Megger MGTR User Manual
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Megger MGTR User Manual

Megger MGTR User Manual

Gps timing reference
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User
Manual
Model MGTR
Megger GPS Timing
Reference
™
Part Number 710015
Rev 2 Date 10/28/04

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  • Page 1 User Manual Model MGTR ™ Megger GPS Timing Reference Part Number 710015 Rev 2 Date 10/28/04...
  • Page 2 The content of this manual is furnished for informational use only and is subject to change without notice. Megger assumes no responsibility or liability for any errors or inaccuracies that may appear in this manual.
  • Page 3 Damage due to incorrect powering of the MGTR is not covered by the warranty. Refer to Section 7 of this manual for complete information.

  • Page 4: Table Of Contents

    TABLE OF CONTENTS Section 1 - Introduction ..................1 ......................1 ANUAL (GPS) ..................1 LOBAL OSITIONING YSTEM MGTR.......................2 NTRODUCTION Section 2 - Unpacking And Installation............... 5 ..........................5 ACKING .........................5 NTENNA NSTALLATION MGPS I ........................5 NSTALLATION ..................6 ONNECTION ERSONAL OMPUTER ..........................6 OWER NPUT Section 3 - Quick Start Instructions ..............
  • Page 5 Section 7 - Hardware Information...............39 ..........................39 RONT ANEL ...................40 OMBINATIONS HEIR EANINGS ................40 ANEL ONNECTORS UNCTIONS ...................43 THER ARDWARE ONSIDERATIONS Section 8 - In Case Of Difficulty................45 .........................45 ONTACTING EGGER ........................45 IMITED ARRANTY ...................46 ETURNING QUIPMENT EPAIR Appendix A - Specifications................47...

  • Page 6: Section 1 - Introduction

    If you are not familiar with GPS timing instruments, you should read this manual carefully before attempting to install or operate the MGTR. Pay particular attention to Section 2 for unpacking and installation instructions, Section 4 for operating modes and functions, Sections 5 & 6 for operating instructions, and Section 7 for hardware information.

  • Page 7: Introduction T O The Mgtr

    MGTR NTRODUCTION The MGTR is a complete GPS time & frequency system offering the following features and performance: • State-of-the-art 12 channel GPS technology. • Exclusive FastStart™ technology offers high accuracy within just minutes of start-up.
  • Page 8 LED status indicators to indicate power, tuning status and alarm status. Control and operation of the MGTR is handled through the Serial Control Port. Consisting of a standard RS-232 serial channel, this accommodates a wide variety of host computers and equipment, including any personal computer or compatible with a serial communications port.
  • Page 9 This is a significant improvement over the typical hour or longer of tuning normally required by previous and competing products. The MGTR comes with control/display software and this user’s manual. Accessories include GPS antenna, antenna mount and cable, an AC power adaptor, and a power/interface adapter cable (Control Cable).

  • Page 10: Section 2 - Unpacking And Installation

    Before attempting to install an antenna, give careful consideration to its location and placement, as this can affect the overall performance of the MGTR. The primary goal is to locate the antenna in a place where it has a clear view of the sky. A secondary goal is to locate the antenna away from radio transmitters or other sources of noise that could possibly interfere with reception of the satellite signals.

  • Page 11: Connection T O A Personal Computer

    AC/DC power supply. See the pin-out table on page 7 for the input pin connection. You may supply power to the MGTR™ from any source that can supply a clean DC voltage in the range of 9 to 35 VDC at 1 ampere.
  • Page 12 AC Adaptor Control Data Cable Assembly The simplest way to supply power to the MGTR is by use of an AC adaptor and the power Control Cable assembly. The adaptor plugs into any standard AC outlet and provides a suitable DC voltage source for the unit.

  • Page 13: Section 3 - Quick Start Instructions

    POWER ALARM 6. Start the software. If the MGTR has been connected to a port other than COM1 on the computer, you will need to change the communications port setting using the Set Communications Options screen available from either the menu or the toolbar.
  • Page 14 GPS remains available) to its maximum accuracy of better than 1 x 10 Now that you have the MGTR up and running, you should read the remainder of this manual to familiarize yourself with the various features, operating modes, and functions that have been designed into the unit.

