Setting up a Pre-5G Measurement

This topic provides information on connecting and successfully demodulating a signal using the Pre-5G demodulator. A typical measurement includes the following measurement setup process (each step is discussed in the following text).

  1. Connect your signal to the VSA
  2. Configure measurement setup and input parameters
    1. Set the Center Frequency
    2. Set the Frequency Span
    3. Configure the Input Range
    4. Configure Triggering (when required)
    5. Verify input signal and initial parameter settings
  3. Configure the Pre-5G demodulator
    1. Select the Pre-5G demodulator
  4. Set up Pre-5G signal parameters
  5. Run the measurement

Pre-5G Measurement Setup Procedure

  1. Connect your Signal to the VSA

    • Single or multiple channel connection

      Connect the antenna signals to the hardware input channels.

      Click Input > Channels and select the number of channels.

    • I+jQ connections

      Connect the I and Q signals to the measurement hardware. To configure the VSA, choose one of the I+jQ selections: Input > Channels > I + jQ.

      Notes for I+jQ input:

      • Selecting an I+jQ configuration enables DC coupling.
      • Use User Correction to correct for any offset or gain imbalance between the I and Q signals.
      • Range is set independently for the I and Q inputs, but can be coupled by selecting the Couple Paired Channels parameter.

    • Recorded signal

      Recall the recorded signal by selecting File > Recall > Recall Recording

      The center frequency and input range will be set by the recording.

      Information about the sample Pre-5G signal included with the 89600 VSA software can be found in the Demo and Recorded Signals topic.

    For more information about your specific measurement hardware, see the Measurement Hardware section of the VSA help.

  2. Configure Measurement Setup and Input Parameters

    1. Set the Center Frequency

      By default, the center frequency of each measurement channel must be set to within approximately ±0.5x subcarrier spacing of the carrier frequency of the Pre-5G signal connected to that channel, otherwise the demodulator may not be able to lock onto your signal.

      Frequency lock range can be extended to ± 4.5x subcarrier spacing by selecting Extended Freq Lock.

    2. Set the Frequency Span (optional)

      At this point, you can set the frequency span for the signal. The span should be larger than the bandwidth of the Pre-5G signal.

    3. Configure the Input Range

      The input range must be set correctly to obtain accurate measurements. Input ranges that are too low overload the measurement hardware's ADC Analog-to-Digital Converter. Input ranges that are too high increase noise, which increases errors reported in error summary data, such as EVM Error vector magnitude (EVM): A quality metric in digital communication systems. See the EVM metric in the Error Summary Table topic in each demodulator for more information on how EVM is calculated for that modulation format..

    4. Set up triggering (optional) 

      The default triggering mode is set to "FreeRun." However, you can configure a different type of configuring if you wish (such as an external frame trigger).

    5. Verify the input signal and initial parameter settings 

      View your signal in the frequency domain (Spectrum trace) to verify the parameters you set.

  3. Configure the Pre-5G demodulator

    1. Click MeasSetup > Demodulator > Cellular > Pre-5G to enable the Pre-5G demodulator properties and measurement parameters.

  4. Set up Pre-5G signal parameters

    These parameters are not autodetected and will need to be set when the default values are not correct for your signal.

  5. Run the Measurement

    Press the Restart () button to restart the measurement.

    For help when your signal is not demodulating correctly, see the Troubleshooting topic.

See Also

Troubleshooting

About Pre-5G Modulation Analysis