Stupid formula question

Owen

Hi Guys,

I've got a formula I've attached to this post, and I'm useless with maths. Great with engineering, shocking with maths. If I were to re-jig this formula to have noise on one side of the equation, and everything else on the other, how would I go about it?

mathew

Engineering kinda relys on being good at maths... you dont really get one with out the other..

Anyway, see here for rules of logs http://www.purplemath.com/modules/logrules.htm

Expand it out and then its a simple matter of moving stuff across the equals sign.

Owen

mathew wrote: »

Engineering kinda relys on being good at maths... you dont really get one with out the other..

Course you do, there's difference disciplines of engineering. When I was in college, I was top of my labs in circuit modelling, etc, but not the may-west in Maths.

mathew wrote: »

Anyway, see here for rules of logs http://www.purplemath.com/modules/logrules.htm

Great site Mathew, cheers for that. Still have the feeling I'll be up all night, but what the hey.

mathew

ned78 wrote: »

Course you do, there's difference disciplines of engineering. When I was in college, I was top of my labs in circuit modelling, etc, but not the may-west in Maths.

Fair 'nuff.. I find without maths the Engineering Im studying (general) would be impossible..

up them Schteps

I seriously hope this is a joke..... BUT

10^(SNR/10) = signal / noise

Noise = Signal / (10^SNR/10)

=> Noise = 10*Signal / 10^SNR

Owen

I'm getting :

10^SNR/10=signal/noise

Noise=signal/10^SNR/10

up them Schteps

ned78 wrote: »

I'm getting :

10^SNR/10=signal/noise

Noise=signal/10^SNR/10

Thats it! Just make sure that you have (10^SNR/10)

Owen

up them Schteps wrote: »

Thats it! Just make sure that you have (10^SNR/10)

Cheers UTS, it seems I've the actual equation right now, but when I substitue values in the result's all over the place

mathew

up them Schteps wrote: »

I seriously hope this is a joke..... BUT

10^(SNR/10) = signal / noise

Noise = Signal / (10^SNR/10)

=> Noise = 10*Signal / 10^SNR

your last line there is wrong i think. the SNR/10 is in the power, so you cant bring the 10 above the line..

up them Schteps

mathew wrote: »

your last line there is wrong i think. the SNR/10 is in the power, so you cant bring the 10 above the line..

I fixed it in my second post. I hate typing equations on computers

Owen

Say for example my signal is 15, and my SNR is 20 ...

20=10Log(15/x)
20/10=Log (15/x)
2=Log(15) - Log (x)
2=1.17609 - Log(x)

Or have I gone horrifically wrong again?

Thomas_S_Hunterson

up them Schteps wrote: »

I fixed it in my second post. I hate typing equations on computers

Yea, I think there's even a TeX plugin for VBulletin, it'd make things nice and neat.

mathew

ned78 wrote: »

Say for example my signal is 15, and my SNR is 20 ...

20=10Log(15/x)
20/10=Log (15/x)
2=Log(15) - Log (x)
2=1.17609 - Log(x)

Or have I gone horrifically wrong again?

no, thats perfect so far
No all you have to do is bring your 1.17609 over to get:

-.82319 = log(x)

then x = 10^(-.82319)

up them Schteps

ned78 wrote: »

I'm getting :

10^SNR/10=signal/noise

Noise=signal/10^SNR/10

Just use these steps! Why are you varying from this

Owen

Woot I'm not as stupid as I think I am. Thanks all for the help