Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Frequency and phase relationship?

Status
Not open for further replies.

neetendra1

Junior Member level 1
Joined
Feb 20, 2010
Messages
18
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Location
Bangalore
Activity points
1,378
If i have a signal of certain Frequency then how to calculate its phase in digital world?
 

saif haider

Full Member level 1
Joined
Mar 28, 2007
Messages
97
Helped
11
Reputation
22
Reaction score
10
Trophy points
1,288
Location
Pakistan
Activity points
1,917
y(t)=A*sin(2*pi*f*t+phase)
w=1/frequency.

sin(w*t+phase) = sin(w*t)cos(phase)+sin(phase)cos(w*t)
sin(phase) = cos(pi/2 - phase)

Combined gives us:
y1 = amp * sin(phase)
y2 = amp * sin(w*t2 + phase) = amp*sin(w*t2)cos(phase) + y1 cos(w*t2)
y3 = amp * sin(w*t3 + phase) = amp*sin(w*t3)cos(phase) + y1 cos(w*t3)
 

kak111

Advanced Member level 4
Joined
Mar 30, 2011
Messages
1,366
Helped
933
Reputation
1,868
Reaction score
907
Trophy points
1,413
Location
Finland
Activity points
10,942
Digital signals has no certain definition as phase.

Because signal has only two values over time ( 1 and 0 )
(versus: ie sine has limitless different values over cycle ( or 1 phase of sine )

We should talk about timing , times , on-off ratio etc.

Of cause you do calculation with values in degrees ( or rad´s ),
if you think a value 100% pulse ratio as 360 degr´s ( or 2*PI )

or do mathematical analysis with Fourier series

count the 1st, 3rd, 5th, 7th, 9th ...... harmonic voltages
multiplied by 1, 1/3, 1/5, 1/7, etc.

here...........

Square wave signals : MIXED-FREQUENCY AC SIGNALS

Square Wave -- from Wolfram MathWorld



Regards KAK
 
Last edited:

neetendra1

Junior Member level 1
Joined
Feb 20, 2010
Messages
18
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Location
Bangalore
Activity points
1,378
Don't consider it to be a square wave, let it be a sine wave with amplitude varying from 1 to -1 ........
Amplitude is not my concern here..........but how to connect its frequency with the phase.
 

kak111

Advanced Member level 4
Joined
Mar 30, 2011
Messages
1,366
Helped
933
Reputation
1,868
Reaction score
907
Trophy points
1,413
Location
Finland
Activity points
10,942
how to connect its frequency with the phase.
= Hmmmm do not understand your question ??????

720px-Sine_and_Cosine.svg.png


If we have a sine wave 1 cycle = 0...2Pi (rad) = 0...360 degr
If frequency is 1000Hz --- Cycle time is 1/1000 s = 1ms

Now 1ms is an analoque to 0...360 degr ( 0...2Pi rad)
So phase 90 degr is 0.25ms and vice versa

When we talk about frequency it is allways 1/ one cycle time
f = 1/T or T = 1/ f

from this picture we can say , that phase difference between cos and sine signal is 90 degr
or Pi/2 rad

when we talk time difference between zero points ( or Umax ) we must know what is
the frequency or cycle time.

KAK
 
Last edited:

albbg

Advanced Member level 4
Joined
Nov 7, 2009
Messages
1,250
Helped
432
Reputation
864
Reaction score
386
Trophy points
1,363
Location
Italy
Activity points
9,465
You cannot know the frequency of a signal if your only knowledge is its frequency. The frequency is defined as the first derivative of the phase with respect to the time, or: f = dphase/dt. Then if you know the frequency you will know the increment of the phase with the time, but not the absolute phase.
To know the absolute phase you must know, or go back, to the origin of the time axis and also you have to refer it to a sin(x) or cos(x).
Another thing you can define is the relative phase between two signals (explained by kak111).
 
Last edited:

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top