Active sonar has been back in use for searching for submarines for a few decades now, the article is out of date. Low frequency active sonar towed sonars are fitted to modern submarine hunting ships; the low frequency is necessary to get a long range as higher frequencies are heavily attenuated. If you've seen news stories about the danger to marine mammals from military sonar it was these systems that were involved, as they put large amounts of energy into the frequency bands that propagate well - these bands being the most useful for whales to communicate with as well.
IIRC very few public transport systems make a profit on running costs - never mind capital costs. The rest operate as money pits.
Useful systems have huge positive externalities that can't be captured by charging passengers at a rate that reflects those benefits (I'm not sure if this is due to a free-loader effect, irrationality on the passengers part or something else).
I think the only systems that have profited on scale commensurate with their benefits are those that were a real estate play, eg.: the Metropolitan Line[1] in London, Los Angeles trams, Hong Kong subways. I might be wrong about these examples, either due to misremembering or to falling to a just-so story.
Edit 2: The point, I think, is that if you rely on direct profits for the transport system you give up on huge benefits and accept huge costs across society.
I think that - in theory - each case is unique and was individually tested at a trial where the evidence was weighed and judgement delivered. For each case lawyers need to prepare a case for appeal. Then the prosecution [1] has an opportunity to assess the case and to decide whether to contest it. If they don't contest the case then the subsequent court hearing (once it happens) should be quick.
The set of people convicted for stealing from the Post Office could include someone who was caught red-handed with an open till, wearing a stripey shirt and a Zorro mask and carrying a large sack with SWAG written on it in bold letters. Obviously this hypothetical thief shouldn't be acquitted with all the innocent people.
IANAL
Since 2010 there have been large cuts to the police, the courts, the pay of barristers and to legal aid [2]. The result is a massive backlog in cases and covid came on top of that. So it currently takes years to get anything done in the British legal system. There is a lot more broken that just this particular piece of software.
[1] I don't know if the response to these appeals is the duty of the Crown Prosecution Service or the Post Office. The costs will ultimately be borne by the public purse in either case, the PO is financially obliterated by it's liabilities.
[2] The system for paying the legal costs of individuals in court in the UK. Very little of it is left now.
Edit: I don't think anyone is still prison for these convictions. Most sentences were for less than three years and the whole process has been dragging on for a long time.
As I recall, Computer Weekly and Private Eye have been reporting this for over a decade.
This is the second major scandal in recent decades where Computer Weekly, a trade rag, have doggedly held truth to power. The other case I'm thinking of is the Mull of Kintyre crash and the terrible state of the firmware in the helicopters.
I cannot find any source files for the FPGA code in the repository (no .v .vhd .vhdl files and I can't see anything by looking around manually). The FPGA directory [1] contains some binaries and some documents relating to commercial code from a Swiss firm [2].
I've seen plenty of projects described as open source when the firmware is open source and the hardware is closed but this is the first time I've seen one where the schematics and board layout are open but the firmware is closed. Note that the hardware itself is quite simple, the smart stuff happens in three modules: GNSS receiver, precision clock and FPGA. To me, the contents of the FPGA source code are the only interesting part of this project. Additionally, you won't be able to meaningfully modify or reuse this project without editing the source code.
The hardware module these FPGA binaries seem to be compiled for is described as an AC7100B, the source given for these is a defunct ebay link [3] [4] :-O This project uses two and half grand's worth of atomic clock and the heart of it runs on a module that fell off the back of a lorry!?
Edit: I realise this comes across as quite negative. This looks like a neat project, one I would actually use, but only if it were meaningfully open source.
It's a particular module for the Xilinx Artix 7 XC7A100T, made by a Shanghai-based integrator. As an individual user, you could buy these on Aliexpress, from eBay resellers, or from Amazon resellers. Facebook presumably has an arrangement with the contract manufacturer that's not going to be possible for an individual developer ordering ones and twos to replicate.
However, to modify the HDL, you'd need a $3,000 license for Xilinx Vivado, which is pretty much a nonstarter for amateurs.
Thank you for id'ing the module. I can now see how using this would work for Facebook's needs.
I think the XC7A100T is supported by the free (and limited) edition of Vivado [1]. Of course, the confusion about what you can and can't do with the HDL is in itself a barrier to open source and hobby work. This is true even when the work is theoretically possible and everyone has the best of intentions. <sigh>
That is not true. First of all, the reason why we used the Alinx module (which you can buy of ebay as well as Amazon), was to make it easier for the community to manufacture and build. Our internal version of the time card does not include the module!
