Meinberg LANTIME M300 User manual

MANUAL
LANTIME M300/GPS
NTP Server
7th February 2013
Meinberg Radio Clocks GmbH & Co. KG

Table of Contents
1 Impressum 1
2 Quick Start 2
3 Network Timeserver with GPS synchronized time base 3
4 The Modular System LANTIME 4
4.1 SupportedNetworkServices...................................... 5
4.2 AdditionalFeatures .......................................... 5
4.3 UserInterface ............................................. 5
4.4 Options ................................................ 6
4.5 Why to use a Network Time Server? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Network Time Protocol (NTP) 7
5.1 NTPTarget .............................................. 7
5.2 NTP-ClientInstallation ........................................ 7
6 GPS satellite controlled clock 9
6.1 GPS170Features ........................................... 9
6.2 Time Zone and Daylight Saving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7 Mounting the GPS Antenna 10
7.1 Example:................................................ 10
7.2 Antenna Short-Circuit Assembly with surge voltage protection . . . . . . . . . . . . . . . . . . . 11
7.3 AntennaShort-Circuit......................................... 12
8 Booting the GPS receiver 13
9 Booting the Single Board Computer 14
10 Configuration User Interface 15
10.1 Introduction: Conguration LANTIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
10.2RootMenu............................................... 16
10.3Menü:ReferenceTime ........................................ 18
10.3.1 Setup GPS Receiver Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.3.2 Set Antenna Cable Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.3.3 Set GPS Receiver Simulation Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.3.4InitGPSReceiver....................................... 19
10.3.5 Initiate Cold Boot of GPS Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
10.3.6 Initiate Warm Boot of GPS Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
10.3.7InitGPSPosition ....................................... 19
10.3.8InitGPSTime......................................... 19
10.3.9InfoGPS............................................ 20
10.3.10GPSStatus .......................................... 20
10.3.11GPSVersion.......................................... 20
10.3.12GPSReceiverPosition .................................... 20
10.3.13GPS Satellite Constallation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
10.3.14SetupGPSOutputs...................................... 21
10.3.15GPSEnableOutputs ..................................... 21
10.3.16SerialOutputs......................................... 21
10.3.17Setup Time Zone of Serial Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
10.4Menu:TimeService.......................................... 23
10.4.1Menu:externalNTP ..................................... 23
10.4.2 Menu: Stratum of local clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
0

10.4.3Menu:RestartNTP...................................... 23
10.5 Programmable pulse (Option) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
10.5.1SETUPPOUTX ....................................... 24
10.5.2Mode ............................................. 25
10.5.3CyclicPulse .......................................... 25
10.5.4SingleShot .......................................... 25
10.5.5Timermode.......................................... 25
10.5.6Idlemode ........................................... 26
10.5.7 Position OK / TimeSync / AllSync . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
10.5.8DCFMark........................................... 27
10.5.9PPS,PPM,PPHModes ................................... 27
10.6 Menu: Synthesizer Frequency Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
10.7Menu:TIMECODEIRIG....................................... 28
10.8Menu:Network ............................................ 29
10.8.1 Setup Global Conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
10.8.2 Setup Network Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.8.3 Setup Network Ipv4 Parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.8.4 Menu: Setup Ipv6 Parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
10.8.5Menu:LinkMode....................................... 31
10.8.6 Menu: Setup Network Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
10.9Menu:System............................................. 31
10.9.1Settimezone ......................................... 32
10.9.2RestartMenu ......................................... 33
11 The graphical user interfaces 34
12 The WEB Interface 35
12.1Conguration:MainMenu ...................................... 36
12.2Conguration:Ethernet........................................ 37
12.2.1SYSLOGServer........................................ 38
12.3 Network interface specic conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
12.3.1 IPv4 addresses and DHCP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
12.3.2 IPv6 addresses and autoconf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
12.3.3 High Availability Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
12.3.4 Additional Network Conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
12.4Conguration:Notication ...................................... 42
12.4.1AlarmEvents ......................................... 43
12.4.2E-mailmessages........................................ 44
12.4.3 Windows Popup Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
12.4.4SNMP-TRAPmessages.................................... 44
12.4.5 VP100/NET wall mount display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
12.4.6 User dened Alarm scripts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
12.4.7 NTPClientMonitoring .................................... 45
12.4.8Alarmmessages........................................ 45
12.5Conguration:Security ........................................ 46
12.5.1Password............................................ 47
12.5.2HTTPAccessControl..................................... 47
12.5.3SSHSecureShellLogin.................................... 47
12.5.4 Generate SSL Certicate for HTTPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
12.5.5 NTP keys and certicates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
12.5.6SNMPParameter ....................................... 50
12.6Conguration:NTP.......................................... 51
12.6.1NTPAuthentication...................................... 53
12.6.2NTPAUTOKEY ....................................... 54
12.7Conguration:Local.......................................... 57
12.7.1 Administrative functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
12.7.2UserManagement....................................... 58
12.7.3 Administrative Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
12.7.4SoftwareUpdate........................................ 61
12.7.5 Automatic conguration check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
12.7.6 Get Diagnostics Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

