Microchip Technology GPS-2700 User Manual
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Microchip Technology GPS-2700 User Manual

Microchip Technology GPS-2700 User Manual

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GPS-2700
User's Guide
 2020 Microchip Technology Inc.
DS50003016A

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Summary of Contents for Microchip Technology GPS-2700

  • Page 1 GPS-2700 User’s Guide  2020 Microchip Technology Inc. DS50003016A...
  • Page 2 Technology, and Symmcom are registered trademarks of Microchip Technology Inc. in other countries. GestIC is a registered trademark of Microchip Technology Germany II GmbH & Co. KG, a subsidiary of Microchip Technology Inc., in other countries. All other trademarks mentioned herein are property of their respective companies.

  • Page 3: Preface

    Microchip's GPS-2700. The guidelines in the document are generic because spe- cific product requirements vary from one application to the other. This material consists of a brief description of GPS-2700 design supported by block diagrams, description of environmental issues, installation guidelines, and unit opera- tion.

  • Page 4: Conventions Used In This Guide

    Curly brackets and pipe Choice of mutually exclusive errorlevel {0|1} character: { | } arguments; an OR selection Ellipses... Replaces repeated text var_name [, var_name...] Represents code supplied by void main (void) user { ...  2020 Microchip Technology Inc. DS50003016A-page 4...

  • Page 5: Warnings, Cautions, Recommendations, And Notes

    Time Systems (FTS) Services and Support: U.S.A. Call Center: including Americas, Asia and Pacific Rim Frequency and Time Systems 3870 N 1st St. San Jose, CA 95134 Toll-free in North America: 1-888-367-7966 Telephone: 408-428-7907 Fax: 408-428-7998  2020 Microchip Technology Inc. DS50003016A-page 5...

  • Page 6: The Microchip Website

    Technical support is available through the website at: http://www.microchip.com/support. DOCUMENT REVISION HISTORY Revision A (July 2020) • Initial release of this document as Microchip DS5000xxxxA.  2020 Microchip Technology Inc. DS50003016A-page 6...

  • Page 7: Table Of Contents

    2.4.4 Connecting the GNSS Antenna..............19 2.4.5 Connecting an LCD Display ............... 19 2.4.5.1 LCD Key ..................21 2.4.5.2 LCD Display Pages ..............21 2.5 Loop Parameter Adjustment................25 2.6 Performance Graphs ..................26  2020 Microchip Technology Inc. DS50003016A-page 7...
  • Page 8 3.4 GYRO Subsystem ..................43 3.4.1 GYRO:MODE <ON | OFF> .................44 3.4.2 GYRO:TRA <int> [0,255] ................44 3.4.3 GYRO:PORT <RS232 | USB> ..............44 3.4.4 GYRO:PORT? ....................44 3.4.5 GYRO:CAL <float,float,float,float,float,float> ..........44 3.4.6 GYRO:CAL:COMP..................45 3.4.7 GYRO:CAL:RESET ..................45  2020 Microchip Technology Inc. DS50003016A-page 8...
  • Page 9 3.9 System Subsystem..................53 3.9.1 SYST:COMM:SER:ECHO <ON | OFF> ............. 53 3.9.2 SYST:COMM:SER:PRO <ON | OFF>............53 3.9.3 SYST:COMM:SER:BAUD <9600 | 19200 | 38400 | 57600 | 115200> ..53 3.9.4 SYST:FACT ONCE ..................53  2020 Microchip Technology Inc. DS50003016A-page 9...
  • Page 10 3.11.18 CSAC:POW <ON | OFF>................62 3.11.19 CSAC? ....................62 Chapter 4. Firmware Upgrade Instructions 4.1 Introduction....................63 4.2 ISP Flash Loader Utility Installation............... 63 4.3 Putting the PCB into In-Circuit Programming (ISP) Mode......63  2020 Microchip Technology Inc. DS50003016A-page 10...
  • Page 11 5.3.2 Sending Manual Commands to the Receiver ..........70 5.3.3 Using the Mouse in the Graph Window ............70 5.3.4 Exporting the Graphics ................71 5.4 Interpreting the Data..................72 Worldwide Sales and Service ..................77  2020 Microchip Technology Inc. DS50003016A-page 11...
  • Page 12 GPS-2700 User’s Guide NOTES:  2020 Microchip Technology Inc. DS50003016A-page 12...

