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TrueTime IRIG NTS-100 Manual

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Network Time Server
IRIG NTS-100
600-201
SERIAL NUMBER_______________
Revision A
January 20, 1997

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Summary of Contents for TrueTime IRIG NTS-100

  • Page 1 Network Time Server IRIG NTS-100 600-201 SERIAL NUMBER_______________ Revision A January 20, 1997...
  • Page 2 NTS-100 Network Settings Record NTS-100 network settings below for quick reference. NTS-100 network setup instructions are detailed in Section 3. Ethernet Address: ____________________________________ IP Address: ____________________________________ Subnet Mask: ____________________________________ Default Gateway: ____________________________________ Network Type: ____________________________________ Clock Type: ____________________________________...

  • Page 3: Table Of Contents

    SECTION I GENERAL INFORMATION 1.1 INTRODUCTION 1.2 LIMITED WARRANTY 1.3 LIMITATION OF LIABILITY 1.4 PROPRIETARY NOTICE 1.5 PHYSICAL SPECIFICATIONS 1.6 ENVIRONMENTAL SPECIFICATIONS 1.7 POWER INPUT SPECIFICATIONS 1.8 NTS-100 SYNCHRONIZATION OPTIONS 1.9 INTERNAL TIMING PERFORMANCE SPECIFICATIONS 1.10 NETWORK TIME PROTOCOLS 1.11 NETWORK TIME PROTOCOL SYNCHRONIZATION SPECIFICATIONS 1.12 INTERFACE SPECIFICATIONS Ethernet Interface User RS-232 Serial I/O Interface...
  • Page 4 3.40 FUNCTION 67 - LEAP SECOND INFORMATION 3-27 SECTION IV NOT USED SECTION V IRIG B SYNCHRONIZATION OPTION 5.1 IRIG B SETUP AND OPERATION SECTION VI MD5 AUTHENTICATION PROTOCOL 6.1 MD5 INTRODUCTION 6.2 TRUETIME NTP MD5 OPERATION 6.3 KEYPAD MD5 CONFIGURATION 6.4 SERIAL MD5 KEY CONFIGURATION...
  • Page 5 SECTION VII SIMPLE NETWORK MANAGEMENT PROTOCOL 7.1 SNMP INTRODUCTION 7.2 SNMP CONFIGURATION 7.3 NTP PARAMETERS 7.4 SNMP TRUETIME ENTERPRISE MIB VARIABLE DEFINITIONS The Enterprise TrueTime's Enterprise MIB Groups in TrueTime Enterprise MIB: Display Strings 7.5 THE TRAPMSG GROUP trapMsgNtpAlarm OBJECT-TYPE trapMsgSnmpAuthFail OBJECT-TYPE 7.6 THE NTP GROUP...
  • Page 6 actsFailedInit OBJECT-TYPE 7-16 actsNoDialTone OBJECT-TYPE 7-16 actsNoCarrier OBJECT-TYPE 7-17 actsBusyLine OBJECT-TYPE 7-17 actsNoAnswer OBJECT-TYPE 7-17 actsBadReply OBJECT-TYPE 7-17 actsNoOnTimeMark OBJECT-TYPE 7-17 APPENDIX A NTP v 3.0 DATA FORMAT per RFC1305 A-1 NTP DATA PACKET A-2 SNTP V 3.0 DATA FORMAT PER RFC1361 APPENDIX B TIME PROTOCOL per RFC868 B-1 INTRODUCTION...

  • Page 7: Section I

    There is no charge for on-site warranty repair labor. 1.2.3 Products not manufactured by TrueTime but included as integral part of a system (e.g. peripherals, options) are warranted for 90 days, or longer as provided by the original equipment manufacturer, from date of shipment.

  • Page 8: Limitation Of Liability

    1.2.5 By purchasing any product manufactured by TrueTime, the buyer consents to and agrees with TrueTime that as a result of the exclusion of all warranties, expressed or implied, of merchantability, fitness for purpose, or otherwise, except for the limited...

  • Page 9: Internal Timing Performance Specifications

    Frequency: 47-440 Hz Power Consumption: <15W NTS-100 SYNCHRONIZATION OPTIONS 1.8.1 The NTS-100 can be factory configured to synchronize to four different types of input signals: • User supplied, on-time 1PPS with operator input of date and time at the next second and any leap second information •...

  • Page 10: Network Time Protocol Synchronization Specifications

    1.11.1 The NTS-100 hardware is designed specifically to implement the NTP server function. As such it was carefully designed to operate with the TrueTime Mark III real time operating system to minimize the unknown latencies in timestamping the received and transmitted NTP packets.

