ni signal generators
TRANSCRIPT
NI Signal Generators
ni.com | NI CONFIDENTIAL
Chinmay Anand Misra
Certified LabVIEW Developer
Staff Applications Engineer
Agenda
• Introduction to Signal Generators
• Specifications
• Types of Signal Generators
• Signal Generation Techniques
2ni.com | NI CONFIDENTIAL
• Signal Generation Techniques
• Signal Generation Modes
• Advanced Features (Streaming, Triggering, Synchronization)
• NI-FGEN Driver
Signal Genrators
• Electronic devices that generate repeating or non-
repeating electronic signals (in either the analog or digitaldomains).
• Generally used in designing, testing, troubleshooting, andrepairing electronic or electro-acoustic devices.
3ni.com | NI CONFIDENTIAL
Comparison DAQ vs. Signal Generators
Analog Output DAQAnalog Output DAQAnalog Output DAQAnalog Output DAQ CardsCardsCardsCards SignalSignalSignalSignal GeneratorsGeneratorsGeneratorsGenerators
Low Cost ($1k to $2k) More Costly ($3k to $14k)
Limited Onboard Memory Deep Onboard Memory
Poor Spectral Purity Good Dynamic Specifications
4ni.com | NI CONFIDENTIAL
Poor Spectral Purity Good Dynamic Specifications
Small Bandwidth Large Bandwidth
Low Sampling Rates High Sampling Rates
Limited Features Advanced Features
Analog Output DAQ Block Diagram
FIFO
DACFixed
Gain
5ni.com | NI CONFIDENTIAL
20 MHz
VCXO
Div/N
Signal Generator Block DiagramWaveform
and Sequence
Memory
Variable
Attenuator/
Gain DAC
Digital pattern generation
Marker signal
Trigger Input
Digital
Filter
6ni.com | NI CONFIDENTIAL
and Sequence
Gain
Low-pass
Analog Filter
100 MHz
VCXO
Div/NDDS
PLL
REF
CLK
Sample Rate
7ni.com | NI CONFIDENTIAL
Bandwidth
8ni.com | NI CONFIDENTIAL
Spurious Free Dynamic Range (SFDR)
Spurious Free Dynamic Range (SFDR)
A.K.A. Dynamic Range
Units: dB, dBc, dBm
Ex: 70 dBc
Level of
fundamental
Level of
9ni.com | NI CONFIDENTIAL
Level of
highest
spur
Passband Flatness
Passband Flatness
How much does the amplitude of a
10ni.com | NI CONFIDENTIAL
How much does the amplitude of a
tone change over frequency.
Units: dB
Ex: 0.25 dB
Total Harmonic Distortion (THD)
Total Harmonic Distortion (THD)
Sum of harmonic power levels
(Typically 2nd through 6th harmonics)
Units: dB, dBc, dBm
Ex: -80 dBc
11ni.com | NI CONFIDENTIAL
Phase Noise
Phase Noise
Units: dBc/Hz
Ex: -135 dBc/Hz
12ni.com | NI CONFIDENTIAL
Types of Signal Generators
• Periodic Signals: Sine, Square, Triangle, Ramp Up,
Ramp Down, DC, Noise, User Defined
• Any single cycle of a waveform can be represented by
214 points and stored into memory
Function Generator (FG)Function Generator (FG)Function Generator (FG)Function Generator (FG)
13ni.com | NI CONFIDENTIAL
Arbitrary Waveform Generator (AWG)Arbitrary Waveform Generator (AWG)Arbitrary Waveform Generator (AWG)Arbitrary Waveform Generator (AWG)
• Large and complex waveforms
• Linking, looping, and scripting of waveforms
• Deep waveform and instruction memory
Signal Generation Modes
Signal Generation
Arbitrary Wfm GenerationFunction Generation
14ni.com | NI CONFIDENTIAL
Arbitrary Wfm GenerationFunction Generation
Standard
Function
Frequency
List
Arbitrary
Signal
Arbitrary
SequenceScript
Function Generators Overview
5402540254025402 5404540454045404 5406540654065406
Type Function Clock Function
Bandwidth 20 MHz 105 MHz 40 MHz
Sample Rate 400 MS/s 300 MS/s 400 MS/s
Resolution (bits) 14 12 16
Memory Depth (MB) 16K Samples N/A 16K Samples
15ni.com | NI CONFIDENTIAL
Output Voltage (V) ±5 ±1 ±5
Single Tone Better Good Better
Sine Sweep Best Better Best
Arbitrary Waveforms Good N/A Good
Price $2,499 $1,750 $4199
Arbitrary Waveform Generators Overview
5412541254125412 5421542154215421 5422542254225422 5441544154415441 5442544254425442 5450545054505450 5451545154515451
Type Arb Arb Arb Arb Arb Arb Arb
Bandwidth 20 MHz 43 MHz 80 MHz 43 MHz 43 MHz 145 MHz 145 MHz
Sample Rate 100 MS/s 100 MS/s 200 MS/s 100 MS/s 100 MS/s 400 MS/s 400 MS/s
Resolution
(bits)14 16 16 16 16 16 16
Memory Depth
(MB)8,32,256,512 8,32,256,512 8,32,256,512 8,32,256,512 32,256,512 128, 512 128, 512, 2GB
16ni.com | NI CONFIDENTIAL
Output
Voltage (V)±6 ±6 ±6 ±6 ±1 ±1 ±2.5
Single Tone Better Best Best Best Best Best Best
Sine Sweep Good Good Good Good Good Good Good
Arbitrary
WaveformsBest Best Best Best Very Best Very Best Very Best
Price $3,999 $6,399 $7,299 $8,499 $9,999 $11,999 $13,499
Signal Generation Techniques
• Analog
• Digital Direct Synthesis
• Analog Mode downloads a waveform to memory and automatically
17ni.com | NI CONFIDENTIAL
National Instruments
• Analog Mode downloads a waveform to memory and automatically selects the best clock mode, sample rate, and buffer size to produce the most accurate waveform possible.
