> All the designs I know of have a pumped (active) cooling loop for the reactor, then a secondary loop where the coolant (typically water) evaporates and drives a turbine, [...] You don't want potentially radioactive water to interact with your turbine directly, makes it a nightmare to maintain
A "Boiling Water Reactor" (BWR) has the reactor and the turbine on the same cooling loop. The radioactivity in the water going through the turbine is not a "nightmare", it is a manageable trade-off.
Some major currently-operating BWRs are Leibstadt (Switzerland, 1.2 GWe), Oskarshamn (Sweden, 1.4 GW) and several dozen in the USA. Germany also had some, they were shut down a few years ago (e.g. Grundremmingen).
1. The recording engineer dialled the operator. Could have been pulse dialling, could have been DTMF, doesn't matter.
2. Operator answered and the engineer said "I'd like to call London, collect, number 01xxx831".
3. Operator entered 044 1 xxx 831, and this was transmitted to another exchange in SS5 tones.
I didn't grow up in the USA, but a couple of people who did have said that, yes, they think that at least some of the time, you could hear the SS5 tones and also the initial conversation between the operator and whoever answered the phone. It may be that it depended on the operator, since they probably had a mute button, and maybe on the particular exchange the operator was in.
That one's just ordinary DTMF. I recorded the audio, trimmed it manually and then made a spectrogram like this:
sox gun1.wav -n rate 4k spectrogram -m -y 500
The 'rate' switch is to cut down on how much of the frequency space we can see. I left the audio as stereo because there's less music power on one channel, making it easier to see the tones.
(And google finds quite a few pages confirming those digits)
You're right; I think CCITT5 is just another name for SS5, because different groups were writing standards. Bell called it one thing, CCITT (an international standards group) called it another thing. And then in the 1990s, the CCITT renamed itself to ITU.
SS5 was derived from AT&T's US MF signaling system, described in "Signaling Systems for Control of Telephone Switching" by Breen and Dahlbom, Bell System Technical Journal, November 1960. PDF here: https://explodingthephone.com/hoppdocs/breen1960.pdf
The BSTJ article has a discussion on international signaling on pp. 1430-1441.
for an early technical article describing the implementation details of the familiar DTMF "touch tone" dialing system, noting that the precise details differ from the final implementation — in particular, the high group frequencies increased from 1,094/1,209/1,336/1,477 Hz to 1,209/1,336/1,477/1,633 Hz, possibly to mitigate the "pulling" effect described on pp. 251–252 (though I can find no reference for the rationale).
Yep, 44 is the UK country code. The problem I got stuck on is that the rest of the number, 1831, didn't make sense. I assumed the number was complete, since it had the right start and stop signalling (KP1/KF).
It's not long enough to be a London telephone number, and, today, I think London numbers start with 020. The UK numbering plan has changed several times since 1980, but I couldn't find a time between 1980 and now where part of 1831 was a London number.
Later on (in the addendum), it turns out that others took a look at the signal in the time domain and spotted a splice, i.e. digits are chopped out of the middle of the number, so the area code probably isn't there at all. It could be that the area code starts with 1, and then the phone number ends with 831.
A London number at the time would be from the UK (01) eee nnnn where e is the exchange[1] and n is just a number, and the 01 can be omitted if you're in the 01 area. For intentional calls it would be (+44) 1 eee nnnn, as you omit the initial 0 that on an internal UK call is an indication you're dialling an STD[2] number and not a local number. There doesn't seem to have been an 831 exchange at the time[3], so as noted in the article the cut to shorten the number is presumably somewhere in the middle.
In 1990 London was split into 071 (central) and 081 (areas), which meant in 1995 all landlines could have an 01 prefix, so London because 0171 and 0181 (and that ruined the Live and Kicking phone number jingle, although I think the Going Live one was better anyway) and finally in 2000 London became 020, with the 7/8 moving to the first digit of the local number (not that the split between local and area codes really matters anymore).
[1] Of course, in ye olden days before all this newfangled "dialling" you'd ask the operator for something like "WHItehall 1212", not 944 1212 (or later 930 1212).
> you'd ask the operator for something like "WHItehall 1212"
I still remember my mom making me memorize our phone number when I was very young, "SPring 9 0273". It wasn't very long afterward that everybody switched to all number dialing though.
Going Live was before PhONE Day, so it was 081 811 8181 back then. Live and Kicking stuck with the same number when it took over, with it gaining the extra digit fairly early in the run.
I started analysing the audio because someone sent me a link to the film (The Wall) on youtube and asked me about the signalling. Once I'd decoded the telephone number, I tried googling it, to see if someone else had already figured out what it was (a US local number? the number to a US operator? the number a US operator called to talk to a UK operator? the number a UK operator dialled to get a London number?), but nothing came up. There's quite a bit of good discussion about that in the comments here.