  • Page 15: Section 4 - Operating Modes And Functions

    The entire cold start process will typically take approximately 3 minutes but can take longer. Fortunately, you should rarely encounter the need for a cold start. The MGTR is shipped with a current almanac in memory. In addition, the receiver retains the almanac and updates time and date for up to 30 days when not powered, so it should usually have time, date and almanac available.

  • Page 16: Oscillator Modes

    When operating in the Static Timing Mode, the MGTR uses a fixed position as the reference for deriving time. In this case, the position may be user entered or previously derived from GPS.

  • Page 17: Mask Angle

    Time Valid condition has again been achieved. While in Coast Mode, the time and frequency outputs from the MGTR degrade very slowly for two reasons. One is that the GPS receiver continues to supply precise time from its internal tracking loops using the loop parameters in effect when timing information was lost.

  • Page 18: Map Datums

    Map datums are coordinate transformations that allow the user to transform the position outputs of the MGTR into a coordinate system used by a particular chart or map so that positions can be plotted with accuracy. There are literally hundreds of different map datums in use around the world as different geographical areas have adopted different earth models for the purpose of creating maps.

  • Page 19: Event Time -Tag (Ett )

    Event times are passed on to the host computer over the control channel as quickly as possible. Since events may occur closely spaced in time, and in bursts, the MGTR buffers up to 23 event times in its memory, and passes them on to the host computer by unloading the buffer as quickly as possible.

  • Page 20: Hardware Fault Monitoring

    However, the user must take into consideration that the accuracy of this signal is not reliable until the unit has reached the Time Valid condition. Until the MGTR reaches this state, the GPS receiver is relying upon its own internal references to generate PPS, rather than using time information derived from the GPS satellites.
  • Page 21 In the MGTR, the variable called GQ is a relative measure of geometric quality on a 0 to 9 scale with 9 representing the best geometry. This relates to PDOP or HDOP as shown in the following...
  • Page 22 In the case of a GPS timing receiver, a specification of absolute accuracy must account for any bias in the measurements. The MGTR has an absolute accuracy of ±50 ns with respect to UTC (SA off). This means that if you could measure the error of the 1 PPS output with respect to the UTC second, an average of a number of such measurements would yield a result within 50 ns of UTC.
  • Page 23 Correction For Antenna Cable Length Since not all users will use the same length of antenna cable, the PPS output from the MGTR is not calibrated for any specific value. In cases where absolute in-time accuracy of PPS is required, the user must calculate the specific User Time Bias for his antenna cable length.

  • Page 24: Operating Suggestions

    The useable power-off backup time of the battery is about 30 days. The MGTR can be operated right out of the box without connecting it to a host computer. In this case, it will execute the cold start sequence and will operate with the factory default settings for options and configuration.

  • Page 25: Master Reset

    The Master Reset function, which is initiated by Message #08 (see Section 6), provides a complete reset of certain memory content in the MGTR. If you are using the Control/Display software, the Master Reset function is available in the Command Menu on the Receiver Status screen (see Section 5).

  • Page 26: Section 5 - Operation Of The Mgps

    16-bit color. The minimally acceptable platform is a 100 MHz Pentium-based computer. The software is supplied on a CD. The MGTR connects to a standard serial port on the PC, and the baud rate for communication is fixed at 9600. In the event that your computer does not have a serial port, but has USB ports only, then a USB to Serial interface adapter will be needed.

  • Page 27: Main Screen

    CREEN Almost all of the information pertinent to the operation, status and control of the MGTR are on the main screen. You can navigate to sub screens using either the menu functions, the toolbar at the bottom, or in the case of fields where the mouse pointer changes from an arrow to a hand, by clicking on those.
  • Page 28 C/No (dB-Hz) >45 <37 EPH - A lit indicator in this field indicates that the GPS receiver has a valid ephemeris for this satellite. NAV - An illuminated indicator in this field indicates that the GPS receiver is using this satellite in its navigation solution.

  • Page 29: Time And Date Panel

    Geometric Quality 0-9: GQ is an indication of the relative geometric quality of the satellite constellation currently being utilized and is represented with a 0-9 scale. A value of nine indicates the best geometric quality and low PDOP (Position Dilution of Precision). GQs of 7-9 allow good accuracy with PDOPs of 1-5.

  • Page 30: Timing Status Panel

    Time Valid Off: Time is not yet valid, or has become invalid. Blue: The MGTR has obtained valid time information from GPS, and the following functions (if incorporated) have been enabled: 1PPS output, ASCII serial time message, Programmed Output Pulse, Event Time Tag, and multiplexed frequency synthesizer outputs.

