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I saw this on an audiophile website and decided more people needed to see itquote:As with any passive network, cables contain both resistive and reactive components. This creates resonances and anti-resonances in the cable. A series resonance is when the reactive components cancel each other. At the resonant frequency the complex impedance will be quite low. This series resonance doesn’t impede the signal flow in a cable. An anti-resonance, however, is formed when the reactive components add together to form a highly complex impedance. This “parallel resonance” does impede signal flow in the cable.
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Aug 17, 2017 22:29
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Oh man that's pretty bad, and misuses terms describing real effects in cables and circuits. However, when you are going at very high speeds, with signals at frequencies much much higher than audio frequencies, you no longer get good functionality from cabling and interconnections for free and the cable and connector construction & design actually matters. Really nice coaxial cabling which is durable, flexible, and has good phase stability for speeds of 10's of GHz can be pretty expensive, and can set you back on the order of a couple grand per cable assembly. High-quality coaxial connectors which work well up to 67 GHz are $50 a connector. silence_kit fucked around with this message at 12:52 on Aug 18, 2017 |
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Aug 18, 2017 00:09
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i used to work at a company that tried to break into that market with zero understanding of the context they had the wherewithal to buy an s-mparameter machine but ran out of steam before anyone figured out how to use it (but after they had already ordered a shitload of fancy coax and connectors, of course)
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Aug 18, 2017 01:17
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qirex posted:I saw this on an audiophile website and decided more people needed to see it ok, i guess i'll be the $80,000 that you need to spend on a cable to mitigate noise up to 200khz please ignore that 48MHz dollar-store USB 1.1 in the corner
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Aug 18, 2017 01:46
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qirex posted:I saw this on an audiophile website and decided more people needed to see it i guess at that price you only need to sell one a month to book 1M in revenue
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Aug 18, 2017 04:54
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Device tree is so easy to learn and good that if you don't understand it in a hour of looking at other device trees you are bad and shouldn't be modifying kernel code.
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Aug 18, 2017 04:58
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ratbert90 posted:Device tree is so easy to learn and good that if you don't understand it in a hour of looking at other device trees you are bad and shouldn't be modifying kernel code. so i guess i won't be seeing device tree in any bsps soon
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Aug 18, 2017 05:26
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good news, i'm not modifying kernel code! i just want this loving thing to boot in a usable state! bindings docs are poo poo so yes i guess you do have to go code spleunking in practice to figure out what the actual gently caress is going on like, why the poo poo doesn't this uart work? gpio pinmux? lack of a clock signal to the functional block?? who the gently caress knows??? the raspberry pi 3 is the only embedded platform i've seen where it is far easier to get a framebuffer console than it is to get a uart console and that's just perversely impressive somehow
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Aug 18, 2017 05:34
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the raspberry pi project exists to trick you into thinking Broadcom is actually good
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Aug 18, 2017 15:04
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oh i'm well aware it's just a broadcom marketing exercise but hmm do i buy a 1GHz 1GB quad core compute module which has a well known retail price of $40 or do i speak to some other vendor's loving salesprick who wants to see how far into the three figures he can push his luck
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Aug 18, 2017 15:37
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the thing I don't understand about the rpi is projects go down like this: start up: woah cool this prototype based on a rpi works great! now we can just get someone to lay it all out on one board and we'll have a product! what's a 30 board pilot going to run? Broadcom: lol no startup: huh? Broadcom: 3k minimum *spam filters startup's email* startup: hey disty what the gently caress how do I buy Broadcom stuff? disty: can I interest you in some nice ti processors?
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Aug 18, 2017 17:19
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that's what they made the rpi compute module for 
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Aug 18, 2017 17:23
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hobbesmaster posted:the thing I don't understand about the rpi is projects go down like this: its easy. you buy rpis and desolder the processors and
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Aug 18, 2017 20:25
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Bloody posted:its easy. you buy rpis and desolder the processors and you buy RPi Compute Modules and SO-DIMM sockets
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Aug 20, 2017 09:42
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eschaton posted:you buy RPi Compute Modules and SO-DIMM sockets only $40 on the bom!
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Aug 20, 2017 15:36
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yeah and if you can meet a 3000 unit moq then you can get an actual application soc and put it right on your design, pi cm isn't intended for large volume applications that and the pi cm doesn't particularly serve the goals of broadcom's marketing department so they actually put a fairly juicy profit margin on it
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Aug 20, 2017 15:57
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let's say you did a beagle board project and want to do that pilot run. processor is $20 in quantity 1 but $20 is a rip off you say. well yes digikey charges a ton for actually stocking stuff. TI says <$10 in 1k quantities. it's probably cheaper if you actually have a distributor quote everything on your bom for a few kilounits
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Aug 20, 2017 16:26
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hobbesmaster posted:so i guess i won't be seeing device tree in any bsps soon Tons of device trees are provided by Bsps.
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Aug 30, 2017 02:03
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how many sign offs do i need for schematics on jokes?
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Aug 30, 2017 02:07
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i have no idea to tell why my stupid complicated teensy 3 project doesn't appear to work lol
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Aug 31, 2017 17:01
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The teensy 3 is real and strong and my friend. What is going wrong?
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Aug 31, 2017 17:23
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Sagebrush posted:The teensy 3 is real and strong and my friend. What is going wrong? well ya boi got too ambitious trying to be the first to get https://crystal-lang.org/ compiled and running on arm-none-eabi https://github.com/bkerley/os-crystal i can actually compile everything into an ELF (this took a couple weeks of free time), link it out to an ihex that teensy_cli_loader accepts, but it doesn't blink the LED like i want it to https://github.com/bkerley/os-crystal/blob/master/src/main.cr#L8 next time i feel like looking at it i'm probably gonna make one of the C files that initializes the chip do something with the LED so i can bisect where it's failing
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Aug 31, 2017 18:03
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Sagebrush posted:teensy 3 
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Aug 31, 2017 18:04
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the kinetis mcu found on the teensy 3 is, shall we say, the dick dastardly of microcontrollers it is fast but it is also bad
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Aug 31, 2017 18:12
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it sounds like you people are trying to use something other than god's own programming language, C++
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Aug 31, 2017 21:21
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just attach with a debugger, whats the big deal
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Aug 31, 2017 21:42
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Sagebrush posted:it sounds like you people are trying to use something other than god's own programming language, C++ c++ is trash though, the safety of c combined with the readability of perl
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Aug 31, 2017 21:43
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JawnV6 posted:just attach with a debugger, whats the big deal I'm pretty sure that conversion therapy doesn't work and even if it did, you should accept people for who and what they are not your opinion of who/what they should be. Hth.
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Aug 31, 2017 21:45
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