12.7.7ReceiverInformation ..................................... 63
12.7.8Webinterfacelanguage.................................... 63
12.8Conguration:Statistics........................................ 64
12.8.1 Statistical Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
12.9Conguration:Manual ........................................ 66
12.10Conguration:PTP.......................................... 67
12.10.1PTPv2 - Global Conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
12.10.2PTP Network Conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
12.10.3PTPStateFiles........................................ 70
13 The Command Line Interface 71
13.1CLIEthernet.............................................. 72
13.2CLINotication............................................ 74
13.3CLISecurity.............................................. 76
13.4CLINTPParameter.......................................... 78
13.4.1CLINTPAuthentication ................................... 79
13.5CLILocal ............................................... 79
14 SNMP Support 82
14.1CongurationoverSNMP....................................... 83
14.1.1 Examples for the usage of the SNMP conguration features . . . . . . . . . . . . . . . . 83
14.1.2 Further conguration possibilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
14.1.3 Send special timeserver commands with SNMP . . . . . . . . . . . . . . . . . . . . . . . 84
14.1.4 Conguration of the timeserver with SNMP: Reference . . . . . . . . . . . . . . . . . . . 86
14.2SNMPTraps.............................................. 90
14.2.1SNMPTrapReference .................................... 91
15 Attachment: Technical Information 92
15.1 Skilled/Service-Personnel only: Replacing the Lithium Battery . . . . . . . . . . . . . . . . . . . 92
15.2 Technical Specications M600/300 Multipac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
15.3 Safety instructions for building-in equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
15.3.1CE-Label............................................ 94
15.4 Front and Rear Panel Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
15.5 Pin Assignment: Serial Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
15.5.1SerialTimeString....................................... 96
15.5.2TERMINAL(Console)..................................... 96
15.6ErrorRelay............................................... 97
15.6.1 Technical Specication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
15.7 Technical Specications GPS receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
15.7.1 Oscillator specications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
15.7.2 Technical Specications GPS Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
15.8 Technical Specications LAN CPU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
15.9TimeCode...............................................102
15.9.1AbstractofTimeCode ....................................102
15.9.2PrincipleofOperation.....................................102
15.9.3 Block Diagram Time Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
15.9.4IRIGStandardFormat.....................................103
15.9.5AFNORStandardFormat...................................104
15.9.6 Assignment of CF Segment in IEEE1344 Code . . . . . . . . . . . . . . . . . . . . . . . . 105
15.9.7GeneratedTimeCodes ....................................106
15.9.8 Selection of Generated Time Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
15.9.9Outputs ............................................106
15.9.10TechnicalData ........................................107
15.10TimeStrings..............................................108
15.10.1Format of the Meinberg Standard Time String . . . . . . . . . . . . . . . . . . . . . . . . 108
15.10.2Format of the Meinberg GPS Time String . . . . . . . . . . . . . . . . . . . . . . . . . . 109
15.10.3Format of the Meinberg Capture String . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
15.10.4Format of the SAT Time String . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
15.10.5Format of the Uni Erlangen String (NTP) . . . . . . . . . . . . . . . . . . . . . . . . . . 112
15.10.6Format of the NMEA 0183 String (RMC) . . . . . . . . . . . . . . . . . . . . . . . . . . 114
15.10.7Format of the NMEA 0183 String (GGA) . . . . . . . . . . . . . . . . . . . . . . . . . . 115