  • Page 11: Interface Specifications

    1.12 INTERFACE SPECIFICATIONS Ethernet Interface Frame Format: DIX Ethernet (Ethernet II) or IEEE 802.3 with 802.2 headers Connector: AUI, female 15-pin D subminiature Pin Assignment Assignment +12V User RS-232 Serial I/O Interface Data: Time, day of year through milliseconds, in ASCII characters, output once per second or on request.

  • Page 12: Led Status Indicator

    Pin Assignment Assignment RXUSER TXUSER LED Status Indicator 1.12.1 A front panel mounted, bi-color LED which reflects the status of the NTS-100: Solid Red: Alarm State, no synchronization Solid Orange: Alarm State, synchronization present, not fully locked Blinking Green: Fully Operational State 1.12.2 The Solid Red and Solid Orange conditions correspond with the Open Collector Alarm Output high impedance, or Alarm state.

  • Page 13: Alarm Output

    Alarm Output 1.12.4 The purpose of the alarm output is to provide an indication of an out of service condition caused by initial power up, extended period without synchronization input, or hardware failure. This output is asserted whenever the Leap Indicator bits of the NTP packet sent by the NTS-100 are set to 3, the alarm condition.
  • Page 14 1/20/97 front panel display. The LED status indicator will illuminate RED or ORANGE during this time and the Open Collector Alarm Output will be in a high impedance state. It may take several minutes for LOCK to occur, depending upon the synchronization input option. When the synchronization option is GPS, allow at least five minutes for the NTS-100 to acquire lock.

  • Page 15: Operation

    Synchronization Option specific operation details are contained in Section 5. NETWORK INTERFACE 3.3.1 TrueTime’s NTS-100 module supports RFC-868, RFC-1119, RFC-1305 and RFC-1361. An NTP or SNTP client daemon compatible with the user’s computer platform is required for accurate network synchronization. The daemon must be told the NTS-100 IP address.

  • Page 16: General Operation

    At power up, the unit will present messages on the small front panel display to indicate the version of software installed in the unit, and how to invoke the keypad help function. The first message is the version of the system software. For example: TRUETIME NTS sys ver 014 3.6.2...

  • Page 17: Front Panel Interface

    1/20/97 FRONT PANEL INTERFACE 3.7.1 The NTS-100 front panel is the primary user interface. Input is via three front panel push-buttons and a 16-key keypad. Output is via the two-line 32-character alphanumeric LCD. The alphanumeric display shows status and various function displays. ALPHANUMERIC DISPLAY 3.8.1 The alphanumeric display is used both to display current clock status and as a means of...

  • Page 18: Selecting Functions And Entering Data

    1/20/97 • To enter a specific function, first press FUNC/ENTR then the function number. Be sure to include the leading zeros for function numbers lower than ten. If the function number is currently unassigned or not implemented the alphanumeric display will show the "Function not implemented"...

  • Page 19: Function 01 - Time Zone Select

    1/20/97 3.15.4 Press any key to see the next display, the first entry in the keypad function description list: F01: Sets time zone 3.15.5 Now, the list of available keypad functions can be viewed by pressing the up or down arrow keys.

  • Page 20: Function 02 - 12/24 Hour Format Select

    1/20/97 3.17 FUNCTION 02 - 12/24 HOUR FORMAT SELECT 3.17.1 Use function 02 to select either the 12-hr or 24-hr time display format. Upon initial out- of-the-box power-up the default is the 24-hr format. Upon subsequent power-ups the default will be whatever the format was before the previous power-down. 3.17.2 Press "FUNC/ENTR", then "0"...

  • Page 21: Function 04 - Serial I/O Setup

    1/20/97 where MM is the month, DD is the day and YY is the year. Press the right or left arrow keys to move the cursor beneath the digit that you wish to change. Press the up or down arrow keys to scroll through the possible choices. Alternately, directly enter the numbers using the keypad.

  • Page 22: Function 05 - Time Quality Enable/Setup

    1/20/97 3.19.7 Press the up or down arrow keys to toggle between 1 and 2 stop bits. When the display shows the desired choice, press "FUNC/ENTR" to enter all the serial port data. 3.20 FUNCTION 05 - TIME QUALITY ENABLE/SETUP 3.20.1 Both the front-panel numeric display and the Serial I/O time output string indicate time quality.