What is DDS?
• Digital technique to create an analog frequency source from a single reference clock frequency
• The instrument downloads 16,384 samples (214 samples) that represent a single cycle of a standard waveform into the lookup memory.
18ni.com | NI CONFIDENTIAL
Digital Direct Synthesis
19ni.com | NI CONFIDENTIAL
Benefits of DDS over Analog Signal Generation
• DDS are more versatile and reliable
• High Frequency, Accuracy, and Resolution
• Phase Continuous and Fast Switching
• Wideband Tuning
• Temperature Stability
20ni.com | NI CONFIDENTIAL
Signal Generation Modes
• Standard Function/Frequency List
• Frequency List mode not on all cards
• Arbitrary Waveform
• Generates waveforms from provided waveform arrays of data
21ni.com | NI CONFIDENTIAL
• Arbitrary Sequence
• Generates waveforms on memory in the order you specify
• Script
• Generates a waveform according to a script
Memory
DAC
Arbitrary Waveform Mode
22ni.com | NI CONFIDENTIAL
Create WaveformIn Software
DownloadWaveform
GenerateWaveform
Arbitrary Sequence Mode
•Linking and Looping1. Define segments
2. Loop segments to create stages
23ni.com | NI CONFIDENTIAL
2. Loop segments to create stages
3. Link stages to create waveform - Create the
staging list
• Two sets of memory on the instruments• Waveform memory
• Instruction FIFO memory
1. Segments are loaded into the waveform memory
2. Linking and looping instructions are loaded into
Arbitrary Sequence Mode
24ni.com | NI CONFIDENTIAL
2. Linking and looping instructions are loaded into the Instruction FIFO memory
3. The instrument puts together the waveform from the segments based on the instructions
Arbitrary Sequence Mode
• Build Complex Waveforms
• Optimize Memory Usage
25ni.com | NI CONFIDENTIAL
Waveform A Waveform B Waveform C
Example Waveforms
Arbitrary Sequence Mode
timetime
Ch0Output
26ni.com | NI CONFIDENTIAL
timetime
Instruction
FIFO
A: #6
B: #3
C: #9
Onboard Memory
What is Scripting?
• Generate complex waveform sequences • Generate waveform based on script triggersscript triggersscript triggersscript triggers• Commands include:
• Generate
• Repeat
• If / Else
27ni.com | NI CONFIDENTIAL
• If / Else
• Wait
• Clear
PXI -5671PXI-5441 PXI -6562
3 Basic Steps of Scripting
Write Waveforms Write Script Initiate Generation
28ni.com | NI CONFIDENTIAL
1 2 3
Configuring Script Triggers
29ni.com | NI CONFIDENTIAL
PXI_Trig0scriptTrigger0 = FALSE scriptTrigger0 = TRUE scriptTrigger0 = FALSE
Repeat until Trigger
repeat until
scripttrigger0
script
repeatingwavefrm
generate
waveform0
generate
30ni.com | NI CONFIDENTIAL
end script
generate
waveform2
generate
waveform1
Generated Signal
scripttrigger0 = TRUE
Wait until Trigger
Clear
scriptrigger0
wait until
scripttrigger0
script
TrigWait
generate
waveform1
31ni.com | NI CONFIDENTIAL
scripttrigger0
end script
generate
waveform3
generate
waveform2
scripttrigger0 = FALSE
( wait period)
scripttrigger0 = TRUE
Generated Signal
Branching with If / Else
then
elseif scripttrigger0
script
ConditionalBranching
generate
generate
waveform1
generate
waveform3
32ni.com | NI CONFIDENTIAL
end script
end if
scripttrigger0 = TRUE
Generated Signal
generate
waveform2
Note that Waveforms in Script Mode will finish
generating before moving to the next waveform
Streaming
• Used when waveform is bigger than your memory size
• Can be used in Waveform, Sequence, or Script Mode
• Write waveform data to “buffer” as you are generating
33ni.com | NI CONFIDENTIAL
Streaming Steps
1. Setup a buffer in memory – streaming waveform
34ni.com | NI CONFIDENTIAL
Streaming Steps
2. Fill Memory with Initial Waveform
35ni.com | NI CONFIDENTIAL
Streaming Steps
3. Begin Generation
36ni.com | NI CONFIDENTIAL
Streaming Steps
4. Write new blocks of data to your buffer
37ni.com | NI CONFIDENTIAL
Triggering
• You can use triggering to start and step through all the
stages during a waveform generation
• Trigger sources (TTL)
• External (I/O connector)
• Over the RTSI Line or PXI backplane bus lines.