Page 0
15.10.8Format of the NMEA 0183 String (ZDA) . . . . . . . . . . . . . . . . . . . . . . . . . . 116
15.10.9Format of the ABB SPA Time String . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
15.10.10Format of the Computime Time String . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
15.10.11Format of the RACAL standard Time String . . . . . . . . . . . . . . . . . . . . . . . . . 119
15.10.12Format of the SYSPLEX-1 Time String . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
15.10.13Format of the ION Time String . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
15.11Manual VP100/NET Display conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
15.12GlobalCongurationFile .......................................123
15.13GlobalOptionFile...........................................125
15.14Thirdpartysoftware..........................................125
15.14.1Operating System GNU/Linux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
15.14.2Samba.............................................125
15.14.3Network Time Protocol Version 4 (NTP) . . . . . . . . . . . . . . . . . . . . . . . . . . 126
15.14.4mini_httpd ..........................................126
15.14.5GNU General Public License (GPL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
15.15USBStick ...............................................131
15.15.1Menu Backup Conguration to USB Stick . . . . . . . . . . . . . . . . . . . . . . . . . . 131
15.15.2Menu Write Diagnostic File to USB Stick . . . . . . . . . . . . . . . . . . . . . . . . . . 131
15.15.3Keypadlocking ........................................132
15.15.4Menu Restore Conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
15.16Reference ...............................................133
0 Date: 7th February 2013 LANTIME M300/GPS

Page 1
1 Impressum
Meinberg Radio Clocks GmbH & Co. KG
Lange Wand 9, 31812 Bad Pyrmont - Germany
Phone: + 49 (0) 52 81 / 93 09 - 0
Fax: + 49 (0) 52 81 / 93 09 - 30
Internet: http://www.meinberg.de
Mail: [e-mail]
Date: 2010-08-10
LANTIME M300/GPS Date: 7th February 2013 1

Page 2 2 Quick Start
2 Quick Start
When booting the system the following message will be displayed while dots will be counted up in the lower line:.
Starting up please wait...
.......
Main Menu will be displayed with some important status informations after booting has nished:
GPS: NORMAL OPERATION Mon, 28.08.2011
NTP: Offs. PPS: -50us UTC 14:33:10
If the GPS receiver remains asynchronous (Refclock LED is still red after 12 minutes) the number of satellites in
view and the good satellites are to check (press bottons ↓, ok, ↓, ok, →, ok from main menu). The antenna has
to be installed without any obstructions to the sky.
SATELLITE CONSTELLATION
In view: 8 Good: 7 Sel: 05 22 17 09
For rst time installation enter TCP/IP address, netmask and default gateway. To get an overview of the current
conguration press F2 from main menu. Press F2 again to enter SETUP conguration page. Please ask your
administrator for propper TCP/IP conguration:
Global Cfg. Services
Interfaces-> <-
Select "Interfaces" and then press 3 times the OK button to change to IPV4 ETH0 conguration page to enter
the IP address, netmask and the default gateway:
SETUP: Ipv4 LAN Parameter ETH0
Ipv4 ADDRESS: 192.168.10.200
NOTE: These settings are related to the rst Ethernet connection (ETH0).
After this all further settings can be done via network interface, either by using a WEB browser or a Telnet Session.
Default user: root
Default password: timeserver
2 Date: 7th February 2013 LANTIME M300/GPS

Page 3
3 Network Timeserver with GPS synchronized
time base
The LANTIME (Local Area Network Time Server) provides a high precision time base to a TCP/IP network
(Stratum-1-Server). The NTP (Network Time Protocol) is used to synchronize all NTP clients with the reference.
The several LANTIME variants dier from each other by the time reference and output conguration. A GPS
or combined GPS/GLONASS receiver, a long wave receiver (like DCF77, MSF or WWVB) or an IRIG time code
receiver can be integrated as an internal reference as well as a combination of these references (hybrid system).
External references are also possible.
The LANTIME system is a set of equipment composed of a internal receiver, a single-board computer and a
power supply, all installed in a metal 19 inch modular chassis and ready to operate. A simplied LINUX operating
system is installed on the single-board computers ash disk. Eight push buttons and a display can be used to
congure and monitor the time server.
After the network connection has been established the time server can also be congured and monitored re-
motely from a workstation via TELNET or FTP. An integrated web server enables access to the LANTIME by
using an ordinary web browser.
LANTIME M300/GPS Date: 7th February 2013 3