  • Page 13: Chapter 1. Introduction

    The CSAC oscillator provides an impressive frequency accuracy, long-term stability, and fast lock with low power consumption. Through hardware and firmware support, the GPS-2700 improves the phase noise performance of the unit, and adds an isolated distribution amplifier with four output channels at 10 MHz. The GPS-2700 provides...

  • Page 14: General Safety Precautions

    CSAC. To calibrate these errors out and achieve phase-lock to USNO UTC, the GPS-2700 uses a GNSS receiver to generate a highly accurate, though unstable 1PPS signal, and this 1PPS signal is compared with a 1PPS signal generated by the CSAC 10 MHz VCXO.

  • Page 15: Chapter 2. Quick-Start Instructions

    Chapter 2. Quick-Start Instructions POWERING UP THE UNIT The GPS-2700 may be powered from an external 8V to 36V DC source, or simply from a standard USB port. Both power sources can be connected at the same time. The internal USB port provides a convenient way to supply power to the unit, as well as establish serial communications to the unit via a standard USB serial link.

  • Page 16: Major Connections

    Please note that the GNSS receiver establishes the internal antenna-gain right after power-on, so for proper operation the GNSS antenna should always be connected prior to turning on the power supply. MAJOR CONNECTIONS The major connections and features of the GPS-2700 PCB are shown in Figure 2-1. LCD Panel...

  • Page 17: Harness Pinning

    33Ω. 2.4.1 Harness Pinning Table 2-2 is a table of the cable harness J1 pinout. TABLE 2-2: J1 PINOUT Name ENTER_ISP# RST_IN# LCD_KEY LOCK_OK_OUT RX RS-232 TX RS-232 GPS_RS232 PPS_IN ALARM +28V +28V  2020 Microchip Technology Inc. DS50003016A-page 17...

  • Page 18: Harness Connectors J1 And J3

    2.4.3 Concurrent-GNSS Capabilities GPS-2700 with firmware revision 0.74 and later and uBlox 8 GNSS receiver is capable of simultaneously receiving up to three concurrent GNSS systems at one time. Firm- ware revision 0.74 and later also supports the GPS-2700 with uBlox 6 GPS receiver.

  • Page 19: Connecting The Gnss Antenna

    Caution: use a Lightning Arrestor on your Antenna setup. Use an amplified GNSS antenna that is 5V compatible. The GPS-2700 GNSS (GPS for uBlox 6) receiver is a 72 (50 for uBlox 6 receiver) channel high-sensitivity multi-GNSS receiver with very fast lock time.
  • Page 20 Name CONTRAST LCD_RS For factory use only LCD_RDWR For factory use only LCD_ENABLE For factory use only LCD_DATA4 For factory use only LCD_DATA5 For factory use only LCD_DATA6 For factory use only LCD_DATA7  2020 Microchip Technology Inc. DS50003016A-page 20...

  • Page 21: Lcd Key

    Following are the LCD display pages: • Time/Date: (Figure 2-4) This page shows the time, date, number of tracked Satel- lites, and the lock status (PH = Position Hold mode). FIGURE 2-4: Time/Date Display Page.  2020 Microchip Technology Inc. DS50003016A-page 21...
  • Page 22 NVRAM once every 24 hours, at which point the offset is set to "0" again. This allows the CSAC oscillator to power-on with the last internal offset stored in NVRAM, effectively storing the calibration parameter inside the CSAC oscillator once per day. FIGURE 2-7: CSAC Steering Display Page.  2020 Microchip Technology Inc. DS50003016A-page 22...
  • Page 23 10 MHz and 1PPS outputs of 4 picoseconds per second averaged over 1000 seconds as compared to the UTC master clock at NIST in Colorado. FIGURE 2-9: TINT Display Page.  2020 Microchip Technology Inc. DS50003016A-page 23...
  • Page 24 GPS/UTC Time Display Page. • Survey Status: (Figure 2-12) This page displays the status (NOT ACTIVE, ACTIVE or VALID), duration (seconds) and variance (mm ) of the position survey. FIGURE 2-12: Survey Status Display Page.  2020 Microchip Technology Inc. DS50003016A-page 24...

  • Page 25: Loop Parameter Adjustment

    Quick-Start Instructions LOOP PARAMETER ADJUSTMENT GPS-2700 with firmware revision 0.74 and later adds support for two different phase loop time constant settings for the CSAC to accommodate different mission scenarios (stationary versus mobile, steady state operation versus power cycling, etc.). These...

