But I see all the "QR codes" have a hexagonal symmetry? So basically you can use only one corner (1/6) to represent a node? Why do they keep the entire hexagon?
And then you try to actually build a GPS network, and ask yourself: what kind of antennas should we use? what should be the freq? how much power? how will the receiver detect the precise nanosecond when it receives an incredible weak signal? (in current GPS the signal is bellow thermal noise)
- They don't use GPS frequencies because there is receiver on the moon that receives GPS L1 signals (LuGRE and potentially more in the future)
- Make it easy to acquire for low complexity hardware
- Use 5G forward error correction code to reuse existing hardware implementation
- Design the signal in a way so that the user can easily find start of a data frame
And those are RF level considerations... there will be more considerations needed for the data transmitted over those navigation signal that the receivers need to use to determine navigation satellite position as lunar orbit is much more complicated than Earth orbit
(also you receive the signal from all satellites at the same time, on the same freq, and some random reflections. and then you need to extract independent streams of bits for each satellite, each with its own nanosecond timestamp for receive time)
The hw implementation of xor is simpler than sub, so it should consume slightly less energy. Wondering how much energy was saved in the whole world by using xor instead of sub.
For a 32 bit number you're looking at going from using 256 to ~1800 transistors in the operation itself. A modern core will have roughly 1,000,000,000 transistors. Some of those are for vector operations that aren't involved in a xor or sub, but most of them are for allowing the core to extract more parallelism from the instruction stream. It's really just a dust mote compared to the power reduction you could get by, e.g., targeting a 10 MHz lower clock rate.
I am always puzzled by such articles - its actually very well made, drawings are good, little interactive pipeline animations are fine. But in order to follow it you must already know and understand what its writeen about and if you dont - the content is just noise for you.
Hi, I'm the author! Thanks for saying it's well made :).
I actually agree with you, the intended audience isn't someone who has never heard of CPUs before.
I tend to either write for myself: you know the saying you don't understand something until you try to explain. Or I'm writing for the person self-studying that is looking for that one explanation where everything finally clicks. I always get a lot out of those type of posts myself, so like to create them for others too.
You could use colors in the step-by-step simulation to show dependencies.
Also show some tooltips/comments when things happen (that you described above). Ideally one should press next next next in the simulation, and understand what happens better than the paragraph description above.
well, rhetorical trick or not, it is worth thinking about the fact that the dynamics of the thing are already outside anyone's control. I mean, everyone is racing and you cannot stop.
I found much more interesting the way the gps electronics work. What do you mean you need to know the exact moment you receive a message from a satellite with nanosecond precision? when the message itself is several seconds long.
A long time ago (pre-internet) I heard a normal person can learn to juggle in 1 day. It took me 2 days, but I learned to juggle 3 balls. But soon I realized what you said, the need for a consistent toss. Not sure of the reason, but I always make some errors with physical movements, they are never perfect. Even with typing, no matter how much I exercise, I cannot get bellow ~3% errors. Wondering if this is some kind of genetic effect, and how many ppl have similar issues.
I haven’t tried juggling for decades but I did manage to teach myself basic three-ball juggling when I was at university (any excuse to avoid revising!)
I think it took me a couple of weeks though. I’m a bit malcoordinated for that sort of thing in general. I think you’re right that there’s some sort of natural aptitude that not everybody has. Fortunately basic juggling is just about easy enough that almost any idiot can do it.
This made me laugh. The number of times I’ve Admiral Ackbar fat-fingered the flag button when I just wanted to hide a post on HN is almost too many to count at this point.
Well, reading the study, I'm not sure more patients could rescue it from methodological bias. They assumed the premise basically -- we should find a biomarker, which is kind of what this thread is discussing. Then they went trawling for biomarker in a sea of millions of biomarkers. They did this by training an model that produced the desired result, using a grid search for hyper parameters that even further expanded the available degrees of freedom here beyond what they had from the biology. No pre-registration; There are millions of places where the researchers could have made a different decision -- would they still have gotten a publishable result? Oh plus the authors mostly work for the company whose data they use, which is hoping to sell a diagnostic test.
I'm giving you a thorough response because I'm detecting a cavalier anti scientism which I think is sadly becoming more common. This stuff is hard; are you sure you understand it enough to have an informed opinion?
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