Page 4 4 The Modular System LANTIME
4 The Modular System LANTIME
The system LANTIME is a set of equipment, composed of a reference clock (e.g.: GPS/GLONASS satellite
controlled clock, DCF77 radio clock or IRIG/AFNOR time code reader), a single-board computer SBC LX800 500
MHz with integrated network card and a power supply unit, all installed in a metal desktop case and ready to
operate. The interfaces provided by LANTIME are accessible via connectors in the rear panel of the case. Details
of the components are described below.
OK
ESC
Time Service
Ref. Time
Network
Alarm
Terminal
USB
5
9
1
6
GPS: NORMAL OPERATION
NTP: Offset PPS: -4µs UTC 12: 00 : 00
Mon , dd.mm.yyyy
F1
F2 LANTIME M300
LANTIME M300
ENGLISH
1. LC Display
2. Function buttons: 4-way navigation
Button; F1, F2, OK, ESC
3. Status LEDs: Ref. Time, Time Service,
Network, Alarm
4. Terminal port, RS232 Time String output
5. USB connector
6. 19” Mounting Rack
DEUTSCH
1. LC - Display
2. Funktionstasten: 4 - Richtungen;
F1, F2, OK, ESC
3. Status LEDs: Ref. Time, Time Service,
Network, Alarm
4. Terminal port, RS232 Zeitstring Ausgang
5. USB Anschluss
6. Haltewinkel für 19” Rackmontage
1 2 3 4 5 6
COM1
COM 0
Error
GPS
Antenna CO NO NC
1
6
5
9
1
6
5
9
100M 10M 100M 10M
ETH0 ETH2
ETH1 ETH3
PPS Out
10MHz Out
8 7 6 5 4 3 2 1
DEUTSCH
RS232 Ausgang: serielle Schnittstellen, Zeittelegramme
3. Error: Störmelderelais Ausgang
4. GPS Antenne
5. Sekunden Impuls Ausgang, 10MHz Ausgang (TTL)
6. für weitere BNC Ausgänge
7. LNE Optional
8. Netzwerk Anschlüsse ETH0, ETH1, 10/100 Mbit Rj45
1. Stromversorgungseingang
2.
ENGLISH
RS232 Output: serial interface, time telegram
3. Error relay output
4. GPS antenna
5. Pulse Per Second (PPS) , 10MHz (TTL) output
6. for additional outputs (e.g. IRIG time code)
7. Option: LNE - additional network interfaces
8. Network interfaces ETH0, ETH1, 10/100 Mbit Rj45
1. Power Supply (AC/DC)
2.
output
The implemented NTPD distributes the reference time from the used receiver cyclic in the network. Information
on the NTPD is monitored on the LC-Display or can be inquired via the network.
The installation of LANTIME is very easy for the system/network administrator. The network address, the
netmask and the default gateway have to be congured from the front panel of LANTIME. The network address
or the equivalent name of LANTIME has to be shown to all NTP clients in the TCP/IP network.
As well as NTP the Linux system also supports a number of further network protocols: HTTP(S), FTP, SSH and
Telnet. Because of this remote conguration or status requests can come from any WEB browser. This access via
the network can be deactivated. Changes in the receiver status, errors or other important events are logged either
on the local Linux system or on an external SYSLOG-Server. In addition messages can be sent to a data center
via SNMP traps or automatically generated e-mails where they can be recorded. Furthermore all alarm messages
can be displayed by the large display VP100/20/NET that is accessed via network connection. In order to avoid
a service interruption several LANTIME NTP servers can be installed in the same network to obtain redundancy.
4 Date: 7th February 2013 LANTIME M300/GPS

