Meinberg SHSPZF LANTIME User Manual
Technical Information
Operating Instructions
LANTIME /
SHSPZF
ETX BGT
Contact Information
Meinberg Funkuhren GmbH & Co. KG
Auf der Landwehr 22
D-31812 Bad Pyrmont
Telephone: +49 (0) 52 81 / 9309-0
Telefax: +49 (0) 52 81 / 9309-30
Internet: http://www.meinberg.de
E-Mail: info@meinberg.de
Bad Pyrmont, 8. November 2006
Table of Contents
Quick Start..................................................................................................................... 8
NTP-Timeserver LANTIME/SHS.................................................................................9
The Modular System LANTIME.................................................................................12
Supported Network Services.............................................................................. 13
Additional Features and Options........................................................................ 14
User Interface..................................................................................................... 14
Options............................................................................................................... 14
Why to use a Network Timeserver.....................................................................15
Network Time Protocol (NTP).................................................................................... 15
NTP Target......................................................................................................... 16
NTP-Client Installation...................................................................................... 16
GPS satellite controlled clock......................................................................................18
GPS167 Features................................................................................................ 19
Time Zone and Daylight Saving.........................................................................19
Mounting the GPS Antenna.........................................................................................20
Assembly with CN-UB/E...................................................................................21
Antenna Short-Circuit........................................................................................ 21
General information DCF77 PZF................................................................................ 22
Features of PZF5xx..................................................................................................23
Antenna....................................................................................................................23
Assembly of antenna................................................................................................23
Powering Up the System..............................................................................................25
Booting the GPS receiver.............................................................................................25
Booting the Single Board Computer............................................................................26
Configuration User Interface....................................................................................... 27
The Front Panel Layout........................................................................................... 28
GPS FAIL LED.................................................................................................. 28
GPS LOCK LED................................................................................................ 28
LC Display......................................................................................................... 28
MENU Key.........................................................................................................28
CLR/ACK Key................................................................................................... 28
NEXT Key..........................................................................................................28
INC Key..............................................................................................................28
Configuration via LC Display..................................................................................29
The menus in Detail................................................................................................. 30
Root Menu..........................................................................................................30
Menu SHS State................................................................................................. 31
Menu RECEIVER POS......................................................................................31
Menu SV CONSTELLATION...........................................................................32
Menu SV POSITION......................................................................................... 32
Menu SETUP..................................................................................................... 33
SETUP SHS Time Limit.................................................................................... 34
SETUP LAN PARAMETERS........................................................................... 34
SETUP PZF PARAMETERS............................................................................ 35
SETUP TIME ZONE......................................................................................... 37
SETUP DAYLIGHT SAV ON/OFF..................................................................37
SETUP SERIAL PORT......................................................................................39
SETUP SERIAL STRING TYPE...................................................................... 39
SETUP INITIAL POSITION.............................................................................40
SETUP INITIAL TIME..................................................................................... 40
IGNORE LOCK................................................................................................. 40
INITIATE COLD BOOT................................................................................... 41
INITIATE WARM BOOT................................................................................. 41
ANTENNA CABLE...........................................................................................41
Resetting Factory Defaults of the GPS...............................................................41
Front panel PZF509................................................................................................. 42
Pilot lamps..........................................................................................................42
Display................................................................................................................42
Control keys....................................................................................................... 42
PZF Menu items................................................................................................. 43
The LANTIME configuration interfaces..................................................................... 44
The web interface.........................................................................................................45
Configuration: Main Menu...................................................................................... 46
Configuration: Ethernet........................................................................................... 47
Network interface specific configuration.................................................................49
IPv4 addresses and DHCP..................................................................................49
IPv6 addresses and autoconf.............................................................................. 49
High Availability Bonding................................................................................. 50
Additional Network Configuration.....................................................................51
Configuration: Notification......................................................................................52
Alarm events.......................................................................................................53
E-mail messages................................................................................................. 53
Windows Popup Messages.................................................................................54
SNMP-TRAP messages..................................................................................... 54
VP100/NET wall mount display........................................................................ 54
User defined Alarm scripts.................................................................................55
Alarm messages..................................................................................................55
Configuration: Security............................................................................................56
Password.............................................................................................................57
HTTP Access Control.........................................................................................57
SSH Secure Shell Login..................................................................................... 58
Generate SSL Certificate for HTTPS ................................................................ 59
NTP keys and certificates...................................................................................60
SNMP Parameter................................................................................................60
Configuration: NTP................................................................................................. 61
NTP Authentication............................................................................................64
NTP AUTOKEY................................................................................................ 66
Configuration: Local................................................................................................69
Administrative functions.................................................................................... 70
User Management...............................................................................................71
Administrative Information................................................................................ 72
Software Update................................................................................................. 74