  • Page 26: Performance Graphs

    PERFORMANCE GRAPHS Figure 2-14 shows the typical Allan Deviation of the GPS-2700 unit when locked to GPS. ADEV performance approaches 1E-13 per day when locked to GPS. The plot shows that at averaging intervals of 1000 seconds and more the GPS disciplining algo- rithm starts to improve the performance of the CSAC oscillator.
  • Page 27 Allan Deviation of Free Running CSAC. As shown in Figure 2-16, the Phase Noise of the GPS-2700 unit with the Phase Noise filter disabled shows a higher baseline noise with a floor of about –145 dBc/Hz, and numerous spurs. FIGURE 2-16: Phase Noise of the GPS-2700 with the Phase Noise Filter Disabled.
  • Page 28 GPS-2700 User’s Guide Beginning in August 2012 and with BOM revision 2.1, the GPS-2700 board had a com- ponent change that improves the phase noise filter performance significantly, espe- cially below 2 kHz offsets from the carrier. Please see Figure 2-17 for a typical plot of the new phase noise performance of the unit.
  • Page 29 Quick-Start Instructions FIGURE 2-19: Alternate Comparative Phase Noise Plot.  2020 Microchip Technology Inc. DS50003016A-page 29...
  • Page 30 GPS-2700 User’s Guide NOTES:  2020 Microchip Technology Inc. DS50003016A-page 30...

  • Page 31: Chapter 3. Scpi-Control Quick Start Instructions

    Chapter 3. SCPI-Control Quick Start Instructions INTRODUCTION The GPS-2700 has two serial ports that can be used simultaneously for accessing the Standard Commands for Programmable Instrumentation (SCPI) subsystem by using a host system terminal program such as TeraTerm or Hyperterminal. By default the ter- minal settings are 115200, 8N1, no flow-control.

  • Page 32: Gps:sat:tra:coun

    3.3.3 NMEA Support The following commands allow the GPS-2700 to be used as an industry standard nav- igation GNSS receiver. The GGA, GSV, RMC, ZDA, and PASHR NMEA commands comprise all necessary information about the antenna position, height, velocity, direc- tion, satellite info, fix info, time, date and other information that can be used by standard navigation applications via the GPS-2700 RS-232 interface.

  • Page 33: Gps:port

    3.3.6 GPS:GPGGA <int> [0,255] GPS-2700 with firmware revision 0.75 and later and uBlox 8 GNSS receiver adds sup- port for switching the talker ID mode between GP and GN for GGA, Microchip GGA, RMC, and ZDA commands. See Section 3.3.32 for detailed operations and restrictions on talker ID mode.

  • Page 34: Gps:gprmc [0,255]

    GPS-2700 User’s Guide This command instructs the GPS-2700 to send a modified version of the NMEA stan- dard string $GPGGA every N seconds, with N in the interval [0,255]. The command is disabled during the initial 2 minute CSAC warm-up phase.

  • Page 35: Gps:pashr [0,255]

    SCPI-Control Quick Start Instructions GPS-2700 with firmware revision 0.74 and later and uBlox 8 GNSS receiver is capable of simultaneously receiving up to three concurrent GNSS systems and tracking up to 24 satellites at one time. When multiple GNSS systems are enabled in Section 3.3.31 and talker ID mode is configured to GN in Section 3.3.32, multiple GSV sentences with...

  • Page 36: Gps:xyzsp [0,255]

    3.3.13 GPS:GNGGA <int> [0,255] GPS-2700 with firmware revision 0.75 and later and uBlox 8 GNSS receiver adds sup- port for switching the talker ID mode between GP and GN for GGA, Microchip GGA, RMC, and ZDA commands. See Section 3.3.32 for detailed operations and restrictions on talker ID mode.

  • Page 37: Gps:gnrmc [0,255]

    3.3.15 GPS:GNRMC <int> [0,255] GPS-2700 with firmware revision 0.75 and later and uBlox 8 GNSS receiver adds sup- port for switching the talker ID mode between GP and GN for GGA, Microchip GGA, RMC, and ZDA commands. See Section 3.3.32 for detailed operations and restrictions on talker ID mode.

  • Page 38: Gps:dynam:mode [0,7]

    Automatic Mode velocity of the vehicle. The GPS-2700 uses a GNSS receiver that is capable of running in a stationary mode with Position Auto Survey called Position Hold Mode. This mode increases timing sta- bility by storing the position into memory, and solving the GNSS signal only for time as the position is not expected to change.