A week or two later, I tried googling 'Pink Floyd Telephone Call', and found that the audio actually comes from the album, i.e. it's not just in the film, and a bit more information about how it was made, and put that in the addendum.
> It's not long enough to be a London telephone number, and, today, I think London numbers start with 020.
I used to work with telephony until 2011. While I worked in Sweden, I am sure this applies for UK, too.
There is no standard in phone number lengths, you can have all sorts of prefixed series, so for example if the area code is "1", then the number 0 could be routed to a destination.
So 04410 is theoretically valid.
Back then we even had 3-digit short form numbers (like 911) that we had to specifically deal with each phone operator for keeping.
I looked at a London telephone book from 1979, when I think the record was released.
Most of the phone numbers were something like 01 361 1234, i.e. seven digits after the 01 area code. The _361_ part was bold, so I think that was an exchange number.
A few numbers were something like "Placename 12345". Wikipedia explains why that was.
> I couldn't find a time between 1980 and now where part of 1831 was a London number.
What about when outer London numbers started 081? Dialed from another country with the 00 international call prefix the number if could be a fragment starting from the second digit (i.e. 0044 1831xxxx)?
the change form 01 was a big deal, and BT ran some very amusing ads playing on snobbishness about where in London one lived.
I remember London area codes being 01 (or 0441 from USA) followed by 6 digits, so maybe 3 are missing. It would be interesting to see if that landline is still available, but with 1000 possibilities (01ABC831) maybe a google search might be the way to go.
In the 90's I recall London area prefix changed from 01 to first 071 (central) and 081 (greater) and then 0171 and 0181. Later still, those codes became 0207 and 0208.
I still notice old shop signs up with the old prefixes.
Normally, films use deliberately fictious numbers, e.g. in the US it's always xxx555xxxxxx. Wikipedia says the UK uses various area codes for the same thing, including 011x and 01x1. The Pink Floyd number is a bit unusual---it's not made up.
According to a previous analysis, the call was the album's "Chief Engineer James Guthrie who called his own London apartment", with a neighbour answering the phone. Someone probably knows roughly where James Guthrie lived in 1979/1980 and what the area code there was. But I don't.
> Wikipedia says the UK uses various area codes for the same thing, including 011x and 01x1.
Ofcom has set aside blocks of numbers within many different area codes for dramatic use[1]. The note on Wikipedia about 011x and 01x1 is that the reserved numbers in those (real) area codes usually end with 496 0xxx (so, for instance, 0114 496 0000 to 0114 496 0999 are reserved numbers in the Sheffield/0114 area - other 0114 numbers may be allocated to real customers).
Per https://en.wikipedia.org/wiki/555_(telephone_number)#Fiction..., the officially reserved block under the NANP has shrunk to XXX-555-01XX, but outside of XXX-555-1212 (directory assistance), and toll-free 800-555-XXXX there is little use of the range.
Somebody could contact James Guthrie since he's still alive and probably has his old apartment phone number written down somewhere (if not still memorized).
Okay. If the call was from within the UK then I think the 0441 code would have been Swansea, but that would have required 3 numbers being cut from the middle.
All UK internal phone numbers start with a zero. However when you dial the UK from abroad, you omit the leading zero, so the UK version of the number in question would be 01831, which sounds a lot like an area code (though apparently is not one in current use)
Best guess: you're confused by the word "smokestack". Smokestack is a synonym for chimney. The power station is closed. The chimneys are still there, but there's no smoke coming out of them.
Supposedly it was the largest size the French contingent to the standards committee would accept. They wanted a very small sample size to reduce the need for echo cancellation in their network.
Not important to the conclusion or reasoning... but Stevena's post says:
"the whole team working on Erlang quit and started their own company."
The same event as described in "A history of Erlang":
"In December, most of the group that created Erlang resigned
from Ericsson and started a new company called Bluetail AB."
https://www.labouseur.com/courses/erlang/history-of-erlang-armstrong.pdf
'most of the group that _created_ Erlang' is not the same thing as 'the whole team _working_ on Erlang'. Or, quantifying it, at the end of the 'history' paper, there's a list of 45 people under 'implementation' and 'tools'. Around 35 were at Ericsson in 1998. Of those, nine or ten quit to form Bluetail, and another two or three left for Bluetail later on.
(In 1998, there were two connected groups working on Erlang in the same building in Älvsjö, Stockholm. One was the computer science laboratory (CSLAB), where Erlang was created, the other was "Open Systems", which had more of a development role. A significant part of CSLAB left. Almost all of 'Open Systems' stayed. Many that stayed were already doing a stellar job on Erlang and many still are.)
"As before, this is a transmit-only proof of concept"
I didn't notice that on my first reading.