Automatic configuration check.......................................................................... 75
Get Diagnostics Information.............................................................................. 76
Web interface language...................................................................................... 76
Configuration: Statistics.......................................................................................... 77
Statistical Information........................................................................................ 78
Configuration: Manual.............................................................................................79
The Command Line Interface...................................................................................... 81
CLI Ethernet.............................................................................................................82
CLI Notification.......................................................................................................85
Alarm events.......................................................................................................85
E-mail messages................................................................................................. 86
Windows Popup Messages.................................................................................87
SNMP-TRAP messages..................................................................................... 87
VP100/NET wall mount display........................................................................ 87
CLI Security.............................................................................................................88
Password.............................................................................................................88
SSH Secure Shell Login..................................................................................... 88
Generate SSL Certificate for HTTPS ................................................................ 89
NTP keys and certificates...................................................................................89
CLI NTP Parameter................................................................................................. 90
CLI NTP Authentication.................................................................................... 91
CLI NTP Autokey.............................................................................................. 91
CLI Local................................................................................................................. 92
Administrative functions.................................................................................... 92
User Management...............................................................................................93
Administrative information................................................................................ 93
Software Update................................................................................................. 95
SNMP Support.............................................................................................................96
Configuration over SNMP ...................................................................................... 98
Examples for the usage of the SNMP configuration features............................ 99
Further configuration possibilities....................................................................100
Send special timeserver commands with SNMP..............................................100
Configuration of the timeserver with SNMP: Reference................................. 102
SNMP Traps...........................................................................................................105
SNMP Trap Reference..................................................................................... 106
Attachment: Technical Information...........................................................................107
Skilled/Service-Personnel only: Replacing the Lithium Battery........................... 107
Technical Specifications LANTIME BGT............................................................ 107
Safety instructions for building-in equipment....................................................... 108
CE-Label................................................................................................................ 108
Rear- / Front Panel Connectors..............................................................................109
Rear View LANTIME........................................................................................... 110
SUB-D Connector Assignments............................................................................ 111
Technical Specifications GPS167..........................................................................112
Accuracy of frequency TCXO quartz (standard)..............................................113
Technical Specifications GPS167 Antenna......................................................114
Signal Description GPS167..............................................................................115
Rear Connector Pin Assignments GPS167...................................................... 116
Technical specifications PZF5xx...........................................................................117
Signal description PZF5xx............................................................................... 119
Rear Connector Pin Assignments PZF5xx....................................................... 120
Technical Specifications LAN CPU...................................................................... 121
Rear Connector Pin Assignments LAN CPU...................................................122
VGA, Keyboard Connector Pin Assignments.................................................. 122
Technical Specifications Power Supply Unit PULS AP 336-505......................... 123
Front Panel and Rear Connector Pin Assignments...........................................123
Time Strings...........................................................................................................124
Format of the Meinberg Standard Time String................................................ 124
Format of the GPS167 Capture String............................................................. 125
Format of the SAT-Time String....................................................................... 126
Format of the Uni Erlangen String (NTP) .......................................................127
Format of the NMEA 0183 String (RMC)....................................................... 129
Format of the ABB SPA Time String.............................................................. 130
Format of the COMPUTIME Time String....................................................... 131
Menu Quick Reference.......................................................................................... 132
Declaration of Conformity.....................................................................................133
Manual VP100/NET Display configuration.......................................................... 134
Global Configuration File...................................................................................... 136
Global Option File................................................................................................. 137
Third party software...............................................................................................138
Operating System GNU/Linux.........................................................................138
Samba............................................................................................................... 138
Network Time Protocol Version 4 (NTP)........................................................ 139
mini_httpd........................................................................................................ 139
GNU General Public License (GPL)................................................................140
Timecode (option)..................................................................................................144
Abstract.............................................................................................................144
Principle of Operation...................................................................................... 144
Block Diagram Timecode.................................................................................144
IRIG Standard Format...................................................................................... 145
AFNOR Standard Format.................................................................................146
Assignment of CF Segment in IEEE1344 Code.............................................. 147
Generated Time Codes..................................................................................... 148
Selection of Generated Time Code...................................................................148
Outputs............................................................................................................. 149
AM - Sine Wave Output...................................................................................149
PWM DC Output..............................................................................................149
Technical Data..................................................................................................149
USB Stick.............................................................................................................. 150
Menu Structure................................................................................................. 150
Menu Configuration Files................................................................................ 151
Menu Script Files............................................................................................. 152
Keypad locking.................................................................................................152
Reference............................................................................................................... 153
Quick Start
NORMAL OPERATION
NTP: Not Ready
Tue, 05.06.2001
MESZ 14:23:03
NORMAL OPERATION
NTP: Not Sync
Tue, 05.06.2001
MESZ 12:00:00
SHS State
act.Diff: < 1ms
GPS: sync
PZF: sync
SETUP
LAN PARAMETERS
TCP/IP ADDR DHCP
0.0.0.0
SAVE SETTINGS ?
INC -> YES
MENU -> NO
- Approximately 30 seconds after power up the lower display line shows "NTP: not
sync" instead of "NTP: not ready".
==>
- When the LANTIME/SHS is switched on the SHS STATE menu is displayed
because the two receivers (GPS and PZF) are usually not synchronized yet.