  • Page 23: Function 06 - Keypad Lock Enable

    1/20/97 Fourth tq flag: 00010000000ns or the current value. Press the right or left arrow keys to position the cursor beneath the digit that you wish to change. Press the up or down arrow keys to scroll through the possible digit choices. Alternately, directly enter the numbers using the key pad. The cursor will advance to the next digit automatically.

  • Page 24: Function 18 - Software Version Request

    Use keypad function 18 to obtain information about the current version of the software installed in the unit. 3.23.2 Press "FUNC/ENTR", then "1" "8". The display will show, for example: TRUETIME NTS-100 sys ver 002 3.23.3 Press any of the arrow keys, to change the display to the clock-specific version. For example: v1.003...
  • Page 25 1/20/97 3.24.7 The Left and Right arrow keys move the cursor beneath the digits of the address. The Up and Down arrow keys or the number keys can be used to modify the address. Upon completion, use the "FUNC/ENTR" key to enter the address shown and proceed to the next parameter, “CLR”...

  • Page 26: Function 66 - Daylight Savings Enable

    DST adjustment if "Off" is selected for the DST function. Some local jurisdictions enter and leave DST at times other than those set by U.S. federal law. Therefore, TrueTime has included a "Manual" choice which allows the user to override the times of entry into and exit from DST by selecting his own.

  • Page 27: Function 67 - Leap Second Information

    1/20/97 3.25.5 When the display shows the desired entry time and date, press "FUNC/ENTR" again, and the display will show: Leave dst: 02:00 Last Sun in Oct or some other entry time and date. Press the right- or left-arrow keys to position the cursor beneath the character that you wish to change.

  • Page 28: Serial I/O Interface

    1/20/97 3.26.3 The NTS-100 will automatically determine the next available date for a leap second. The Up and Down arrows can be used to scroll between None, +1, and -1. A setting of “+1” will cause a second to be added to the end of June 30, 1996. A setting of “-1” will cause a second to be subtracted from the end of June 30, 1996.

  • Page 29: Function 02 - 12/24 Hour Format Entry/Request

    1/20/97 where = ASCII character F. = function number. <SEP> = one or more separator characters: either space, comma or tab. SIGN> = either no character or + for positive offsets or - for negative offsets. <HH> = one or two digit hours offset from +12 to -12 hours. = ASCII character for a colon.

  • Page 30: Function 03 - Time/Date Entry/Request

    1/20/97 3.31 FUNCTION 03 - TIME/DATE ENTRY/REQUEST 3.31.1 Use Serial I/O function F03 to enter or request time and date. To request time and date send F03<CR> to the Serial I/O port. The port will respond with the ASCII character string: F03<SEP><TYPE><SEP><mm>/<dd>/<yy><SEP><HH>:<MM>:<SS><LT>...

  • Page 31: Function 05 - Time Quality Enable/Setup

    1/20/97 3.32 FUNCTION 05 - TIME QUALITY ENABLE/SETUP 3.32.1 Use function F05 to enable or disable the time quality indicators or to set the four worst- case-error thresholds. The Serial I/O output string indicates the time quality. Refer to "SERIAL I/O FUNCTION F08 - CONTINUOUS TIME ONCE PER SECOND" for a description of the time quality indication in the Serial I/O time output string.

  • Page 32: Function 09 - Time On Request Enable

    1/20/97 output string format may be changed with Serial I/O Function F11. The default output string format is: <SOH>DDD:HH:MM:SSQ<CR><LF> where <SOH> = ASCII Start-of-Header character (HEX 01). <CR> = ASCII Carriage Return character (HEX 0D). <LF> = ASCII Line Feed character (HEX 0A). = day-of-year.

  • Page 33: Function 11 - Time Output Format Entry/Request

    1/20/97 where <SOH> = ASCII Start-of-Header character (HEX 01) <CR> = ASCII Carriage Return character (HEX 0D) <LF> = ASCII Line Feed character (HEX 0A) = day-of-year = hours = minutes = seconds = milliseconds = colon separator = time quality character. Refer to Function 08 for values Sample entry: F09<CR>...
  • Page 34 1/20/97 3.35.4 If non-volatile memory is corrupted the format string will be set to the "null" string. 3.35.5 When the unit returns the current format string in response to "F11<CR>" (as shown in the following example) the first character after the "F11" is always a blank and is not part of the format string but is only a separator.

  • Page 35: Function 13 - Worst-Case Time Error Request

    1/20/97 3.35.12 The above format means that days are deleted, the first separator is a vertical bar and all other characters are enabled and assume their default values. 3.35.13 When entering a new format string the character after "F11" is required but is ignored. To enter a "null"...

