PTB Modem Time Service

### 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/metrology/timefreq/eng/tandf.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

#### Additional Information

Reference Clock Drivers