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How is spectral regrowth measured?
To find the true spectral regrowth power, convert the measured spectral power levels to mW and subtract the spectrum analyzer noise floor from the measured DUT power. Reconvert to dBm to get the true spectral regrowth.
What causes spectral regrowth?
Because a transmitter’s power amplifier gain is set to provide a specific average power, high peaks can cause the power amplifier to move toward saturation. This causes intermodulation distortion, which generates spectral regrowth. Consequently, spectral regrowth interferes with communication in the adjacent bands.
What are spectral frequencies?
Spectrum refers to the invisible radio frequencies that wireless signals travel over. The full electromagnetic spectrum ranges from three Hz (extremely low frequency) to 300 EHz (gamma rays). The portion used for wireless communication sits within that space and ranges from about 20 KHz to 300 GHz.
How is RF harmonics measured?
The high frequency components are harmonic distortion. The most straightforward method for measuring harmonic distortion is to use a continuous wave (CW) tone as an input signal, and measure the output signal with a signal analyzer; see Figure 1. A device under test (DUT) might be an RF amplifier or mixer.
What is RF harmonic?
A harmonic is a signal or wave whose frequency is an integral (whole-number) multiple of the frequency of some reference signal or wave. The term can also refer to the ratio of the frequency of such a signal or wave to the frequency of the reference signal or wave.
What is RF clipping?
Clipping is a form of distortion that limits a signal once it exceeds a threshold. Hard clipping results in many high-frequency harmonics; soft clipping results in fewer higher-order harmonics and intermodulation distortion components.
What is signal clipping?
Clipping is a form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. The extra high-frequency weighting of the signal could make tweeter damage more likely than if the signal was not clipped.
What is the highest frequency?
The highest frequency colour, which is violet, also has the most energy when it comes to visible light. The lowest visible light frequency, which is red, has the least energy. There is more energy in higher-frequency waves. Gamma rays have the shortest wavelengths and highest frequencies of all electromagnetic waves.
How to find the true spectral regrowth power?
To find the true spectral regrowth power, convert the measured spectral power levels to mW and subtract the spectrum analyzer noise floor from the measured DUT power. Reconvert to dBm to get the true spectral regrowth.
How to find true spectral regrowth in ACPR?
For ACPR/AltCPR, center the measurement band 5MHz/10MHz above the center of the highest carrier. To find the true spectral regrowth power, convert the measured spectral power levels to mW and subtract the spectrum analyzer noise floor from the measured DUT power. Reconvert to dBm to get the true spectral regrowth.
What is the maximum allowable spectral regrowth in the adjacent band?
Tony J. Rouphael, in RF and Digital Signal Processing for Software-Defined Radio, 2009 ACLR is a figure of merit that describes the maximum allowable spectral regrowth in the adjacent band. It is attributed to nonlinearities in the PA and in some cases the PA-driver.
Why is 30kHz resolution used for spectral regrowth?
A 30kHz resolution bandwidth is used because the spectrum analyzer shown has the lowest noise figure (about 24dB) at that resolution bandwidth. The spectrum analyzer shown includes an RMS display detector mode, which is specifically designed to measure noise-like signals.