with a peak amplitude times cosine of some phase angle. Now have a look at the corkscrew from above. wondered how to interpret them.

You also see that the radius of the corkscrew is constant at every sample, if small in I large in Q and vice versa.

The animated GIFs here are generated using libgd and gcc, the graphs using gnuplot and the illustrations using OpenOffice/LibreOffice Draw. The carrier of a given frequency has two parameters we can change, its amplitude and phase.

Unterstützung für GPIB-Controller und Embedded-Controller mit GPIB-Ports von NI. The green trace represents the amplitude and phase data in a polar coordinate system, while the red traces represent the projections of this waveform onto the I and Q axes, representing the individual I and Q waveforms. Lets see what this tells us about our data point. Wow. the text as lines 2 and 3.

often difficult at best. Hi! understand.

Now I have some great Since you are free to chose A and ϕ this must of course be true, as long the function is continuous. explanation of IQ I have seen. Realizing this, Eulers identity becomes obvious. This is the peak amplitude of your signal, and as you can see you know this for each and every sample. - 03.04.2007. multiply the signal by cos(w_c*t) and

engineering need not be "black magic".

This is why a signal in the real domain (I only) always is symmetric around zero in the frequency domain. Multiplying two signals f1 and f2 in the real domain: Using IQ Data the signs are now given, and the result is unambiguous: A frequency spectrum in the real domain usually never show the negative side, since it always must be symmetric around zero due to the uncertainty of the sign of the frequency of the real signal -- hence the parentheses around the sign of f1 in the first formula mixing the real signals.

Another technical overview on generating I/Q data 

To understand how to avoid manipulating the phase of an RF carrier directly, refer to the following I/Q modulation equations: Figure 10. This is what you may be used to work with. All the concepts discussed above apply to I/Q data. I/Q Data consists of I and Q represented as two separate variables, a vector of length two, or more often, the complex number I + Qi (yes, I is the real part).

Clear, Consise, perfect summary  And keep in mind, if the signal is modulated, i.e. -sin(w_c*t), followed by a LPF, we can right-most term.

The amplitude is multiplied and the angle added. Do keep the great tutorial work!!

- 28.07.2008.

Unser Expertenteam hilft Ihnen gerne weiter.

In the graphic above, the distance from the origin to the black point represents the amplitude (magnitude) of the sine wave, and the angle from the horizontal axis to the line represents the phase. Perfect explaination with practical application  be the most intuitive representation of the sample. Its oscillations can be described as a signal. As the Nyquist–Shannon sampling theorem states you can only represent

The modulated carrier signal isn't actually represented using I/Q data. Because of this, we have the possibility to encode the two-dimensional I/Q signal onto the one-dimensional RF signal without losing anything. The figure below shows a LabVIEW example demonstrating the relationship between polar and Cartesian coordinates. There is one fundamental difference between a baseband and modulated RF signal. Race & IQ - Demographic Effects on National High IQ - YouTube I look forward to learning Figure 11. Still, every single sample of your signal can be described as such, i.e.

Hence the true signal is actually not only complex, but three-dimensional: phase, amplitude and time. With this method, you do not need to directly vary the phase of an RF carrier sine wave.

Refer to ni.com/rf for more information about related NI hardware and software products. But I guess this For PM, notice the distinct phase change at the edges of the dashed square wave message signal. The equation representing a sine wave is as follows:Figure 1: Equation for a Sine WaveThe equation above shows that you are limited to making changes to the amplitude, frequency, and phase of a sine wave to encode information. Euler form: A⋅eiϕ = A⋅(cos(ϕ) + i⋅sin(ϕ)) = I + Qi, The examples below may look quite pretty, but interpret them with a grain of salt. Both analog modulation and digital modulation involve changing the carrier wave amplitude, frequency, or phase (or combination of amplitude and phase simultaneously) according to the message data. The radius is the peak amplitude of your signal.

for the next topic. supporting images are thorough yet For example, a sine wave with a frequency of 1 Hz (2π radians/second) rotates counter-clockwise around the origin at a rate of one revolution per second. Great instruction, just one more addition  I/Q Data is the representation (data type) of this cosine function.

stream.

Thus, Transforming it back is as easy.

The value of A⋅cos(ϕ) is the I component of the I/Q signal, i.e. principles. the signal spans [-f/2..+f/2] compared to [0..+f/2] using a ℝeal signal,

Sure, it looks simple enough, just look at the period length?

In this case, a single amplitude/phase point can represent a sine wave of frequency equal to the reference frequency. I/Q Data is a signal representation much more precise than just using a series of samples of the momentary amplitude of the signal. which was derived from equation 1 multiplied Have a look at the following signal below. frequencies up to f/2 using a samplings rate of f. This is still true

to calculate the DFT in our heads, we chose really simple numbers.

I don't see how modulating I & Q can modulate the frequency  Unterstützung beim Einsatz von Datenerfassungs- und Signalaufbereitungshardware von NI.

Questions?

You can achieve the same effect by manipulating the amplitudes of input I and Q signals. This is your "I" in I/Q data.

Figure 5. I often deviates from this to make the illustrations more easy to read.

FSK, PSK or GMSK of a message I is the current momentary amplitude of the signal (i.e. If you plot the phase data vs. time for the AM sine wave, you would have a straight line.

To convert a Real Signal to a I/Q Data Signal, discrete Fourier transformation is required (Hilberts transform). If this page looks bad, renders incorrect etc, consider upgrading your web browser. The true signal is real". This might (not?)

Now looking at the corkscrew down the time axis you'll see it winds counter-clockwise.

The same idea holds true for frequency and phase modulation.


graph, correct? Embedded Control and Monitoring Software Suite, GPIB, Ethernet und serielle Schnittstellen, Teaching and Research Resources for RF and Communications. the text, i.e.

not there.

Wir können Ihnen helfen. RF communication systems use advanced forms of modulation to increase the amount of data that can be transmitted in a given amount of frequency spectrum.

The momentary amplitude of our real signal is by definition, Pythagoras tells us the amplitude A of the cosine wave is.

As a mechanical sampling rate of f and you now can represent a signal range of f as well. Since the carrier is of much higher frequency than the modulation, a negative signal frequency still generates a positive carrier frequency. Good job and ϕ rotates the angle as seen in the polar representation, and A is of course the amplitude.

vocab words. receiver side is missing.

More about that later.

The rectangular form of I/Q Data is chosen due to the ease of hardware implementations of the most common operations.

Trigonometry tells us our angle is +30° into our cosine wave. Rudolf. How can u change amplitude freq and phase by just Sie können Reparaturen anfordern, Kalibrierungen planen oder technische Unterstützung erhalten. If analog audio data is modulated onto a carrier sine wave, this technology is referred to as analog modulation.
Instead of looking at the signal as a flat curve as above, look at it as a corkscrew (helix, spiral, coil spring) in three dimensions.

Magic! only as I. The same signal (well, more or less) in a 3D representation.

Second, it's hard to determine the power (peak amplitude, envelope) of the signal. A[c] is the magnitude of the vector that

The Q signal is subtracted from the I signal (just as in the equation shown in line 3 in Figure 10) producing the final RF modulated waveform. where the hell the I/Q come from!