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Symmetricom SA.22c User Manual
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Symmetricom SA.22c User Manual

Symmetricom SA.22c User Manual

Rubidium oscillator
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Summary of Contents for Symmetricom SA.22c

  • Page 1 sales@artisantg.com artisantg.com (217) 352-9330 | Visit our website - Click HERE...
  • Page 2 SA.22c Rubidium Oscillator Designer’s Reference and User’s Guide Revision A – May 2007 Part Number 097-16313-201...
  • Page 3 2300 Orchard Parkway San Jose, CA 95131-1017 U.S.A. http://www.symmetricom.com Copyright © 1999 – 2007 Symmetricom, Inc. All rights reserved. Printed in U.S.A. All product names, service marks, trademarks, and registered trademarks used in this document are the property of their respective owners.

  • Page 4: Warranty

    (v) customer or third party-supplied software, interfacing or parts; or (vi) operations outside of Symmetricom published specifications. Symmetricom, at its own expense and as its sole obligation, and customer's sole remedy for any breach of the foregoing warranty, whether express or implied, howsoever arising, will use commercially reasonable effort to repair or replace the defective unit upon return of such article to Symmetricom's factory.

  • Page 6: Table Of Contents

    Greater Than ±1E –9 Internal or External Control ....31 Time Response of External Frequency Control ....31 Part Number 097-16313-201 Revision A – May, 2007 SA.22c Rubidium Oscillator User’s Guide...
  • Page 7 Symmetricom Serial Interface Protocol Using the Symmetricom Serial Interface Protocol..... . .54 Host Terminal Emulator Setup ....... . .54 Data Format .
  • Page 8 ............79 Part Number 097-16313-201 Revision A – May, 2007 SA.22c Rubidium Oscillator User’s Guide...
  • Page 9 Table of Contents SA.22c Rubidium Oscillator User’s Guide Part Number 097-16313-201 Revision A – May, 2007...
  • Page 10 SA.22c Rubidium Oscillator ........20...
  • Page 11 List of Figures SA.22c Rubidium Oscillator User’s Guide Part Number 097-16313-201 Revision A – May, 2007...
  • Page 12 SA.22c Design Absolute Maximum Ratings ......24 SA.22c Design Operating Characteristics ......24 Hardware and Software Selectable Items .
  • Page 13 List of Tables SA.22c Rubidium Oscillator User’s Guide Part Number 097-16313-201 Revision A – May, 2007...

  • Page 14: How To Use This Guide

    Conventions Used in This Guide Warnings, Cautions, Recommendations, and Notes Related Documents and Information Where to Find Answers to Product and Document Questions What’s New In This Guide Part Number TBD Revision A – February, 2007 SA.22c Rubidium Oscillator User’s Guide...

  • Page 15: Purpose Of This Guide

    Oscillator. The guidelines in this user guide are generic because specific product requirements vary from application to application. This material consists of a brief description of SA.22c design supported by block diagrams, description of environmental issues, installation guidelines, required mating connectors, and unit operation.

  • Page 16: Conventions Used In This Guide

    Appendix C, One Pulse Per This appendix Second Source Connection second (1PPS) source to an SA.22c. Index Provides references to individual topics within this guide. Conventions Used in This Guide This guide uses the following conventions: Acronyms and Abbreviations –...

  • Page 17: Warnings, Cautions, Recommendations, And Notes

    Note: All notes use this symbol. Notes contain installation, operation, or maintenance procedures, practices, conditions, or statements, that alert you to important information, which may make your task easier or increase your understanding. SA.22c Rubidium Oscillator User’s Guide Part Number TBD Revision A – February, 2007...

  • Page 18: Related Documents And Information

    How to Use This Guide Related Documents and Information Related Documents and Information See your Symmetricom representative or sales office for a complete list of available documentation. Note: Symmetricom offers training courses designed to enhance your knowledge of the SA.22c Rubidium Oscillator. Contact your local representative or sales office for a complete list of courses and outlines.
  • Page 19 How to Use This Guide What’s New In This Guide SA.22c Rubidium Oscillator User’s Guide Part Number TBD Revision A – February, 2007...

