1 / 17

Lab. 9 Signal Analyzer

Lab. 9 Signal Analyzer S ignal/spectrum analyzer (SA): an equipment analyzing spectrum properties of signals. 1. T ype of SA: S wept (downconvert one carrier at a time) F ourier (downconvert a band of carrier at a time). 2. S wept analyzer:. 3. R esolution bandwidth:

kim-spears
Download Presentation

Lab. 9 Signal Analyzer

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lab. 9 Signal Analyzer Signal/spectrum analyzer (SA): an equipment analyzing spectrum properties of signals. 1

  2. Type of SA: • Swept (downconvert one carrier at a time) • Fourier (downconvert a band of carrier at a time) 2

  3. Swept analyzer: 3

  4. Resolution bandwidth: • The higher the resoultion, the slower the scan. 4

  5. Vector signal analyzer: • A SA that can conduct demodulation 5

  6. Fourier analyzer: 6

  7. Agilent approach: Software Hardware 7

  8. Software analyzer: • Analyze the signal recorded by hardware • Load recorded signal: • File  Recall  Recall demo  (Help  Signals)  QPSK • Four windows (traces) are usually used: • Time constellation • Spectrum • EVM (time) • EVM (average number) • Find the length of the recoded signal: • Window  Player • Find the properties of the recorded signal: • Help  Demo 8

  9. 9

  10. 10

  11. Use the label of each window to select what you want to see • Time • IQ measurement • Spectrum • Use the unit of y-axis to have more selections • Adjust the overlayed percentage: • MeasSetup Frequency  Time • Change MaxOverlapp • The higher the percentage, the slow the time sweep. • Find out the demodulation properties: • MeasSetup  Digital demodulation properties 11

  12. Use markers: • Add markers from the command bar • Marker Calculation  select band power (set the center frequency and bandwidth) • Can also use mouse to draw the band. • Use OBW to select the band automatically. • The connect used for general equipment is BNC and that for RF transmission is SMA. For SA, we need to plug SMA into N type. We need some kind of connector transferring SMA to BNC. • The transmitter and receiver are not ideal in real-world. We have to give specifications for their performance so as to insure reliable communications. 12

  13. Analog/RF Impairments: • DAC • Transmit IQ imbalance • Phase noise of the mixer • PA nonlinearity • Channel effect • Noise • Receive IQ imbalance • DC offset • Phase noise of the mixer • ADC • Carrier frequency offset • Digital processing: • Precision (fixed-point processing) • Receiver algorithms

  14. How to test/specify a communication system? • Transmitter/receiver performance (separated) • Combine all impairments (combined) • Transmitter: • Transmit signal distortion (for receiver) • Spectrum characteristic (for interference control) • Indices for transmitter • Error vector magnitude (EVM) • Spectrum mask • Index for receiver: • Sensitivity • Interference performance * EVM is usually used for QAM signals.

  15. EVM: • A signal sent by an ideal transmitter would have all constellation point at the ideal locations • For real-world transmitter, however, the constellation points will deviate from the ideal locations in a random fashion. • EVM is a measure of how far the constellation points are from the ideal locations * - 40dB~1.00% * - 30dB~3.16%

  16. Spectrum mask: • Confine the spectrum used for transmission (interference control for the Bluetooth system) 20dB 20dB

  17. Practice 1: • Choose at least two kind of signals and analyze the performance of the transmitters.

More Related