1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<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>
<link href="../scripts/style.css" type="text/css" rel="stylesheet">
</head>
<body>
<h3>PTB Modem Time Service and other European Laboratories Time Services</h3>
<hr>
<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></p>
<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>
<ul>
<li>In Germany by Physikalisch-Technische Bundesanstalt (PTB)'s timecode service. Phone number: +49 5 31 51 20 38.
<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>
<li>In the UK by National Physical Laboratory (NPL)'s TRUETIME service. Phone number: 0891 516 333
<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>
<li>In Italy by Istituto Elettrotecnico Nazionale "Galileo Ferrais" (IEN)'s CTD service. Phone number: 166 11 46 15
<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>
<li>In Switzerland by Swiss Federal Office of Metrology 's timecode service. Phone number: 031 323 32 25
<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>
<li>In Sweden by SP Swedish National Testing and Research Institute 's timecode service. Phone number: +46 33 415783.
<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>
</p>
</ul>
<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>
<h4>Additional Information</h4>
<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>
<h4>Additional Information</h4>
<p><a href="../refclock.html">Reference Clock Drivers</a></p>
<hr>
<script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script>
</body>
</html>
|
