Meinberg PZF600 - Manual (Page 17)

17
Asynchronous serial interfaces
Four independant serial RS232 interfaces are available at the rear connector of the
PZF600. As set in menu SER.MODE, the serial ports can send a time string either once
per second, once per minute or on request only by sending an ASCII '?' (3F hex) to the
clock. Additional menus are used to set the framing and baudrate of these interfaces as
well as the format of the time string. The structure of the strings are described in the
chapter "Time Strings".
Pulse outputs
TTL-low and TTL-high active pulses per minute and per second are generated by the
PZF600, which are available at the VG-connector.
Corresponding to the settings made in the menu OUTP ENA, the pulses are generated
either immediately after power up or not until the first synchronisation of the receiver
occurs.
Standard frequencies
The PZF600 provides four standard frequencies. The outputs 100kHz, 155kHz, 1MHz
and 10MHz are derived from the main oszillator of the clock which is phase locked to the
DCF-system by a digital PLL (phase locked loop). The temperature-dependant drift and
the aging of the oszillator can be compensated by this procedure. Therefore the excellent
short-term stability of the standard frequencies of +/- 5·10
-9 (standard version with
TCXO) is achieved. The value for regulating the digital-to-analog converter of the PLL
is avilable directly after reset because it is stored in the battery-backed RAM of the clock.
If the DCF-transmitter fails, the oszillator is controled by this value also. The accuracy of
the standard frequencies will not be worse than 1·10
-8 for one hour without receition
therefore.