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Junk_Collector commented on Rohde and Schwarz AMIQ Modulation Generator Teardown   tomverbeure.github.io/202... · Posted by u/iamsrp
jandrese · 3 months ago
R&S equipment is pretty common in the cellular industry. There is more of it out there than you would think. While this particular signal generator is maybe not the most common piece of equipment you will see lots of R&S spectrum analyzers and the like.
Junk_Collector · 3 months ago
It's technically not a signal generator but an Arbitrary Waveform Generator. It provides a base-band modulated signal to the signal generator which the sig gen upconverts to the RF carrier. If you purchased a Vector Signal Generator this would be built in but you can still buy them stand alone and they are pretty common. NI, R&S, Tek, and Keysight all have product lines of them.

Another way to think about it, this would be comparable to a signal generator in the same way that an oscilloscope is comparable to a spectrum analyzer.

Junk_Collector commented on FCC opens entire 6 GHz band to low power device operations   docs.fcc.gov/public/attac... · Posted by u/impish9208
palata · 9 months ago
This (and the parent) really sound super interesting to me, but I don't understand. Before I spend hours on Wikipedia reading about EIRP and phased array (and probably give up), is there a chance one of you could explain this briefly in words I may understand? :)
Junk_Collector · 9 months ago
In the simplest possible terms, EIRP is the equivalent of power density. It takes into account how narrow the beam from your antenna is.
Junk_Collector commented on "Phantom chemical" identified in drinking water is new to science   newatlas.com/environment/... · Posted by u/Brajeshwar
Junk_Collector · 9 months ago
From the article "I agree that a toxicological investigation of this anion would be useful now that we know its identity, but I am not overly worried about my tap water,” says Oliver Jones, Professor of Chemistry at RMIT. “The compound in question is not newly discovered, just newly defined. Its presence in some (not all) drinking waters has been known for over 30 years."

Chloramine has been in broad use for over a hundred years and this breakdown byproduct was well documented over 50 years ago and detectable in water over 30 years ago. What the article is claiming as new, or a "Phantom" is that someone imaged its particular molecular structure and is now requesting funding to run toxicology studies on it. There is no current reason to believe that it is harmful since tens of millions of exposures have not indicated any reactions to it over the past hundred years.

Junk_Collector commented on Americans see their savings vanish in Synapse fintech crisis   cnbc.com/2024/11/22/synap... · Posted by u/hunter2_
binary_slinger · 9 months ago
The linked website for Yotta is withyotta.com which looks like some sort of online gambling site? The slogan is "Play games. Win Big." Am I missing something? It doesn't look like something I'd trust to put any amount of money into.

Looking at archive.org for September 2023 [1] they claim an "average annual savings reward" of "~2.70%*". At a real major US bank, I was getting 4.65% in my savings account at this same time.

Reading the terms at the bottom of the page it says: "Please note that the approximate Average Annual Savings Reward of 2.70% is a statistical estimate based on the probabilities of matching numbers each night. The Annual Savings Reward will vary from member to member depending on one’s luck in the Daily Drawings and is subject to change in the future."

[1] https://web.archive.org/web/20230912164609/https://www.withy...

Junk_Collector · 9 months ago
Yotta marketed itself as a "bank" where every time you deposited to savings you would get a free lotto ticket for the month based on how much you deposited. They did this by offering below average interest rates on savings then parking people's money in accounts at banks with higher interest rates than they paid out and pulling some of the difference into a prize pool. Over time (very quickly actually) to increase revenue they pivoted into more traditional gambling.

Notably, Yotta is neither a bank nor a payment processor. They are just an "app" front end. Yotta's processor went bankrupt and the fintech bank they were working with to hold the accounts now disputes the amount of money they actually are holding to the tune of ~$96M being missing. This will probably be in courts for several years while things are unwound, someone will go to jail for financial crimes, and a lot of people will never be made whole. Some people have called for the FDIC to step in, but the FDIC has helpfully pointed out that no FDIC insured account has defaulted which is the necessary condition for FDIC insurance to pay out.

