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yzhou

31 karma · joined February 28, 2012

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yzhou··on How to Design a New Chip on a Budget
minimum 5.5mm^2 is required, so we are talking about 3575 euros here. Besides, it is very rare that you can get a production grade chip on the first try, bug happens all the time, you might need 2 or 3 or even more tries to get a working product.
yzhou··on What People Think You Can’t Say in Silicon Valley
why do you say Scott Adams is purely evil?
yzhou··on 24/192 Music Downloads Are Very Silly Indeed (2012)
the devil is in the DAC and ADC. You just can't turn 16bit/24bit data directly to/from analog without much loss. The 1/65536 accuracy voltage divider simply don't exist.

So, you have to up-sample the songs to high rates with less bits, like 1bit to 6bits, then do the conversion, and get the best SNR you can.

In this sense, there's simply a lot of advantage of using 24/196 since the above conversion can result in less loss and higher SNR

yzhou··on 24/192 music downloads make no sense
The low-passing with a brick wall filter on 44.1KHz audio can be a bad thing sometimes, for example, pre-echo https://en.wikipedia.org/wiki/Pre-echo You won't hear the pre-echo on a 2.8MHz DSD audio.
yzhou··on 24/192 music downloads make no sense
the probe is placed on the headphone jack. The difference in the vertical scaling is that 0dB DSD signal is 6dB below a 0dB PCM.
yzhou··on 24/192 music downloads make no sense
In the real world, it is almost impossible to make a voltage divider with 24bit resolution. So all the DAC makers have to convert 24bit audio into lower bits(6bits to 1bits), this step requires oversampling the original audio. It is a lot easier to oversample a 192KHz/24bit audio than a 44.1K/24bit audio, and the ringing is much less after oversampling the 192KHz/24bit audio.
yzhou··on 24/192 music downloads make no sense
The brick wall filters used on low sample rate sound cause ringing in the time domain, which can "blur" the neighboring impulse.
yzhou··on 24/192 music downloads make no sense
There's a big difference in impulse response with different sample rates, any one can see it on a oscilloscope, I bet some one can hear the difference.

Those who don't have a oscilloscope can see the picture here: http://i.imgur.com/wY0wzcW.png

yzhou··on Chinese Number Websites
many older people like my dad, don't know pinyin well. he doesn't input texts, but he browses web sites. He uses a default home pages full of links to start exploring the web.
yzhou··on Chinese Number Websites
the point of using number in the domain is, a lot of Chinese people don't know letters, they don't know English words and they can't get "PinYin"(using letters to represent Chinese words) right. How do you make these people type urls in the browser? well, luckily, they all know numbers!
yzhou··on Ask HN: Idea Sunday
Here's what I want: A cheap text ssh terminal with wifi,or cellular, nice keyboard hardware, with extremely long battery life (or solar powered), which i can just throw it in my car and forget it. Whenever I am away of my computer I can always log in to my cloud server and write codes or do some quick fixes.
yzhou··on Ask HN: Freelancer? Seeking freelancer? (December 2013)
SEEKING WORK Remote (SF Bay area) Speciality: C/C++>20years experience , Python, PHP, javascript, digital/analog circuit design, embedded programming, FPGA Contact: jerryzy@gmail.com
yzhou··on Taobao.com breaks record for online sales in a day - $3.1 billion USD
I've been using taobao intensively for our business for quite a long time. we are a hardware start-up, we bought components from taobao, make, assemble PCB prototypes from taobao, It's so much better than ebay, for example, they have a IM client for you to chat with the seller, negotiate price and shipping cost in real time, and once the deal is made, they can change the price instantly for you. There also sites that buy taobao things for you and ship them to the US, so all you need is a paypal account or a credit card, and the ability to read Chinese.
yzhou··on New Arduino released: the 32bit Due
we have made a A3P250 FPGA board, with build-in USB interface, total cost of building the board is less than $50, can do a ton of things MCU can not do. would anyone want it if we commercialize it? http://cdn.shopify.com/s/files/1/0117/1482/products/IMG_0305... The design was based on http://skywired.net/blog/projects/a3pn250-fpga-breakout-boar..., added regulator chips, got rid of the power-on-reset chips.
yzhou··on Evolutionary algorithms and analog electronic circuits
This kind of work is OK for some simple block level circuit designs. In the real world designs, as circuits grow complicated, and parasitics add in, the SPICE convergence issue kicks in and automation becomes difficult.
yzhou··on Anti-Piracy Patent Aims to Stop Students from Sharing Textbooks
Just another reason for not hiring people based on their grades.
yzhou··on Why multi-armed bandit algorithm is not "better" than A/B testing
From a EE's point of view, what the OP said is that there's too much noise involved in multi-armed bandit algorithm. If that's the case, a low pass loop filter is needed. It's kind of like locking a PLL to a reference clock right?
yzhou··on ShopLocket Promises Customers They Can Sell Anything, Anywhere
I think your idea is awesome! I always believe in those "step removing" ideas.
yzhou··on There is no point to distributing music in 24-bit/192kHz format.
high dynamic range is not about the lowest volume you can hear, it's about the voltage resolution between this sampling point and the next. Base on your assumption, we can all see black whether we use 16bit RGB color or 24bit RGB color, what's the point of using 24bit RGB?
yzhou··on There is no point to distributing music in 24-bit/192kHz format.
The hearing of ears is a time-domain thing, not a frequency domain thing. It's the frequency response of all the frequency components added together. people might not be able to respond well to a single high frequency tone, but might respond well to a combination of tones.
yzhou··on There is no point to distributing music in 24-bit/192kHz format.
why do you think "This difference gets lost in the THD already at the DAC "? Do you have numbers to back it up? What's the noise floor of DAC? What's the noise floor of an output stage? Do you have the number?
yzhou··on There is no point to distributing music in 24-bit/192kHz format.
A person can not hear a 22kHz tone doesn't mean he can not hear a sound that contains 22kHz components. For example, a square wave contains lots of high frequency harmonics, the more higher frequency harmonics it have, the "squarer" the square wave gets. An ideal square wave forms ideal "0" "1" states. A person's ear might not be able to hear a 22Khz sine wave tone, but he might be able to sense the steepness of "0" "1" state.
yzhou··on Linus Torvalds on C++
I guess what he meant was signal to noise ratio, i mean, Aplayer/Cplayer ratio. Too many Cplayer programmer start learning c++ without any idea how cpu and memory works, if you let them to mess with the kernels it would be a nightmare for Linus.