4.1 Supported Network Services Page 5
4.1 Supported Network Services
The following network services are provided via RJ45 10/100Base-T Ethernet (Auto sensing):
- NTP v2, v3, v4
- NTP broadcast mode
- NTP multicast
- NTP symmetric keys
- NTP Autokey
- Simple Network Time Protocol (SNTP)
- TIME
- SNMP v1,2,3 with extended SNMP-Agent and SNMP-Traps
for NTP and reference clock status
- DHCP Client
- NFS
- TELNET
- FTP
- HTTP
- HTTPS with Openssl2
- SSH2 Secure Shell Login
- Alarm messages via e-mail
- IPv6 3 global IPv6 addresses congurable
Autoconf Feature to be disabled
supported network services: NTP, HTTP, HTTPS, SNMP, SSH
- Windows net time via NETBIOS
- Winpopup (Window Mail)
4.2 Additional Features
• external NTP timeserver
• free conguration of NTP: thereby MD5 authentication and access control via address & mask restriction
• extended menu guidance for conguration and monitoring via Telnet, SSH or serial terminal interface
• extended HTTP statistic support with long-term graphic and access statistic to NTP
• alarm messages can be displayed on external large display VP100/20/NET
• USB memory stick slot for extended functionality: software update, transfer of secure certicates, log les
and congurations, keypad locking
4.3 User Interface
• Terminal connection via serial interface, status LED
• Web browser interface with graphical statistic of the one-day cycle osets
• Telnet or Secure Shell Login for password protected operation of the Linux operating system
• FTP access for updating the operating system and downloading log les
• Simple Network Management Protocol for automatically SNMP-Traps in case of alarm
• SYSLOG messages can be passed to dierent computers
• Congurable e-mail notication
• Simulation of a synchronous radio clock in order to operate without antenna
LANTIME M300/GPS Date: 7th February 2013 5

Page 6 4 The Modular System LANTIME
4.4 Options
• Additional Ethernet RJ45 connectors available (eight in 3U housing, four in 1U housing and eight additional
connectors in HS - XL railmount housing)
• Frequency and pulse outputs via BNC connectors (e.g. 10 MHz, 2.048 MHz, PPS)
• Higher free running accuracy with optional oscillators (OCXO)
• IRIG-B outputs
• ANZ14NET or VP100/20/NET as display connected via network
4.5 Why to use a Network Time Server?
In principle it is possible to synchronize your computers with time servers on the internet. However, a lot of our
customers rely on their own time server in their network environment for security and/or maintainability reasons.
• Particularly in the case of our LANTIME you or a responsible person can be notied by mail or SNMP trap
if there is a malfunction in your time synchronization.
• The clients on the network do not depend on an active internet connection.
• The clients on the network do not depend on the availability of an external time server.
• A test of other freely available time servers reported that many NTP servers distributed a signicantly
wrong time, although they were classied as stratum-1 time servers. This is the responsibility of the server's
administrators.
• If an internet connection is working properly then NTP can determine and account for the packet transmis-
sion delays quite reliable. However, if the internet connection is at its capacity limit, time synchronization
can be signicantly degraded due to high dispersion in packet transmission delays. Reasons for this may be
hacker attacks, which must not address your own network, or new viruses causing a huge ood of emails,
like it has already happened in the past.
In the United States the U.S. Naval Observatory (USNO) has a similar function to spread the legal time as the
PTB in Germany, and also operates publicly available NTP servers for a long time. Those NTP servers are more
and more constrained by "bad" clients, which makes the future of the public service questionable. There are
already precautions to limit the aect of such clients. Dave Mills, the originator of NTP, cooperates with the
USNO and has already adverted this in the NTP news group.
The topics outlined above should provide some arguments to install an own time server, if an accurate time
is a requirement for the reliable operation of a local network.
6 Date: 7th February 2013 LANTIME M300/GPS

