Contents
- 1 What determines frequency resolution?
- 2 What is amplitude spectrum of a signal?
- 3 What is time and frequency resolution?
- 4 What is the frequency of a signal?
- 5 How is frequency related to time?
- 6 Why does the amplitude of a FM signal remain constant?
- 7 How does limiting the top frequency affect the bandwidth?
- 8 How is the frequency spectrum related to the phase spectrum?
What determines frequency resolution?
The frequency resolution is equal to the sampling frequency divided by FFT size. For example, an FFT of size 256 of a signal sampled at 8000Hz will have a frequency resolution of 31.25Hz. If the signal is a sine wave of 110 Hz, the ideal FFT would show a sharp peak at 110Hz.
What is amplitude spectrum of a signal?
The amplitude spectrum simply gives amplitude at each frequency. The phase spectrum simply gives the phase at each frequency (Figure 2.20).
How do the number of time samples & frequency samples affect the resolution of the DFT?
For the DFT, the resolution is equal to fs/N, from Equation 4.8. So, for a given sampling frequency, the more samples (N) in the signal, the smaller the frequency increment between successive DFT data points. The more points sampled, the higher the spectral resolution.
What is time and frequency resolution?
A pure sinusoidal wave has a clearly defined frequency, but it is spread over the infinitely long time axis. At the other extreme is an impulse function (often called a delta function), which is nicely compressed to a point on the time axis but contains a mixture of all frequencies.
What is the frequency of a signal?
Frequency is the rate at which current changes direction per second. It is measured in hertz (Hz), an international unit of measure where 1 hertz is equal to 1 cycle per second. Hertz (Hz) = One hertz is equal to one cycle per second.
How do you find the frequency of a signal?
If x is an point segment of , one way to determine its frequency content is to take its discrete Fourier transform (DFT) by using the fast Fourier transform (FFT) to compute it: >> X=fft(x); This gives us an component vector , which in general will be complex valued.
Frequency equals two cycles per second. Time, T, is 1 divided by f, the number of cycles in a second.
Why does the amplitude of a FM signal remain constant?
Recall that for an FM wave the amplitude of the signal, and hence the power, remains constant. This means that the power in the individual frequency components of the wave must add up to the transmitter output power. Furthermore, if the modulation index changes, the total power must
How is the amplitude of a frequency modulation?
Frequency modulation is a type of modulation where the frequency of the carrier is varied in accordance with the modulating signal. The amplitude of the carrier remains constant. The information-bearing signal (the modulating signal) changes the instantaneous frequency of the carrier.
How does limiting the top frequency affect the bandwidth?
It can be seen that limiting the top frequency of the modulating signal limits the overall bandwidth of the amplitude modulated signal. For audio transmissions, like broadcast transmissions, the overall bandwidth of the signal is dependent upon the highest frequencies to be transmitted.
Understanding Signal Frequency Spectrum A signal can be viewed as a composition of a number of sinusoidal signals with varied amplitude, frequency and phase. Distinguishing this composition requires analyzing the corresponding frequency, amplitude and phase spectrum of the signal.