Project TUNA II Bode Analyzer and Teaching Tool

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Project TUNA IIBode Analyzer and Teaching Tool

• David M. Beams
• University of Texas at Tyler

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BackgroundProject TUNA

• Dictionary definition of tedious
• Etymology Middle English, from Late Latin
  taediosus, from Latin taedium1 tiresome because
  of length or dullness BORING lta tedious public
  ceremonygt
• 2 manual frequency-response measurements-
  tediously adverb- tediousness noun
• With apologies to the Merriam-Webster On-line
  Dictionary

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Development of Project TUNA

• Developed as class project in Electronics II in
  1999 six permanent copies made in 2000.
• Combined GPIB-based laboratory instruments
  (Agilent E3631A Power Supply, HP33120 Arbitrary
  Waveform Generator, HP34401A Digital Multimeter)
  with a LabVIEW virtual instrument (VI) and custom
  external hardware.
• Used successfully in measuring frequency response
  in Electronics I and II Laboratory procedures.
• Upgraded VI with capability to write to
  spreadsheet file for graphing.

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Structure of Project TUNA instrument
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Structure of Project TUNA Hardware
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Structure of Project TUNA Hardware

• Quadrature networks analog all-pass networks
  that produce quadrature output signals over a
  wide range of frequencies (251) designed by the
  process described by Keely 1

1 Keely, T. A. Design of constant phase
difference networks. RF Design 12 (4), pp. 32,
37, 38, 40, 42 (April, 1989).
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Operation of Project TUNA

• Determination of network voltage gain from
  measured dc outputs of switching-type
  phase-sensitive demodulator

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Experience with Project TUNA

• Successful in laboratory students reported
  significant time savings in making
  frequency-response measurements
• Allowed introduction of advanced topic
  (phase-sensitive demodulation) into curriculum
• Maximal operating frequency did not achieve
  expectations due to charge injection in the
  ADG201HS high-speed analog switches
• Analysis time longer than necessary due to
  fixed-bandwidth low-pass filters
• Required major investment in GPIB-based
  instrumentation

• Somewhat limited dynamic range (30dB to -30dB)

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Genesis of Project TUNA II

• Measurement frequency to 1MHz
• Shorter analysis times
• Greater dynamic range (40dB to -40dB)
• Reduced reliance on GPIB-based instrumentation
• Use of multifunction I/O card to perform analog
  input and digital output function
• Work begun in 2001 as a senior project by Zinnour
  Soultanov permanent hardware and revised VI
  created in 2004

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Project TUNA II vs. Project TUNA

• Multiplying (instead of switching)
  phase-sensitive demodulator
• Attenuator to adjust voltage applied to network
  under test over a range of 10001
• Selectable time-constant low-pass filters to
  shorten analysis times at frequencies greater
  than 200Hz
• Amplifier with selectable voltage gain (1 or 10)
  
• Data-acquisition card measures dc output voltages
  VOI and VOQ simultaneously instead of
  sequentially
• Digital outputs of data-acquisition card control
  the attenuator, In/Out Relay, amplifier gain, and
  low-pass filter time constant
• Fourth quadrature network (utilizing two poles
  per channel instead of four) covering the
  frequencies from 100kHz to 1MHz

• Requires only one GPIB test instrument (HP 33120A
  arbitrary waveform generator).

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Structure of Project TUNA II


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Implementation of Project TUNA II

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Project TUNA II Virtual Instrument Panel

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Project TUNA II Performance
Bandpass filter Center frequency1kHz Q10,
AV20dB TUNA 6 m 24s TUNA II 1 m 10s
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Project TUNA II Performance
Series RCL network Series resonant frequency
229kHz
TUNA II analysis time 46s Matches PSPice
results within 1dB and 4 from 30kHz to 300kHz
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Project TUNA II Instructional Use and Resources

• Instructional use
• Used in Electronics I and Electronics II as
  laboratory instrument
• Used in EENG 4302 (Measurement and
  Instrumentation Systems) to explain
  phase-sensitive demodulation
• Quadrature networks discussed in connection with
  active filters
• Resources
• LabVIEW VI
• Tutorial on phase-sensitive demodulation
• Schematics and documentation
• Spreadsheet for design of quadrature networks
• Printed circuit board artwork