  • Page 36: Function 18 - Software Version Request

    The ethernet address is a six byte, hexadecimal value specific to each NTS-100 module. The first three bytes are registered to TrueTime Inc, and the last three bytes are the hex value of the unit’s unique number. The ethernet address of the NTS-100 is a fixed address established at the factory.

  • Page 37: Subnet Mask

    1/20/97 F36 IP:nnn.nnn.nnn.nnn<CR> F36 IP:206.54.0.21<CR> (Example) Changing this parameter will cause a software reset of the NTS-100 module. Subnet Mask 3.38.6 To return the subnet mask of the NTS-100 module, send the string: F36 SM<CR> 3.38.7 The unit will respond with: F36 SM:nnn.nnn.nnn.nnn<CR><LF>...

  • Page 38: Complete Nts-100 Network Configuration

    1/20/97 3.38.15 Note that this setting affects only the packet type that the NTS-100 will transmit. The NTS-100 will receive packets of either type, regardless of this setting. Changing this parameter will cause a software reset of the NTS-100 module. Complete NTS-100 Network Configuration 3.38.16 To review the entire current network configuration of the NTS-100 module, send the...

  • Page 39: Function 66 - Daylight Savings Enable

    1/20/97 properly set. To obtain the current setting of the accuracy of the local time source, send the string: F36 A<CR> 3.38.25 The unit will respond with (example): F36 A:1.0e-5<CR><LF> This example illustrates a unit with an accuracy of 10 µs. 3.38.26 To set the accuracy of the NTS-100 module, send the string (example): F36 A:0.5e-3<CR>...
  • Page 40 1/20/97 3.39.3 If the DST function is in Manual, the port will respond with the longer string described below. Sample request: F66<CR> Response: F66 OFF<CR><LF> 3.39.4 To alter the state of the daylight savings enable send a character string with the format above to the serial port.

  • Page 41: Function 67 - Leap Second Information

    1/20/97 Response: OK<CR><LF> Meaning: DST will now be entered 04 a.m. on the 2nd Monday in March and exit DST at 01 p.m. on the 4th Friday in November. 3.40 FUNCTION 67 - LEAP SECOND INFORMATION 3.40.1 Though strictly they may be performed at two other times during the year, in practice UTC leap second adjustments are only performed on two days of the year: June 30 and December 31.

  • Page 42: Not Used

    1/20/97 SECTION IV NOT USED...

  • Page 43: Irig B Synchronization Option

    1/20/97 ace Marker SECTION V IRIG B SYNCHRONIZATION OPTION IRIG B SETUP AND OPERATION 5.1.1 This Section describes setup and operating procedures for using the NTS-100 with IRIG B as the synchronization source. 5.1.2 The NTS-100 IRIG-B Sync Input characteristics are: Format: IRIG-B Input Range:...
  • Page 44 1/20/97 5.1.8 During the six months prior to the addition of a new leap second, the USNO will publish to the user community its plan to implement a leap second. Leap seconds are added (or subtracted) only at the end of the days of June 30 and December 31. If the NTS-100 is informed of an impending leap second adjustment at any time during the six months prior to the next leap second adjustment, then it will store that information in its EEPROM.
  • Page 45 1/20/97 5.1.15 To set the IRIG Lock Quality, send a string of the form: F36 IQ: setting<CR><LF> 5.1.16 F36 IQ: None<CR><LF> (Example)

  • Page 46: Md5 Authentication Protocol

    1 to 4294967295 (0xFFFFFFFF). Note: Zero is an illegal value, and for TrueTime setup purposes, 0 internally means the key identification is unused. This number specifies an index into a table of many possible MD5 keys. A key is an ASCII alpha/numeric character string that is from 1 to 31 characters in length.

  • Page 47: Keypad Md5 Configuration

    MD5 Main Menu:. There are three menu choices from this menu: 1) Modify MD5 keys, 2) Output On/off, and 3) Back one menu. Note for all TrueTime menus: the up and down arrow keys scroll through the list of menu items and FUNC/ENTR actuates the selected menu option.