  • Page 20: Chapter 1 Description

    Chapter 1 Description This section contains a description of the SA.22c and lists its typical applications. It provides information on dimensions, performance, and connector pinouts. In This Chapter Overview Typical Applications Specifications Part Number 097-16313-201 Revision A – May, 2007...

  • Page 21: Description Overview

    Figure 1-1. SA.22c Rubidium Oscillator Drawing on over 30 years of experience, the SA.22c design has been refined for low cost mass production and can be easily integrated into time, frequency and synchronization systems. It can be mounted directly onto a circuit board as a component of a module.

  • Page 22: Sa.22C Rubidium Oscillator Simplified Block Diagram

    Chapter 1 Description Typical Applications The SA.22c produces a stable frequency with good short and long term stability with excellent spur performance. The microprocessor-based SA.22c is a more cost-effective system design that allows serial command selection and enabling of TTL-level digital output frequencies.

  • Page 23: Chapter 1 Description Specifications

    SA.22c Dimensions Note: The mating connector is a SAMTEC TMMH-109-01-G-DV-ES-A 2 X 9 shrouded header. Caution: To avoid damage to the SA.22c, ensure that power and ground are properly connected. Note: All pins on the I/O connector must be connected.

  • Page 24: Sa-22C Pin Assignment And Function Chart

    1PPS input, positive edge triggered. DOUT Output UART data out at ACMOS logic levels. Note: Refer to Appendix A, Using the Developer’s Kit for the connector manufacturer's drawings and specifications. Part Number 097-16313-201 Revision A – May, 2007 SA.22c Rubidium Oscillator User’s Guide...

  • Page 25: Sa.22C Design Absolute Maximum Ratings

    Chapter 1 Description Specifications Table 1-2. SA.22c Design Absolute Maximum Ratings Characteristic – 10° C to 75° C Symbol Units Base-plate (Unit in ambient still air – convection) Supply relative to ground +15Vdc Input ±5 Supply relative to ground +5Vdc Input ±5...
  • Page 26 Chapter 1 Description Specifications Table 1-3. SA.22c Design Operating Characteristics (Continued) – 10° C to 75° C Characteristic Symbol Base-plate Units (Unit in ambient still air – convection) Min - Max - Typ High level input 5.25 voltage 1PPS IN 5.25...

  • Page 27: Total Sa.22C Quiescent Power Dissipation, Typical (Free Convection)

    Total SA.22c Quiescent Power Dissipation, Typical (free convection) Figure 1-5. Typical AP1 Level TEMPCO [-10º C to 75º C Base Plate Temperature] Note: Refer to the SA.22c Performance Characteristics document for more detailed information. SA.22c Rubidium Oscillator User’s Guide Part Number 097-16313-201 Revision A – May, 2007...

  • Page 28: Chapter 2 Design Integration Considerations

    In This Chapter Mechanical Considerations Thermal Considerations External Interfaces and Grounding Electrical Interface Frequency Control Analog Modifiable Unit Settings Susceptibility to Input Noise Reliability and Maintenance Part Number 097-16313-201 Revision A – May, 2007 SA.22c Rubidium Oscillator User’s Guide...

  • Page 29: Design Integration Considerations Mechanical Considerations

    Chapter 2 Design Integration Considerations Mechanical Considerations Mechanical Considerations Mounting Recommendations To mount the SA.22c to a custom-designed circuit card, use the SAMTEC mating connector (see Figure 1-3). Use the six mounting holes located on the base plate. Note: Contact Symmetricom for information on an adapter test board and for information on designing your own interface circuit board.

