PTB Modem Time Service and other European Laboratories Time Services

Synopsis

Address: 127.127.23.u
Reference ID: PTB
Driver ID: ACTS_PTB
Serial Port: /dev/ptbu; 1200 baud, 8-bits, no parity
Requires: /usr/include/sys/termios.h header file with modem control

Description

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..

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.

The only change between this driver and the NIST one is the data format. Infact PTB data format is the following:

Data format
0000000000111111111122222222223333333333444444444455555555556666666666777777777 7
0123456789012345678901234567890123456789012345678901234567890123456789012345678 9
1995-01-23 20:58:51 MEZ 10402303260219950123195849740+40000500 *
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>
A year
B month
C day
D hour
E : normally
A for DST to ST switch first hour
B for DST to ST switch second hour if not marked in H
F minute
G second
H timezone
I day of week
J week of year
K day of year
L month for next ST/DST changes
M day
N hour
O UTC year
P UTC month
Q UTC day
R UTC hour
S UTC minute
T modified julian day (MJD)
U DUT1
V direction and month if leap second
W signal delay (assumed/measured)
X sequence number for additional text line in Y
Y additional text
Z on time marker (* - assumed delay / # measured delay)
<CR>!<LF> ! is second change !

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:

• In Germany by Physikalisch-Technische Bundesanstalt (PTB)'s timecode service. Phone number: +49 5 31 51 20 38.

For more detail, see http://www.ptb.de/english/org/4/43/433/disse.htm

• In the UK by National Physical Laboratory (NPL)'s TRUETIME service. Phone number: 0891 516 333

For more detail, see http://www.npl.co.uk/npl/ctm/truetime.html

• In Italy by Istituto Elettrotecnico Nazionale "Galileo Ferrais" (IEN)'s CTD service. Phone number: 166 11 46 15

For more detail, see http://www.ien.it/tf/time/Pagina42.html

• In Switzerland by Swiss Federal Office of Metrology 's timecode service. Phone number: 031 323 32 25

For more detail, see http://www.ofmet.admin.ch/de/labors/4/Zeitvert.html

• In Sweden by SP Swedish National Testing and Research Institute 's timecode service. Phone number: +46 33 415783

For more detail, see http://www.sp.se/pne/ElectricalMetrology/ElMeteng/frameset.htm

Fudge Factors

time1 time

Specifies the time offset calibration factor, in seconds and fraction, with default 0.0.

time2 time

Not used by this driver.

stratum number

Specifies the driver stratum, in decimal from 0 to 15, with default 0.

refid string

Specifies the driver reference identifier, an ASCII string from one to four characters, with default PTB.

flag1 0 | 1

Not used by this driver.

flag2 0 | 1

Not used by this driver.

flag3 0 | 1

Not used by this driver.

flag4 0 | 1

Not used by this driver.

Additional Information

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.

Example:

server 127.127.23.1

phone DIRECT

Reference Clock Drivers