Baud Rate

leshea2

·Is there an equation for coverting Hz (Hertz) into baud rate, or vic versa ?
·
What is the difference between measuring·speed with baud rate and Hz ?

Thanks !

stamptrol

Hmmm,

Normally the two are describing pretty different parameters.

The original description for baud represented the number of state changes in a given period of time. So, if you were comparing the frequency of a serial signal, it would fluctuate depending on the number of on and off bits in a given character.

In contrast, we use HZ to describe a repeating waveform ( sinusoidal, square or what have you). Hz is the repetition rate from the beginning of one cycle of the waveform to the beginning of the next cycle.

If you try to compare the two, consider a serial signal of 300 baud. If we choose,each character is a string of 8 bits, and we have a start bit and a stop bit for each character, our 300 baud rate is more like 30 characters per second. Thirty of anything per second can be described as 30 HZ. But, depending on the actual character being sent, a frequency meter might read upto 300 HZ if the bit pattern changes from character to character.

All of which begs the question: what is it you're trying to do?

leshea2

I'm just trying to answer someone else’s question really, and now I’m interested too.

I'm trying to see what baud rate you would use for the human brain, since the brain is measured in HZ ?

Scientists are using monkeys brain signals to move robot arms, and have even started using humans brain signals to move the robot arms, so what would that baud rate be, since I assume the scientist are using some kind of microcontrollers .

Thanks !

Beau Schwabe

leshea2,

The answer to your question is much more involved than simply knowing what the frequency of the human brain is.


GOOGLE is your friend! ... I was surprised to find this... with a search criteria of "Alpha Beta Brainwaves control"

http://webideas.com/biofeedback/store/prod_brainmaster.shtml

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Bean

Hz = Cycles per second
Baud = Bit per second

Cycle <> Bit

It's a bit like saying "My robot moves 5 ft per second, and water comes out of a spigit at 1 gal per second, so what is the speed of the water"

Wouldn't that be cool if your brain gave off serial data... Hmm maybe not...

Bean.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"SX-Video·Module" Now available from Parallax for only $28.95

http://www.parallax.com/detail.asp?product_id=30012

Product web site: www.sxvm.com

"One experiment is worth a thousand theories"
·

SteveW

Baud = Bit per second --I'm pretty sure this is wrong. I think it's symbols per second - if you're coding more than one bit per symbol (which is quite likely in any serious coding scheme), then baud rate < bits per second. Similarly, with RS232, you might be sending at 115200 baud, but with start & stop bits, and a completely arbitrary inter-byte gap, baud rate > bits per second. And then there's ADSL, behaving like a huge stack of rather good modems, all on the same copper pair, all working in different frequency bands. At that point, goodness knows [noparse]:)[/noparse]

Steve

leshea2

So would bites per second be the same as cycles per second, I mean would they = the same measure ?
Thanks !

steve_b

Not necessarily.

Think of it like this. BAUD rates refer to data being sent.

Typically it's sent in packets or "bursts".
These bursts of data are not happening all the time. As I type this message, the data from the keyboard is being sent at some baud rate. But when I stop typing (like now............) no data is being sent. So whenever I type....it goes at the BAUD RATE (speed).

Frequency (Hertz) is defined as 'cycles per second'. So, if you only transmit for half a second (the other half second being no data) then you won't get a measurement that's actually reflective of the frequency (as it's measured for the full second).
I work on radars and we use a Magnetron (glorified vacuum tube) that transmits at 160kW "PEAK". Because of the duty cycle we use our average power is only about 125W.
It's misleading but understanding dutycycle will make it logical.

Hope I didn't ramble too much so to muddle the explanation!! (I'm good at that..haha)

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·

Steve

"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."

pjv

Hi Leshea2;

As Steve W·said, baud rate is the rate of signalling; that is the rate at which uniquely identifyable signals (symbols) are presented every second. In more advanced schemes there may be more than one bit embedded into a symbol.

For example, one could transmit an analog voltage having 256 discrete levels in 10millivolt steps from 10 millivolts through 2,570 millivolts. Any one of those levels therefore would represent 8 bits of data as there are 256 possibilities defined. Hence, if one were to transmit, and at the receiving end recover any one of these 256 possible levels every millisecond, then one would be signalling (baud rate) at the rate of 1,000 baud, yet the data rate would be 8 times that, 8,000 bits per second.

The scheme I suggest is for illustration purposes, transmitting and receiving 256 discrete voltage levels over any distance is not practical.

Other methods of embedding more than one bit per baud are more practical.

And by the way, "Bites per second" is when you're eating corn.

Cheers,

Peter (pjv)

Post Edited (pjv) : 8/12/2005 6:08:10 PM GMT

Newzed

Steve, would I be correct in assuming your duty cycle is about .08
percent?



▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Sid Weaver
Do you have a Stamp Tester yet?
http://hometown.aol.com/newzed/index.html

·

steve_b

Close....NEwzed...
It's actually 0.8uS and 2.0uS (and 1.6uS for detail!).

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·

Steve

"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."