Spectrum Analyzer
The Spectrum Analyzer instrument measures the magnitude of an input signal versus its frequency.
The Spectrum Analyzer uses the oscilloscope channels to acquire input signals. Because of this, all instruments that use the oscilloscope channels will cease acquisition when the Spectrum Analyzer begins sampling.

1. Menu
See Menu in Common Interfaces.
1.1. View

2. Control

The control toolbar by default only shows the important options. The down/up arrow in the top-right corner shows/hides the other features. This toolbar contains the following:
- Single button: starts a single acquisition.
- Run/Stop button: starts repeated acquisition. While the acquisition is in progress, the Run button becomes the Stop button.
- Freq. Range: The frequency range options selects the operation range of the Spectrum Analyzer. Having the auto option selected, the maximum frequency or sampling rate is determined based on the stop or highest value between start and stop.
- Scale: Selects between Linear and Logarithmic frequency scale.
- Center/Span or Start/Stop: The frequency halfway between the stop and start frequencies is known as the Center frequency. This is the frequency that is in the middle of the display’s frequency axis. The Span parameter specifies the range between the start and stop frequencies. Alternatively, the Start and Stop frequencies can be specified.
- BINs: Adjusts the number of frequency bins.
- Samples: Adjusts the number of time domain and oscilloscope acquisition samples.
- Resolution: Adjusts the frequency resolution bandwidth.
The gear drop-down contains the following options:
- Algorithm:
- FFT: Fast Fourier Transform (quick process) expects a number of input samples (always a power of 2). It then outputs half of this number in frequency BINs, linear from 0 to half of the sampling frequency.
- CZT: Bluestein's Chirp-Z Transform expects an arbitrary number of input samples. It then outputs arbitrary number of frequency BINs, linear from the specified start to stop frequencies. This allows resolution to increase by interpolation. It allows smooth adjustment of resolution bandwidth with a flexible number of input samples and output BINs.
- Update: This specifies the time period at which the application will check the oscilloscope device status and read the acquired data. Increase the time to reduce the update rate.
3. Traces
3.1. Magnitude

- Units: Selects the amplitude units:
- Vpeak: Relative to 1V amplitude sine wave.
- Vrms: Relative to 1V RMS (1.41V amplitude) sine wave.
- dBV: dB reference to 1Vrms sine wave, 20*Log10(Vrms).
- dBu: dB reference to 0.775Vrms sine wave, 20*Log10(Vrms/0.775).
- dB: dB reference to peak voltage value.
- Top: Adjusts the top amplitude level. The channel's input range with Auto option is configured according to this setting.
- Range: Selects the amplitude range.
- Reference: Adjusts the peak voltage reference for dB unit selection.
3.2. Channel
The options in the drop-down menu allow configuration of each oscilloscope channel as follows: Offset, Range, Attenuation, and Sample Mode; and to configure trigger. Having the Auto option for Range, the range is adjusted based on Magnitude Top value.


3.3. Trace
The Add Trace drop-down menu contains:
- Add Normal Trace: This adds a trance with default or its last settings.
- Reference: This allows cloning an existing trace settings and data with Hold option, to be used as reference trace.


Up to eight traces can be added. For each trace the following options can be individually configured:
- Channel:The channel option selects the input of the trace, one of the oscilloscope inputs of the connected device, or Hold keeps the trace unchanged/unaffected by the new sweeps.
- Type: Selects one of the following:
- Sample: The trace is updated after each sweep.
- Peak Hold Cont.: Continuous peak hold, keeps the maximum values for each bin from consecutive sweeps.
- Peak Hold: The trace is updated after the specified count of sweeps.
- Min Hold Cont.: Continuously keeps the minimum amplitude values for each bin from consecutive sweeps.
- Min Hold: The trace is updated after the specified count of sweeps.
- Linear RMS Average: The trace is updated after the specified count of sweeps with linear average of Vrms amplitudes.
- Linear dB Average: The trace is updated after the specified count of sweeps with linear average of dB amplitudes.
- Exp. RMS Average: Performs exponential averaging of Vrms amplitudes. It is calculated using the following formula:
Averagei = Rrms(Sweep)/Weight + Rms (Average)(i-1)*(Weight -1)/Weight
- Exp. dB Average: Performs exponential averaging of Vrms amplitudes. It is calculated using the following formula:
Averagei = dB(Sweep)/Weight + dB (Average)(i-1)*(Weight -1)/Weight
- Count/Weight: Specifies the count or weight for the selected averaging methods.
The options drop-down contains the following settings:
- Color: sets the channel waveform color.
- Window: Selects the window function:
- Rectangular: Good for closely spaced sine waves and white noise analysis.
- Triangular
- Hamming: Good for closely spaced sine waves.
- Hann(ing): Good for unknown content, narrowband, and combination of sine waves.
- Cosine
- Blackman-Harris
- Flat Top: Reduces resolution but is good in amplitude accuracy.
- Kaiser: See Window Functions for more information.
- Beta: Adjusts the π*α parameter of Kaiser window.
- Export: Opens export window with the respective trace data. See Export in Common Interfaces.
- Name: specifies the channel name.
- Label: specifies the channel label.
4. Plot
The main spectrum plot shows the magnitude versus frequency. About frequency settings see the Control toolbar and Magnitude options.