After the configured time limit is reached the LANTIME/SHS goes to normal
operation. The following notes should be taken into consideration:
- The GPS antenna/converter unit must be installed in a location from which as
much of the sky as possible can be seen (see "Mounting the GPS
antenna")
- The PZF antenna must be positioned to maximize the correlation value greater
then 60 %. Also the distance to DCF77 transmitter must be configured
- The time limit (the max. accepted time difference between GPS and PZF) has to
be set to the needed accuracy (default 10 ms)
- Enter TCP/IP address, netmask and default gateway:
- Press Menu four times to enter the LAN PARAMETERS setup menu
- Press CLR/ACK to see the TCP/IP address first
- Press CLR/ACK once again to be able to enter the IPv4 TCP/IP address
- With NEXT the respective digit is to select while INC is used to set the value
- To take over the changes it is necessary to press CLR/ACK again
- A wildcard '*' is displayed to confirm the changes
- Pressing NEXT, netmask and the default gateway can be entered
- Pressing MENU following by INC causes the changes to become active
NOTE: All settings are related to the first 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
8
NTP-Timeserver LANTIME/SHS
Secure Hybrid System with Strongly Verificated Reference Time
Meinberg LANTIME devices are Stratum-1 time servers which provide a high-
accuracy reference time to TCP/IP networks via the Network Time Protocol (NTP).
The main difference between the LANTIME models is the primary time source from
which a device derives its reference time. Primary time source options include
external radio clocks, built-in DCF77, GPS, or IRIG receivers, and even a hybrid
combination of a DCF77 and a GPS receiver.
The LANTIME/SHS/BGT (Secure Hybrid System, 19" modular case) has a built-in
hybrid radio clock which derives its reference time from both the satellite based
Global Positioning System (GPS) and long wave receiver PZF5xx. During normal
operation the hybrid radio clock passes the highly accurate reference time on to the
built-in NTP time server which makes the reference time available to the network.
In order to prevent the NTP server from spreading a faulty reference time in the
network, the hybrid receiver includes two independent standard radio clocks. Both the
satellite receiver GPS167 and the long wave receiver PZF5xx have their own signals
and high quality crystal oscillators which let the radio clocks provide accurate time
even if their primary time transmitters cannot be received for a few days.
The two radio clocks derive their time telegrams and high accuracy pulse-per-second
(PPS) signals from two independent primary time sources. The time telegrams and the
PPS signals output by the clocks are compared against each other. If either the
difference between the time telegrams or the difference between the PPS signals
exceeds a configurable limit of some milliseconds, or if one of the receivers stops
generating a time telegram, then the hybrid radio clock stops passing any timing
information to the NTP server. So the NTP server can only spread a very strongly
verificated reference time.
The radio clock modules are assembled in a 19" modular case (3UE) which also
includes a single board computer, and a power supply unit. Configurable settings can
be modified via menus on the 4 line LC display and the four buttons in the front
panel. A failure output can be used to generate an alarm signal if any malfunction is
detected.
The single board computer runs a Linux system which is loaded from flash disk into
RAM at power-up. Aside from NTP, the Linux operating system supports additional
network protocols like HTTP(S), SSH, FTP, or telnet, which allows remote
configuration or monitoring across the network, e.g. using a common web browser.
Remote access from the network can also be disabled for security reasons.
Changes in the radio clocks' receiver status, errors conditions, and other events
generate error messages which can be logged on either the local Linux system, or on
another SYSLOG server in the network. Additionally, those messages can be sent to a
management console by SNMP traps or automatic e-mails.
9
If it is necessary to provide redundancy against hardware failure then it is also
possible to install several LANTIME NTP servers in the same network.
LANTIME/SHS: Modes Of Operation
Normal mode of operation: Both the radio clocks are synchronized to their primary
time sources, the difference between the independent reference times is below the
configured limit. The NTP server receives the time information including the status
"synchronized", so it acts as Stratum-1 server and makes the reference time available
to the network.
One of the radio clocks falls out of sync e.g. due to an antenna failure or other
reception problems. The clock changes its status to "not synchronized" and continues
counting time based on its built-in high-accuracy crystal oscillator. Depending on the
configuation, it takes some days up to several weeks until the difference between the
time signals exceeds the limit. Since one of the radio clocks is still synchronized, the
timing information is passed to the NTP server with status "synchronized" until the
limit is exceeded.
Both the radio clocks are not synchronized to their primary time sources although
at least one of them has been synchronized before. As long as the time difference
doesn't exceed the limit, the time information is passed to the NTP server, but the
status included is set to "not synchronized". The NTP server keeps accepting the time
information for a given trust time, after the trust time it discards the time information.
Both the radio clocks are not synchronized to their primary time sources and have
not been synchronized after the last power-up. The hybrid clock does not pass any
time information to the NTP server until at least one of the independent radio clocks
is synchronized and the time difference between the clocks is below the configured
limit.
The radio clocks output time information with a difference which exceeds the
configured limit, or one of the radio clocks does not output any time information
at all. One of the following circumstances can be the reason why:
An intended external fake
Failure or malfunction of one of the primary time transmitters
Failure or malfunction of one of the radio clocks
Persistent reception problems
In all the cases listed above the plausibility checks on the timing information fail,
so the hybrid radio clock stops passing any timing information on to the NTP server.