  • Page 30: Chapter 2 Design Integration Considerations Thermal Considerations

    In order to achieve the highest ambient operating temperature for the SA.22c operating base plate temperature Symmetricom recommends that the bottom (“base plate”) of the SA.22c have good thermal contact to the mounting surface. It is also very important to maintain a uniform temperature into the base plate of the SA.22c through its mounting points.

  • Page 31: External Interfaces And Grounding

    Rb atomic clock. If the LOCK signal is high, atomic lock has been lost and the SA.22c goes into sweep mode to reacquire lock. The sweep ranges from approximately –21 ppm to +21 ppm in approximately a 20 second period.

  • Page 32: Frequency Control Signal

    SSIP to eliminate any source of noise. In some versions of the SA.22c, this function can be turned off by customer request on power up. If it is to be used later it must be enabled through the SSIP (refer to...

  • Page 33: Modifiable Unit Settings

    If you have an application where the output spectrum phase noise and spur integrity is crucial, the SA.22c must have a comparatively clean source of dc power (free of spurious current or voltage noise). Connecting fans, heaters, and other switching devices to the dc supply powering the SA.22c can result in degraded phase noise...

  • Page 34: Reliability And Maintenance

    Reliability and Maintenance Reliability The SA.22c is designed with a goal of ten years of operation without retuning. To accomplish this, the major mechanisms impacting the need for maintenance were addressed. Thus, each SA.22c has been designed to have excess rubidium fill in...
  • Page 35 Chapter 2 Design Integration Considerations Reliability and Maintenance SA.22c Rubidium Oscillator User’s Guide Part Number 097-16313-201 Revision A – May, 2007...

  • Page 36: Chapter 3 Installation And Operation

    Chapter 3 Installation and Operation This section provides information on details to consider when installing the SA.22c and the procedure to follow when turning on the unit. There is an explanation of the start-up sequence, monitoring performance, and theory of operation. It also contains a troubleshooting guide, customer support information, and warranty information.

  • Page 37: Installation

    SA.22c, ensure that the temperature limits are not exceeded. The SA.22c is sensitive to external dc and ac magnetic fields (refer to specification) and should not be installed in locations subjected to strong magnetic fields from transformers or large power supplies.

  • Page 38: Chapter 3 Installation And Operation Start-Up Sequence

    1E of center frequency. Thirty minutes after applying power to the SA.22c the rf output frequency will be very close to full accuracy (refer to SA.22c specifications). Note: The output frequency of the SA.22c is more accurate than most counters.

  • Page 39: Sequence Of Start-Up Events

    Chapter 3 Installation and Operation Start-up Sequence Figure 3-2. Sequence of Start-up Events Note: The Service signal can be Active High or Active Low depending on the unit configuration. SA.22c Rubidium Oscillator User’s Guide Part Number 097-16313-201 Revision A – May, 2007...

  • Page 40: Theory Of Operation

    Chapter 3 Installation and Operation Theory of Operation Theory of Operation The Model SA.22c makes use of the atomic resonance property of rubidium ( to control the frequency of a quartz crystal oscillator via a frequency-locked loop (FLL). The FLL function block is shown in Figure 3-3.

  • Page 41: Chapter 3 Installation And Operation Troubleshooting

    Is the ambient temperature below –10° C or above +75° C (the unit will not startup properly in excessively cold or hot temperatures) Repairs The SA.22c is not field repairable, but some firmware upgrades can be done in the field, as noted in Start-up Sequence, on page 37.

  • Page 42: Appendix A Using The Developer's Kit

    Appendix A Using the Developer’s Kit Chapter This appendix provides information on using the SA.22c Developer’s Kit. It includes information on interfacing the Adapter Test Board as well as information on the various options for providing power and viewing signals from the SA.22c through the Adapter Test Board.

  • Page 43: Introduction

    Figure A-1 shows the mounting of the SA.22c onto the adapter test board. Four 5 mm length screws are needed to properly mount the SA.22c onto the adapter test board if the optional heat sink is not used. Note: To achieve and maintain the highest level of performance for the SA.22c, Symmetricom strongly recommends utilizing a suitable...

