- Frequency Resolution
SignalScope simplifies Spectogram configuration by allowing you to choose a frequency resolution for narrowband spectral analysis. SignalScope then automatically calculates the FFT length required for that frequency resolution at the audio input hardware's current sample rate. It should be noted that in this case, frequency resolution refers to the distance between adjacent spectral lines (or frequency bins) in the spectrum. The smallest frequency difference over which two independent sinusoids can be resolved will also remain a function of the Spectrogram's data window type.
- Data Window
SignalScope provides a selection of different data windows that may be applied to the time domain data before the application of the FFT. The data windows offer different trade-offs between spectral resolution and spectral leakage.
The available data windows include:
- Uniform (rectangular)
- Flat Top
- Hann (Hanning)
- Rife-Vincent 2
- Time Scale
Use the Time Scale selection to set the total amount of time for which Spectrogram data is acquired and displayed.
If an accelerometer is in use (that is, if the input channel units are set to "g" or "m/s^2"), then the acceleration signal can be optionally integrated once or twice to produce velocity or displacement values, respectively. The Vibration option allows Acceleration, Velocity, or Displacement to be specified for vibration measurements in the Spectrogram.
- If units are set to "g," velocity units will be "ips" (inches per second) and displacement units will be "mils."
- If units are set to "m/s^2," velocity units will be "mm/s" and displacement units will be "mm."
Successive spectra for each signal may be averaged according to the selection of this segmented control. Available average types include: Linear (Stable), Exponential, and Peak Hold. Linear averaging weights all spectra equally. Exponential averaging applies an exponential weighting such that more recent spectra contribute to the current average value more than older spectra. Peak Hold keeps the maximum value in each frequency bin over all the spectra included in the measurement (it is not a true average). When either linear or peak hold averaging is selected, the Spectrogram will automatically stop after the specified number of averages has been reached.
The number of spectra to include in the current average is specified in the Averages text box. When linear or peak hold averaging is the selected average type, the Spectrogram will automatically stop after the specified number of spectra have been included in the average. Exponential averaging allows the analyzer to continue running even after the specified number of spectra have been processed. The exponential average can be thought of as including only the most recent N (time-weighted) spectra, where N is the specified number of averages.
- Current Location
When this option is enabled, the latitude, longitude, and altitude at the time of the measurement will be included in exported data files. Horizontal and vertical accuracy (in meters) will also be included.