  • Page 31: Operational Session

    The MGTR is now searching for satellites. As the unit finds and tracks satellites, SQ numbers will be displayed. When enough satellites have been found and their ephemeris data collected, the...

  • Page 32: Setting Options

    Log to File option on the ETT sub screen, and choose a filename if necessary. This filename must conform to the standard MS-DOS 8.3 format. Long filenames are not supported. The file will be located in the same folder the application has been installed to (usually C:\MEGGER). Page 27...

  • Page 33: Programmed Output Pulse Operation

    Note: there is another operation mode that disables message broadcast, and sets the unit to only output ETT and acknowledge messages. This is recommended for advanced users only. See the section on message #12 (page 32) for details. Programmed Output Pulse Operation To use the Programmed Output Pulse feature (POP), perform the following steps: 1.

  • Page 34: Section 6 - Communicating With The Mgps

    • One stop bit Messages from the MGTR to the host appear on pin 3 of the HD 15-pin D-sub connector. Messages to the MGTR from the host must be applied to pin 4 of the HD 15-pin D-sub connector. OMMUNICATION...

  • Page 35: Messages From The Host

    Exercise caution and care when sending messages to the MGTR. It is possible to send an illegal or ill-formed message and still receive message #50. Behavior is not always consistent with an illegal message. Usually, the unit will ignore a bad message and not change corresponding modes or outgoing messages, but the POP output messages are an exception.
  • Page 36 MESSAGE #07 - SET TIMING MODE #07,XCRLF where: X = 0 for dynamic timing mode X = 1 for static timing mode X = 3 for Auto Survey mode MESSAGE #08 - MASTER RESET #08,1CRLF MESSAGE #09 - SET MULTIPLEXER #1 OUTPUT #09,XCRLF where: X = 0 for 10 MHz output X = 1 for 5 MHz output...
  • Page 37 MESSAGE #13 – REQUEST MESSAGE OUTPUT #13,XXCRLF where: XX = Two-digit message number for the desired message. This message is only enabled when the MGTR is set to polling NOTE: mode. MESSAGE #14 - SET MULTIPLEXER #2 OUTPUT #14,XCRLF where: X = 0 for 10 MHz output...
  • Page 38 MESSAGE #20 – Reserved MESSAGE #21 – SET POP PARAMETERS #21,X,P,MMDDYYYY,HHMMSS.SSSSSSS,RRRRRRRR,WCRLF where X selects the mode: X = 0 POP Off X = 1 for POP One-Shot X = 2 for POP Repeat where P selects the polarity: P = + for positive P = - for negative where: MMDDYYYY is the POP date (UTC) HHMMSS.SSSSSSS is the POP time (UTC)

  • Page 39: Messages From The Mgps

    MESSAGES FROM THE MGTR The following messages have been defined for transfer of information from the MGTR to a host computer: MESSAGE #50 - ACKNOWLEDGE #50,1CRLF MESSAGE #51 - DATE AND TIME #51,MMDDYYYY,HHMMSSCRLF where: MMDDYYYY is UTC month, day, and year...
  • Page 40 MESSAGE #56 - USER TIME BIAS #56,SXXXXXCRLF where: S = sign (+ or -) X = bias value (5 digits) MESSAGE #57 - TIMING MODE #57,XCRLF where: X = 0 for dynamic timing mode X = 1 for static timing mode X = 3 for Auto Survey mode MESSAGE #59 - GQ AND ALMANAC STATUS #59,X,YCRLF...
  • Page 41 HHMMSS.SSSSSSS = UTC time of event MESSAGE #63 - POP/ETT STATUS This message is obsolete and has been replaced by Message #74. NOTE: It is valid only for MGTR units that do not support simultaneous POP/ETT. #63,X,P,MMDDYYYY,HHMMSS.SSSSSSS,RRRRRRRRCRLF where X indicates the POP/ETT mode:...
  • Page 42 Z = 0 indicates no 10 MHz frequency output fault condition Z = 1 indicates 10 MHz frequency output fault condition MESSAGE #66 – HARDWARE INFORMATION STRING This message is reserved for Megger’s internal use, and is not described. MESSAGE #68 – MULTIPLEXER #2 STATUS #68,XCRLF...
  • Page 43 Z = receiver status: 2 = search the sky 3 = almanac collect 4 = ephemeris collect 5 = acquisition 6 = position VV,W,X,Y repeats twelve times, corresponding to each of the NOTE: twelve channels. MESSAGE #70 – Reserved MESSAGE #71 – Reserved MESSAGE #72 –...

