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Measurement Guidelines

    • IMD Tests - more Receive Attn is better
    • Noise Figure - Use 0 dB Rec Attn.
    • Set DB Current Limit = DB I Meas Max.
    • Set VI Current Limit > VI I Meas Max.
    • RF Sources - Levels <-22 to >+13 dBm
    • DMSG - Optimum levels <-5 dBm
    • RF Off is <-30 dBm
System Gain Adjustment
    • Receive Attenuation
    • IF Gain
    • Signal Dependent
      • Single tone
      • Multi tone
    • Measurement Repeatability

Simplified Diagram for Understanding Gain Measurements
    • Receive Attenuator
    • Mixer
    • IF Filter
    • IF Amplifier
    • Receiver Detector



System Sensitivities
    • System Receiver Mixer
      • Saturate
      • Generate Intermodulation Distortion
    • Receiver Detector
      • Compression
      • "Fold Over"

Single Tone Measurements
    • RF Power, S-Parameter, Noise Figure
    • Objectives
      • Maximize Power to Receiver
      • Maximize Power to Mixer
      • Set Appropriate IF Gain

Single Tone Method
    • Set IF Gain to 20dB or lower
    • Reduce Rx Atten Until Warning Message
    • Backoff One Rx Atten Setting
    • Increase IF Gain Until Warning Message
    • Backoff One IF Gain Setting

Multi Tone Measurements
    • IM3/5/7 and ACPR
    • Measure Device not Tester's Mixer
    • Operate in the Mixer's Linear Range
    • The Mixer Can Add to or Subtract from
    • the Measurement

Mixer Intermods
    • Receive Attenuator Controls Mixer IM
    • Performance and System Noise Floor

Muilti Tone Method

    • Measuring Main Tone(s)
      • Not Sensitive to Mixer IMs
      • Use Method for Single Tone
    • Measuring IM & ACPR Tones
      • Sensitive to Mixer's IM performance
      • IF Gain usually at or near Maximum (Minimize noise floor)
      • Verify with Spectrum Analyzer (SA)
      • Be careful of SA's intermods!

Measure IM Tone
    • Set IF Gain 50/55; Receive Atten 20 dB
    • Measure C/I
    • Verify with Spectrum Analyzer
      • Go to break point
      • Set Receive input to Aux out
      • Measure C/I
    • If Different, Increase RF Attenuator
    • Repeat

IM Considerations
    • Verify High and Low IM Tones
    • Use Highest Linear Power DUT Condition
    • Typically 20 dB Rx Atten, 55 dB IF Gain
    • Too Much Rx Atten Raises Noise Floor

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