Search found 51 matches

by david753
Sat Dec 04, 2004 12:41 am
Forum: General Discussion
Topic: variance euqation?
Replies: 5
Views: 843

Re: variance euqation?

http://user52.starbeta.org/others/ANSWER.DOC
I already found the answer.
Thanks for help.
by david753
Fri Dec 03, 2004 9:56 pm
Forum: General Discussion
Topic: variance euqation?
Replies: 5
Views: 843

Re: variance euqation?

Thnaks for your reply, first. I still confused what you said. Then, I updated the file, that attached my explaination. If you are not agree with my ratiocination, could you explain and prove it step by step as I did? How does the equation on page14 become the equation on page16?<p>P.S. If you cannot...
by david753
Fri Dec 03, 2004 5:06 am
Forum: General Discussion
Topic: variance euqation?
Replies: 5
Views: 843

variance euqation?

Recently, I am studying DSP paper. http://user52.starbeta.org/others/ch2.pdf At page16, there is equation2-3 Please refering the the first equation on the document. http://user52.starbeta.org/others/question.doc I supposed it is wrong. I revised it as the second equation on the document. Am I right?
by david753
Thu Dec 02, 2004 1:07 am
Forum: General Discussion
Topic: sensitivity calculation?
Replies: 5
Views: 850

Re: sensitivity calculation?

In my practical circuit, the minimum sensitivity is -22dbm.
It means the noise floor is -22dbm.
Is it reasonable?
How to calculate the reasonable noise floor?
Which item of specification is refering in terms of noise issue?
by david753
Wed Dec 01, 2004 2:26 am
Forum: General Discussion
Topic: sensitivity calculation?
Replies: 5
Views: 850

sensitivity calculation?

I have a AD convert AD9057BSR-80.
http://www.analog.com/UploadedFiles/Dat ... 9057_d.pdf
I design a decoder circuit, that 40MHZ modulation signal input(BPSK) -> AD9057 -> FPGA.<p>Does anybody know what the value of minimum sensitivity is?
And how do you calculate it?
by david753
Tue Nov 30, 2004 5:00 am
Forum: General Discussion
Topic: appliance without batteries
Replies: 8
Views: 1626

Re: appliance without batteries

I was so pleasant that there are so many people who are interested in this topic.
But, Does anyone know how to do it by myself?
It seems using a motor connecting to a cap, and diode, that all.
What kind of motor suitable for in terms of energy transfer efficient?
by david753
Mon Nov 29, 2004 1:22 pm
Forum: General Discussion
Topic: appliance without batteries
Replies: 8
Views: 1626

appliance without batteries

There is a type of appliance that doesn't need to use batteries.
Such as mobil phone recharge system via pushing by fingers.
And I heard my colleague said, there is a kind of flashlight, which energy come from hand compressing repeatedly.
Does any body know this technology in details?
by david753
Sat Nov 27, 2004 3:12 am
Forum: General Discussion
Topic: music box
Replies: 2
Views: 538

music box

Recently, I disassembled a music box. I found there are a slice that looks like a comb, a rolling column, and spring generator. I am quite interested to implement by myself. I'd like to replace the original column, implementing my favorite music on it. But, I don't know how to make a column by mysel...
by david753
Mon Nov 15, 2004 5:21 am
Forum: General Discussion
Topic: LPT port for logic analysis
Replies: 2
Views: 497

LPT port for logic analysis

I just got an idea, is it possible to implement a visual logic analysis instrument (software) on PC via printer port?
Where can I get related information?
Does it exist in now market?
Does it have marketing potential?
by david753
Wed Nov 10, 2004 11:37 am
Forum: General Discussion
Topic: BSII Pulls For Cheap...
Replies: 2
Views: 801

Re: BSII Pulls For Cheap...

Could you please attach the photo of selling stuff on web?
And add details specification of it.
Thanks
by david753
Wed Nov 10, 2004 11:34 am
Forum: General Discussion
Topic: battery leaking
Replies: 3
Views: 785

battery leaking

I installed some batteries in a flashlight weeks ago.
But, I found the batteries are leaking something as white liquid after I opened it.
Now, I am curious about why the white liquide were leaking, and how can I avoid it?
by david753
Fri Oct 08, 2004 6:19 am
Forum: General Discussion
Topic: energy efficiency
Replies: 4
Views: 697

energy efficiency

There are some heating devices that were used in our lives, such as microwave oven, electromagnetic oven electronic heating oven and gas oven, but do you know the order of energy efficiency?
by david753
Thu Sep 09, 2004 8:40 am
Forum: General Discussion
Topic: pc gun principle?
Replies: 4
Views: 849

pc gun principle?

Have you ever played the pc game with gun shooting?
Do you know the principle of it?
How can I make it by myself?
by david753
Fri May 28, 2004 2:58 pm
Forum: General Discussion
Topic: electro-therapy circuit
Replies: 1
Views: 564

electro-therapy circuit

people said, electro-therapy circuit is quite easy.
Refer to:
http://www.rolor.com/e-gp8016series.htm
Does anyone know where I can find the circuit?
by david753
Thu Apr 15, 2004 5:18 pm
Forum: General Discussion
Topic: midi player
Replies: 15
Views: 2969

Re: midi player

I'd like to implement a music box.
When the box is opened, the midi will be played with midi that was burned on a rom, hardware.
How to implement it?