IEEE1641 Signal & Test Definition A Quick Tutorial Chris Gorringe

1. IEEE1641Signal & Test DefinitionA Quick TutorialChris Gorringe

2. Signals (and Waveforms) • Within STD a signal definition is used to define the signal (set of waveforms) that have the particular characteristics required. • The term signal is used to represent a definition • e.g. bsc:Trapezoid • A waveform is an instance, implementation or manifestation of a signal. • A signal may be represented by many waveforms. • E.g. Sinusoidal signal • Sine Wave • Cosine Wave

3. Source Conditioning Connection Event ‘Real’ Signals • In order for a signal to be realisable (produced by a test system) the signal definition must contain… • Where the signal is required (Connection To UUT) • When the signal is applied (Events) • What are signal types & attributes values

4. Sensor Conditioning Connection Event ‘Real’ Tests • In order for a test to be realisable (produced by a test system) the test definition must have contain… • Where the test is made (Connection from UUT) • When the measurement is made (Events) • What limits/pass criteria is to be applied • What are signal types & attributes values

5. Signals Types • Signals characteristics are defined as the relationship between one property (dependent type, ordinates) and another property (independent type, abscissa) • How voltage varies with time • How temperature varies with distance • How pressure should remain constant over time • Can define characteristics as multiple signal types • Need to make sure the properties are orthogonal. • Voltage over time, Temperature over time • Bad Example - Voltage 2V, Current 2mA • Since these are related (V=IR) • Implies change the impedance to get desired effect.

6. Examples Exponential Temperature decay Pink Noise

7. Different Ways of thinking of a Sinusoidal Signal

8. Signal COTS Support (Techi-Bit) • Language Interfaces through IDL (Interface Definition Language) • Resource Manager class • IDispatch for scripts and test executives • Support Co-classes for Visual Basic • Support Dual Interfaces for C++, Visual Studio, .NET • XML Signal Schemas • Define Signals and Tests in XML • XML Signal definitions are used by the Resource Manager to create the signal • XML Definition of Library Components (TSFs)

9. Basic Signal Components • Basic building blocks to create any signal • Attributes configure individual BSCs • Default values and units simplify use • Signal passed through In connection

10. Events • Event sources • Event conditioners • Provide Sync and Gate

11. Measurement • Direct measurements can be made; e.g. RMS • Monitor signals for certain trigger conditions; e.g. Greater Than • Raise Events when trigger conditions are met • Sequence measurements for analysis; e.g. Find Next Peak • IEEE 1641 achieves program sequencing though other languages

12. BSC Listing Signal Sources Signal Conditioners Event Sources & Conditioners Measurement List is not 100% correct

13. XML • XML template is included in IEEE 1641 Annex I • BSC names & attributes and physical types are mapped onto XML tags • Sinusoid XSD example : -

14. ILS example

15. Sinusoid Sinusoid ThreePhaseSynchro Product Product Product Sinusoid Sinusoid S1 Rotor Field 1 S3 Field 2 ThreePhaseSynchro Field 3 S2 Test Signal Framework (TSF) • Build your own re-useable signal definitions • Framework enables mapping external attributes to internal attributes via formulae and event behaviour • Popular ATLAS signal definitions carried into STD as TSFs angle_rate angle trans_ratio ampl freq channelWidth = 3 phase = angle - (2π /3) amplitude = trans_ratio frquency = angle_rate SML provides functional behavioural model phase = angle amplitude = trans_ratio frquency = angle_rate SYNCHRO phase = angle + (2π /3) amplitude = trans_ratio frquency = angle_rate

16. Types of TSF Attributes • Control Attributes • An interface attribute is mapped onto a model property, • Expressions or formulae • An interface attribute is mapped onto a model property via an expression • Period = 1/freq • delay= range/c -- where c is constant speed of light • Capability Attributes • An interface attribute that is not mapped onto any signal model is regarded as a capability attribute. It holds information as to capability of the resource to supply the signal. • e.g. current 2A - the resource must be capable of supplying a signal which may draw up to 2A • Value Attributes • A value attribute represents a value from the TSF, as such they tend to be read only attributes. • When a interface attribute is mapped on to a model measurement attribute

17. Generic Measure & TSFs • The concept of the generic measurement is that it provides an inverse function, or demodulating function, for any library component (TSF) or basic signal component (BSC) to measure any of their control attributes. • Since users can define TSFs, the generic measurement is naturally extended and can be used to measure any control attribute of such a TSF signal. • As an example of this principle: reading back an RS232 message • <Measure As=”rs232” attribute=”data_word” In=… /> • To read back a list of pulses from a PULSED_AC_TRAIN • <Measure As=“PULSED_AC_TRAIN” attritute=”pulse_train” In=… /> • Measure the rise time of a square(ish) wave • <Measure As=“Trapezoid” attritute=”riseTime” In=… /> • The use of the generic measure is not restricted to measuring single attributes, an example of performing multiple measurements is • <Measure As=”Sinusoid” attribute=”ac_ampl phase” In=… />

18. Waveform Aberration • The generic measure selects the reference waveform described by the reference signal that contains the least error (best match) with respect to the input waveform. The attributes of the reference signal that produce the least error (best match) become the measured attributes.

19. Measuring Waveform Aberration • The generic measure can also be used to measure the actual waveform aberration by measuring the error (difference) between this reference waveform and the input waveform. • Example measure the ‘best match’ value or rms error between the input signal and reference signal • <Measure As=”Trapezoid” nominal=’trms’ In=… />

20. Summary • Given we thought we had a square wave (Green) but what we actually have to measure has some unexpected components (Blue)

21. Definition Of Terms

23. IEEE 1641 - STD • Defines Signals and Tests • Highlights the need to know measurement methods, in order to quote meaningful limits and therefore by implication portable tests • Allows user defined signals and tests that are portable across systems, through TSFs • Provides an integrated XML and IDL interface for using the standard, across different platforms and technologies.

24. End

25. IEEE 1641 - STDA Worked Example • PQSK Signals and Error Vector Magnitude measurements • The PQSK is a digital modulation technique the shifts the phase of a sinusoidal carrier depending on the value of the next ‘set’ of digital bits • 00 – (0, 360) No phase shift • 01 – (90, -270) phase shift • 10 – (180, -180) phase shift • 11 – (270, -90) phase shift 00 01 10 11 11 01 10 01 01 11 01 11 11 01 01 01 01 01 00 11

26. Phase Vs Time • PQSK TSF with a data attribute • Frequency capability attribute • Formula to convert data onto the relevant phase value (mod 360) required • Signal Model is <WaveformStep type=‘PlaneAngle’ points=‘(data)’ /> • Relies on context, but is a simple model • Use Generic Measure to demodulate the signal • Convert the signal back into the message • Measure the phase error associated with the message.

27. Want Voltage vs Time Waveform • PQSK TSF with a data attribute • Frequency control attribute or carrier • Formula to convert data onto the relevant digital data stream (L,H) • Signal model is more complex • Use generic measure to demodulate the signal • Convert the signal back into the message • Error vector magnitude is the rms value of the waveform aberration

28. I & Q Channels • We can create a further TSF I_Q that separates out the I & Q channels from the input signal by conditioning the input signal • In*Sin(wt) • In*Cos(wt) • Then perform further processing or conditioning on these channels