The NTP server's stratum changes to a worse value to let the clients know that the
server's reference time source fails. The hybrid radio clock continues supplying time
to the NTP server after all error conditions have been removed and the error has
been acknowledged by an operator.
10
If one or more additional LANTIME NTP servers are available on the network then
clients which have been configured to use all of them will automatically discard the
LANTIME with the bad stratum and synchronize to another NTP server which is
operating correctly at a better stratum. If no redundant LANTIME is available,
however, the clients will continue to synchronize to the LANTIME with worse
stratum. This way it is guaranteed that all the client devices on the network operate
using the same system time.
All changes of the reception status of one of the radio clocks, and also failure of the
hybrid clock's plausibility check are logged by the local Linux system and optionally
reported across the network. If the hybrid receiver passes the status "not
synchronized" to the NTP server, or it has disabled time information output at all,
then the alarm signal output of the LANTIME/SHS is activated.
11
The Modular System LANTIME
LANTIME is a set of equipment composed of a satellite controlled clock GPS167,
a long wave receiver PZF5xx, a single-board computer SBC GEODE 266 MHz with
integrated network card, and a power supply unit T60B, 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.
Front View LANTIME/SHS
The implemented NTPD distributes the reference time from the SHS 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 configured 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 configuration 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.
12
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 configurable
- Autoconf Feature to be disabled
- supported network services: NTP, HTTP, HTTPS, SNMP, SSH
- Windows „net time“ via NETBIOS
- Winpopup (Window Mail)
13
Additional Features and Options
- external NTP timeserver
- free configuration of NTP: thereby MD5 authentication and access control via address & mask restriction
- extended menu guidance for configuration and monitoring via Telnet, SSH or
serial terminal interface
- optional up to 3 RJ45/10/100 Mbit Ethernet interfaces
- 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 certificates, log files and configurations, keypad locking
User Interface
- terminal connection via serial interface, status LED
- Web browser interface with graphical statistic of the one-day cycle offsets
- Telnet or Secure Shell Login for password protected operation of the Linux operating system
- FTP access for updating the operating system and downloading log files
- Simple Network Management Protocol for automatically SNMP-Traps in case of
alarm
- SYSLOG messages can be passed to different computers
- configurable e-mail notification
- Simulation of a synchronous radio clock in order to operate without antenna
Options
- up to two further Ethernet RJ45 connectors
- 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
- ANZ14/NET or VP100/20/NET as display connected via network
14
Why to use a Network Timeserver
A network timeserver should be used if accurate time is essential for undisturbed
operation. It is possible to synchronize computers in a network using Public Domain
Time servers over the Internet, but there are good reasons not to use them:
- The possibility to send notification via e-mail or SNMP-Trap to an administrator
in the event of any synchronisation failure.
- The computers in the network do not have a reliable internet connection.
- The computers in the network cannot rely on the availability of external timeservers. Most operators of these timeservers do not guarantee continuous availability nor the accuracy of their service.
- NTP is able to compensate for the propagation delay of the network packets only
in case of “usual” internet traffic. However, if unforeseen occurrences cause
badly fluctuating propagation times, it is possible that the time synchronisation
is disturbed. Reasons for this may be: hacker attacks, numerous upcoming new
viruses etc.
- An own timeserver cannot be easily compromised by external sources.
Network Time Protocol (NTP)
NTP is a common method for synchronization of hardware clocks in local und
global networks. The basic concept, version 1 [Mills88], was published in 1988 as
RFC (Request For Comments). Experiences made from the practical use in Internet
was followed by version 2 [Mills89]. The software package NTP is an
implementation of the actual version 3 [Mills90], based on the specification RFC1305 from1990 (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's way of operation is basically different from that of most other protocols. NTP
does not synchronize all connected clocks, it forms a hierarchy of timeservers and
clients. A level in this hierarchy is called a stratum, and Stratum-1 is the highest level.
Timeservers of this level synchronize themselves by a reference time source, such as
a radio controlled clock, GPS-receiver or modem time distribution. Stratum-1-Servers
distribute their time to several clients in the network which are called Stratum-2.
A high precision synchronization is feasible because of the several time references.
Every computer synchronizes itself by up to three valued time sources. NTP enables
the comparison of the hardware times and the adjustment of the own clock. A time
precision of 128 ms, often better than 50 ms, is possible.
15
NTP Target
The software package NTP was tested on different UNIX systems. Many UNIX
systems have pre-installed a NTP client. Only some configurations have to be made
(/etc/ntp.conf - see NTP Client Installation). NTP clients as freeware or shareware are
also available for the most other operating systems like Windows
XP/2000/NT/95/98/3x, OS2 or MAC. The following WEB site is recommended to
get the latest version of NTP: "http://www.eecis.udel.edu/~ntp/". More information
you can find on our web page at "http://www.meinberg.de/english/sw/ntp.htm".