See Plots in Common Interfaces.
4.1 HotTrack
See HotTrack in Common Interfaces.
Having the mouse cursor in the upper half of the plot, the HotTrack will search and position at a nearby peak. In the lower half of the plot it is not searching for peaks.
4.2. Cursors
See Cursors in Common interfaces.
5. Views
5.1. Time
The time plot shows the last oscilloscope acquisition. This view is used to help adjusting optimal offset and range for each channel.

5.2. Measurements
The Measurements view shows the list of the selected measurements. The first column in the list shows the channel, the second shows the name, the third shows the measurement value, the fourth displays the frequency, and the fifth shows the alias frequency for components, along with some other measurements. At the top are Add and Remove and Options drop-down button.
Pressing the Add button opens the Add Measurements window. On the left side is the channel list, and on the right side is a tree view containing the measurement types in groups. Pressing the Add button here (or double-clicking an item) will add it to the measurement list.

The measurement options:
- Harmonics: Maximum number of harmonics to search for.
- Alias: Search for high frequency harmonics, above analysis frequency limit, reflected by sampling frequency.
- Excursion: The minimum excursion level needed for a peak to be considered a valid harmonic.
Constant
- ENBW: Normalized equivalent noise bandwidth of window function.
- Resolution: Resolution of bins, bin to bin distance.
- RBW: Resolution bandwidth is calculated from the transform resolution and window bandwidth.
- FS: Full scale is the input range, maximum magnitude of sine wave before clipping.
- DNR: Dynamic range is the ratio, in dB, of the largest to the smallest signals that can be detected.
- Bits: AD Converter bits.
- BINs: Number of frequency bins, selectable from the frequency toolbar.
- Samples: Number of time domain acquisition samples, selectable from the frequency toolbar.
Dynamic
- NF: Noise floor is a root mean square (RMS) of all the bins except the peak signal and its harmonics.
- WoSpur: Worst spur level may or may not be a harmonic of the original signal; DC and bins on the descending slope are excluded.
- SFDR: Spurious free dynamic range is the ratio of the RMS value of the peak signal to the RMS value of the worst spurious signal. Expressed in dBc units, with respect to the actual signal amplitude.
- SFDRFS: Spurious free dynamic range, expressed in dBFS units, with respect to full-scale.
- SNR: Signal to noise ratio, S/N:

Where Vmrsi are all bins except peak signal, its harmonics, and DC. The exceptions are the descending slope bins of the earlier mentioned peaks.
- SNRFS: Signal to noise ratio, expressed in dBFS units, with respect to full-scale.
- THD: Total Harmonic Distortion, S/D

Where Vmrsi are the harmonic peak values.
- SINAD: Signal to noise and distortion, S/(N + D).

Where Vmrsi are all BINs except peak signal and DC, also excluding bins in the descending slopes of these.
- ENOB: Effective number of bits.

Harmonics
- FF: Fundamental frequency and magnitude.
- Nth: Harmonics frequency and magnitude value relative to fundamental frequency. The maximum number of harmonics can be configured in the Measurement options.
5.3. Components
The components view shows the spectral component list for the chosen trace ordered by magnitude. The count parameter sets the number of component to list.

5.4. Cursors
See Cursors.
6. Export
See Export in Common Interfaces.