  • Page 48: Serial Md5 Key Configuration

    1/20/97 Entering a key identification that is already in use effectively edits that key to the new value. Further note: The key list can have up to 16 MD5 keys. 6.3.5 Back in the MD5 Edit Menu: you can select Delete a key or Delete all keys to remove one or all MD5 keys.
  • Page 49 1/20/97 6.4.8 To delete a NTP MD5 key type: F36 MD:x Where x is the key identification number ranging from 1 to 4294967295. The unit will respond with: 6.4.9 To delete all NTP MD5 Keys type: F36 MD:ALL 6.4.10 The unit will respond with:...

  • Page 50: Section Vii

    IP (Internet) host that supports a SNMP agent. A SNMP agent is protected from unauthorized use through a security authentication scheme. Further, TrueTime has extended the MIB II database with its own custom enterprise MIB that allows a manager more control than what is specified in the MIB II database.
  • Page 51 Note: this address must be chosen carefully, or conflicts with other protocols may occur. Save settings When any setting is changed, this becomes visible and answering yes immediately saves the changes to TrueTime’s SNMP. Answering No will negate the changes.
  • Page 52 When SNMP Global Enable Traps is changed, this becomes visible and answering yes immediately saves the change to TrueTime’s SNMP. Answering No will negate the change. 7.2.3 The following table summarizes the TrueTime factory default settings for SNMP: Key word () Definition Community 1 Community Name public Trusted IP Address 0.0.0.0, 0.0.0.0, 0.0.0.0, 0.0.0.0...

  • Page 53: Ntp Parameters

    For this reason, it is more efficient to use the serial port, or the TrueTime Enterprise MIB to set the SNMP community name parameters.

  • Page 54: Display Strings

    7.5.2 This is an ASCII string sent to UDP port 162 (or user defined) when the TrueTime time server reinitializes. The message is "Cold Start Trap PDU from: ###.###.###.###". Where ###.###.###.### is the dotted decimal notation of the IP address of the booting unit.

  • Page 55: The Ntp Group

    7 to 14 are culled from Dr. Mills' definition of sys variables in RFC 1305. Note: the NTP variables simplify because the TrueTime units are primary time servers. Variables used directly by NTP packets are provided in their raw forms.

  • Page 56: Ntpesterr Object-Type

    1/20/97 7.6.6 The desired (worst case time) accuracy in microseconds that the time server will attempt to steer to. This variable is related to ntpEstError. Should ntpEstError be greater than ntpDesiredAcc, the NTP alarm condition will be set (ntpSysLeap will be equal to 3). Note: Outgoing NTP packets will have their leap indicator field set to ntpSysLeap.

  • Page 57: Ntpsyshostmode

    1/20/97 ntpSysHostMode SYNTAX INTEGER { reserved (0), symmetric active (1), symmetric passive (2), client (3), server (4), broadcast (5), reserved (6), reserved (7) ACCESS read-write STATUS mandatory 7.6.9 The value of this variable indicates the mode that the host is operating in. Note: This is the value of the time server's outgoing NTP packet mode field.

  • Page 58: Ntpsysprecision Object-Type

    1/20/97 ntpSysPrecision OBJECT-TYPE SYNTAX INTEGER { (-127..+127) } ACCESS read-only STATUS mandatory 7.6.12 This is an integer indicating the ultimate precision of the synchronizing clock, in seconds to the nearest power of two. Note: a primary time server's outgoing NTP packet will have its precision field set to ntpSysPrecision.

  • Page 59: The Ntscontrol Group (Preliminary)

    IRIG Inter-Range Instrumentation Group signal 7.6.16 Note, for TrueTime time servers only GPS, ACTS and IRIG are presently used. Further, a primary time server's outgoing NTP packet will have its reference identifier field set to ntpSysRefClockIdent. ::= { ntp 14 } THE NTSCONTROL GROUP (PRELIMINARY) 7.7.1...

  • Page 60: Ntpcontrolinput Object-Type

    SNMP get command reads the result of the set command. It is important to note that any TrueTime function string parameter can be issued using this method. Also note: that only one function string set may be issued at a time.

  • Page 61: Gpsgroupvalid Object-Type

    1/20/97 time synchronization source and it is the most accurate source of timing for TrueTime's NTS product line. gpsGroupValid OBJECT-TYPE SYNTAX INTEGER { (0..1) } ACCESS read-only STATUS mandatory for GPS capable units 7.8.2 A test flag indicating if data contained in this SNMP GPS group is valid or not. This flag equals 1 when GPS is used as the time synchronization source and 0 for all other sources.

