Order Analysis for Bode Display

Order Analysis for Bode Display

Use this dialog box to calculate the amplitude and phasing for specific orders from signals of vibration sensors. Orders are a multiple of the shaft revolution and are the basis for evaluating vibrations in and at a machine in relation to rpm.

Use the calculated amplitude and phase channels in the Bode diagram in DIAdem VIEW in order to display the amplitude as well as the phasing of a vibration over rpm. Use the amplitude, phasing, and rpm in a polar diagram in order to display them as a Nyquist diagram.

Settings

	Time channel	Specifies the data channel containing the time values for the signal channels and the tachometer channels. The data channel must not contain NoValues and must start from zero.
	Signal channels	Displays the data channels with the sensor signals. The sensor channels must not contain NoValues.
	Select Channels	Opens the channel selection list. The number of signal channels must be the same as the number of pulse time channels.
	Pulse times	Displays the data channels with the pulse start times. The pulse start times are the intervals between the individual pulses, which you can specify with the PulseStartTime Pulse Detection result channel.
	Select Channels	Opens the channel selection list. The number of signal channels must be the same as the number of pulse time channels.
Order Calculation
	Add Order	Creates a new row to define a further order.
	Delete Order	Deletes the selected order.
	Move Order Up	Moves the selected order up.
	Moves Order Down	Moves the selected order down.
	Order	Specifies the orders to be calculated.
	From	Specifies the start value of the bandwidth of an order.
	To	Specifies the end value of the bandwidth of an order.
	Amplitude	Specifies the value for the runout correction of the amplitude which DIAdem subtracts from the amplitude calculated for the first order.
	Phase	Specifies the value for the runout correction of the phase which DIAdem subtracts from the phase calculated for the first order.
	Calculate power spectrum over the entire channel	Specifies whether DIAdem calculates the power spectrum over the entire channel or half the channel.
Window Functions
	Window type	Specifies the window function for the FFT. You can select: rectangle, Hanning, Hamming, Blackman, and FlatTop.
	Amplitude attenuation correction	Specifies whether DIAdem corrects the damping effect of the window function on the amplitude. You can select either periodic or random correction.
Time Intervals If you select exactly one signal channel and one pulse time channel, you can separate them into intervals.
	Include all values	Specifies that DIAdem uses all measured values in the calculation.
	Number of intervals	Specifies that DIAdem divides the signal channel and the pulse time channel into a specified number of equidistant intervals and calculates an individual result for each interval. The calculation ignores surplus values.
	Number	Specifies the number of intervals.
	Length of the intervals	Specifies that DIAdem divides the signal channel and the pulse time channel into into intervals of a specified length and calculates an individual result for each interval. The calculation ignores surplus values.
	Length	Specifies the number of values in an interval.

If you want to use waveform channels in this dialog box, follow Rule 2.2 for Calculating with Waveform Channels. If you specify a time channel although the tachometer channels are waveform channels, the sampling rate is specified from the time channel.

Result

For every N order and for every time interval, DIAdem generates the result channels BodeAmplitudeNOrder with the amplitude spectrum (square of the peak amplitude) and BodePhaseNOrder with the phases. The result channel BodeSpeed contains the RPM and BodeTime the time values of the reference axis. The calculated amplitudes only depend on the bandwidth and not on the order. The calculated phases, on the other hand, also depend on the order.
Unlike Order Analysis for Bode Display, Pulse Detection calculates the specific rpm for each revolution and not just average rpm over the selected interval. If the selected interval does not contain pulses, Order Analysis for Bode Display cannot calculate rpm. To select the intervals appropriately, you can use the PulseStartDetected pulse start status channel of the Pulse Detection.

The peak amplitude results from the auto spectrum by square root calculation. Calculate the RMS value from the peak amplitude divided by the square root of 2.

Note Due to a change in the calculation, the amplitude values of the result channels in DIAdem 2015 were greater than the calculation results of the current version by a factor of four.

To calculate quantity-based in DIAdem, click the Calculate Quantity-Based button on the DIAdem ANALYSIS toolbar. When executing quantity-based calculations, DIAdem checks whether the program can also execute calculations on physical quantities in the same calculation. If DIAdem cannot execute the calculation because the physical quantities are unsuitable, the program displays an error message. Refer to the Help page Calculating Quantity-Based and Non-Quantity-Based in DIAdem for the conditions and rules for quantity-based calculations.

Script Call

Call SUDDlgShow("Main", ResourceDrv & "AnaChnOrderBodeCalc")

ChnOrderBodeCalc

Procedures

Examining Measurement Signals in the Frequency Domain

Examples

AC/DC Coupling | Adapted DIAdem Functions | Calculate Characteristics of an Oscillation | Communicating with MATLAB | Frequency Weighting (A-, B-, C-Filtering) | Hysteresis Analysis | Optimized Heating Control