Spectrum Analyzer_ITU PDF

Egyptian African Telecom Regulatory Training Center Spectrum Analyzer By: Eng.Ayman Hamdy Contents o Spectrum Analyzer Types o Theory of Operation o Spectrum Analyzer Settings o Spectrum Analyzer Measurements o Spectrum Analyzer Parameters o Receiv...

Egyptian African Telecom Regulatory Training Center Spectrum Analyzer By: Eng.Ayman Hamdy Contents o Spectrum Analyzer Types o Theory of Operation o Spectrum Analyzer Settings o Spectrum Analyzer Measurements o Spectrum Analyzer Parameters o Receivers vs. Spectrum Analyzers Time-Domain vs Frequency-Domain  Spectrum Analyzer o Measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. o The primary use is to display and measure Amplitude vs. Frequency of known and unknown RF and Microwave signals.  Spectrum Analyzer Types 1. Sweep Analyzer Based on super-heterodyne configuration that used a voltage control oscillator and mixer and intermediate frequency filter. 2. Fast Fourier Transform (FFT) Analyzer Based on the conversion of time domain waveform to the frequency domain using digital signal processing ( real-time spectrum analyzer implementation).  Theory of operation 6 Spectrum Analyzer Settings Reference Level Resolution Bandwidth (RBW) Video Bandwidth (VBW) Sweep Time Span Attenuation Dynamic Range Displayed Average Noise Level (DANL) Detector Types Trace  Spectrum Analyzer Measurements o Frequency o Bandwidth o Emission Mask o Save on Event o Channel Power Frequency Frequency Bandwidth  Emission Mask o Measure out-of-band emissions and spurious emissions. o Detect and measure the unauthorized (illegal) emissions in free bands. o Detect the violation of power limit for authorized signals. Emission Mask Save on Event  Channel Power o Measures total power over the specified Integrated BW  Spectrum Analyzer Parameters o Frequency Parameters o Amplitude Parameters o Signal Processing Parameters o Input and Output Parameters o Measurement and Display Parameters  Spectrum Analyzer Parameters o Frequency Parameters: o Frequency Range: The range of frequencies the analyzer can measure (e.g., 9 kHz to 50 GHz) o Resolution Bandwidth (RBW): The ability to separate two closely spaced signals; a lower RBW gives finer resolution but increases measurement time o Video Bandwidth (VBW): The bandwidth of the low-pass filter applied after detection, used to smooth noise in the displayed signal o Sweep Time: The time it takes for the analyzer to sweep across the selected frequency range  Spectrum Analyzer Parameters o Amplitude Parameters: o Reference Level: The top level of the display, which represents the highest signal power being measured o Dynamic Range: The ratio between the highest and lowest detectable signal levels, typically expressed in dB o Noise Floor: The lowest measurable signal level, determined by the internal noise of the analyzer o Attenuation: The amount of input signal reduction to prevent overload, which affects the displayed amplitude o Sensitivity: The minimum signal power that the analyzer can detect above the noise floor  Spectrum Analyzer Parameters o Signal Processing Parameters: o Span: The frequency range being displayed, from the start to the stop frequency o Sweep Mode: The method of scanning the frequency range (e.g., continuous, single, zero-span) o Detector Types: The method used to measure amplitude at each frequency (e.g., peak, RMS, average) o Trace Averaging: Reduces noise in the display by averaging multiple sweeps  Spectrum Analyzer Parameters o Input and Output Parameters: o Input Impedance: Typically 50Ω or 75Ω to match RF systems o Input Power Range: The range of power levels the analyzer can handle without distortion o Pre-Amplifier: Used to improve sensitivity by amplifying weak signals  Spectrum Analyzer Parameters o Measurement and Display Parameters: o Marker Functions: Allows precise frequency and amplitude measurements at specific points o Trace Storage: Stores signal traces for comparison and analysis o Display Resolution: Determines the clarity and detail of the measured spectrum  Receivers VS Spectrum Analyzer o Test Receivers o Spectrum Analyzers o Radiomonitoring Receivers  Test Receivers Measurement of commonly known signals with high accuracy. EMI test receivers: measure conducted or radiated interference in accordance with relevant international standards (CISPR, MIL, VG, etc.). They are needed to demonstrate equipment compliance with EMC standard specifications, which is the prerequisite for putting a product on the market Test receivers measuring useful signals: measure the level and the modulation of known useful signals and the bandwidth they occupy. For example, they are used to verify whether radio services comply with