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 file configures the compilation of the NTP daemon and all
tools.
configure
All necessary information from the system will be collected and the corresponding
make files 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 different ways. Either the system time can be set
once by using the tool "ntpdate lantime" or the NTPD daemon is started. In the first
case it is recommended to set the time automatically with "cron" or once when
booting the system. The second case is described below.
First a file named /etc/ntp.conf has to be generated with an editor. Adapting the file 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: Driftfile
# driftfile /etc/ntp.drift
# optional: activate all messages in syslogfile
# logconfig =all
16
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 configuration).
e.g.: tail /var/log/messages
shows the last lines from the file "messages"
The status messages can also be redirected in a log file by using the following option:
ntpd -llogfile
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:
remote refid st t when poll reach delay offset jitter
================================================================================
LOCAL(0) LOCAL(0) 3 l 36 64 3 0.00 0.000 7885
lantime .GPS. 0 l 36 64 1 0.00 60.1 15875
with the following meaning:
- remote: list of all valid time servers (ntp.conf)
- refid: 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)
- offset: difference between system time and reference time
(milliseconds)
- jitter: variance of the offsets (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 differs 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").
17
GPS satellite controlled clock
A Meinberg GPS167 satellite controlled radio clock is used as a reference time
base. The satellite receiver clock GPS167 has been designed to provide extremely
precise time to its user. The clock has been developed for applications where
conventional radio controlled clocks can not meet the growing requirements in
precision. High precision available 24 hours a day around the whole world is the main
feature of the new system which receives its information from the satellites of the
Global Positioning System.
The Global Positioning System (GPS) is a satellite-based radio-positioning,
navigation, and time-transfer system. It was installed by the United States Department
of Defence and provides two levels of accuracy: The Standard Positioning Service
(SPS) and the Precise Positioning Service (PPS). While PPS is encrypted and only
available for authorized (military) users, SPS has been made available to the general
public.
GPS is based on accurately measuring the propagation time of signals transmitted
from satellites to the user’s receiver. A nominal constellation of 21 satellites together
with 3 active spares in six orbital planes 20000 km over ground provides a minimum
of four satellites to be in view 24 hours a day at every point of the globe. Four
satellites need to be received simultaneously if both receiver position (x, y, z) and
receiver clock offset from GPS system time must be computed. All the satellites are
monitored by control stations which determine the exact orbit parameters as well as
the clock offset of the satellites' on-board atomic clocks. These parameters are
uploaded to the satellites and become part of a navigation message which is
retransmitted by the satellites in order to pass that information to the user’s receiver.
The high precision orbit parameters of a satellite are called ephemeris parameters
whereas 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 offset, 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.
18
GPS167 Features
The hardware of GPS167 is a 100 mm x 160 mm microprocessor board. The front
panel integrates a 2 x 40 character LC display, two LED indicators and 5 push
buttons. The receiver is connected to the antenna/converter unit by a 50 Ω coaxial
cable (refer to "Mounting the Antenna"). Feeding the antenna/converter occurs DC
insulated via the antenna cable. Optionally an antenna splitter for up to four receivers
connected to one antenna is available.
The navigation message coming in from the satellites is decoded by GPS167´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 the oscillators aging.
The last recent value is restored from the battery buffered memory at power-up.
Time Zone and Daylight Saving
GPS system time differs from the universal time scale (UTC) by the number of leap
seconds which have been inserted into the UTC time scale after GPS had been
initiated in 1980. The current number of leap seconds is part of the navigation
message supplied by the satellites, so GPS167´s internal real time is based on UTC.
Conversion to local time including handling of daylight saving year by year can be
done by the receiver’s microprocessor if the corresponding parameters are set up by
the GPS Monitor (included Windows software).
Internally LANTIME always runs on UTC based time. NTP calculates this UTC time
from the GPS receivers local time. The time zone of LANTIME is fixed to UTC.
However, the time monitored on the LC display is the GPS receiver's local time.
19
Mounting the GPS Antenna
Type of cable diameter
Ø [mm]
Attenuation at 100MHz
[dB]/100m
max. lenght
[m]
RG58/CU 5mm 15.9 300
1
RG213 10.5mm 6.9 700
1
1)This specifications are made for antenna/converter units produced after January, 2005
The values are typically ones; the exact ones are to find out from the data sheet of the
used cable.
The GPS satellites are not stationary but circle round the globe in 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/converter unit must be installed in a location
from which as much of the sky as possible can be seen. The best reception is given
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 a mostly free view to the equator
because of the satellite courses which are located between latitudes of 55° North and
55° South. If this is not possible problems occur especially when at least four
satellites for positioning have to be found.
The antenna/converter unit can be mounted on a pole with a diameter up to 60 mm or
on a wall. A 50 cm plastic tube, two holders for wall-mounting and clamps for pole-
mounting are added to every GPS167. A standard coaxial cable with 50 Ω impedance
should be used to connect the antenna/converter unit to the receiver. The maximum
length of cable between antenna and receiver depends on the attenuation factor of the
used coaxial cable.
