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13 <h3>PTB Modem Time Service and other European Laboratories Time Services</h3>
16 <p>Address: 127.127.23.<i>u</i><br>
17 Reference ID: <tt>PTB</tt><br>
18 Driver ID: <tt>ACTS_PTB</tt><br>
19 Serial Port: <tt>/dev/ptb<i>u</i></tt>; 1200 baud, 8-bits, no parity<br>
20 Requires: <tt>/usr/include/sys/termios.h</tt> header file with modem control</p>
22 <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>
23 <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>
24 <p>The only change between this driver and the NIST one is the data format. Infact PTB data format is the following:</p>
25 <p><font size="-1" face="Courier New">Data format<br>
26 0000000000111111111122222222223333333333444444444455555555556666666666777777777 7<br>
27 0123456789012345678901234567890123456789012345678901234567890123456789012345678 9<br>
28 1995-01-23 20:58:51 MEZ 10402303260219950123195849740+40000500 *<br>
29 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>
35 A for DST to ST switch first hour<br>
36 B for DST to ST switch second hour if not marked in H<br>
43 L month for next ST/DST changes<br>
51 T modified julian day (MJD)<br>
53 V direction and month if leap second<br>
54 W signal delay (assumed/measured)<br>
55 X sequence number for additional text line in Y<br>
57 Z on time marker (* - assumed delay / # measured delay)<br>
58 <CR>!<LF> ! is second change !<br>
60 <p>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>
62 <li>In Germany by Physikalisch-Technische Bundesanstalt (PTB)'s timecode service. Phone number: +49 5 31 51 20 38.
63 <p>For more detail, see <a href="http://www.ptb.de/english/org/4/43/433/disse.html">http://www.ptb.de/english/org/4/43/433/disse.htm</a></p>
64 <li>In the UK by National Physical Laboratory (NPL)'s TRUETIME service. Phone number: 0891 516 333
65 <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>
66 <li>In Italy by Istituto Elettrotecnico Nazionale "Galileo Ferrais" (IEN)'s CTD service. Phone number: 166 11 46 15
67 <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>
68 <li>In Switzerland by Swiss Federal Office of Metrology 's timecode service. Phone number: 031 323 32 25
69 <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>
70 <li>In Sweden by SP Swedish National Testing and Research Institute 's timecode service. Phone number: +46 33 415783.
71 <p>For more detail, see <a href="http://www.sp.se/metrology/timefreq/eng/tandf.htm">http://www.sp.se/metrology/timefreq/eng/tandf.htm</a><br>
74 <h4>Fudge Factors</h4>
76 <dt><tt>time1 <i>time</i></tt>
77 <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0.
78 <dt><tt>time2 <i>time</i></tt>
79 <dd>Not used by this driver.
80 <dt><tt>stratum <i>number</i></tt>
81 <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0.
82 <dt><tt>refid <i>string</i></tt>
83 <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default PTB.
84 <dt><tt>flag1 0 | 1</tt>
85 <dd>Not used by this driver.
86 <dt><tt>flag2 0 | 1</tt>
87 <dd>Not used by this driver.
88 <dt><tt>flag3 0 | 1</tt>
89 <dd>Not used by this driver.
90 <dt><tt>flag4 0 | 1</tt>
91 <dd>Not used by this driver.
93 <h4>Additional Information</h4>
94 <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>
96 <p><font face="Courier New">server 127.127.23.1</font></p>
97 <p><font face="Courier New">phone DIRECT</font></p>
98 <h4>Additional Information</h4>
99 <p><a href="../refclock.html">Reference Clock Drivers</a></p>
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