38ni.com | NI CONFIDENTIAL
• Over the RTSI Line or PXI backplane bus lines.
• Software generated (internal)
• Triggering Modes
• Single, Continuous, Stepped, Burst
Triggering Mode – Single
• Single Trigger for 5412/5421/5422/5441/5450/5451
• Arbitrary Waveform Mode
39ni.com | NI CONFIDENTIAL
• Arbitrary Sequence Mode
Triggering Mode - Continuous
• Continuous Trigger for 5412/5421/5422/5441/5450/5451
• Arbitrary Waveform Mode
40ni.com | NI CONFIDENTIAL
• Arbitrary Sequence Mode
Triggering Mode – Stepped
• Stepped Trigger for 5412/5421/5422/5441/5450/5451
• Arbitrary Waveform Mode
41ni.com | NI CONFIDENTIAL
• Arbitrary Sequence Mode
Triggering Mode – Burst
• Burst Trigger for 5412/5421/5422/5441/5450/5451
• Arbitrary Waveform Mode
42ni.com | NI CONFIDENTIAL
• Arbitrary Sequence Mode
Synchronization of SMC cards
Signal Generator Block Diagram
D/A ConverterSMC
DACDigital FIR
2x, 4x, 8x
Onboard
MemoryAnalog
Filter
Waveform
GenerationDigital
Gain
43ni.com | NI CONFIDENTIAL
DAC2x, 4x, 8x
InterpolationMemory
8 MB – 512 MBFilter
Trigger
and EventTiming and
Synchronization
Generation
Engine
Clocking
EngineDirect Digital
Synthesis
Gain
Multi Module Synchronization – Ref Clk
• Synchronization within chassis
Internal Reference Clock
44ni.com | NI CONFIDENTIAL
External Reference Clock
Multi Module Synchronization –TClk
• Synchronization using three TClk VIs
• Single or Multi Chassis
• Single PC
• Triggers are used for any purpose (Start Trigger/Reference Trigger)
• Sample Clocks can be same or different
45ni.com | NI CONFIDENTIAL
FGEN Configuration TClk Configuration
NI-FGEN
• Driver for NI 54xx cards
• Development Software:• LabVIEW & LabVIEW Real-Time
• LabWindows™ /CVI™
• LabWindows™ /CVI™ Real-Time Module
• Measurement Studio
• Microsoft Visual C++ (MSVC)
46ni.com | NI CONFIDENTIAL
• Microsoft Visual C++ (MSVC)
• Microsoft Visual Basic 6.0
• Includes the FGEN Soft Front
Panel
• IviFgen Class Specificationcompliant
Programming Function Generators
• Programming• Register level
• Application programming interface (API)
• NI-FGEN• LabVIEW Express VIs for rapid Competitor
47ni.com | NI CONFIDENTIAL
• LabVIEW Express VIs for rapid configuration
• Intuitive API layout
• Tight integration with other LabVIEW functions
• CVI, MStudio, Visual Studio support
Competitor
NI-FGEN
NI-FGEN General Programming Flow
48ni.com | NI CONFIDENTIAL
niFGEN Initialize
Opens session to ARB
niFGENAbort Generation
Abort previous generation and Switch to Configuration Mode
niFGEN Configure Output Mode
Configure Mode to Arbitrary WaveformniFGEN Clear Arbitrary MemoryniFGEN Configure Clock Mode
niFGEN Create Waveform
Download a new Waveform to MemoryniFGEN Configure Arbitrary Waveform
Configures Arbitrary Waveform Gain and DC OffsetniFGEN Configure Sample Clock SourceniFGEN Set Sample RateniFGEN Configure Analog FilterniFGEN Configure Digital FilterniFGEN Output EnableniFGEN Initiate Generation
FGEN Soft Front Panel• SFP supports Arbitrary Waveform Mode
• Reads HWS, binary, and ASCII files
• Generate waveforms from files created with
Analog Waveform Editor
49ni.com | NI CONFIDENTIAL
Thank you!
ni.com | NI CONFIDENTIALHigh-Speed Digitizers