Digital Signal Processing with
LabVIEW 8.6
Lab # 06
Introduction to Digital Signal Processors
and Processing
Designed by
Adnan Niazi
Lab Engineer
Signal Processing/Signal & Systems Lab
CECOS University of IT & Emerging Sciences
27th- 28th Feb 2009
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Agenda
▌ Virtins Sound Card Instrument
▌ What are fixed point numbers
▌ What are Floating point Numbers
▌ Fixed point DSPs VS Floating Point DSPs
▌ What is MIPS and MFLOPS
▌ Speedy-33 Kit Teardown
▌ Designing an Audio VU meter
008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Virtins Sound Card Instruments
▌ It’s a multipurpose software
▌ It can transform any sound card into:
Signal generator
Oscilloscope
Spectrum Analyzer
We will be using this software to generate signals using
the signal generators. Its very easy to generate a variety
of signals using this software
©2008
09 All rights reserved.
CECOS University of IT & Emerging Sciences
Fixed point Numbers
▌ Fixed point numbers are the ones that you use on daily
basis
▌ Fixed point numbers have fixed number of digits after
the radix (decimal) point
▌ Most Fixed point DSP are 16-bit (meaning that they have
a 16 bit wide data bus)
▌ Fixed point numbers can be represented in four formats
Unsigned (0 to 63,535)
Signed (-38,768 to 38,767)
Fractional Unsigned (0 to1)
Fractional Signed (-1 to 1)
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Floating Point Numbers
▌ Floating point DSPs are mostly 32-bit
▌ For 32-bit single precision floating point numbers the
range of possible values is from 3.4x10exp38 to 1.175x
10exp-38
▌ For 64-bit single precision floating point numbers the
range of possible values is from 1.7x 10exp308 to 1.7x
exp-308
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Fixed Vs Floating Point DSP
Floating point DSPs are
▌ Much easier to use than Fixed point DSP
▌ Capable of implementing complex algorithms very
accurately
▌ Expensive compared to fixed point
▌ Consume more power then fixed point processor
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Fixed Vs Floating Point DSP
Fixed point DSPs are
▌ Less accurate because of the smaller dynamic range
and large truncation errors
▌ More difficult to work with as optimizing an algorithm for
fixed point implementation may eat up a lot of design
time
▌ very fast compared to floating point DSPs and are
widely used in video application such as medical
imaging, surveillance etc
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
MIPS
▌ MIPS (Million Instructions Per Second)
▌ TMS320VC33 is capable of delivering 75MIPS
▌ Processors with CISC (Complex Instruction Set
Computing) architecture perform much more tasks then
processors with RISC (Reduced Instruction Set
Computing) architecture. A 20MIPS CISC processor may
perform a task much faster then its 75MIPS RISC
counterpart
▌ So, MIPS is not a processor benchmark
▌ Don’t ever judge the processors by their MIPS
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
MFLOPS
▌ MFLOPS (Million Floating Point OPerations per Second)
▌ It indicates the number of floating point multiply
operations in one second
▌ MFLOPS is a processor benchmark
▌ The higher the MFLOPS delivered by a processor the
fast it is.
▌ TMS320VC33 comes in two Speed Grade
TMS320VC33PGE120 (Delivers 120MFLOPS)
TMS320VC33PGE150 (Delivers 150MFLOPS)
▌ Speed-33 used TMS320VC33PGE150 DSP
©2008
09 All rights reserved.
CECOS University of IT & Emerging Sciences
Speedy-33 Kit
▌ Based on TMS320VC33 floating point DSP
▌ 512Kx8 (4MB) of on-board flash memory
▌ 1.1Mbit on-chip SRAM
▌ 32-Bit CPU
▌ Capable of 75 MIPS
▌ Capable of 150MFLOPS
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Speedy-33 I/O Capabilities
▌ Stereo Input
Supported sampling rates of 8 kHz, 18 kHz, 24 kHz, 36
kHz & 48 kHz
Maximum Input Voltage 600mV (Signal + Common Mode)
▌ Stereo output
Supported sampling rates of 8 kHz, 18 kHz, 24 kHz, 36
kHz & 48 kHz
Maximum output Voltage of 1.4mV (Signal + Common
Mode)
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Speedy-33 I/O Capabilities
▌ 16 Digital Lines
8 Digital inputs
8 Digital outputs
▌ 8 Led indicators for Digital output
▌ 8 DIP Switches for Digital Input
▌ Capable of Standalone operation
▌ Input jack for 9V supply (9V-500mA)
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Speedy-33 Architecture
When Audio in
Connector is
plugged in
When Audio in
Connector is
Disconnected
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
PCM3003
▌ PCM3003 is a stereo audio Codec
▌ Audio codec compresses High Fidelity audio signals so
as to have minimum number of bits without sacrificing
audio quality
▌ PCM3003 contains Sigma-Delta ADC and DAC
▌ Sigma delta ADCs and DACs are ideal for audio
applications because of their high precision and built-in
filtering
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Why Σ∆ ADC/DAC in Speedy-33
▌ There are three types of ADC
Flash ADC or Direct-Conversion ADC
• Very fast sampling rates (1GSPS)
• Very low resolution usually 8-bits or 12bit maximum
• Used in very high data rate applications such as
Oscilloscopes and Spectrum analyzer
• Audio must be represented by 16bits or more so that’s
why Flash ADC is not the correct choice
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Why Σ∆ ADC/DAC in Speedy-33
SAR (Successive Approximation ADC)
• Moderate Sampling Rates (1 MSPS)
• Moderate resolutions usually 16-18bits
• Used for motor control and industrial application
• They don’t have any built-in filtering that’s why they are
not preferred in audio application
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Why Σ∆ ADC/DAC in Speedy-33
Σ∆ or ∆Σ ADC
• Very high resolution 16-24bits
• Very low sample rate (256KSPS)
• Used in very high fidelity and very sensitive
applications such as Audio,
EEG(Electroencephalogram),
ECG(Electrocardiogram), ECoG (Elecrtocorticogram),
EMG(Elecrtomyogram)
• Built-in digital filtering in these ADC is an extra bonus
• That’s why Speedy-33 kit is using PCM3003 chip
which employs Σ∆ ADC and DAC
008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Speedy-33 Kit
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Speedy-33 Kit
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Speedy-33 Kit
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Speedy-33 Kit
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Audio VU Meter
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Designing an Audio VU Meter
▌ VU is an essential part of audio equipments
▌ A VU meter displays the RMS value of the sound signal
▌ Instead of Instantaneous display of the volume level it
displays a smoothed out version of the volume
▌ A volume unit is equal to number of dbm above the
reference power level of 1dbm
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
Saw Stop Demo at NI Week
©2008-2009 All rights reserved.
CECOS University of IT & Emerging Sciences
