* Posts by Dafyd Colquhoun

19 posts • joined 3 May 2013

The radio environment is noisy – so use the noise as a carrier for signals

Dafyd Colquhoun

-80dBm is a big signal

"As low as -80dBm" doesn't ring true for me. The 12dB SINAD spec (limit of intelligibility) for most VHF/UHF handheld radio transceivers (i.e. not a dedicated receiver) is 0.18μV to 0.45μV, this equates to -122dBm to -114dBm.

That's 2500x the signal level.

Engineer who blew lid on Uber's toxic sexist culture now menaced by creepy 'smear campaign'

Dafyd Colquhoun

Re: Why does Uber even exist?

Pretty much the same situation in New Zealand. If meet the business rules and notify the government of your fare structure then you can run a taxi company. I guess surge pricing breaks those rules, so Uber skirts them and trots out the old 'scarcity' argument (which is valid in Australia and other countries) regardless.


QANTAS' air safety spiel warns not to try finding lost phones

Dafyd Colquhoun

BZZT! Lithium ion is not Lithium metal, just as Sodium ions in salt are not dangerous like Sodium metal.

The flammable aspect of a Li-ion battery is the organic electrolyte. Lots of heat from a short, especially when the separator is punctured, can set the organic goodness on fire. This is not a combustible metal fire.

Cabling horrors unplugged: Reg readers reveal worst nightmares

Dafyd Colquhoun

Staple guns should be banned

Had a day's worth of fault finding with a TDR (an old CRT Tektronix one that weighed a tonne) because some dopey 'leccy had installed a new 10BASE-2 coax run using a staple gun in the Forestry Dept of the uni I went to.

The problem was that the numpty had missed quite a few times and put the staple through the coax. So he pulled the staple out and redid the job over the top. Problem was that withdrawing the staple dragged the shield through the centre conductor and shorted out the cable. TDR found each short, and since laying new cable wasn't an option it was a matter of cutting back just enough cable to fit two new BNC plugs and then join them with a barrel connector.

Had a weird one in the electronics lab too. This lab had 10BASE-2, but with the fancy floor connectors that allowed a cable to be plugged in that broke the circuit, diverted up to the PC, and then went back down again (totally superseded by 10BASE-10). The floor ports had little covers secured by a chain. Someone had used sink plug chain, the one with lots of little ball bearings. The balls would fall out, roll across the floor and down into a port, shorting out the special connector. Apparently took AGES to figure out the fault, but then all it needed was a strong vacuum cleaner to 'fix' it.

I don't miss 10BASE-2 in the slightest. The best part of going to 10BASE-10 was the part time work I had making patch leads for the computer centre (they were too cheap to buy them). I still have the wiring pattern burnt into my brain!

Checkpoint chap's hack whacks air-gaps flat

Dafyd Colquhoun

If there are common cables it's not an air gap!

If you really want machines to be secure then the only bit of wire/cable in common should be the power (and avoid that if you can). Connecting a USB (or even PS/2) device to two computers breaks the barrier.

The stupid things people will do (not calling the researchers stupid, just those that do use a KVM to in this way) in the name of convenience. Much like hooking the SCADA system of a factory to the corporate LAN so executives can look at the pretty graphs...

Slip-streaming Tesla, Oz battery-maker plots home-biz launch

Dafyd Colquhoun

Flow batteries are the opposite of everything else

I'm surprised that Redflow haven't mentioned that flow batteries (including theirs) are different to all other batteries. The prefer to be empty, not charged. Not so good for a backup application, but OK for solar load shifting. And they need pumps to circulate electrolyte, and those pumps use power.

I've never considered lead-acid charging to be complex. They float charge with a constant voltage source quite nicely, and don't have the thermal runaway problems of more complex chemistry. They might have a low energy density, but how often do you pick up and move a battery bank that is not installed in a car?

NBN Co's HFC build will be DOCSIS 3.1 ready, but use 3.0 only

Dafyd Colquhoun

Any details on UPLOAD speeds?