Page 7
5 Network Time Protocol (NTP)
NTP is a common method for the synchronization of hardware clocks in local and global networks. The basic
concept, version 1 [Mills88], was published in 1988 as RFC (Request For Comments). Experiences acquired from
its practical use on the Internet was followed by version 2 [Mills89]. The NTP software package is an implemen-
tation of the actual version 3 [Mills90], based on the specication RFC-1305 from 1990 (directory doc/NOTES).
Permission to use, copy, modify and distribute this software for any purpose and without fee is hereby granted
(read File COPYRIGHT).
NTP operates in a way that is basically dierent from that of most other timing protocols. NTP does not
synchronize all connected clocks; instead it forms a hierarchy of timeservers and clients. Each level in this hier-
archy is called a stratum, and Stratum 1 is the highest level. Timeservers at this level synchronize themselves by
means of a reference time source such as a radio controlled clock, satelliet receiver or modem time distribution.
Stratum 1 Servers distribute their time to several clients in the network which are called Stratum 2.
Highly precise synchronization is feasible because of the several time references. Every computer synchronizes
itself with up to three valued time sources. NTP enables the comparison of the hardware times and the adjustment
of the internal clock. A time precision of 128 ms, and often better than 1 ms, is possible.
5.1 NTP Target
The NTP software package was tested on dierent UNIX systems. Many UNIX systems have an NTP client pre-
installed. Only some basic congurations need to be done (/etc/ntp.conf). NTP clients as freeware or shareware
are also available for most other operating systems like Windows 7/Vista/XP/NT/2000/98/95/3x, OS2 or MAC.
The following WEB site is recommended to get the latest version of NTP:
http://www.ntp.org
You can nd more information on our web page at: http://www.meinberg.de/english/sw/ntp.htm
5.2 NTP-Client Installation
The following example shows the installation of a NTP client under UNIX. First make sure that there is no NTP
installed on your computer because many UNIX operating systems include NTP already.
The shipped source code of the NTP daemon has to be compiled on the target system. Using the enclosed
script le congures the compilation of the NTP daemon and all tools.
congure
All necessary information from the system will be collected and the corresponding make les will be generated in
the subdirectories.
After that the NTP daemon and all needed utilities will be generated. Therefore type:
make
While compiling the NTP daemon several warnings may appear. These warnings are mostly unimportant. In case
of problems during the compilation read the system dependent notes in the subdirectory 'html'.
Afterwards the generated programs and tools have to be moved in the corresponding directories. Therefore type:
make install
The time adjustment can occur in dierent ways. Either the system time can be set once by using the tool "ntp-
date lantime" or the NTPD daemon is started. In the rst case it is recommended to set the time automatically
with "cron" or once when booting the system. The second case is described below.
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Page 8 5 Network Time Protocol (NTP)
First a le named /etc/ntp.conf has to be generated with an editor. Adapting the le to Meinberg LANTIME it
should contain the following:
# Example for /etc/ntp.conf for Meinberg LANTIME
server 127.127.1.0 # local clock
server 172.16.3.35 # TCPIP address of LANTIME
# optional: Driftle
# driftle /etc/ntp.drift
# optional: activate all messages in syslogle
# logcong =all
The NTP daemon is started with 'ntpd' or, using 'rc.local', while booting the system. Status messages during
operation are saved in /var/adm/messages and /var/adm/syslog (corresponding to the syslog conguration).
e.g.: tail /var/log/messages
Shows the last lines from the le messages . The status messages can also be redirected in a log le by using the
following option:
ntpd -llogle
The command 'ntpq' in the directory ntpq requests the actual status of the NTP daemon (see also doc/ntpq.8).
e.g.: ntpq/ntpq
An interpreter appears; Type "?" for a list of all available commands. The command 'peer' is used to list all
active reference clocks:
         

         
         
with the following meaning:
- remote: list of all valid time servers (ntp.conf)
- red: reference number
- st: actual stratum value (hierarchy level)
- when: last request (seconds)
- poll: period of requesting the time server (seconds)
- reach: octal notation of the successful requests, shifted left
- delay: delay of the network transmission (milliseconds)
- oset: dierence between system time and reference time
(milliseconds)
- jitter: variance of the osets (milliseconds)
Repeatedly 'peer' commands lets the user observe the accuracy of the NTP daemon. Every 64 seconds (value
of -poll) a new time string is red in from the radio clock. The NTP daemon needs approx. 3...5 minutes for
initialisation. This is indicated by a wildcard (*) on the left side of the remote name.
The NTP daemon terminates itself if the system time diers from the UTC time by more than 1024 seconds.
This often happens when the time zone is not correctly set (see also system manual "zic" or "man zic").
8 Date: 7th February 2013 LANTIME M300/GPS