The second piece about the XC7A100T, you do not need any license to do any development as the free version of vivado is more than enough to work with.
Give us a bit of time and we will have a fully functional open HDL ready for you to add things.
It is very easy to sit down and nag about a project. I want you to understand that I had only one goal in mind when I released this project to public and that was allowing others to have a head start to work on time related project. Of course, I work for Facebook and I try to help my company with new technologies as a researcher, but helping the community and releasing the source code (to whatever I had) is just a core value of how I love to support the community.
you don't need vivado to modify the hdl, you need vivado (or some other proprietary xilinx toolchain) to produce the bitstream which actually deploys to the fpga.
That's a level of nitpicking that I didn't bother with.
Of course the Verilog or VHDL is just plaintext, which you can modify anywhere, but to actually do anything with it you need to compile it into a bitstream.
It does make me wonder if someone could set up a CI server to get around proprietary compilers like Vivado. Point the community resource at your source and get back a binary! Obviously you'd need to strip the license ID...
where if you wanted a tracker that wasn't a full controller you had to build it yourself. This involved a paid workshop in Seattle to get access to the dev kit and learn their tooling. Hardware was open source, but firmware was closed. If you wanted firmware changes you had to pay Synapse consulting fees for them to do it for you, and the updated firmware would then be made available free of charge to anyone else who paid for the workshop.
The Valve situation sounds like they attempted to open source after the fact, which doesn’t work with large hardware projects.
The only way to really open source a hardware project of this magnitude is to set open source as a constraint from the start. If you don’t, you inevitably end up with someone licensing some code somewhere from a vendor that can’t be open sourced. It gets integrated deeply enough that the project can’t exist without that piece and it’s too late to rewrite around it so the open source commitment goes out the window.
If I had to guess, it sounds like Valve tried to work around the situation with the workshop where participants entered into some contract as part of the workshop.
And if I had to guess about the Facebook situation, it was probably decided to open source the project after the fact. I’m guessing they wrote the website copy while someone else went off to try to secure open source permission for all components involved and they never reconciled the two efforts, hence the weird dead eBay links and missing files.
I shouldn't have called it open source, it was source available to customers who paid for the training course and signed a license agreement. Don't think they ever had intention of making it open. I found the model especially strange because of the requirement that any custom changes you asked for would be available to everyone else (your competitors). I guess they didn't actually want the workload of custom changes so this was a way of further disincentivizing it?
> I found the model especially strange because of the requirement that any custom changes you asked for would be available to everyone else (your competitors).
It's the same model as any game-console SDK. If you ask for changes to the SDK, those changes are going into "the SDK", which all customers get access to. Platform providers don't tend to offer work-for-hire for custom forks of their code; instead, what they're offering is to prioritize adding certain features to the shared upstream codebase. In the end, the platform provider wants there to just be one SDK, that solves the superset of all their customers' problems. Anything else is a ridiculously-large maintenance burden.
Just give us a bit of time. We had to use some IPs that due to licensing limitations prohibited us to release the source and we were only allowed to release the bin files. We are replacing them to open source cores and we will have that part of the project available to you too. I hope you understand the situation of the project. I would love to see people adding more features to the FPGA part of it such as IRIG-B output and many other cool things that can be done. Please stay tuned.
However, I think they've used code from NetTimeLogic under a licence [1][2] that precludes distributing the source:
> 3.2 Distribution Rights. LICENSEE may reproduce and distribute the Licensed Materials, solely in binary form that operates in LICENSEE’s system-level hardware products.
This is a perfectly reasonable way of developing a system but it is sadly incompatible with sharing your work as open source.
I have no problem with this project either and find it interesting, but I agree with you completely that it looks like someone took a hobby-level experiment with a corporate budget to the prototype stage then realized it had near zero practical application so, "Open source!"
> So GPS doesn’t exactly need leap seconds but it really does care about how long a rotation of the earth takes which… amounts to the same thing.
I don't think this is right. GPS explicitly uses a timebase that does not include leap seconds [1].