100Mb/s download speeds -- whoopdie-doo! I'm sick of being subject to <1Mb/s upload speeds as this stuffs up VPN to home, video conferencing and video uploads. Time for the HFC providers to allocate more channels towards the node for the end users to use. If HFC cannot provide a minimum of 10Mb/s upload speeds then there is no way in hell it can be considered equivalent to GPON NBN.

BOFH: The Great HellDesk geek leave seek

Dafyd Colquhoun

The fun of a corporate card

I've had a couple of corporate cards, both as a graduate engineer and as a senior engineer. The days as a graduate were a lot more fun: lots of travel, buying electronics etc. All good. One day-trip up north took a turn for the worse when we missed the last flight out of Rockhampton. Trying to find accommodation at short notice in Beef Week took considerable effort. I swear that most of the room in the establishment were rented by the hour (as happens when cashed up country boys arrive in town) ... Anyway, the only way to get home the following morning was business class on the first flight, which left before the corporate travel agent opened. We had surprisingly few restrictions on the corporate cards: no booking travel. The travel rules were: no domestic business class travel. So when the team leader said to us: book the business class flight on your card and we'll sort it out later I don't think he appreciated the quantum of faeces in the ventilation. It was all justified (compared to accommodation for another night and flying out the next day). The reaction of the guy in row 2 of the plane was priceless. He was a board member of an associated company (common shareholders), and was very interested to know why slightly smelly people in trade clothes were sitting in front of him.

At another place the corporate card was a Diners. Biggest piece of shit I've ever used. Companies love it because the cardholder is jointly liable for expenses, so if the company refuses to pay the bill you're on the hook. The problem is that in rural areas nobody accepts the bloody thing, even petrol stations, so you need to have some spare $ on your personal card.

Still beats the risk of using a personal card to buy stuff for the company and hope to get reimbursed. It was nice scoring the points for $20000 worth of GSM modems, but the boss wised up. When I went to spend $15000 on a new oscilloscope I was told that he'd pay for it through the company accounts since it was a capital purchase. When the scope was delivered it included the credit card receipt on the invoice which showed he'd paid with his personal card and scored the points. Out bastarded!

'Camera-shy' Raspberry Pi 2 suffers strange 'XENON DEATH FLASH' glitch

Dafyd Colquhoun

Flashes are banned in substations too

Flashes are not a good thing around power electronics that use light triggered semiconductors (for voltage isolation). I've heard of one model of static AFLC (ripple control) generator that blew up when someone took a photo in the factory. The flash trigged ALL the transistors, resulting in a DC bus fault.

Flashes are also not good around switchboards with arc detectors. Flash, then black. Not good if that panel controls a 400MW steam turbine generators ...

Attackers planting banking Trojans in industrial systems

Dafyd Colquhoun

AV is often not an option

I worked on a substation SCADA system that was infected with viruses. One of the reasons is that the SCADA vendors bastardise Windows (XP in this case, installed in 2013!) to do things it isn't meant to. They then do not guarantee it will work if ANY anti-virus software is installed. The mods included blocking Ctrl-Alt-Del until an Admin user was logged in. That isn't mean to be possible, but somehow they managed!

The only way we got to clean things up was AV boot CDs, and taking one server down at a time (thank goodness for redundancy). I was ready to chew out our technicians for sloppy behaviour, but then found viruses on a server fresh from being supplied.

The functional spec required vendors include AV and provide a certificate of cleanliness. When the Contract Dept was challenged they shrugged and said 'so what?' With an attitude like that is it any wonder that crap gets delivered, accepted and paid for?

'Speargun' program is fantasy, says cable operator

Dafyd Colquhoun

Fibre optic cable can be tapped by bending it in a serpentine manner. You clamp a pick up device around the individual cores and the photons that 'escape' are used to recover the message. THIS IS BLOODY DIFFICULT, it would be easier to 'encourage' the backhaul provider to make space for a special box in their data centre.

