These parameters require a Download to update the signal.
The multitone signal is generated from the values in the tone table. The parameters in this section are used to fill the tone table. The tone table can also be edited directly. When editing the tone table directly be sure to set Update Tone Table Automatically to Off to prevent your settings to be overwritten.
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These parameters require a Download to update the signal. |
The name assigned to the waveform segment stored in the arbitrary waveform generator. The Waveform Name can contain up to 22 alpha numeric characters. The name can also contain the following special characters: _ $ & # + - [ ]. The Waveform Name is not case sensitive.
Multiple waveforms can be stored in the arbitrary waveform generator. Just change the waveform name before each download. The different waveforms can be played back by changing the waveform name and executing Play.
Range:
1 to 4097
Default: 8
Set the number of tones in Tone Table. If Update Tone Table Automatically is On, changing the Tone Count parameter updates the number of tones in the tone table and then overwrites all of the tone parameter values including Frequency, Power, and Phase.
This parameter also tracks the actual number of tones in the tone table when the tone table is being modified directly.
A waveform set up with many tones will have less dynamic range as the power is distributed to more tones. The IMD suppression can be approximated by the following formula:
Dynamic Range = 80 – 10Log (n / 8) where n is the number of tones.
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You cannot change the Tone Count when Update Tone Table Automatically
is Off. |
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Range: |
Internal Arb: 10 Hz to 100 MHz |
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Wideband Arb: 100 Hz to 1000 MHz |
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Default: |
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Enter a value to set equal frequency spacing between the tones in the tone table.
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If Place Tone on Carrier is Off, the tones will be centered about the carrier. An odd number of tones results in a tone being placed on the carrier. If Place Tone on Carrier is On, the tone frequency values are set such that a tone will fall on the carrier. |
Tone Frequency Resolution
Update Tone Table Automatically
Sample Rate Calculation
Sample Rate
Waveform Size
Choices: Random | Constant | Parabolic
Default: Random
Select the phase distribution used while updating the tone table.
Random – results in Gaussian noise when used with large number of tones. The phase distribution of the tones is determined by a random seed value entered in the Phase Seed text box. Different seed values will give different phase offsets. The random phase offset is pseudo-random, so a particular phase seed value will always produce the same phase offset.
Constant – not really noise – more like an impulse. Constant phase distribution aligns the tones so that they all have the same phase. This occurrence will duplicate a real world situation where signals are additive. Constant phase distribution will produce the signal with the highest possible peak-to-average ratio (highest crest factor).
Parabolic – produces softest crest factor. Parabolic phase distribution produces the signal with the lowest peak-to-average ratio and is, therefore, the least stressful.
Update Tone Table Automatically
Phase Seed
Phase Value
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Changing this parameter may affect the multitone waveform CCDF curve. |
Range: 0 to 2147483647
Default: 1
Set the seed used by the random number generator when Random phase distribution is selected.
When Phase Distribution is set to Random, Phase Seed allows you to specify the seed for the randomizer. The seed value is used to start the sequence of random numbers.
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Changing this parameter may affect the multitone waveform CCDF curve. |
Update Tone Table Automatically
Range: 0 to 360 Degrees
Default: 0 Deg
Sets all the tone phase values in the tone table when using constant phase distribution.
Update Tone Table Automatically
Choices: On | Off
Default: On
When Place Tone on Carrier is On, a tone is placed on the carrier. When it is set to Off, tones are spaced evenly about the carrier.
If the tone count is odd a tone is always placed on the carrier. A tone at 0 Hz falls on the carrier.
Update Tone Table Automatically
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Placing a tone on the carrier reduces the number of distortion products that can be produced by the signal generator by a factor of at least 2. Placing a tone on the carrier results in a faster correction measurement. |
Choices: On | Off
Default: On
When this parameter is set to On, the tone table values are updated automatically when any of the following parameters are changed:
Tone Count
Tone Spacing
Phase Distribution
Phase Seed
Phase Value
Place Tone On Carrier
Sample Rate
Waveform Size
Setting Update Tone Table Automatically to On also updates the tone table parameters.
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Set this parameter to Off to preserve user edits in the tone table. |
Range: 10 Hz to 1000 MHz
Default: 1 MHz
Enter a value to specify the frequency resolution of the tones in the tone table. This parameter is calculated automatically when Update Tone Table Automatically is set to On.
Set this value to the desired frequency resolution when editing the tone table. The finest frequency resolution is (Sample Rate) / (Waveform Size). The Tone Frequency Resolution must be (Tone Spacing) / 2 when an even number of tones are centered about the carrier.
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Set the Tone Frequency Resolution to the highest value possible that still provides the frequency resolution needed. This ensures the fastest possible correction measurement. For example, if three tone frequencies are desired, 2 MHz, 4 MHz and 8 MHz, the Tone Frequency Resolution could be set to 1 MHz. However, setting the Tone Frequency Resolution to 2 MHz still works and results in a faster correction measurement. |