  • Page 62: Gpssatmaxsigstrength Object-Type

    1/20/97 stationary, or slowly moving and mode 3 is for accurate position information when the unit is moving quickly. ::= { gps 4 } gpsSatMaxSigStrength OBJECT-TYPE SYNTAX INTEGER { ( 0..30) } ACCESS read-only STATUS mandatory for GPS capable units 7.8.6 Strongest signal strength of all tracking satellites in Trimble linear units.

  • Page 63: Acts Group Variables

    ACTS GROUP VARIABLES 7.9.1 The ACTS group is present in all TrueTime network products. However, only products synchronized by ACTS will have meaningful data in this group. This group reports on the number and status of ACTS dial up modem calls. ACTS is a telephone modem dial-up time service that is not as accurate as GPS, but does not suffer from the antenna restrictions of GPS.

  • Page 64: Actsgroupvalid Object-Type

    1/20/97 actsGroupValid OBJECT-TYPE SYNTAX INTEGER { (0..1) } ACCESS read-only STATUS mandatory for ACTS capable units 7.9.2 A test flag indicating if data contained in this SNMP ACTS group is valid or not. This flag equals 1 when ACTS is used as the time synchronization source and 0 for all other sources.

  • Page 65: Actsfailedinit Object-Type

    1/20/97 7.9.6 This is the phone number of the ACTS dial-up service, including any prefixes needed to reach an outside line or international dialing. Prefixes are separated by a comma from the main phone number. ::= { acts 5 } actsNumberOfCalls OBJECT-TYPE SYNTAX COUNTER { (0..4294967295) }...

  • Page 66: Actsnocarrier Object-Type

    1/20/97 7.9.11 Time server's internal modem found no dial tone. This may be caused by a broken phone line to the time server. ::= { acts 10 } actsNoCarrier OBJECT-TYPE SYNTAX COUNTER { (0..4294967295) } ACCESS read-only STATUS mandatory for ACTS capable units 7.9.12 Time server's internal modem found no carrier.
  • Page 67 1/20/97 7.9.16 The reply from remote modem had no on time mark, possibly due to line noise. ::= { acts 15 }...
  • Page 68 1/20/97 APPENDIX A NTP v 3.0 DATA FORMAT per RFC1305 NTP DATA PACKET A-1.1 The layout of the NTP data packet information following the UDP header is shown below. Leap Version Indicator Number Mode Stratum Poll Precision Synchronizing Distance (Root Delay Version 3) Synchronizing Dispersion (Root Dispersion Version 3) Reference Clock Identifier Reference Timestamp...
  • Page 69 The root delay is a signed 32 bit fixed point number representing the predicted roundtrip delay in seconds to the primary synchronizing source. The fraction point is between bits 15 and 16. This value is set to 0 seconds in TrueTime’s NTS-100 module. Synchronizing Dispersion (Root Dispersion Version 3) A-1.10...
  • Page 70 Strata 0 and 1 use a four-octet, left justified, zero-padded ASCII string. TrueTime’s NTS-100 module operates as Stratum 1 and uses this four-octet string based on the local time source input as shown in the table below. This setting is determined based on the NTS-100 synchronization input option.
  • Page 71 1/20/97 Reference Timestamp A-2.12S This field is set to the time that the reply left the NTS-100 server host. Receive Timestamp A-13S This filed is set to the time that the reply left the NTS-100 server host. Transmit Timestamp A-15S This field is set to the time that the reply left the NTS-100 server host.
  • Page 72 1/20/97 APPENDIX B TIME PROTOCOL per RFC868 INTRODUCTION B-1.1 This protocol provides a site-independent, machine readable date and time. The TIME service sends back to the originating source the UTC time in seconds since midnight on January 1, 1900. B-1.2 This protocol may be used either above the Transmission Control Protocol (TCP) or above the User Datagram Protocol (UDP).
  • Page 73 1/20/97 APPENDIX C IRIG B TIME CODE INTRODUCTION C-1.1 The document 200-70 "IRIG STANDARD TIME FORMATS" by the Telecommunications Working Group, Inter-range Instrumentation Group, Range Commanders Council describes IRIG B, IRIG H and IRIG E time codes. It is available by writing Secretariat, Range Commanders Council, White Sands Missile Range, New Mexico, 88002.
  • Page 74 1/20/97 EMBEDDED WORST-CASE TIME ERROR FLAGS C-3.1 Five flags are encoded in the control function segment of the IRIG B code. The first flag encoded at element P5+40ms is the LOCK indicator. It is a binary 1 when the unit has lost contact with satellite signals.
  • Page 75 1/20/97 APPENDIX D DETAILED DRAWINGS / BILL OF MATERIALS...

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