Page 9
6 GPS satellite controlled clock
A Meinberg GPS170 satellite controlled radio clock is used as a reference time base. The GPS170 satellite receiver
clock provides extremely precise time. The clock has been developed for applications where conventional radio
controlled clocks can not meet the growing demand for precision time. The advantage of the GPS clock is that
it can provide highly precise time worldwide, 24 hours a day using the Global Positioning System.
The Global Positioning System (GPS) is a satellite-based radio-positioning, navigation, and time-transfer sys-
tem. It was installed by the United States Department of Defense and provides two levels of accuracy: The
Standard Positioning Service (SPS) and the Precise Positioning Service (PPS). SPS has been made available to
the general public, but the PPS is encrypted and only available for authorized (military) users.
GPS accurately measures the propagation time of signals transmitted from satellites to the user's receiver. A
nominal constellation of 24 satellites together with 3 active spares, in six orbital planes at 20,000 km altitude
provides a minimum of four satellites in view 24 hours a day at every point on the globe. Four satellites need
to be received simultaneously to determine both the receiver position (x, y, z) and the receiver clock oset from
GPS system time. All the satellites are monitored by ground control stations which determine the exact orbit
parameters and clock osets of the satellites' onboard atomic clocks. These parameters are uploaded to the
satellites and become part of a navigation message, which is retransmitted by the satellites and passed on to the
user's receiver.
The high precision orbit parameters of the satellites are called ephemeris parameters, and a reduced precision
subset of the ephemeris parameters is called a satellite's almanac. While ephemeris parameters must be evaluated
to compute the receiver's position and clock oset, almanac parameters are used to check which satellites are in
view from a given receiver position at a given time. Each satellite transmits its own set of ephemeris parameters
and almanac parameters of all existing satellites.
6.1 GPS170 Features
The GPS170 module is a 100 mm x 160 mm microprocessor board, and is connected to the antenna/converter unit
by a 50 ohm coaxial cable (refer to "Mounting the Antenna"). DC power to fed to the antenna/downconverter
via the antenna cable. An optional antenna splitter is available to operate up to four receivers from a single
antenna.
The navigation message coming in from the satellites is decoded by the GPS170s microprocessor in order
to track the GPS system time with an accuracy of better than 500 ns (or 250 nsec OCXO). Compensation of
the RF signal's propagation delay is done by automatic determination of the receiver's position on the globe. A
correction value computed from the satellites' navigation messages increases the accuracy of the board's TCXO
or OCXO to 10
-9
and automatically compensates for the oscillators aging. The last recent value is restored from
the battery buered memory at power-up.
6.2 Time Zone and Daylight Saving
GPS system time diers from the universal time scale (UTC) by the number of leap seconds which have been
inserted into the UTC time scale since GPS was initiated in 1980. The current number of leap seconds is part of
the navigation message supplied by the satellites, so the internal real time of the GPS170 is based on UTC time
scale. Conversion to local time and annual daylight saving time can be done by the receiver's microprocessor if
the corresponding parameters are set up by the user.
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Page 10 7 Mounting the GPS Antenna
7 Mounting the GPS Antenna
The GPS satellites are not stationary, but circle round the globe with a period of about 12 hours. They can only
be received if no building is in the line-of-sight from the antenna to the satellite, so the antenna/downconverter
unit must be installed in a location that has as clear a view of the sky as possible. The best reception is achieved
when the antenna has a free view of 8
◦
angular elevation above the horizon. If this is not possible, the antenna
should be installed with the clearest free view to the equator, because the satellite orbits are located between
latitudes 55
◦
North and 55
◦
South. If this is not possible, you may experience diculty receiving the four satellites
necessary to complete the receiver's position solution.
The antenna/converter unit can be mounted on a wall, or on a pole up to 60 mm in diameter. A 45 cm
plastic tube, two wall-mount brackets, and clamps for pole mounting are included with every GPS170. A standard
RG58 coaxial cable should be used to connect the antenna/downconverter unit to the receiver. The maximum
length of cable between antenna and receiver depends on the attenuation factor of the coaxial cable.
Up to four GPS170 receivers can be run with one antenna/downconverter unit by using an optional antenna
splitter. The total length of an antenna line from antenna to receiver must not be longer than the max. length
shown in the table below. The position of the splitter in the antenna line does not matter.
High voltage protectors must be installed directly after reaching the indoors. The optional delivered protec-
tion kit is not for outdoor usage.
7.1 Example:
Type of cable diameter Ø Attenuation at 100MHz max lenght.
[mm] [dB]/100m [m]
RG58/CU 5mm 17 300 (1)
RG213 10.5mm 7 700 (1)
(1)This specications are made for antenna/converter units produced after January, 2005
The values are typically ones; the exact ones are to nd out from the data sheet of the used cable
10 Date: 7th February 2013 LANTIME M300/GPS