Junk_Collector commented on Amplification of electromagnetic fields by a rotating body   nature.com/articles/s4146... · Posted by u/keepamovin
kstrauser · 10 months ago
My gut instinct is you’d really need perfect incompressibility such that pushing one end of the rod would propagate the pressure wave to other end instantaneously. In other words, you have to make the speed of sound faster than the speed of light. I have no idea what the physical construction would look like. Maybe a string of singularities lined up and touching (hey, there’s your 0!) without tearing spacetime apart?
Junk_Collector · 10 months ago
Force cannot transmit through the material faster than the speed of sound and because fundamentally at a subatomic level, mechanical force is the interaction of electromagnetic and gravitational fields between molecules, the speed of sound cannot exceed the speed of light in a material. The rod will compress or physics breaks down. Solid particles are an abstraction.
Junk_Collector commented on The U.S. government may finally mandate safer table saws   npr.org/2024/04/02/124114... · Posted by u/walterbell
galangalalgol · a year ago
Why are radial arm saws so dangerous? I have an old one and other than shooting wood into the shop wall when ripping, or holding the wood with your hand it seems pretty hard to hurt yourself. Circular saws seem way more dangerous, and the only injury I've ever had was from a portaband.
Junk_Collector · a year ago
There used to be some pretty wild published advice on how to use a radial arm saw including ripping full sheets of plywood by walking the sheet across the cutting plane with the saw pointed at your stomach. They also travel towards the operator in the event of a catch because of the direction of the blade and the floating arbor. This makes positioning yourself out of the potential path of the blade critical and the one thing we know is that you can't trust people to be safe on a job site when they are in a hurry.
Junk_Collector commented on The U.S. government may finally mandate safer table saws   npr.org/2024/04/02/124114... · Posted by u/walterbell
nemothekid · a year ago
>The question is, how fast does it need to be?

I don't know - the marketing material actually says 5 milliseconds. That's the crux of the problem and I don't believe you can actually move the saw fast enough to not cause serious damage to the human without damaging the saw. The problem, as I understand it, is stopping the saw. The saw actuator only makes sense if it moves fast enough and given the saw stop works on detection, I'm not convinced you have that much time.

I'm considering the physical reality here - if the saw must be yanked down quickly, how much force must be applied to the saw to move it, and then can that equal and opposite force be applied to stop it without damaging the saw?

>Look at the incentives, you'll find the truth.

This is true of any safety device? The SawStop inventor created his company after trying to license it and eventually won in the marketplace after nearly 30 years. Surely his competitors would have released an actuator based solution if it is was possible rather than ceding marketshare of high end saws?

Junk_Collector · a year ago
Bosch did release an actuator-based solution. They got sued by SawStop for patent violations and lost and pulled it from the market. SawStop's main patent just covers the concept of a blade brake, not a specific implementation.
Junk_Collector commented on The U.S. government may finally mandate safer table saws   npr.org/2024/04/02/124114... · Posted by u/walterbell
pnw · a year ago
Sawstop already offered their key patent for free to get this technology adopted.

https://www.sawstop.com/news/sawstop-to-dedicate-key-u-s-pat...

Junk_Collector · a year ago
They offered to relinquish one important patent, but they have a huge portfolio of patents covering blade breaks specifically applied to table saws. If you go look at the actual testimony instead of a summarized article, SawStop's representative very explicitly will not even discuss relinquishment of their other patents including their patent on "using electrical signals to detect contact with arbor mounted saws" which does not expire until 2037.

A large part of the testimony was companies such as Grizzly complaining that SawStop is unwilling to engage with them in good faith on licensing their technology. Given SawStop's history, I'm unfortunately inclined to believe them.

Junk_Collector commented on 100kHz to 6GHz 2 port USB based VNA   github.com/jankae/LibreVN... · Posted by u/sleepingreset
rkagerer · 2 years ago
First paragraph of the Overview section is borked:

Network analyzers are used mostly at high frequencies; operating frequencies can range from 1 Hz to 1.5 THz. Special types of network analyzers can also cover lower frequency ranges down to 1 Hz.

What's the first figure supposed to be?

Junk_Collector · 2 years ago
Most likely 10 MHz. The reference links to Keysight.com and that's more or less industry standard for compensated directional couplers which are used in the large high performance VNAs. To go lower than that they usually use a directional bridge.
Junk_Collector commented on Tiny crystal films could make night vision an everyday reality   theconversation.com/seein... · Posted by u/dance-me
xyzzy123 · 4 years ago
ITAR.

I think many people in the US (who can buy NV pretty easily) don't notice that export is not allowed without approval from the state department.

Export is regulated for sure, but I think there are also performance limits on what you are allowed to sell to non law enforcement / military.

Junk_Collector · 4 years ago
This is coming out of Australia so it wouldn't be ITAR, but they do have their own export restrictions on this sort of technology.

u/Junk_Collector

KarmaCake day751July 6, 2017View Original