Example:
Up to four GPS167 receivers can be run with one antenna/converter unit by using the
optional antenna splitter. The total length of one antenna line between antenna,
splitter and receiver must not be longer than the max. length shown in the table above.
The position of the splitter in the antenna line does not matter. When installing the
high voltage protector CN-UB/E (CN-UB-280DC) be aware to set it directly after
reaching indoor. The CN-UB/E is not for outdoor usage.
20
Assembly with CN-UB/E
Type N / BNC
male
Type N
male
Type N
male
CN-UB/E
1.5m max.
Type N
male
GPS167
Antenna
Meinberg
GPS
As short as possibl e!
ANTENNA
SHORT-CIRCUIT
DISCONNECT POWER
!!!
display:
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 in a range of 18.5 VDC (no load) and 17 V
antenna).
Antenna Short-Circuit
In case of an antenna line short-circuit the following message appears in the
(connected GPS
21
DC
General information DCF77 PZF
The German long wave transmitter DCF77 started continuous operation in 1970.
The introduction of time codes in 1973 build the basic for developing modern radio
remote clocks.
The carrier frequency of 77.5 kHz is amplitude modulated with time marks each
second. The BCD-coding of the time telegram is done by shifting the amplitude to
25% for a period of 0.1s for a logical '0' and for 0.2s for a logical '1'. The receiver
reconstructs the time frame by demodulating this DCF-signal. Because the AM-signal
is normally superimposed by interfering signals, filtering of the received signal is
required. The resulting bandwidth-limiting causes a skew of the demodulated time
marks which is in the range of 10 ms. Variations of the trigger level of the
demodulator make the accuracy of the time marks worse by additional +/-3 ms.
Because this precision is not sufficient for lots of applications, the PTB (Physical and
Technical Institute of Germany) began to spread time information by using the
correlation technique.
The DCF-transmitter is modulated with a pseudo-random phase noise in addition to
the AM. The pseudo-random sequence (PZF) contains 512 bits which are transmitted
by phase modulation between the AM-time marks. The bit sequence is build of the
same number of logical '0' and logical '1' to get a symmetrical PZF to keep the
average phase of the carrier constant. The length of one bit is 120 DCF-clocks,
corresponding to 1,55 ms. The carrier of 77.5 kHz is modulated with a phase
deviation of +/-10° per bit. The bit sequence is transmitted each second, it starts
200ms after the beginning of an AM second mark and ends shortly before the next
one.
Compared to an AM DCF77-receiver, the input filter of a correlation receiver can be
dimensioned wide-bandwidth. The incoming signal is correlated with a reconstructed
receiver-PZF. This correlation analysis allows the generation of time marks which
have a skew of only some microseconds. In addition, the interference immunity is
increased by this method because interference signals are suppressed by averaging the
incoming signal. By sending the original or the complemented bit sequence, the
BCD-coded time information is transmitted.
The absolute accuracy of the generated time frame depends on the quality of the
receiver and the distance to the transmitter, but also on the conditions of transmission.
Therefore the absolute precision of the time frame is better in summer and at day than
in winter and at night. The reason for this phenomenon is a difference in the portion
of the sky wave which superimposes the ground wave. To check the accuracy of the
time frame, the comparison of two systems with compensated propagation delay is
meaningful.
22
Features of PZF5xx
The PZF5xx is a high precision receive module for the DCF77-signal build in euro
card size (100 mm x 160 mm).
The micro controller of the system correlates its receiver-PZF with the incoming
pseudorandom sequence and decodes the time information of the DCF-telegram
simultaneously. The controller handles input and output functions of the PZF5xx and
synchronizes the internal real-time clock.
By evaluating the pseudorandom phase noise, the PZF5xx is able to generate time
frames with thousand times the accuracy of standard AM-time code receivers. The
precise regulation of the main oscillator (TCXO, OCXO optional for higher accuracy)
of the radio clock is possible therefore. So, the PZF5xx can be used as a standard
frequency generator besides the application as a time code receiver. Six fixed and one
settable TTL-level standard frequencies are available at the rear VG-connector. The
synthesizer frequency exists as an open drain output and a sine wave signal also.
The PZF5xx delivers TTL-low and TTL-high active pulses per minute and per second
further. To distribute information concerning date, time and status, two independent
serial interfaces (RS232) are used which are configurable in a setup menu.
Like mentioned before, the PZF5xx includes a battery-backed real-time clock which
runs crystal-precise if the main power supply fails.
Important system parameters are stored in a battery-backed (RAM of the RTC) or
non-volatile (EEPROM) memory.
If an update of system software becomes necessary, the new firmware can be loaded
via serial interface (COM0) without removing the PZF5xx for inserting a new
EPROM.
Antenna
The PZF5xx operates with a ferrite antenna which is damped to match the
bandwidth needed for the correlation reception.
Assembly of antenna
The antenna has to be mounted as exactly as possible. Turning it out of the main
receive direction will result in less accurate time frames. The antenna must be placed
in longitudinal direction to the DCF-transmitter (Frankfurt). The nearness to
microcomputers should be avoided and the antenna should be installed with a
minimum distance of 30cm to all metal objects, if possible. A distance of several
meters to TV- or computer monitors must be kept.
