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© 2012 Jackson Labs Technologies, Inc.

29

LC_XO GPSDO User Manual

4

SCPI-Control Quick 

Start Instructions

4.1 Introduction

The SCPI (

S

tandard 

C

ommands for 

P

rogrammable 

I

nstrumentation) subsystem is accessed via the 

RS-232 interface and a terminal program. By default the terminal settings are 115200, 8N1.
There are a number of commands that can be used as listed below. Most of these are identical or 
similar to Symmetricom 58503A commands.To get a listing of the available commands, send the 
HELP? query. This will return a list of all the available commands for the LC_XO GPSDO.
Additional information regarding the SCPI protocol syntax can be found on the following web site:
http://www.scpiconsortium.org
Please refer to the document SCPI-99.pdf for details regarding individual SCPI command 
definitions. A basic familiarity with the SCPI protocol is recommended when reading this chapter.

4.2 General SCPI Commands

4.2.1 Quick Start Commands

For a quick start, try the following SCPI serial port commands:
help?
syst:stat?
gps?
sync?
meas?

4.2.2 *IDN?

This query outputs an identifying string. The response will show the following information:
<company name>, <model number>, <serial number>, <firmware revision>

Summary of Contents for LC_XO

Page 1: ...onsumption 0 7W with OCXO 0 5W with TCXO Operating Temperature 0 C to 60 C 20C to 75C optional Storage Temperature 45 C to 85 C Additional Features Firmware field upgradable external 1PPS input status...

Page 2: ...Revision 08 29 12 B LC_XO PINOUT DESCRIPTION...

Page 3: ...LC_XO GPSDO User Manual Document 80200517 Version 1 0 Date 23 September 2012...

Page 4: ...LC_XO GPSDO User Manual Copyright 2012 Jackson Labs Technologies Inc...

Page 5: ...Up 11 3 2 1 1 Parameter Setup 11 3 2 1 2 Serial Echo 12 3 2 1 3 Windows Compatibility 13 3 2 2 Running the program 14 3 2 2 1 Zoom and Pan 14 3 2 3 View menu 14 3 2 3 1 Satellite Azimuth Elevation Ch...

Page 6: ...4 5 4 SYNChronization HOLDover RECovery INITiate 34 4 5 5 SYNChronization TINTerval 34 4 5 6 SYNChronization IMMEdiate 34 4 5 7 SYNChronization FEEstimate 35 4 5 8 SYNChronization LOCKed 35 4 5 9 SYN...

Page 7: ...ual 4 9 7 SERVo AGINGcompensation 39 4 9 8 SERVo PHASECOrrection 39 4 9 9 SERVo 1PPSoffset 39 4 9 10SERVo TRACe 39 4 9 11SERVo 40 5 Certification and Warranty 41 5 1 Certification 41 5 1 1 Warranty 41...

Page 8: ...LC_XO GPSDO User Manual iv 2012 Jackson Labs Technologies Inc...

Page 9: ...dustry standard NMEA GPS interface providing Position Velocity Timing PVT information as well as full control command serial interface using SCPI GPIB like serial commands The LC_XO board will use the...

Page 10: ...ot reverse the power pins as this will cause serious damage to the circuit board 1 2 3 Environmental Conditions This instrument is intended for indoor use It is designed to operate at a maximum relati...

Page 11: ...will start to search for Satellites as soon as power is applied and will start to lock the internal OCXO TCXO to UTC as soon as the 1PPS LED starts blinking with a GPS antenna attached After 1 hour o...

Page 12: ...LC_XO GPSDO User Manual 4 2012 Jackson Labs Technologies Inc Figure 2 1 LC_XO Module Top side Figure 2 2 LC_XO Module Bottom side...

Page 13: ...2012 Jackson Labs Technologies Inc 5 LC_XO GPSDO User Manual 2 1 2 LC_XO Mechanical Diagram Figure 2 3 LC_XO Pin Locations and Outline Drawing...

Page 14: ...LC_XO GPSDO User Manual 6 2012 Jackson Labs Technologies Inc 2 1 3 LC_XO Pinout and Pin Description Figure 2 4 LC_XO Pinout and Pin Description...

Page 15: ...OS 10ns rise time 5 1PPS IN 1PPS Input External optional 1PPS Reference Input 6 5V Out 5V Output 5V 5 100mA output from internal DC DC switcher Bypass with optional 33uF or more for improved phase noi...

Page 16: ...ght in its GPGGA GPS and syst stat output strings The LC_XO also provides raw NMEA and uBlox binary output strings on pin 12 for additional information The internal GPS receiver generates a 1PPS time...

Page 17: ...this is the proportional gain of the PID loop Higher values will give quicker convergence and faster locking of the GPS time lower loop time constant lower values give less noise Values between 0 7 an...

Page 18: ...LC_XO GPSDO User Manual 10 2012 Jackson Labs Technologies Inc Figure 2 5 LC_XO board phase compensation plot...

Page 19: ...tively to the Z38xx application GPSCon is a third party program for the monitoring and control of a variety of GPS time and frequency standard receivers It communicates with the receiver using the SCP...

Page 20: ...on in the Z38XX manual To turn off serial echo click on the Manual Command Entry tab The drop down menu shown in Figure 3 2 will appear Scroll all the way down and click on SYST COMM SER ECHO OFF Wait...

Page 21: ...ws Compatibility Z38XX may not operate properly under the Windows Vista or Windows 7 operating systems It is best to start these versions of Windows in XP Compatibility Mode This will ensure proper op...

