Welcome to the MSA Web Site,
the Modularized Spectrum Analyzer

Interested in owning your own RF Spectrum Analyzer ?
This site is dedicated as a Home Experimenter's Guide to building a Quality,
yet, Inexpensive 1000 MHz Spectrum Analyzer.

The Original MSA, mated with a laptop computer.  Not pretty, but works quite well.

The newer version, the SLIM MSA.
msapictures/msa_pic_front.gif msapictures/msa_pic_top.JPG msapictures/msa_pic_bot.JPG
Same concept, but constructed using Standardized Laboratory Integration Modules, SLIM's.

Updated Nov 1, 2013  Updated software to Version 117. Download software from Initial Set-Up and Calibration of the MSA
The MSA project was started in Jan, 2001 and has evolved under several titles.
By Scotty Sprowls
    If you want to build your own Home-Brew 1000 MHz Spectrum Analyzer, you already have half of it completed. That half is the computer you are using to read this. The processors and displays are very expensive portions of modern spectrum analyzers, and those functions can be replaced by your home computer. The computer's monitor is the Spectrum Analyzer's display.  The other half is the MSA hardware, to be constructed (as seen in the photos).  The MSA Software is free to download.  It will operate on any computer with a parallel port, USB 2, or USB3 and any Microsoft Windows platform. USB operation has been tested using Win ME, Win XP, Win7, Win8, and Win10.
    Previous visitors to this Site will notice significant changes.  I have deleted most references to previous versions of the MSA and will concentrate on the MSA using SLIMs, Standardized Laboratory Integration Modules.  The previous designs and web pages are retained in the MSA Archives, for those who need the references.  The SLIM MSA does not obsolete the Original MSA design.  The Original MSA will continue to be supported in the software.

    The title of this page and the opening paragraph seem to indicate that the Function of the MSA is a Spectrum Analyzer with operation limited to 1000 MHz.  This was my original concept and design goal.  The computer would command the Spectrum Analyzer to a specific frequency and display a received magnitude as spectral graphics on its monitor. However, software and hardware additions have allowed the MSA to provide many more Functions than just that of a Spectrum Analyzer. The Functions depend upon the level of construction. There are 3 Build Levels of the MSA.

Basic MSA, Build Level 1:
    The Basic Modularized Spectrum Analyzer (Level 1) is the core of the MSA Project  It is comprised of 11 modules and is common to all higher levels of construction. Its basic function is that of a
Spectrum Analyzer
, with these specifications:
3 band ranges:                            0-1 GHz, 1-2 GHz, and 2-3 GHz
(or higher using harmonic mixing)
Frequency Resolution:                 less than 3 Hz
Instantainous Dynamic range:       greater than 100 dB. Average 110 dB.
Sensitivity:                                 -20 dBm to -120 dBm
Resolution Bandwidth:                 Optional, with Resolution Bandwidth filter selection.
When not used as an SA, the Basic MSA can provide these other Functions:
Logging Voltmeter (future development with A to D Converter)
Frequency Sources:
Fixed, 64 MHz Clock Source, 50 ohm, square (Master Oscillator)
Variable, 1-1.5 GHz, 50 ohm, sine. Selectable in steps. (PLO 2)
Variable, 1-2 GHz, 50 ohm, sine, <3 Hz resolution. (PLO 1)
Variable, 0-1 GHz, 50 ohm, sine, <3 Hz resolution. (PLO 1 - PLO 2)
Variable, 2-3 GHz, 50 ohm, sine, <3 Hz resolution. (PLO 1 + PLO 2)
CW or Swept DDS Signal Generator, 0-32 MHz, 50 ohm, sine, 0.014 Hz resolution. (DDS 1)

MSA with Tracking Generator, MSA/TG, Build Level 2:
Build Level 2 is the addition of 3 modules to add a Tracking Generator to the Basic MSA. The following functions are added:
Spectrum Analyzer with Signal Generator
Spectrum Analyzer with Tracking Generator
    Normal Tracking Generator, or
    Offset Tracking Generator, or
    Reversed Tracking Generator, with or without offset
Scalar Network Analyzer
Crystal Analyzer, a Crystal Tester
Additional Frequency Sources:
Variable, 1-2 GHz, 50 ohm, sine, <3 Hz resolution. (PLO 3)
CW or Swept DDS Signal Generator, 0-32 MHz, 50 ohm, sine, 0.014 Hz resolution. (DDS 3)

VNA, Vector Network Analyzer, MSA/TG/VNA, Build Level 3:
This is the addition of 2 more modules to the MSA/TG (Build Level 2) to create a Phase Measurement System.
Vector Network Analyzer, Transmission
Vector Network Analyzer, Reflection
The VNA has the same Functions as the Basic MSA and MSA/TG, plus the Functions:
Filter Analyzer
RLC Analysis, Circuit conversion
Component Meter, for measuring resistors, capacitors, inductors.
Coax Tester, a
Transmission Line Analyzer
Antenna Analyzer

MSA Requirements for the Home Computer and its Software:
    PC or Laptop Computer (any speed), with USB 2 or LPT standard or enhanced parallel port (SPP, EPP).  Monitor can be any size, but MSA software uses 800 by 600 pixel resolution. Windows 98 or later. MSA software is executable, but builders who wish to modify the MSA software will need Liberty Basic 4.03.  The Liberty Basic is free, but it will nag you to buy it.  Go visit their web site at www.libertybasic.com.