After switching the PZF5xx to the menu 'PZF STATE', the adjustment of the antenna
can be executed. The displayed value is proportional to the received field strength.
23
The best method of mounting the antenna is to look for the minimum field strength
and turn the antenna by 90° to maximum then. A high field strength on its own is no
guarantee for good conditions of reception, because interfering signals within the
bandwidth of the receiver also have an effect on the displayed value.
The maximum interference immunity can be found by looking at the autocorrelation
coefficient (in percent) in the menu 'PZF-STAT'. The displayed value should be close
to 75 % for best reception.
24
Powering Up the System
Server not ready
NTP: Not Ready
Tue, 05.06.2001
MESZ 14:23:03
When the LANTIME/SHS is switched on the SHS STATE menu is displayed
because the two receivers (GPS and PZF) are usually not synchronized yet. After the
configured time limit is reached the LANTIME/SHS goes to normal operation. The
following notes should be taken into consideration:
- the GPS antenna/converter unit must be installed in a location from which as
much of the sky as possible can be seen (see "Mounting the GPS antenna")
- the PZF antenna must be positioned to optimise the correlation better than 60 %
- the distance to the German long wave transmitter have to be configured
- the time limit (the max. accepted time difference between GPS and PZF) has to
be set to the needed accuracy (default 10 ms)
Some menues can be called not before the single board computer has booted. Because
of this the state menues for the PZF and the setup for the LAN parameters can not be
edited until the bootphase has finished (approx. 1 minute).
Booting the GPS receiver
If both the antenna and the power supply have been connected the system is ready
to operate. About 10 seconds after power-up the receiver’s oscillator has warmed up
and operates with the required accuracy. If the receiver finds valid almanac and
ephemeris data in its battery buffered memory and the receiver’s position has not
changed significantly since its last operation the receiver can find out which satellites
are in view now. Only a single satellite needs to be received to synchronize and
generate output pulses, so synchronization can be achieved maximally one minute
after power-up.
If the receiver position has changed by some hundred kilometres since last operation,
the satellites´ real elevation and Doppler might not match those values expected by
the receiver thus forcing 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 had been disconnected the receiver has to scan for a satellite
and read in the current almanacs. 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.
25
Booting the Single Board Computer
NORMAL OPERATION
NTP: Not Ready
Tue, 05.06.2001
MESZ 14:23:03
NORMAL OPERATION
NTP: Not Sync
Tue, 05.06.2001
MESZ 12:00:00
NORMAL OPERATION
NTP: Offs:3ms
Thu, 05.06.2001
MESZ 12:00:00
The LINUX operating system is loaded from a packed file on the flash disk of the
single board computer to a RAM disk. All files of the flash disk are stored in the
RAM disk after booting. Because of that it is guaranteed that the file system is in a
defined condition after restart. This boot process takes approx. one minute. During
this time the following message appears on the display:
Once per second the GPS compares the GPS time with the PZF5xx time. Both the
pulses per second and the serial time strings are compared. If the calculated deviation
exceeds the configured time limit or one of the receiver stops generating time strings
or pulses, the hybridsystem stops sending time information to the NTP server. Once
the hybridsystem sent a time string, the NTP daemon is started with the
corresponding parameters. After that the NTPD starts synchronisation with the
references. The references are usually the RTC of the single board computer, the
serial time string and the pulse per second (PPS) from the hybridsystem. If the NTPD
is started but not synchronous with the hybridsystem yet, the following message is
displayed:
For the synchronisation of the NTPD with the GPS it is necessary that the GPS
receiver is synchronous with the GPS time (LOCK LED is turned on). Also the time
difference between the GPS und PZF receiver must be less then the time limit error.
In this case the following message is monitored on the display:
The second line shows the user that the NTPD is synchronized with the GPS with an
offset of -3 ms. 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 offset. The
NTPD tries to keep the offset below ±128 ms; if the offset becomes too large the
system time is set with the GPS time. Typically values for the offset are +-5 ms after
the NTPD has already synchronized. If NTPD is not synchronised and GPS receiver
is then, the green LOCK-LED is blinking.
26
Configuration User Interface
There are several ways to configure the LANTIME parameters:
Command Line Interface (CLI) via TELNET
Command Line Interface via SSH
Command Line Interface via serial interface terminal (BGT versions only)
HTTP Interface
Secure HTTP Interface (HTTPS)
Front panel LCD Interface
SNMP Management
To put LANTIME into operation for the first time an IP address is entered via the
front panel keys and LC display (refer to: DHCP IPv4 or AUTOCONF IPv6).
LANTIME variants without LC display have to be given the IP address via the serial
interface in the front panel, running a terminal software e.g. on a laptop. If once the
IPv4 address, netmask and IPv4 GATEWAY are configured, or the network interface
is initialised by IPv6 SCOPE-LINK, the LANTIME is accessible from any computer
in the network (remote).