  • Page 39: Gps:dynam:mode 8 (Automatic Dynamic Mode)

    3.3.18 GPS:DYNAM:MODE 8 (Automatic Dynamic Mode) Automatic Dynamic Mode allows the GPS-2700 firmware to automatically configure the GNSS receiver Kalman filter parameters based on actual mission velocities and motion profiles. The unit will try to set the GNSS receiver to the optimal setting for any given velocity.

  • Page 40: Gps:ref:adel [-32767Ns,32767Ns]

    This command starts a Survey. At the end of the Survey, the calculated Hold position will be stored in NV memory. The Survey parameters can be set with the command GPS:SURV:DUR and GPS:SURV:VAR. 3.3.25 GPS:SURV:DUR <sec> This command sets the Survey minimal duration.  2020 Microchip Technology Inc. DS50003016A-page 40...

  • Page 41: Gps:surv:var

    3.3.31 GPS:SYST:SEL [GPS | SBAS | QZSS | GAL | BD | GLO] GPS-2700 with firmware revision 0.74 and later and uBlox 8 GNSS receiver is capable of simultaneously receiving up to three concurrent GNSS systems at one time. Firm- ware revision 0.74 and later also supports the GPS-2700 with uBlox 6 GPS receiver.

  • Page 42: Gps:nmea:talk

    GPS:SYST:SEL GPS SBAS GAL GLO The following command will query the currently enabled GNSS systems: GPS:SYST:SEL? The GPS-2700 with uBlox 8 receiver will respond to the query with the list of enabled GNSS systems such as: GPS SBAS GAL GLO GPS-2700 with firmware revision 0.75 and later and uBlox 8 GNSS receiver adds sup-...

  • Page 43: Gps:nmea:svn

    3.3.33 GPS:NMEA:SVN <GP | GN> GPS-2700 with firmware revision 0.75 and later and uBlox 8 GNSS receiver adds sup- port for switching the talker ID mode to GP for GSV command where only $GPGSV (i.e., no $GLGSV, $GAGSV, or $GBGSV) string will be outputted for GPS, SBAS, and QZSS.

  • Page 44: Gyro:mode

    By default, the unit is shipped with a normalized output of 0 Degrees Offset, and a gain of 1.0, and the user will need to calibrate their unit in their system. This command has the following format: GYRO:CAL <float>, <float>, <float>, <float>, <float>, <float>  2020 Microchip Technology Inc. DS50003016A-page 44...

  • Page 45: Gyro:cal:comp

    Used for factory calibration of Gyro subsystem. 3.4.8 GYRO:SENS <float,float,float> Used for factory calibration of Gyro subsystem. 3.4.9 GYRO:GLOAD? This command will return the present acceleration on the X, Y, and Z axis.  2020 Microchip Technology Inc. DS50003016A-page 45...
  • Page 46 SYNC:SOUR:MODE EXT command. This allows time-synchronization at the nanosecond level between two units which can be useful when operating in GPS denied environments. The following command returns the PTIME output setting stored in NV memory:  2020 Microchip Technology Inc. DS50003016A-page 46...
  • Page 47 The returned value is 59, 60 or 61 if GPS Almanac data is available, and 0 oth- erwise. A response of 60 indicates that no leap second is pending. 3.5.11 PTIM? This query returns at once the result of the five following queries: PTIM:DATE? PTIM:TIME? PTIM:TINT? PTIM:OUT? PTIM:LEAP:ACC?  2020 Microchip Technology Inc. DS50003016A-page 47...
  • Page 48 GPS-2700 User’s Guide SYNCHRONIZATION SUBSYSTEM This subsystem regroups the commands related to the synchronization of the GPS-2700 with the GNSS receiver. The list of the commands supported for this sub- system is the following: SYNC:HOLD:DUR? SYNC:HOLD:STAT? SYNC:HOLD:INIT SYNC:HOLD:REC:INIT SYNC:SOUR:MODE <GPS | EXT | AUTO>...
  • Page 49 The command allows an optional external 3.3V CMOS, 5V CMOS or TTL level 1PPS input to be connected to the GPS-2700 board on connector harness J1. The unit can use this external 1PPS input instead of the internal, GPS generated 1PPS. Switching...
  • Page 50 3.6.13 SYNC:OUT:1PPS:WIDTH <int> <ms | μs > [200μs,600ms] GPS-2700 with Firmware revision 0.75 and later adds support for changing the pulse width of CSAC 1PPS output signal. By default the unit generate an asynchronous or UTC-aligned 1PPS pulse with pulse width of 600 ms. With the command SYNC:OUT:1PPS:WIDTH 200 ms the unit can now configure the 1PPS pulse width to 200 ms or any integer value between 200 μs and 600 ms.
  • Page 51 SYNC:HOLD:DUR? SYNC:FEE? SYNC:TINT? SYNC:TINT:THR? SYNC:OUT:FILT? SYNC:HEA? DIAG SUBSYSTEM This subsystem regroups the queries related to the diagnostic of the GPS-2700.The list of the commands supported for this subsystem is the following: DIAG:ROSC:EFC:REL? DIAG:ROSC:EFC:ABS? DIAG:LIF:COUN? 3.7.1 DIAG:ROSC:EFC:REL? This query returns the Electronic Frequency Control (EFC) output value of the internal reference oscillator.
  • Page 52 EFControl Absolute: 5 Lifetime: +871 MEASURE SUBSYSTEM The MEASURE subsystem regroups the queries related to parameters that are mea- sured on-board on the GPS-2700. The list of the commands supported for this subsys- tem is the following: MEAS:TEMP? MEAS:VOLT? MEAS:CURR? MEAS:POW? 3.8.1...