the limit values specified for these parameters Calibration test receivers: measure the level of RF signals at extremely high accuracy and over a wide dynamic range. They are mainly used to calibrate signal sources  Characteristics of a Test Receiver Characteristics: Less important for test receivers: High measurement accuracy Audio processing parallel to spectrum Optimized operating concept for T&M tasks display Attenuator at the input Demodulation (usually no SSB present) Usually no gain control (AGC) Realtime capability Pulse-protected input Weight - dimensions - mobility Regular calibration intervals Increased temperature range not required (total calibration) Essential radiomonitoring functions Result display and evaluation according to FSCAN, MSCAN, squelch, dwell time, standards etc. are not necessary and therefore are Special marker function limit lines either not available or only to a limited extent.  Spectrum Analyzers Spectrum analyzers are typically connected to the device under test (DUT) via a cable during the measurement. Featuring a broadband RF frontend, they are usually not suitable for measurements on antennas. They are mainly used in laboratories for: development, production, quality assurance and certification. Typical measurements include the RF level, spectral purity, adjacent channel power and spurious emissions. Today's spectrum analyzers can be used, in particular, to measure the modulation characteristics of RF signals with analog or digital modulation.  Characteristics of a Spectrum Analyzer Characteristics: Less important for spectrum analyzers: No preselection Audio processing 1st mixer directly at the input High measurement accuracy Demodulation Optimized operating concept for T&M tasks Increased temperature range not required No gain control (AGC) Essential radiomonitoring functions FSCAN, Regular calibration intervals MSCAN, squelch, dwell time, etc. are not (total calibration) Result display and evaluation to standard necessary and therefore are either not available or Special marker function limit lines only to a limited extent.  Radiomonitoring receivers Radiomonitoring receivers are optimized specifically for spectrum monitoring tasks and differ fundamentally from test receivers and spectrum analyzers. Fast detection of unknown signals Search for activities over wide frequency ranges Monitoring of individual frequencies, lists of frequencies or frequency ranges Detection of spectral characteristics of very short or rarely occurring signals Storage of activities Triggering of further activities after a signal is detected Demodulation of communications and/or transfer of demodulated signals for processing Integration into civil and military systems Homing, i.e. localization of signal sources Simple coverage measurements Measurements in line with ITU recommendations  Characteristics of a Radiomonitoring Receiver Characteristics: Less important for monitoring receivers: Integrated preselection fast tuning/switching: concurrent to scans! Level accuracy Fast AGC Limit lines Built in antenna selector Optimized operating concept for monitoring tasks Measurements on communications Essential radiomonitoring functions: standards FSCAN, MSCAN, RF and IF panorama, squelch, dwell time, hold time etc. (e.g. EDGE, Bluetooth) Audio processing parallel to spectrum display AC/DC power supply and/or battery operation Built in test equipment (BITE) Increased temperature range Stringent EMC requirements  Receivers VS Spectrum Analyzer Feature Spectrum Analyzer Receiver Precision signal reception & Purpose General-purpose frequency analysis measurement Tuned to specific frequencies or Frequency Coverage Wide frequency range bands Dynamic Range Moderate to high Very high for precise measurements Very high (designed for weak Sensitivity Lower compared to receivers signals) Selectivity Moderate Very high (narrowband filtering) Very narrow for detailed Resolution Bandwidth (RBW) Adjustable, typically wider measurements Sweep Speed Fast, scans broad frequency ranges Slower, focuses on specific signals Measurement Accuracy Moderate High precision EMI/EMC testing, spectrum Compliance testing, signal Application monitoring demodulation  Radiomonitoring Receiver VS Spectrum Analyzer Monitoring receiver Spectrum analyzer Direct keys for monitoring applications Direct keys for measurement applications ▪ Scan functions (FFT Scan, FSCAN, ▪ Sweep functions (Span, Center) MSCAN) ▪ Resolution filter (RBW) ▪ Demodulation ▪ Trigger ▪ Level detector ▪ Measurements ▪ Bandwidth (Demodulation) ▪ Traces ▪ AGC/MGC ▪ Display ▪ AFC ▪ Lines ▪ Attenuator ▪ Probe (e.g. power measurements) ▪ Save-Recall for memory channels ▪ Squelch level ▪ Attenuator ▪ Markers