MSA Web Pages supporting the MSA Project. Some are still in-work:
Construction of the SLIM MSA, a Construction Guide for integrating the MSA using Standardized Lab Integration Modules. The Basic MSA, Tracking Generator addition, and Vector Network Analyzer extension are covered.  Specifications for the SLIM MSA and links to pages for the construction of the individual SLIMs.
Construction Hints.  Hints on constructing the SLIMs.  It may save you a lot of potential grief.
Initial Set-Up and Calibration of the MSA, including instructions for downloading the software.
Test-As-You-Build, A test procedure for SLIMs as they are built and integrated into the MSA.
Testing the Integrated MSA, A test procedure and troubleshooting guide for a fully integrated MSA.
Control and Operation of the MSA is common to all Build Levels of the MSA. A description of screens, controls, and operation.
Technical Analysis of the MSA.  In-depth circuit analysis. Very handy for troubleshooting the MSA.
Temperature Testing of the MSA. Testing the MSA/VNA for temperature induced error. In-work.
SLIM Web Page. The Standardized Laboratory Integration Module philosophy and links supporting the SLIMs.
Coaxial Cavity Filter, description and construction of a high-Q, 1013 MHz bandpass filter.
USB control for the MSA.
Using the MSA to Test Phase Noise of PLO 2, DDS 1 as a Low Phase Noise Sweep Source
Using the DDS 1 to Sweep a Crystal Filter,
DDS 1 as a Tracking Generator or Scalar Network Analyzer
MSA Archives, old stuff no longer maintained.  Use it, but many links don't work.  I will repair them as time permits.
VNA Operating Guide, by Sam Wetterlin

Other Web Sites supporting the MSA Project 
Sam Wetterlin's Site, a Gold Mine of information, containing some great items for the MSA, examples:
Wide Band Leveler.  An AGC Amplifier with constant output amplitude, for calibrating the MSA.
1 MHz Calibration Source.  Sine and Square Wave Generator, for calibrating the MSA.
OSL Standards.  Construction and explanation for precision open, short, and load for use with the VNA.
Attenuators.  Precision fixed and switchable attenuators.

Reflection Bridges, passive and active.  For use with the MSA/VNA.
Test Fixtures. Series and Shunt Test Fixtures.  Used as test bridges with the MSA.
    Sam has written several documents supporting his MSA/VNA.  I will refer to many of them:
Title: The MSA as a Vector Network Analyzer, 12/12/09.  This is his MSA overview web page with links to the following PDF documents:
Title: The MSA in Bands 1G, 2G, and 3G. Description of Frequency Bands
Title: Three-Bead-Balun Reflection Bridge, 250 KHz to 1.5 GHz, 9/22/08
Title: A Baluns and Beads Reflection Bridge, 50 KHz to 1.5 GHz, 10/21/08
Title: The Active Bridge, 11/20/09
Title: Manual Return Loss Measurements, 10/5/08. A manual analysis of Return Loss
Title: The Buffer Op Amp, 12/6/09. Dual buffer amp for use to 150 MHz.
Title: Using Test Fixtures for Measurement with the MSA, 12/4/09. Various test fixtures and procedures for MSA, with test results.
Title: Test Results of Component Measurement with the MSA, 10/24/09
Title: A Series Test Fixture for Measuring Impedance with the MSA, 10/5/09. Test results using OSL calibration in component measurements with the Series fixture.
Title: Antenna Testing with the MSA, 10/17/09
Title: Determining Characteristic Impedance of Transmission Lines with the MSA, 11/26/09
Title: Analyzing Open and Short Coax Stubs with the MSA, 11/26/09
Title: Measuring Transmission Line Loss with S21, 11/26/09. In Transmission mode
Title: Analysis of Components with the MSA, 11/6/09
Title: Filter Analysis. The Filter Analysis Function
Title: Changing the Graph Appearance in the MSA
Title: OSL Calibration Standards for the MSA. Nature and construction of OSL standards.
Title: The Basis of OSL Calibration of the MSA. Mathematics of OSL calibration
Title: Illustration of Plane Extension for the MSA, 10/21/09. Use of Plane Extension
Title: Introduction to the Smith Chart for the MSA, 10/12/09
Title: S-Parameters and Related Quantities, 10/20/09. Introduction to S-Parameters
Title: More Transmission Line Math Than You Want, 11/26/09. Details of transmission line math.
Title: a Walk Through the MSA Software Spectrum Analyzer Mode, 12/12/09
Title: a Walk Through the MSA Software Vector Network Analyzer Transmission Mode, 12/12/09
Title: a Walk Through the MSA Software Vector Network Analyzer Reflection Mode, 12/12/09
Title: Spectrum Analyzer Operating Guide for the MSA, 12/12/09. Bench-top guide to SA operation.
Title: VNA Operating Guide for the MSA, 12/12/09. Bench-top guide to VNA operation.
MSA Builder's Group for those interested in sharing ideas on the MSA.  There are many people in the process of building or using the MSA and can offer suggestions and comments.  This is a Yahoo Group page and you are welcome to join and contribute.

    A little about me:  My name is Scotty Sprowls.  I am a retired RF Design Engineer from E-Systems / Raytheon.  Although I am not an Amateur Radio Operator, I repair radios as a hobby.  My frustration in tuning cavity filters in diplexers for a couple of Hams caused me create this Spectrum Analyzer to aid me.  You can get in touch with me, via email, at   wsprowls(at)yahoo.com
  I will try to answer your questions or comments as soon as possible.
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