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Reference Design for Synchronizing DSA Devices using GPS

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Overview

This example demonstrates how to synchronize a single PXI chassis with either PXI-446x or PXI-449x devices to GPS. The GPS Time Coordinator will synchronize multiple systems together which allows you to create a very large and flexible synchronized measurement system. Refer to GPS Synchronization Architecture for DSA Devices for an overview and links to other GPS example code.

Table of Contents

  1. Hardware Required
  2. Hardware Setup
  3. Software Required
  4. Software Setup

Downloads

Filename: gps_sync_dsa_1_chassis.zip
Requirements: View

Setup Instructions

Hardware Required

  • PXI Chassis and controller
  • PXI- 446x or PXI-449x
  • PXI-6682
  • GPS Antenna
  • Trimble Thunderbolt E (or other GPS receiver which can provide a GPS disciplined 10MHz signal)
  • GPS Splitter (recommend part number ALDCBS1X2-B/5 from GPS Networking)

Hardware Setup

  • Connect GPS Antenna, GPS Splitter, Thunderbolt and PXI-6682 together appropriately.
  • Connect 10MHz output from Thunder to PXI-6682 Clk In terminal.

Software Required

Software Setup

After connecting all of the signals and booting the system, you will need to wait for the self survey of the PXI-6682 to complete.  The self survey process takes about 15 minutes to complete.  By default, the PXI-6682 will perform a self survey each time it is reset.  To change this behavior so that a self survey only one time, open Measurement & Automation Explorer (MAX), right-click on the PXI-6682 and select “Properties”.  The following screenshot shows the option to uncheck.

You will only need to perform a self survey if you move the PXI chassis from its current location.

After the self survey is complete, you should calibrate out any offset errors in the PXI-6682’s GPS time reference.  This is accomplished by measuring the amount of error between the PPS signal from the Trimble Thunderbolt and the timestamps from the PXI-6682.  Calibration code is included in the code set.  Once an adjustment has been made, you can make the adjustment persist through resets by applying the settings in MAX.  Below is another screenshot of the PXI-6682’s property page:

Now, we are ready to make some measurements.  On the measurement system, open the “GPS Sync with 446x or 449x – Single CPU Single Chassis – Slave.vi”.  Configure the inputs and run the VI.  On the same PC or a different one, open the “GPS Time Coordinator.vi”.  Configure the inputs appropriately and run the VI.  The measurement system will stream to disk all of its data and send one channel back to the GPS Time Coordinator over TCP/IP.

 

  

Requirements


Filename: gps_sync_dsa_1_chassis.zip

Software Requirements


Application Software: LabVIEW Base Development System 8.5
Language(s): LabVIEW

Hardware Requirements


Hardware Group: PXI/CompactPCI, Dynamic Signal Analyzers (DSA)
Hardware Model: PXI-4462, PXI-4462 eHM, PXI-6682, PXI-4498, PXI-4496
Driver: NI-Sync 3.0, NI-DAQmx 8.6

 
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This example program (this "program") was developed by a National Instruments ("NI") Applications Engineer. Although technical support of this program may be made available by National Instruments, this program may not be completely tested and verified, and NI does not guarantee its quality in any way or that NI will continue to support this program with each new revision of related products and drivers. THIS EXAMPLE PROGRAM IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND AND SUBJECT TO CERTAIN RESTRICTIONS AS MORE SPECIFICALLY SET FORTH IN NI.COM'S TERMS OF USE (http://ni.com/legal/termsofuse/unitedstates/us/).