  • Page 44: Section 7 - Hardware Information

    Subsequently, this LED may flash or illuminate steadily depending upon GPS condition and the mode the MGTR was in prior to a change in conditions. If the unit was in coarse or fine tuning (Modes 2 or 4, respectively) mode and GPS is lost, this LED will flash. There is also a defined condition called Coast Alarm, in which the MGTR has achieved Mode 4 but has lost GPS and has been in the fine tuning hold mode (Mode 5) for longer than 60 minutes.

  • Page 45: Led Combinations And Their Meanings

    MUXOUT1A or some other custom output in lieu of the 1 PPS signal. The PPS signal is supplied as soon as the MGTR finishes its initialization tasks, but is not locked to GPS until the unit achieves the Time Valid condition.
  • Page 46 CPTXD232, CPRXD232: These are the serial communication lines for control of the unit via a host computer and for receiving status messages from the MGTR. This interface is standard RS-232C. CPTXD232 is the transmit line for sending commands to the MGTR and CPRDX232 is the input line for receiving data from the unit.
  • Page 47 Time Valid condition. DC IN: Power to the MGTR may be supplied by the AC/DC adaptor or from an external DC source. In the later case, the source must be a stable and clean source of DC in the range of 9 to 35 VDC over a load current range of 200mA to 1A.

  • Page 48: Onsiderations H C

    New Zealand, and Continental Europe electric sockets. Antenna Power The optional antenna for the MGTR requires approximately 15 mA of current at an input voltage of 5.0 VDC. The unit supplies this voltage on the center pin of the antenna connector from a current- limited source.
  • Page 49 It is this retention of critical data and time that allows the MGTR to have a very short time to first fix and high precision under normal conditions, after the unit has been operated and allowed to achieve Mode 4 (fine-tuning) status at least once.

  • Page 50: Section 8 - In Case Of Difficulty

    This product is warranted to be free from defects in material and workmanship for a period of two years from date of shipment. During the warranty period, Megger will, at its option, either repair or replace products which prove to be defective. The repaired or replaced product will be warranted for a period of 90 days from the date of return shipment, or for the balance of the original warranty, whichever is longer.

  • Page 51: Returning Equipment For Repair

    LIMITATIONS & DISCLAIMER The remedies provided by this warranty are the buyer’s sole and exclusive remedies. Megger shall not be liable for any direct, indirect, special, incidental, or consequential damages resulting from the buyer’s use of this product or software supplied by Megger.

  • Page 52: Appendix A - Specifications

    Appendix A - Specifications PHYSICAL (MGTR) 1.50 in. (38.1mm) HEIGHT: 4.125 in. (104.8 mm) WIDTH: 4.00 in. (101.6 mm) DEPTH: 1.0 lbs. (.453 kg) WEIGHT: PHYSICAL (ANTENNA) 5.0 in. (126.6 mm) HEIGHT: 3.54 in. (90.0 mm) DIAMETER: 0.66 lbs. (0.30 kg) WEIGHT: MOUNTING: Flush mount.
  • Page 53 PERFORMANCE (FREQUENCY) GPS-CORRECTED 10 MHz SINE WAVE FREQUENCY OUTPUT: Conditions: Time Valid. Long-term Stability (while tracking): 1x10 - after 24 hours of tracking (∆t=24 hours) Short-term Stability: 1x10 - (∆t=1 second) Accuracy (while coasting): <5x10 - per day after 3 days of locked operation. Phase Noise, 1 Hz Bandwidth: 1 Hz: <-85 dBc 10 Hz: <-115 dBc...
  • Page 54 CONTROL AND AUXILIARY I/O, contd.: ANTENNA INPUT: CONNECTOR: TNC DC POWER INPUT: CONNECTOR: Pin 11 of DB-15HD CAUTION: NEVER APPLY INPUT POWER TO OTHER PINS ON THE DB-15 CONNECTOR! POWER INPUT SUPPLY VOLTAGE: 9 to 35 VDC WARM-UP CURRENT: 270 mA @ 24 VDC typical OPERATING CURRENT: 135 mA @ 24 VDC typical Page 49...

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