Page 22: ...ail To do so position the cursor at the bottom or top of the screen next to the beginning of the area you wish to zoom in on Using the left mouse button drag the cursor up and to the right or down and...

Page 23: ...e shown in Figure 3 4 It may take a few hours for the graph to display all the satellites within your antenna s view The chart changes over time as the satellites move in and out of view Figure 3 4 Sa...

Page 24: ...ters are not supported by the LC_XO 3 2 3 4 Time Stability Measures Select Time Stability Measures from the View menu to bring up the chart shown in Figure 3 6 This chart is primarily used to display...

Page 25: ...2012 Jackson Labs Technologies Inc 17 LC_XO GPSDO User Manual Figure 3 6 Time Stability measures window...

Page 26: ...d commands are mentioned in this chapter for convenience 3 3 1 1 Setting the options To set up the options for your GPSCon session press the Options button below the display area The window shown in F...

Page 27: ...ugh this is the factory default it could have been set to OFF for use with the Z38XX utility To set it to ON open the manual command dialog box see Section 3 3 2 Manually enter the command SYST COMM S...

Page 28: ...LC_XO GPSDO User Manual 20 2012 Jackson Labs Technologies Inc Figure 3 8 Setting the communications parameters...

Page 29: ...such as paths for logging or exporting graphics 3 3 2 Sending manual commands to the receiver You can send SCPI commands manually by using the drop down box under the display window as shown in Figur...

Page 30: ...des the span setting To display all of the data in the file without manually setting the span to zero you should right double click in the graph This has the effect of setting the start time to zero t...

Page 31: ...u have locked the start and stop time using the mouse you can scroll left or right through the data without changing the span To scroll to a later time use Shift Left click To scroll to an earlier tim...

Page 32: ...ogfile contents Use the checkbox All to make this choice You may nominate a size in X and Y The file format may be BMP JPG GIF or PNG Your settings will be stored and will be the default next time you...

Page 33: ...with and without GPS reception of course The OCXO heater current is shown in turqoise We can see it ranges from 0 135607A to 0 178146A The OCXO current jumps lower every 24 hours because the unit is s...

Page 34: ...performance of the LC_XO board after one week of burn in locked to GPS and shielded from airflow Corrections from the GPS receiver improve the short term phase stability of the TCXO oscillator above 5...

Page 35: ...2012 Jackson Labs Technologies Inc 27 LC_XO GPSDO User Manual Figure 3 14 Typical LC_XO Phase Noise TCXO version...

Page 36: ...LC_XO GPSDO User Manual 28 2012 Jackson Labs Technologies Inc...

Page 37: ...uery This will return a list of all the available commands for the LC_XO GPSDO Additional information regarding the SCPI protocol syntax can be found on the following web site http www scpiconsortium...

Page 38: ...satellite constellation 4 3 2 GPS SATellite TRAcking COUNt This query returns the number of satellites being tracked 4 3 3 GPS SATellite VISible COUNt This query returns the number of satellites PRN t...

Page 39: ...fference between MSL and GPS height can be significant 35m or more are common 4 3 6 GPS GGASTat This command instructs the LC_XO to send a modified version of the NMEA standard string GPGGA every N se...

Page 40: ...e velocity vector every N seconds with N in the interval 0 255 GPS XYZSPeed int 0 255 4 3 9 GPS POSition This command will return the position and height of the GPS antenna including velocity and trac...

Page 41: ...is equivalent to the command SYNChronization TINTerval 4 4 6 PTIME This query returns at once the result of the four following queries PTIME DATE PTIME TIME PTIME TZONE PTIME TINTerval 4 5 SYNChroniz...

Page 42: ...the resolution is 1 second If the Receiver is in holdover the response quantifies the current holdover duration If the Receiver is not in holdover the response quantifies the previous holdover The sec...

Page 43: ...s are monitored and indicated through the health status indicator Individual parameters are ored together which results in a single hexadecimal value encoding the following system status information A...

Page 44: ...is as follows DIAGnostic ROSCillator EFControl RELative DIAGnostic ROSCillator EFControl ABSolute 4 6 1 DIAGnostic ROSCillator EFControl RELative This query returns the Electronic Frequency Control E...

Page 45: ...l ECHO ON OFF 4 8 1 2 SYSTem COMMunicate SERial PROmpt This command enables disables the prompt scpi on the SCPI command lines The prompt must be enabled when used with the software GPSCon This comman...

Page 46: ...omatically adjusts this setting The user should not have to change this value This command has the following format SERVo COARSeDac int 0 225 4 9 2 SERVo DACGain This command is used for factory setup...

Page 47: ...ion float 10 0 10 0 4 9 8 SERVo PHASECOrrection This parameter sets the Integral part of the PID loop Loop instability will result if the parameter is set too high Typical values are 10 0 to 30 0 This...

Page 48: ...ble indicates one of the following states 4 9 11 SERVo This command returns the result of the following queries SERVo COARSeDac SERVo DACGain SERVo EFCScale SERVo EFCDamping SERVo SLOPe SERVo TEMPCOmp...

Page 49: ...tomer shall prepay shipping charges and shall pay all duties and taxes for products returned to Jackson Labs Technologies Inc for warranty service Except for products returned to Customer from another...

Page 50: ...kson Labs Technologies Inc products are not intended for use in medical life saving or life sustaining applications 5 1 3 Exclusive Remedies THE REMEDIES PROVIDED HEREIN ARE THE CUSTOMER S SOLE AND EX...

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