7.2 Antenna Short-Circuit Assembly with surge voltage protection Page 11
7.2 Antenna Short-Circuit Assembly with surge voltage protection
Optional a surge voltage protector for coaxial lines is available. The shield has to be connected to earth as short
as possible by using the included mounting bracket. Normally you connect the antenna converter directly with
the antenna cable to the system.
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Page 12 7 Mounting the GPS Antenna
7.3 Antenna Short-Circuit
(optional for displayed systems)
In case of an antenna line short-circuit the following message appears in the display:
ANTENNA
SHORT-CIRCUIT
DISCONNECT POWER
! ! !
If this message appears the clock has to be disconnected from the mains and the defect eliminated. After that
the clock can be powered-up again. The antenna supply voltage must be 15V DC .
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Page 13
8 Booting the GPS receiver
If both the antenna and the power supply have been connected, the system is ready to operate. About 2 minutes
after power-up the receiver's oscillator has warmed up and operates with the required accuracy. If the receiver
nds valid almanac and ephemeris data in its battery buered memory and the receiver's position has not changed
signicantly since its last operation, the receiver can determine which satellites are presently in view. Only a single
satellite must be received to synchronize and generate output pulses, so synchronization can be achieved within
one minute after power-up.
If the receiver position has changed by more than one hundred kilometers since last operation, the satellites'
real elevation and Doppler might not match those values expected by the receiver, and this will force the receiver
to start scanning for satellites. This mode is called Warm Boot because the receiver can obtain ID numbers of
existing satellites from the valid almanac. When the receiver has found four satellites in view it can update its
new position and switch to Normal Operation . If the almanac has been lost (because the battery has been
disconnected) the receiver has to scan for a satellite and read in the current almanac. This mode is called Cold
Boot . It takes 12 minutes until the new almanac is complete and the system switches to Warm Boot mode,
scanning for other satellites.
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Page 14 9 Booting the Single Board Computer
9 Booting the Single Board Computer
The LINUX operating system is loaded from a packed le on the ash disk of the single board computer to a
RAM disk. All les of the ash disk are stored in the RAM disk after booting. Because of that it is guaranteed
that the le system is in a dened condition after restart. This boot process takes approx. two minutes. During
this time the following message appears on the display:
Starting up please wait...
.......
After starting up the LINUX system the network function is initiated and the program for communication with
the GPS and the NTPD (NTP daemon) is started. After that NTPD starts synchronization with the reference
clocks (usual the hardware clock of the single board computer and the GPS receiver). Until synchronization is
nished the following message is displayed:
GPS: NORMAL OPERATION Mon, 28.08.2006
NTP: sync to local UTC 14:33:10
GPS: NORMAL OPERATION Mon, 28.08.2006
NTP: not sync UTC 14:33:10
For the synchronization of the NTPD with the GPS it is necessary that the GPS receiver is synchronous with the
GPS time. In this case the following message is monitored on the display:
GPS: NORMAL OPERATION Mon, 28.08.2011
NTP: Offs. PPS: -50us UTC 14:33:10
The second line shows the user that the NTPD is synchronized with the GPS with an oset of -50us. Because
of the internal time of the NTP which is adjusted by a software PLL (phase locked loop) it takes a certain time
to optimise this oset. The NTPD tries to keep the oset below +-128 ms; if the oset becomes too large the
system time is set with the GPS time. Typically values for the oset are +-5 ms after the NTPD has already
synchronized.
14 Date: 7th February 2013 LANTIME M300/GPS