  • Page 53: Syst:id:sn

    3.9.5 SYST:ID:SN? This query returns the serial number of the board. 3.9.6 SYST:ID:HW? This query return the Hardware version of the board. 3.9.7 SYST:LCD:CONT [0,1.0] This command sets the contrast of the LCD.  2020 Microchip Technology Inc. DS50003016A-page 53...

  • Page 54: Syst:lcd:cont

    SERV:DACG <float> [0.001, 10000] SERV:EFCS <float> [0.0, 500.0] SERV:EFCD <int> [2, 4000] SERV:TEMPCO <float> [-4000.0, 4000.0] SERV:AGING <float> [-10.0, 10.0] SERV:PHASECO <float> [-500.0, 500.0] SERV:1PPS <int> ns [-5000000, 5000000] SERV:TRAC:PORT <RS232 | USB>  2020 Microchip Technology Inc. DS50003016A-page 54...

  • Page 55: Serv:loop

    3.10.2 SERV:MODE <OFF | NORM | FAST | AUTO> GPS-2700 with firmware revision 0.74 and later adds support for two different phase loop time constant settings. This command allows auto-setting of all of the servo loop time constants to factory-default values as described in Section 2.5 with one single command entry.

  • Page 56: Serv:efcs [0.0, 500.0]

    3.10.5 SERV:EFCS <float> [0.0, 500.0] GPS-2700 with firmware revision 0.74 and later adds support for two different phase loop time constant settings. See Section 2.5 “Loop Parameter Adjustment” for details of recommended loop time constant settings. Changing this parameter while response of SERV:STAT? command is FAST will NOT change current operation of the servo loop.

  • Page 57: Serv:aging [-10.0, 10.0]

    SERV:PHASECO? 3.10.10 SERV:1PPS <int> ns [-5000000, 5000000] This command sets the GPS-2700 1PPS signal’s offset to UTC in 100 ns steps. Using the SERV:1PPS command results in immediate phase change of the 1PPS out- put signal. This command has the following format: SERV:1PPS <int>...

  • Page 58: Serv:efcs:fast [0.0, 500.0]

    Locked and GPS active 3.10.13 SERV:EFCS:FAST <float> [0.0, 500.0] GPS-2700 with firmware revision 0.74 and later adds support for two different phase loop time constant settings. See Section 2.5 for details of recommended loop time con- stant settings. Changing this parameter while response of SERV:STAT? command is NORMAL will NOT change current operation of the servo loop.

  • Page 59: Serv:phaseco:fast [-500.0, 500.0]

    SCPI-Control Quick Start Instructions 3.10.15 SERV:PHASECO:FAST <float> [-500.0, 500.0] GPS-2700 with firmware revision 0.74 and later adds support for two different phase loop time constant settings. See Section 2.5 for details of recommended loop time con- stant settings. Changing this parameter while response of SERV:STAT? command is NORMAL will NOT change current operation of the servo loop.

  • Page 60: Csac:rs232

    0x0020 DC Light level High 0x0040 Heater Power Low 0x0080 Heater Power High 0x0100 μW Power control Low 0x0200 μW Power control High 0x0400 TCXO control voltage Low 0x0800 TCXO control voltage High  2020 Microchip Technology Inc. DS50003016A-page 60...

