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<HTML>
<HEAD>
<META NAME="GENERATOR" CONTENT="Adobe PageMill 3.0 per Windows">
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<TITLE>PTB Modem Time Service </TITLE>
</HEAD>
<BODY>
<H3>PTB Modem Time Service and other European Laboratories Time
Services</H3>
<HR ALIGN=LEFT>
<H4>Synopsis</H4>
<P>Address: 127.127.23.<I>u</I> <BR>
Reference ID: <TT>PTB</TT> <BR>
Driver ID: <TT>ACTS_PTB</TT><BR>
Serial Port: <TT>/dev/ptb<I>u</I></TT>; 1200 baud, 8-bits, no
parity <BR>
Requires: <TT>/usr/include/sys/termios.h</TT> header file with
modem control</P>
<H4>Description</H4>
<P>This driver supports the PTB Automated Computer Time Service
(ACTS) and it is a modified version of the NIST ACTS driver so
see it for more informations..</P>
<P>It periodically dials a prespecified telephone number, receives
the PTB timecode data and calculates the local clock correction.
It designed primarily for use when neither a radio clock nor connectivity
to Internet time servers is available. For the best accuracy,
the individual telephone line/modem delay needs to be calibrated
using outside sources.</P>
<P>The only change between this driver and the NIST one is the
data format. Infact PTB data format is the following:</P>
<P><FONT SIZE="-1" FACE="Courier New">Data format<BR>
0000000000111111111122222222223333333333444444444455555555556666666666777777777
7<BR>
0123456789012345678901234567890123456789012345678901234567890123456789012345678
9<BR>
1995-01-23 20:58:51 MEZ 10402303260219950123195849740+40000500
*<BR>
A B C D EF G H IJ K L M N O P Q R S T U V W
XY Z<CR><LF><BR>
A year<BR>
B month<BR>
C day<BR>
D hour<BR>
E : normally<BR>
A for DST to ST switch first hour<BR>
B for DST to ST switch second hour if not marked in H<BR>
F minute<BR>
G second<BR>
H timezone<BR>
I day of week<BR>
J week of year<BR>
K day of year<BR>
L month for next ST/DST changes<BR>
M day<BR>
N hour<BR>
O UTC year<BR>
P UTC month<BR>
Q UTC day<BR>
R UTC hour<BR>
S UTC minute<BR>
T modified julian day (MJD)<BR>
U DUT1<BR>
V direction and month if leap second<BR>
W signal delay (assumed/measured)<BR>
X sequence number for additional text line in Y<BR>
Y additional text<BR>
Z on time marker (* - assumed delay / # measured delay)<BR>
<CR>!<LF> ! is second change !<BR>
</FONT><BR>
This format is an ITU-R Recommendation (ITU-R TF583.4) and is now available from the primary
timing centres of the following countries:
Austria, Belgium, Germany, Italy, The Netherlands, Poland, Portugal, Romania, Spain, Sweden,
Switzerland, Turkey, United Kingdom.
Some examples are:
</P>
<UL>
<LI>In Germany by Physikalisch-Technische Bundesanstalt (PTB)'s
timecode service. Phone number: +49 5 31 51 20 38.
</UL>
<BLOCKQUOTE>
<P>For more detail, see <A HREF="http://www.ptb.de/english/org/4/43/433/disse.htm">http://www.ptb.de/english/org/4/43/433/disse.htm</A></P>
</BLOCKQUOTE>
<UL>
<LI>In the UK by National Physical Laboratory (NPL)'s TRUETIME
service. Phone number: 0891 516 333
</UL>
<BLOCKQUOTE>
<P>For more detail, see <A HREF="http://www.npl.co.uk/npl/ctm/truetime.html">http://www.npl.co.uk/npl/ctm/truetime.html</A></P>
</BLOCKQUOTE>
<UL>
<LI>In Italy by Istituto Elettrotecnico Nazionale "Galileo
Ferrais" (IEN)'s CTD service. Phone number: 166 11 46
15
</UL>
<BLOCKQUOTE>
<P>For more detail, see <A HREF="http://www.ien.it/tf/time/Pagina42.html">http://www.ien.it/tf/time/Pagina42.html</A></P>
</BLOCKQUOTE>
<UL>
<LI>In Switzerland by Swiss Federal Office of Metrology 's timecode
service. Phone number: 031 323 32 25
</UL>
<BLOCKQUOTE>
<P>For more detail, see <A HREF="http://www.ofmet.admin.ch/de/labors/4/Zeitvert.html%20">http://www.ofmet.admin.ch/de/labors/4/Zeitvert.html
</A></P>
</BLOCKQUOTE>
<UL>
<LI>In Sweden by SP Swedish National Testing and Research Institute
's timecode service. Phone number: +46 33 415783
</UL>
<BLOCKQUOTE>
<P>For more detail, see <A HREF="http://www.sp.se/pne/ElectricalMetrology/ElMeteng/frameset.htm">http://www.sp.se/pne/ElectricalMetrology/ElMeteng/frameset.htm</A><BR>
<BR>
</P>
</BLOCKQUOTE>
<H4>Fudge Factors</H4>
<DL>
<DT><TT>time1 <I>time</I></TT>
<DD>Specifies the time offset calibration factor, in seconds
and fraction, with default 0.0.
<DT><TT>time2 <I>time</I></TT>
<DD>Not used by this driver.
<DT><TT>stratum <I>number</I></TT>
<DD>Specifies the driver stratum, in decimal from 0 to 15, with
default 0.
<DT><TT>refid <I>string</I></TT>
<DD>Specifies the driver reference identifier, an ASCII string
from one to four characters, with default PTB.
<DT><TT>flag1 0 | 1</TT>
<DD>Not used by this driver.
<DT><TT>flag2 0 | 1</TT>
<DD>Not used by this driver.
<DT><TT>flag3 0 | 1</TT>
<DD>Not used by this driver.
<DT><TT>flag4 0 | 1</TT>
<DD>Not used by this driver.
</DL>
<P>Additional Information</P>
<P>A keyword in the ntp.conf file permits a direct connection
to a serial port of source of time like IEN CTD signal. It is
sufficient to use the string DIRECT in place of the phone number.</P>
<P>Example:</P>
<P><FONT FACE="Courier New">server 127.127.23.1</FONT></P>
<P><FONT FACE="Courier New">phone DIRECT</FONT></P>
<P><A HREF="refclock.htm">Reference Clock Drivers</A> <HR ALIGN=LEFT></P>
<ADDRESS>by Marco Mascarello (masca@tf.ien.it) for David L. Mills
(mills@udel.edu)</ADDRESS>
</BODY>
</HTML>
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