On the subject of the article: my modest and very reasonable proposal is that we apply a leap second every six months without fail, dithering between positive and negative leap seconds so as to remain close to sidereal time. That way we would flush out bugs every six months and wouldn't have them accumulate and hit us all at once.
Or we could be boring and use TAI or GPS time as the system clock every where and apply leap second corrections when we go from the system clock (currently UTC) to local time.
I mean, the article is literally about GPS satellites transmitting leap second data as part of their messages. So yes, the basic clock is just counting seconds but leap seconds are a pretty important component of the GOPS model.
Surely dissolving CO2 in the ocean acts as a buffer, not a sink? We will have to stop emitting all of that CO2 as well (and future generations will have to sequester it).
The net absorption / emission from the biosphere involves a lot of emission following from our changes to the planet. We can significantly reduce our emissions (and slowly recover some of them) with better stewardship of the environment but there is a risk to the sequestered carbon: eg. where climate change causes forests to die and release most of their stored carbon.
Moreover, higher CO2 content in the oceans leads to acidification. This is bad for coral and organisms that build shells. I don't recall the exact reason but my understanding is that it tends to dissolve carbonates.
Most types of carbon capture technology [1] being touted are credit cards for climate change:
You burn enough fuel to generate 4MJ worth of heat...
Your internal combustion engine generates 1MJ worth of mechanical effort from this...
You use this to propel a 2 ton vehicle...
Carrying 1 person...
To take part in the rat race or indulge in some consumerism. [2]
The carbon dioxide sits in the atmosphere for 50 years where it heats the planet, trashes the ecosystem and likely feeds at least as many positive feedbacks as negative - amplifying the climate change effects.
To capture this carbon you (your descendants) are going to have to:
Put 4MJ of energy into the breaking the carbon-oxygen bonds...
Which will take more than 4MJ of process energy and embodied energy in the capital plant...
Once you have collected the diffuse CO2 from the atmosphere, which will not be free.
Our 'plan' for dealing with climate change is that we hand a burning planet to our descendants to deal with, if we can stagger to hand-off without crashing the system first. Future generations will have to be far more responsible than us, for centuries, and imagining what they will have to say makes me squirm.
[1] I am mildly optimistic about techniques that accelerate the weathering of (silicate?) rocks; and more trees will be nice. These technologies will be useful for the centuries of cleanup that will be needed, but cannot keep up with the huge rate of current emission.
[2] Yes, much of our current consumption delivers real benefits to people's lives; but much (most) of it doesn't. The point of my analogy is that the sheer wastefulness of the present excess will be paid for in the future at far greater cost and is being spent on such trivial or actively harmful goals.
Genuine question - if CO2 half life in the atmosphere is less than 50 years, why are we so concerned about it? Wouldn’t the problem solve itself given that we are both reaching peak consumption of fossil fuels and that they are expected to deplete with the next century?
In other words, wouldn’t the co2 concentration go down naturally within the next 100 years even if we let thing run naturally?
Because if it’s somewhat true to say that stopping CO2 emissions would rapidly pause climate change, there is no short term « reverse » (in hundreds of years) of the climate.
We are in such a situation that every +0.01°C increase in global warming is gained more or less indefinitely.
The only thing we can do is stopping net emissions and learn to live with the climate as it is when we achieve this.
We really don’t care a lot about concentrations going down in the next centuries because by the time it happens, the harm would be done already for multiple centuries.
We are really facing today, 50°C in summer and devastating events, for our generation and our kids. This precise battle is already lost but we must fight for it to not be even more dramatic.
50 years was my (over optimistic) estimate of how long the CO2 would be left in the atmosphere before being sequestered by one of the carbon removal technologies being touted. In reality it's going to take centuries for our descendants to stabilise the climate - and I'm still being optimistic.
On short time scales, the oceans take up a lot of CO2 because there's an equilibrium with the atmosphere. However, increased acidification of the oceans is bad on its own, and this buffering hurts when you try to take the CO2 out of the atmosphere since then the oceans will turn into a net contributor.
This article seems to conflate "Time it takes for 50% of the CO2 increase to be removed from the atmosphere" with "time it takes a specific molecule that was released to the atmosphere to be removed".
The former is more relevant to the discussion, and is stated as ~30 years.
Much of the corn is being grown in a way that erodes the soil and depletes the water reserves being used, compromising our ability to grow crops in those areas in the future.
eg: https://en.wikipedia.org/wiki/Sonar_2087