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Swept Sine Test
The CoCo is ideal for swept sine measurements and includes customized software to simplify and automate the process.
CoCo is ideal for swept sine tests
Swept sine display shows frequency profile and current frequency
The Swept Sine Testing option of CoCo-80 has several unique advantages over similar products in the market, including:
1. The measurement channels have very high dynamic range to ensure continuous test over high dynamic range UUT (Unit Under Test). It is common to achieve 130~150dB dynamic range with CoCo-80.
2. Special tracking filters realized based on TVDFT (Time Variant Discrete Fourier Transform) provide excellent spectrum estimation.
3. Special algorithm enables test in wide frequency range. The result of both low and high frequency testing is excellent.
4. Time domain signals are always available for viewing and recording
5. Log, Linear sweep modes are available.
6. Auto-gain adjustment with close-loop control capability to prevent input range overloading
Measurement quantities that can be monitored during the swept sine test include: time stream of each channel (raw data), spectrum of each channel, frequency responses, coherence, and phase between responses to the reference channel.
Time streams: this is the same as any other applications on CoCo. Time streams are always available for viewing and recording. It is a very useful tool to observe whether the input signals are in the valid range. The recorded sine wave can be used for further post-processing. In CoCo, the time streams are often denoted as ch1, ch2 etc.
Spectra: The term spectrum is used to refer to the measurement trace in the frequency domain of each channel. It is represented in 0~Peak. The engineering unit of the spectrum is determined by the sensor used by the input channel. The resolution of spectra does not have impact to the quality of sine wave. In CoCo, the spectra are often denoted as Spec(ch1), Spec(ch2) etc..
Frequency Response Functions (FRF): FRF of UUT can be measured using input channel 1 as reference channel and other channels as response channels. The connection should be like this:
Frequency response measurement with CoCo.The CoCo provides the FRF functions of each response channel to the output channel. FRF signals include both phase and magnitude information. In CoCo. The number of FRF signals that can be monitored depend on the number of input channels on the CoCo hardware. For example, a CoCo-8, with 4 input channels can monitor 3 FRFs: H(ch2,ch1), H(ch3,ch1) and H(ch4,ch1).
Output Modes include constant level, frequency profile and auto gain modes. Frequency profile lets you change the amplitude based on frequency to avoid overloading the system at resonance. With Auto Gain Control the output amplitude is calculated in real time based on the target input and close-loop control gain.
Auto gain control mode monitors the response of the system and modifies the output level in real time to match the desired profile.
Output Control Modes for Swept Sine Measurements include Constant Level, Output Level Profile (Frequency Profile) and Input Control Profile (Auto Gain Mode)
