282 Keysight EXG and MXG X-Series Signal Generators User’s Guide
Using Custom Digital Modulation for N5172B/82B with Option 431 and 653/655/656/657
Using the Arbitrary Waveform Generator
Building an Asymmetric FSK Modulation with the FSK Table Editor
You can use the FSK table editor to create customized asymmetric FSK modulation of up to 16
levels, then apply the custom FSK modulation to one of the modulation standards. An example of
this capability is to create an interfering signal for adjacent channel selectivity testing of FLEXTM
pagers. To do this, build a 4-level FSK modulation at 4.8 kHz and 1.6 kHz in the FSK table editor,
shown in Figure 9-22. Then use this signal to modulate a PN15 data transmission. In the FLEXTM
protocol, each of the levels in 4-level FSK represents a 2-bit sequence.
Create a Continuous 4-Level FSK Signal
Use this procedure to create a 4-level FSK signal for adjacent channel testing of FLEXTM pagers.
1. Press Preset on the signal generator.
2. Press Mode > Real-Time Custom Modulation > Modulation Setup > Modulation Type > Define
User FSK.
3. Enter the frequency deviations shown in Figure 9-22 into the FSK table editor.
4. Store the file as 4FSK. Press Load/Store > Store To File > 4FSK > Enter.
5. Load the file. Press Load from Selected File > Confirm Load From File.
6. Turn on Custom Modulation. Press Return > Return > Return > Real-Time Custom On.
7. Set the Frequency to the desired carrier frequency for the adjacent channel.
8. Set the desired Amplitude.
9. Press RF On. The amplitude of the interferer can then be adjusted to measure the performance
of the device under test.
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