  • Page 44: Sa.22C Developer's Kit Without Heatsink Assembly

    SA.22c Developer’s Kit Without Heatsink Assembly Figure A-2 shows the mounting of the SA.22c onto the adapter test board and to the optional heat sink. Six 10 mm length screws are needed to properly mount the SA.22c with the adapter test board onto the optional heat sink.

  • Page 45: Interfacing Of The Adapter Test Board

    The adapter test board was designed to allow the user a flexible means of delivering power to and retrieving signals from the SA.22c. Additionally, the Adapter Test Board also allows the user to electrically integrate the SA.22c into an existing system (via J2).
  • Page 46 Output UART data out at ACMOS logic levels J2 is a 26-pin Molex receptacle connector used for delivering power and transmitting/receiving signals and data to and from the SA.22c all from one connector. See Table A-2 for the Molex pin configuration.
  • Page 47 Power and signal ground (All ground pins must be connected) 1PPS IN Input 1PPS input, positive edge triggered 1PPS Output 1PPS output, may be enabled/disabled digitally LOCK Output If low, then the SA.22c is locked SA.22c Rubidium Oscillator User’s Guide Part Number 097-16313-201 Revision A – May, 2007...

  • Page 48: Sma Connectors' Signal Information

    SINE Output SINE signal output (50 ohm) J7 is a 9-pin D-Sub connector used for transmitting/receiving data to and from the SA.22c via the Symmetricom Serial Interface Protocol (SSIP). See Table A-4 for the D-Sub connector pin configuration. Warning: When using J3, J4, J5, and J6, it is required that J2 not be connected.

  • Page 49: Options For Supplying Power To The Adapter Test Board

    SA.22c with the adapter board. It also show which connections are used to access the various inputs and outputs of the SA.22c depending on which option you use.

  • Page 50: Block Diagram Of Suggested Test Setup

    Appendix A Using the Developer’s Kit Options for Supplying Power to the Adapter Test Board Figure A-4. Block diagram of suggested Test Setup Part Number 097-16313-201 Revision A – May, 2007 SA.22c Rubidium Oscillator User’s Guide...

  • Page 51: Power Supply And Output Options

    Mixing any combination of these options may result in a system failure and possibly cause damage to the existing circuitry. Figure A-5. Power Supply and Output Options SA.22c Rubidium Oscillator User’s Guide Part Number 097-16313-201 Revision A – May, 2007...
  • Page 52 DC-to-DC converter and a voltage regulator to supply the SA.22c with the +15Vdc and the +5Vdc it needs to operate. For this option, J7 is used for serial interface communications. J3, J5, and J6 are used for signal outputs while J4 is used for 1PPS input.
  • Page 53 Appendix A Using the Developer’s Kit Options for Supplying Power to the Adapter Test Board SA.22c Rubidium Oscillator User’s Guide Part Number 097-16313-201 Revision A – May, 2007...

  • Page 54: Appendix B Symmetricom Serial Interface Protocol

    Appendix B Symmetricom Serial Interface Protocol Chapter This appendix provides information on communicating with the SA.22c through the serial interface connector as provided in the Developer’s Kit (see Appendix A, Using the Developer’s Kit). It includes output examples and a description of commands.

  • Page 55: Using The Symmetricom Serial Interface Protocol

    Note: Flow control is not permitted in “Run Mode”. Data sent to the SA.22c in run mode should not be encoded. The following is an example of output from the SA.22c after power is applied to the unit. SA22C by Symmetricom, Inc., Copyright 2006 SA22 Version 6.01C of 7/2006;...
  • Page 56 Save Tuning Data w: Display Health Data x: Exit Run Mode r> The following print out shows the response to the command for “w” for SA.22c “Health Data” (wellness): r>w AData: Part Number 097-16313-201 Revision A – May, 2007...

