a fantastic coming-together of technology. You could have yourself an iPlayer set-top box for £180 (aside from the huge fun you get from the Wii) - that is the kind of things that will mean that video-on-demand will really penetrate and I'm thankful that it's the Beeb. After all they made DVB-T a reality in this country (ITV couldn't/wouldn't sustain OnDigital) and if this keeps Murdoch out of the space then so much the better.

Wednesday, April 09, 2008

The 17th Edition IEE wiring regs BS7671:2008

I went to a superb training day at my institute to get all tooled up for the 17th Edition of the IEE wiring regulations - BS7671:2008, standards fans! These updated regs replace the venerable 16th Editions (4th revision!) in July and although they will only apply to new designs and aren't retrospective for older installations I thought it was important to start getting up to speed. A lot of the changes are due to the IEE / IET's involvement with the European standards body CENELEC.
When I started at the Beeb the 15th Edition was still in force and some of the things that came in 1991 with the 16th were universally mistrusted by engineers at the time. I remember reading a couple of days before a senior engineer job interview (internal) that they had relaxed the regulation on how close bays powered by different phases could be. That question came up in the interview and with a but of quick thinking I stretched out my arms and replied about this far! - the engineer questioning me saw I understood the principle and I got the tick! (In case you're wondering - you don't want to be able to put one hand on one phase of live and our other hand on a different live phase!).
Anyway - as mentioned it was a very interesting day at Savoy House (how do they afford to keep such a prestigious building?!). I have a scan of the 1st Edition from 1882 here - it runs to four pages! I've also stuck the various presentations on my server here as they are well worth looking at if your interested in electrical safety and standards.

Anyway, some of the significant changes are;

  • Terminology - There are several re-definitions. The phrases direct and indirect contact are replaced with basic and fault protection. These cover the protective measures you design-in for normal operation and for fault conditions. Section 4 of Darrell Locke's presentation covers this well.
    There are also changes to the 'zones' found in bathrooms (and elsewhere).

  • Expanded use of RCDs - They pretty much insist that RCDs need to be incorporated into all domestic circuits unless there is a good reason not to. They have this concept of experienced and instructed persons and if you're not one of those your an ordinary person who who only be exposed to RCD-protected circuits. Apparently this aspect was fought by the banks who worry about computers being wrongly taken down by residual current detectors. Whilst chatting over lunch every engineer I spoke to thought this was a good addition and if it makes us a bit more innovative in how we lay out supplies all the better.
  • Recognising the problem of harmonics - This is something that is a perennial problem when every piece of equipment has a switch-mode supply (like a typical datacomms or television machine room). I've often hooked an oscilloscope across the mains in the various facilities where I've worked and what you see is rarely a sine wave! These reverse-leaked harmonics cause RCDs to misbehave and mean that you don't get predictable heating effects in linear (i.e. non-inductive) loads. In inductive loads the acronym CIVIL tells us that the voltage leads the current;

  • New specs for allowable voltage drops - previously voltage drop from supply point (consumer unit) to the furthest point was allowed to be 5% - this is now set at 3% for lighting circuits. Apparently this was a French specification.

  • New special location definitions - in the case of a TV outside broadcast vehicle an NIC recognised inspector now has to check every time the supply is re-connected - that may be problematic! I'm sure there has to be a way around this. Either that or every SIS-Link/BBC/Sky engineer will become an inspector!

  • Phase sequences - Incredibly up until now the regs don't have anything to say about maintaining the sequence of the three phases. You don't want suckers to become blowers!

  • New earth loop impedance (0.3 ohms) and minimum insulation impedance (0.5M ohms)
The regs aren't legally binding but if you are in court under EAWR (electricity at work regulations) the man in the curly wig will look on you favourably if you took them seriously and showed you abided by them.
Best phrases heard today; A corpse changes everything and (in relation to a current-carrying conductor) Is is as hot as a cup of tea?!

Tuesday, April 08, 2008

Video of Radiohead doing "Bangers and Mash"

You love it!
(Well, I do!)

Monday, April 07, 2008

Friday, April 04, 2008

Audiophiles are gullible fools

See the previous post above for a giggle!

I gratified to see that the ASA have made a ruling concerning the kind of expensive mains cables sold by HiFi snake-oil company Russ Andrews Accessories. Nice to see their conclusion;
We told Russ Andrews not use the claims again unless they could substantiate them with robust scientific evidence.

Here here! The Guardian carried a similair story a couple of years back.

Thursday, April 03, 2008

Got my laptop back and the Apple/Scientology connection.

I got a new 15" Macbook Pro (the gen-1 MacBook had served me well for a couple of years). After getting Leopard right the version of BootCamp that comes with 10.5 is superb - makes installing Windows a breeze. As promised a few weeks back I went back to XP and what a revelation. It seems like I've got my computer back. It's snappy - Explorer windows appear as you double-click and network copies feel like their going over a LAN rather than a modem. If you are still stuck in Vista-hell then 'upgrade' to XP and you'll see what I mean. I used no Vista-specific features and so there were no compelling reasons for me to stay with it.
In an attempt to keep this new machine looking nice I went to the Apple Store on Regent's Street to buy one of those second-skin covers. Got a nice red one but felt quite uncomfortable being in there - I imagine it's how you'd have felt at a Nazi Youth Rally - so long as you're on-topic they love you, but mention that you run Windows or Linux on your MacBook and......
I wonder how how many of the folks who hang out in the Apple Store are Scientologists - I think the degree of compliance is similair!

Wednesday, April 02, 2008

A good read, a bad ISP!

I've just finished A Sea Change by Michael Arditti (ISBN-10: 1904559212) and was left very uplifted. I got downstairs for breakfast to find my cable is down again - less uplifting!

Based on a real-life voyage from Nazi Germany to Havana in 1939, The Sea Change is the "memoir" of Karl. As heir to a fortune, he begins as a spoilt, self-conscious young aesthete and, in the course of the voyage, becomes a man - falling in love with the beautiful Johanna, becoming reconciled to his father, battling Nazi crew members and eventually having his bar mitzvah.

Tuesday, April 01, 2008

I'm very proud!

On Saturday we went to Evesham for the day to celebrate Sarah's Auntie and Uncle 50th Anniversary. Joe, Dan and James played - they did Lean on Me.