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.
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.