  • Page 57: Factory Mode

    “p”: r>p Control Reg: 204C Factory Mode Data output from the SA.22c in factory mode is not intended for users outside the factory and is not described in this document beyond Table B-1. Caution: Using factory mode can result in the erasure of firmware on the SA.22c rendering it inoperable and making it necessary to return...

  • Page 58: Serial Interface Initialization

    The serial interface is initialized as follows: Table B-1 defines the SA.22c’s Run Mode Commands. Table B-2 defines the bit functions of the factory mode commands of the SA.22c. Table B-3 defines the administrative mode commands. Table B-1. Run Mode Commands Response to User Output to SA.22c...

  • Page 59: Factory Mode Commands

    Appendix B Symmetricom Serial Interface Protocol Using the Symmetricom Serial Interface Protocol Table B-1. Run Mode Commands (Continued) Response to User Output to SA.22c Command Name and Description Host None To be Specified Displays Control Register. Hex data to set or reset bits...

  • Page 60: Sa.22C Administrative Mode Commands

    Appendix B Symmetricom Serial Interface Protocol Using the Symmetricom Serial Interface Protocol Table B-3. SA.22c Administrative Mode Commands User Output to SA.22c Response to Host Command Name and Description Command DATA None Outputs 7 lines of Unit Information Same as the "i"...
  • Page 61 Appendix B Symmetricom Serial Interface Protocol Using the Symmetricom Serial Interface Protocol SA.22c Rubidium Oscillator User’s Guide Part Number 097-16313-201 Revision A – May, 2007...

  • Page 62: Appendix C One Pulse Per Second Source Connection

    Appendix C One Pulse Per Second Source Connection Chapter This appendix describes how to connect a one pulse per second (1PPS) source, such as a commercial GPS receiver, to an SA.22c to achieve long term accuracy and excellent holdover, or flywheeling performance. In This Appendix...

  • Page 63: Connection Requirements

    GPS 1PPS system to steer various oscillators (Cesium, Rubidium, and Quartz). These products make it possible to combine the short term with long term stability. Now, with SA.22c, the solution can be even more cost effective. When used with a GPS receiver the SA.22c provides telecommunications system performance levels that rival levels obtained using Cesium oscillators.

  • Page 64: 1Pps Functions

    1PPS input and the 1PPS generated internally by the SA.22c. The “j” command produces a number representing the number of TICS in a delta register. If the SA.22c has a 60 MHz crystal, each TIC is –8 16.7 ns (1.67E...

  • Page 65: System Requirements

    Test Bench setup System Requirements The following information lists the requirements for 1PPS setup and operation: SA.22c with 1PPS output enabled. GPS receiver with less than 300 ns noise. One pulse per second input signals must have repeatable rise time with minimal ringing and must conform to the following: –...

  • Page 66: 1Pps Algorithm Operation

    – Input impedance is >100K Ω allowing the user to terminate the 1PPS at the input to the SA.22c with 50 Ω at the SA.22c input pin or drive the SA.22c high impedance directly with a low impedance source such as 50 Ω...

  • Page 67: Changing The "Y" Coefficients

    FC mode is enabled 1pps mode is enabled r> Note: It is not necessary for the SA.22c to be locked to enter the 1PPS configuration commands, but it must be locked for actual synchronization to occur. Changing the “y” Coefficients...

  • Page 68: The "Y" Coefficients - Factory Default

    If the factory default values of Damping Factor = 1 and Tau = 400 are acceptable for your application, no modifications to the y coefficients are required. The SA.22c 1PPS disciplining is enabled at the factory allowing the unit to work right out of the box.

  • Page 69: The "G" Command

    Appendix C One Pulse Per Second Source Connection Setting the 1PPS Synchronization The “g” Command The “g” command allows you to change the SA.22c to operate in any of three modes which affect the output of the Lock Pin (pin 14 see Note 10, on page 69).

