Explore the relationship of signals in the time and frequency domain. Adjust time parameters and see how the spectrum changes! Take a look at selected Fourier transform pairs of waveforms and pulses.
Signal-to-noise ratio demonstrator
How does music or speech sound in different signal qualities? Recognize that it's the signal-to-noise ratio (SNR) that matters. Observe the visual and auditive impact of added noise.
Peak-to-average power ratio of signals
The Peak-to-average power ratio (PAPR) of a signal is the peak power divided by the average power.
LTI system - RC low-pass filter
Measure amplitude and phase of the output sine wave signal using an oscilloscope. Compare the results with the transfer function representing the linear time-invariant (LTI) system.
See the impulse response and transfer function of various LTI systems. Measure amplitude and phase responses. Why do these filters have a linear phase?
Spectra of FM signals
Frequency modulation signal spectra show sidebands for sinewave modulation. In this experiment we take a look how they change with the modulating signal amplitude.
Produce a frequency modulated transmission signal. Select music, speech, microphone or take your own audio file. Demodulate the signal using the FM receiver or let a USRP SDR transmit...
Demodulate the FM transmission signal. Listen to the received music or speech. Check if you modulated the audio signal properly and the frequency deviation is adjusted properly...
The invention of amplitude modulation made radio broadcasting possible. The message signal varies the carrier amplitude. Analyze an AM-signal in time and frequency domain and...
AM transmission - envelope detector
An easy way to recover the messsage signal of an AM-modulated signal is the envelope demodulator. In its simplest form the envelope...
AM transmission - synchronous detector
In AM transmissions without carrier a simple envelope detection is not possible. A more complex synchronous or coherent detection is required...
How does music or speech sound for different quantization resolutions? Explore how the quantization error degenerates the audio signal and each bit per sample improves the Signal-to-quantization-noise ratio by 6 dB.
Explore how the use of compressors and expanders (companding) improves the signal quality compared to uniform quantization - especially for quiet voice. Logarithmic Laws - piecewise linear approximation.
See also: | Signal Spectra 1 | Signal Spectra 2 | Pulse Spectra | LZI-System | Noise bandwidth demonstration | Amplitude modulation | Amplitude modulation (exercise in script) | AM transmitter 1 - record audio transmit signal to file | AM transmitter 2 - transmit recorded signal via USRP | Frequenzmodulation | Frequency modulation audio demo | FM transmitter (2) - transmit recorded signal from file to USRP |