  • Page 61: Csac:mode

    3.11.13 CSAC:SN? This query returns the Serial Number of the CSAC in the form YYMMCSNNNNN where YYMM is the year and month of production and NNNNN is the serialized unit of that month.  2020 Microchip Technology Inc. DS50003016A-page 61...

  • Page 62: 3.11.14 Csac:life

    This query returns the accumulated number of hours that the CSAC has been powered on since the last factory reset of the GPS-2700 board. The value is stored in the exter- nal NV memory and updated every hour when the CSAC is powered on.
  • Page 63 SCPI-Control Quick Start Instructions CSAC:FW? CSAC:LIFE? CSAC:POW?  2020 Microchip Technology Inc. DS50003016A-page 63...
  • Page 64 GPS-2700 User’s Guide  2020 Microchip Technology Inc. DS50003016A-page 64...

  • Page 65: Chapter 4. Firmware Upgrade Instructions

    ISP FLASH LOADER UTILITY INSTALLATION Microchip Technology Inc. recommends using the Flash Magic utility to upgrade the contents of Flash memory on the GPS-2700. It is available for download on the Flash Magic website: http://www.flashmagictool.com/ Follow the directions given on the website for installing the utility on your computer.

  • Page 66: Downloading The Firmware

    RS-232 serial port prior to firmware download. Connect a DB-9 serial connector to the GPS-2700 as indicated in Section 2.4. Please note that the unit can only be upgraded through the RS-232 port, not through the USB serial port.

  • Page 67: Verifying Firmware Update

    During power on, the unit sends an ID string out of the serial port at 115200 Baud by default. The firmware version can also be queried by sending the *IDN? command. Verify that the firmware version is the version that was downloaded.  2020 Microchip Technology Inc. DS50003016A-page 67...
  • Page 68 GPS-2700 User’s Guide NOTES:  2020 Microchip Technology Inc. DS50003016A-page 68...

  • Page 69: Chapter 5. Gpscon Utility

    Chapter 5. GPSCon Utility DESCRIPTION GPSCon is a program for the monitoring and control of GPS-2700. It communicates with the receiver using the SCPI command set. This free version of the GPSCon utility is available for download from the support section of the GPS-2700 product webpage.

  • Page 70: Communication Parameters

    5. Any of the eight traces can be replaced by auxiliary traces as described in Section 5.3.1.2 “Auxiliary Parameters”. Press the “Help” button for a full description of each option in the Traces tab. FIGURE 5-2: Setting the Communications Parameters.  2020 Microchip Technology Inc. DS50003016A-page 70...

  • Page 71: Sending Manual Commands To The Receiver

    GPS-2700. Once you’ve selected the command you can press “Send” to send it to the GPS-2700. You can also send common commands by clicking on the buttons below the message window.

  • Page 72: Using The Mouse In The Graph Window

    When you have locked the start and stop time using the mouse, you can scroll left or right through the data. To scroll to a later time, use Shift + Left click. To scroll to an earlier time, use Shift + Right click.  2020 Microchip Technology Inc. DS50003016A-page 72...

  • Page 73: Exporting The Graphics

    If you export the graph, you have the option to export only that which is currently visible, or to export the graph which is a plot of the entire logfile contents. Use the checkbox "Export All Graph Data" to make this choice.  2020 Microchip Technology Inc. DS50003016A-page 73...

  • Page 74: Interpreting The Data

    INTERPRETING THE DATA Figure 5-8 shows the data acquired by the GPS-2700 unit over a period of more than 200 hours. The red trace is EFC (CSAC frequency steering value). The crystal is aging (becoming faster in frequency over time). This requires the steering value to be increased to maintain precisely 10.0 MHz.
  • Page 75 The unit disciplines its internal 10 MHz reference to within less than ±9 ns peak to peak of UTC at all times, which is less than one complete clock cycle at 10 MHz.  2020 Microchip Technology Inc. DS50003016A-page 75...
  • Page 76 GPS-2700 User’s Guide NOTES:  2020 Microchip Technology Inc. DS50003016A-page 76...

  • Page 77: Worldwide Sales And Service

    New York, NY Tel: 46-31-704-60-40 Tel: 631-435-6000 Sweden - Stockholm San Jose, CA Tel: 46-8-5090-4654 Tel: 408-735-9110 UK - Wokingham Tel: 408-436-4270 Tel: 44-118-921-5800 Canada - Toronto Fax: 44-118-921-5820 Tel: 905-695-1980 Fax: 905-695-2078  2020 Microchip Technology Inc. DS50003016A-page 77 05/14/19...

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