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IEEE1641
Signal & Test Definition
A Quick Tutorial
Chris Gorringe
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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
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‘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
Source
Event
Conditioning
Connection
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‘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
Connection
Conditioning
Sensor
Event
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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.
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Examples
Exponential Temperature decay
80
60
Temperature
(C)
40
20
0
Distance (m)
Pink Noise
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Different Ways of thinking of a
Sinusoidal Signal
1.0
1.0
0.8
0.8
0.6
0.4
0.6
0.2
Voltage
Time
0.0
0.4
-0.2
-0.4
0.2
-0.6
-0.8
0.0
-1.0
Time
Power
1.0
1000
0.8
800
0.6
600
Voltage
Frequency
0.4
400
0.2
200
0.0
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Frequency
Time
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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)
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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
Sinusoid
amplitude = 1.1V
frequency = 90Hz
phase = 0
In
AM
modIndex = 0.2
Sinusoid
amplitude = 1V
frequency = 108MHz
phase = 0
Carrier
In
Sum
Carrier
In
AM
modIndex = 0.2
Sinusoid
amplitude = 0.9V
frequency = 150Hz
phase = 0
In
Key: Source
Conditioner
default Value
Signal
Out
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Events
•Event sources
•Event conditioners
•Provide Sync and Gate
Sinusoid
Exponential
In
amplitude = 1V
frequency = 1kHz
phase = 0
Out
dampingFactor =
1000.0
Sync
Gate
Key: Source
Clock
In
clockRate = 100Hz
ProbabilityBased
Event
Conditioner
prob = 50
Event Conditioner
Event
default Value
Signal
Event
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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
Key: -
Sinusoid
Source
amplitude = 1V
frequency = 1080kHz
phase = 0
In
RMS
Out
Conditioner
Default Value
Signal
Event
SingleRamp
amplitude = 1V
riseTime = 1s
startTime = 0
Sinusoid
MaxInstantaneous
In
condition = GT
limit = 0.9V
Gate
amplitude = 1V
frequency = 1080kHz
phase = 0
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BSC Listing
Signal
Sources
Signal
Conditioners
Event Sources
& Conditioners
Measurement
List is not 100% correct
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XML
•XML template is included in IEEE 1641 Annex I
•BSC names & attributes and physical types are mapped onto XML tags
•Sinusoid XSD example : -
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ILS example
Sinusoid
(SinusoidalVoltage19)
amplitude = 1.1V
frequency = 90Hz
phase = 0
Sinusoid
(SinusoidalVoltage20)
amplitude = 1V
frequency = 108MHz
phase = 0
Sinusoid
(SinusoidalVoltage21)
amplitude = 0.9V
frequency = 150Hz
phase = 0
In
AM
(AM5)
modIndex = 0.2
Carrier
In
Sum
(Sum10)
Carrier
In
AM
(AM6)
modIndex = 0.2
In
Out
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Test Signal Framework (TSF)
•Build your own re-useable signal definitions
•Framework enables mapping external attributes to internal
attributes via formulae and event behaviour
trans_ratio
angle
angle_rate
freq
ampl
•Popular ATLAS signal definitions carried into STD as TSFs
channelWidth = 3
phase = angle - (2π /3)
amplitude = trans_ratio
frquency = angle_rate
Sinusoid
Product
Field 1
S1
phase = angle
amplitude = trans_ratio
frquency = angle_rate
Sinusoid
Product
S2
Field 2
phase = angle + (2π /3)
amplitude = trans_ratio
frquency = angle_rate
Sinusoid
Field 3
Sinusoid
Rotor
Product
S3
ThreePhaseSynchro
ThreePhaseSynchro
SYNCHRO
SML provides functional
behavioural model
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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
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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=… />
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Waveform Aberration
Exponential Vs Square Wave
1.0
V o lta ge
0.8
0.6
0.4
0.2
0.0
Time
Error Abberation
1.0
0.8
0.6
V o lta ge
• 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.
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
Time
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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=… />
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Summary
Square Wave Example
1.5
V o lta ge
1.0
0.5
0.0
Time
Square Wave Abberration with RMS
Error
0.4
0.3
0.2
0.1
V o lta ge
• Given we thought we
had a square wave
(Green) but what we
actually have to
measure has some
unexpected
components (Blue)
0.0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
Time
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Definition Of Terms
MaxInstantaneous (inst_max)
1. 5
1. 4
1. 2
1. 1
0. 7
0. 5
0. 4
nominal
amplitude
DC offset
0. 6
PeakNeg
(pk_neg)
Voltage
0. 8
0. 3
RMS (trms)
nominal
pk_pk amplitude
0. 9
PeakToPeak
(pk_pk)
1. 0
nominal
amplitude
Peak
(pk)
PeakPos
(pk_pos)
1. 3
Average (av)
0. 2
MaxInstantaneous (inst_min)
0. 1
0. 0
Time
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Period
1s
<Measure As=”SQUARE_WAVE” attribute=”period” />
Duty Cycle
75%
<Measure As=”SQUARE_WAVE” attribute=”duty cycle” />
Waveform Aberration
trms 0.08467V
<Measure As=”SQUARE_WAVE” nominal=”trms” />
Level 0
0.23V1
0.24931V2
<Instantaneous Gate=”State0” In… />
<Instantaneous name=”State0” Condition=’LE’ nominal=”0%” In=…/>
Level 1
1.21V1
1.190972
<Instantaneous Gate=”State1” In… />
<Instantaneous name=”State1” Condition=’GE’ nominal=”100%” In=…/>
nominal pk_pk ampl
nominal pk_pk ampl
pk_pk amplitude
pk_pk 0.98V1
pk_pk 0.941772
pk_pk 0.95648V
Level 1 – level 0
nominal amplitude
nominal amplitude
amplitude
0.49V1
0.47083V2
0.47824V
(Level 1 – level 0)/2
DC Offset
0.72V1
0.72014V2
0.73098V
(Level 1 + Level 0)/2
Max Instantaneous
1.46446V
<MaxInstantaneous In…/>
Min Instantaneous
0.16765V
<Mainnstantaneous In…/>
Peak To Peak
pk_pk 1.29681V
<PeakToPeak In… />
Average
av 0.97027V
<Average In… />
RMS
trms 1.05444V
<RMS In…/>
Peak (Peak Pos)
pk_pos 0.49319V
<Peak In… />
Negative Peak
pk_neg 0.80262V
<PeakNeg In… />
<Measure As=”SQUARE_WAVE” attribute=”ampl” />
<Measure As=”SQUARE_WAVE” attribute=”ampl” />
<Measure As=”SQUARE_WAVE” attribute=”dc_offset” />
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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.
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End
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IEEE 1641 - STD
A 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
QPSK
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
00 01 10 11 11 01 10 01 01 11 01 11 11 01 01 01 01 01 00 11
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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.
Phase vs Time
300
250
200
150
100
50
0
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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
QPSK
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
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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
I/Q Channels
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
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