Tapping fibre:



NBN Co adds apartments to FTTP rollout

Dafyd Colquhoun

"...in the Fortitude Valley..." clearly written by a non-Brisvegan. It's either "... in the Valley..." (colloquial) or "...in Fortitude Valley..." (formal). Fortitude Valley was named after a ship, not a geographic feature. Just one of those things to confuse tourists :-)

Are you broke? Good with electronics? Build a better AC/DC box, get back in black with $1m

Dafyd Colquhoun

Re: No they don't

The reason we use AC is that voltage transformation is easier, so the changes needed to get from power stations to homes is easier. For long distance efficient transport of power we use DC in the form of HVDC. This is 80kV or more (800kV in china). These converters are expensive, so only used when the power transfer justifies it or where AC just doesn't work (e.g. underground cables more than 100km long).

AC is good for spinny things too. Not everyone has nice variable reluctance motors in their appliances (thanks F&P), so single phase induction motors are going to be around for some time.

A standard home DC bus of 48V or so would be nice. ELV, so no licence required for DIY work here in Australia at least.

Telstra to grinch WAP 1 network five days before Christmas

Dafyd Colquhoun

Or kep your device and swap the SIM card

If you're happy with your old phone (my Sony W880i is going strong, and it is basically a skinny W800i) then another option is to keep the phone and ditch Telstra. They're trying to get out of GSM anyway, so it won't be long before 2G phones won't work at all.

My Motorola 3200 International still works with Vodafone, and you can't get an older GSM handheld phone than that!!!

Uncivil engineering: US society skewers self-published science

Dafyd Colquhoun

Editing is not free

Part of the 'value' that journals provide is taking perfectly reasonable English sentences and mangling them into American 'English'. It isn't enough that 's' becomes 'z' at the end of many words. Oh noes, there is a LOT of effort required to change the comma after 'however' into a semi colon and to make double quotes into single quotes. This all takes effort and must be recovered by extorting libraries.

Societies like IEEE and ASCE at lease use their publishing revenue to sponsor conferences and are generally 'non profit'. The likes of Elsevier are there to make dividends for their shareholders. That's why I am prepared to write papers, review papers and be an editor for IEEE journals at no charge, but I WILL not submit papers or review for the 'for profit'.

The open access journals are not exactly free for the author to submit too either (since someone has to pay and it isn't the reader), and the review times can be LONG. The IEEE has a goal of it being no more than 13 weeks from submission to first decision, and in my experience it can be as short as 8 weeks.

Dafyd Colquhoun

Most publishers will not let you put up the finished edited & typeset version of a paper, but will let you host the 'author accepted version'. If the publisher won't let you self-host the author accepted version then publish elsewhere. I have quite a few IEEE papers done this way, and one benefit of the IEEE is that a very close facsimile of publishing style is available for LaTeX, and so my self published version looks very much like the final thing.

The real crime here is people not reading & respecting the copyright agreement that they've signed.

ASIO seeks new hires for telecoms interception teams

Dafyd Colquhoun

Why are the cyber-spies all in Canberra?

Surely electronic interception is one job that could be done in any of the major cities in Australia. Why do ASIO and DSD insist on having their people relocate to Can-bore-a?

Oz Green's plans exempt some phone metadata from warrants

Dafyd Colquhoun

If you WANT to go missing

IF you are really keen on 'going missing' then dumping your phone would be the first thing to do. I think there's been enough phone tracking on TV and in the movies for people to know that you can be tracked.

Phone location, even down to 900m accuracy, is a big help in missing person searches. I've been on plenty as an SES volunteer and when the Police can limit the search area it really does help speed things up. Now if only we could get elderly people with dementia to carry a mobile phone with them ... or for their care homes to secure the premises properly ...

Forget choice: 50% of firms will demand you BYOD by 2017

Dafyd Colquhoun

Re: BYOD - The other side of the coin

Companies that really care about security are using 802.1x. Unless your personal/private computer has a corporate certificate installed your WiFi or Ethernet connection is not going to be much use.

Heck, one place I worked even had 802.1x installed on the printers so you couldn't 'borrow' a printer's Ethernet jack like you could in the past. Just like a fax line for was great for long-distance calls when you could arrange 'approval' in time (yeah, that's it).


Biting the hand that feeds IT © 1998–2020