  • Page 70: 1Pps Firmware Versions

    4. Use “z” command to save your settings. 5. SA.22c Rubidium system locks approx. 5 minutes after startup. 6. SA.22c initial frequency must be less than ± 3PPB for 1PPS to lock. 7. Initial 1PPS lock occurs between 3 and 5 minutes after both lock and valid 1PPS are present.

  • Page 71: Flywheeling Recovery - Normal

    Figure C-3. Flywheeling Recover with 1PPS offset < 1µsec In this test, the SA.22c was synchronized to 1PPS before this data set. Antenna is removed at hour 0 and reapplied at approximately hour 12.5. The SA.22c 1PPS output signal had reached an offset of 220 nanoseconds.

  • Page 72: Recovery With Jamsynch

    Figure C-4. Flywheeling Recover with 1PPS offset > 1µsec In this test, the antenna to the GPS receiver is removed. The SA.22c is purposely put off frequency long enough to induce a 1PPS error over 1µsec. When the antenna is reapplied, the SA.22c 1PPS recovers by resetting to 1PPS 0 nanoseconds (JamSynch).

  • Page 73: 1Pps Algorithm Theory Of Operation

    1PPS output (JamSynch state). The algorithm then begins to adjust the output frequency of the SA.22c to keep the 1PPS output aligned with the 1PPs input. This is the disciplining state and the control method is a Proportional Integral Derivatives (PID) scheme.

  • Page 74: 1Pps Algorithm High Level Flow Chart

    Appendix C One Pulse Per Second Source Connection 1PPS Algorithm Theory of Operation 1PPS Algorithm High Level Flow Chart Figure C-5. SA.22c 1PPS Algorithm States Part Number 097-16313-201 Revision A – May, 2007 SA.22c Rubidium Oscillator User’s Guide...

  • Page 75: Initialization

    During initialization the algorithm sets up variables based on the time constant (TC) and damping factor (DF). The SA.22c checks for 1PPS input once per second, and if present, it enters the holdover state. Automatic mode is used when the time constant is set to 0.

  • Page 76: Holdover

    During holdover, 1PPS input statistics are accumulated and periodically the results are calculated (CalcSlope State). The sample size is set to 120 data points (120 seconds). Figure C-7. SA.22c Holdover State Part Number 097-16313-201 Revision A – May, 2007 SA.22c Rubidium Oscillator User’s Guide...

  • Page 77: Calcslope

    Appendix C One Pulse Per Second Source Connection 1PPS Algorithm Theory of Operation Calcslope When the frequency difference between the SA.22c and the 1PPS source is calculated, if –9 the difference is < ±3E the state changes from holdover to JamSynch.

  • Page 78: Jamsynch

    1PPS Algorithm Theory of Operation JamSynch When the SA.22c 1PPS output is compared to the SA.22c 1PPS Input, if the difference is ≥ 1 µsec. the state returns to holdover to collect a second data set. When two consecutive slopes are in range, the SA.22c’s 1PPS output is synchronized to...

  • Page 79: Discipline

    Discipline In the Discipline State, the SA.22c uses a PID (proportional-integral-derivative) method to steer the 1PPS output of the SA.22c. This method means the SA.22c average frequency offset is close to zero. You can expect to see some frequency change when recovering from holdover.

  • Page 80: Index

    FC mode power up firmware 21, 37, purpose of this guide firmware upgrades frequency control frequency control signal recommendations defined frequency output related documentation frequency-locked loop Part Number 097-16313-201 Revision A – May, 2007 SA.22c Rubidium Oscillator User’s Guide...
  • Page 81 Symmetricom Serial Interface Protocol (see SSIP) y command temperature limits range z command thermal tape troubleshooting SA.22c Rubidium Oscillator User’s Guide Part Number 097-16313-201 Revision A – May, 2007...