Notepad/enter/R&S Everything Test Seminar...


Rhode and Schwarz Presentations


Presentation 1: James

- EmC presentations - gtime FFT
- Emissions

Summary:

- Compliance testing is required for most electrical devices
- Failure rate in full compliance is quite  high
- Redesign + retest is retired

- Precompliance testing is very important


Questions:

- Anyone melted a probe? (people have definitely melted antennas)


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Signal Generators


Topics:

- Primary purpose of signal generators

- Produces electrical wave forms of various a mplitudes, frequency and phase properties


- Signal sinusoidal (CW - Continuous wave, SMW-2WA - the “flagship” Signal Generator)


Why are they important?

- They provide close to ideal input signals to the device under test (DUE_

- They emulate real-worls signals in the case of complex - moulations 5G, LTE, Wifi


- Good performance ois important to minimize generators


Signal Generators → 1. Analog Generators 2. Digital Generators

Analog Signal Generators

- Frequency, basic modulation, boise and spectral p

- Major reason for switching to analog


Veector Signal Generators

- Frequency and level range

- Noise and spectral purity → modulation BW + capabilities


Analog


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Vector


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What do we need an analog generator for

- High quality singals

- Reference code

- Gain

- Component development / testing (ADCD_

- Receiver testing

- Military / radar applications


AM  Frequency modulation    FM frequency modulation Phase freqeuncy modulation


Analog Generator Selection Criterai -- things to consider


Primary:

- Frequency range

- Phase-noise

- Harmonics

- Output power


Secondary

- Switching speeds

- Frequency + amplitude accuracy

- Very bad modulation support


- Very important to understand your input signals


Vector Signal Generator Applciations

- Receiver testing - a huge applications

- Impairment generation

- Impulse testing

- Fading capbiliites, ability to generate attenuated delayed signals

- Radar echo preparations (GNSS)

- Multipath signal generators


Vecotr Signal Basics:

- Analog signals defined by magnitude

- Vector signals defined by: magnitude + phase


- Used in digita modulation


- LTE, SGNR, Wifi, Bluetooth, SatCOM


ASK, PSK, FSK


Generating IQ Values

- Start with Symbol that represents particular magnitude _ phase

- Magnitude + phase can be converted into can be converted into


- In-phase (“real”)

- Quadratic (“imaginary”)


- Simplifies the pair of IQ vzlaues


IQ Modulatior

- Converts base band (transmitting) signals into RF Signals

- This allows the AM FM PM to sum the signals


IQ Modulation Steps

- Many licensing keys that you buy/input

- ca n bring data in digitally (bring the IQ values in digitally) - various  ways to define the baseband

- Can have a file of IQ values

- Specific data that has been mapped to IQ values


- Appropriate IQ values are generated based on what you selected

- Seiteis fo steps involved in creating a vector modulated signal

- Basic Digital Modulation - each variations of a signal magnitude _ phase represent a unique symbol


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Each symbol  represents a specific  digital bit or combination of  bits  -

ASL - Amplitude  of  100%  and 50%

BPSK - phase 0 degrees and 180 degrees


Constellations (Symbol Mapping)

- Constellations - collection of symbols on a polar chart representing a signal and magnitude and phase

- X - acist depicting amplitude (I )

- Y -  as  depicting phase (Q)

- ASK depicts 2 symbols with 1 bit of info - modulating in amplitude


- BPSK chart depicts 2 symbols molulating only in phase


How do we add more bits/symbols/information for faster data transmission?

- Through QAM symbol mapping

- Could transmit only 1 bit previously can transmit 4 bits now!

- These mits make up the frame of  our wifi, transmission, bluetooth, etc..


Modulation Bandwidth

- Some LTE at least 10 MHz of bandwidth requires
- Frequency - generators RF frequency , usually the carrier signal
- Bandwidth
- ** important tto distinguish what the signal rate is and what the bit-rate is **
- Flatness is the gain variation of the  platform


Impairment Generation

- Another huge reason for vector
- previously  talked about band base generation
- Able to do fading and noise injection


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- impairment s emulate real-world effects
- Keeps up with standards as well
- Base band impairments - noise - SW interferes - impulse noise - phase noice -
- Fading - ability t o generate copies of a signal , attenuate them, or dopplegang them


AWFN impairments

- Additive white gaissian noise additive -
- Additive Combine dwith useful
- White: noise constant other frequency
- Gaussian - describes how noise changes over time ODFM (orthogonal)
- 23 ASK Constellations   ODFM orthogonal
- Considered more immune than QM
- Device under test → mini circuits amplification


AWGN Generation

- Constellation drawn by the analyzer

- Analyzer (receiver basically) no trouble achieving

- Signal to rnoise ratio - APSK (PVB -52, Digital Viceo Broad cast

- This  is  very important for devices that  are  re-timing the circuit

- Needs to be able to filter out the (phase) noise that you inject


Phase noise impairment:

- Anything coming up in time domain (called jitter)

- Anything long0term in time domain (called wonder)

- Excessive phase noise can cause many issues

- Disturbance  in communication systems for instance

- Phase noise can be addes to base bands signal by

- Define amount of phase noise at gain  - frequency offsets

- Adding phase noise to signal leads to rotation

- Errors → adjacent signal  /  symbols  bleeding into other symbols - bit-error


Impulse Noise impairment - many real wprld examples of impulse noise impairment

- unintentional - spark plugs motors,

- Intentional - radars, or bursty , modulation time


Fading:**