To set up a TELNET connection the following commands are entered:
telnet 198.168.10.10 // LANTIME IP address
user: root
password: timeserver
With “setup” the configuration program is started.
To set up a SSH connection the following commands are entered:
ssh root@198.168.10.10 // LANTIME IP address
password: timeserver
With “setup” the configuration program is started.
To set up a HTTP connection the following address is to enter in a web browser:
http://198.168.10.10 // LANTIME IP address
password: timeserver
To set up a Secure HTTP (HTTPS) connection the following address is entered in a
web browser:
https://198.168.10.10 // LANTIME IP address
password: timeserver
27
The Front Panel Layout
GPS FAIL LED
The FAIL LED is turned on whenever the TIME_SYN output is low (receiver is
not synchronized).
GPS LOCK LED
The LOCK LED is turned on when after power-up the receiver has acquired at least
four satellites and has computed its position. In normal operation the receiver position
is updated continuously as long as at least four satellites can be received. The LOCK
LED is blinking when the GPS has locked and the NTP is not synchronized. If a time
limit error occurs both LEDs FAIL and LOCK are blinking.
LC Display
The 4 x 16 character LC display is used to show the receiver’s status and let the
user edit parameters. The keys described below let the user select the desired menu.
The next chapter lists all available menus in detail. A quick reference of the available
menus and submenus can be found at the end of this document.
MENU Key
This key lets the user step through several display menus showing specific data.
CLR/ACK Key
This key has to be used when parameters are to be modified. When this key is
pressed the parameters that have been edited are saved in the battery buffered
memory. If the menu is left without pressing CLR/ACK all changes are discarded.
NEXT Key
When editing parameters (LCD cursor is visible) this key moves the cursor to the
next digit with respect to the next parameter to be edited. If the current menu just
displays data (cursor not visible) pressing this key switches to a submenu (if
available).
INC Key
When editing parameters this key increments the digit or letter at the cursor
position.
28
Configuration via LC Display
On first installation of LANTIME the network parameters can only be configured
by the front panels push buttons and the LC display. Press MENU until the SETUP
menus appear on the display. The first setup menu are the LAN PARAMETERS.
Pressing NEXT further setup menus appear. Pressing CLR/ACK the LAN
PARAMETERS menu is entered. The submenu TCP/IP ADDRESS appears. Pressing
NEXT the following submenus can be chosen: NET MASK, DEFAULT
GATEWAY, IPv6 address, HOSTNAME, DOMAINNAME, NAMESERVER and
REMOTE CONNECT. CLR/ACK lets the user enter the corresponding submenu to
make changes with NEXT and INC. Pressing CLR/ACK after changing parameters
acknowledges the changes. Leaving the menu with MENU all changes are discarded
and the setup menu is displayed again. All changed settings of the LAN
PARAMETER’s sub menu come into affect not before MENU is pressed once again
and the changes are confirmed.
The unique 32 bit TCP/IP address must be set by the network administrator. The net
mask will be defined by the network. It is probable that you will need to set up the
default gateway also.
The correct connection to the LANTIME can be reviewed from any other workstation
in the network with the program PING.
REMOTE CONNECT lets the user enable or disable all connections via network (e.g.
TELNET, FTP or HTTP). If changes occur via HTTP interface or setup program the
message “REMOTE CONNECT: partial enabled” may appear. The NTP protocol will
restart after any change.
NOTE: Any HTTP, HTTPS, SSH or TELNET connection to the LANTIME is
possible only if REMOTE CONNECT is enabled!
29
The menus in Detail
NORMAL OPERATION
NTP: Offs:3ms
Thu, 05.06.2001
MESZ 12:00:00
LANTIME:2.00
S/N:10000110
GPS167 :2.06
S/N:10000110
RECEIVER INFO
PROUT: 0 NCOM:2
SYNTH: n/a
TCXO_LQ gps167_3
1024 8c:2c:72:5e
:9b:5b:10:83:c9:
c8:eb:7d:49 tim
eserver
NTP:4.0.99f
OS:2.2.14.01
MAC:000000000000
Meinberg
Root Menu
The root menu is shown when the receiver has completed initialisation after powerup. The left side of the first line of the display shows the receiver’s mode of operation
as described above. The text "NORMAL OPERATION" might be replaced by
"COLD BOOT", "WARM BOOT" or "UPDATE ALMANAC". If the antenna is
disconnected or not working properly, the text "ANTENNA FAULTY" is displayed
instead.
On the right side of the display the current date, the name of the time zone (as defined
in the setup menu) and local time are monitored. If the "IGNORE LOCK" option is
enabled an "*" will be shown behind the time.
If the NEXT key is pressed from the root menu a submenu is displayed showing the
receiver’s software revision of the LANTIME software and the GPS167 flash
software:
If the NEXT key is pressed twice from the root menu a submenu is displayed showing
the NTP software version, the operating system version and the MAC address of the
integrated net card.
Pressing NEXT the third time the fingerprint of the SSH key is displayed:
Pressing NEXT the fourth time the receiver info is displayed:
30
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