Meinberg GEN170TGP - Manual (Page 21)

21
Selection of Generated Time Code
The time code to be generated can be selected by Menu Setup TIMECODE OUT.
DC-Level Shift Codes (PWM signal) B00x and modulated sine wave carrier B12x are
always generated simultaneously. Both signals are provided at the VG64-Connector,
i.e. if code B122 is selected also code B002 is available. This applies for the codes
AFNOR NFS 87-500 and IEEE1344 as well.
The TFOM field in IEEE1344 code is set dependent on the 'already sync'ed' character
('#') which is sent in the serial time telegram. This character is set, whenever the
preconnected clock was not able to synchronize after power up reset. The 'time figure of
merit' (TFOM) field is set as follows.
Clock synchronized once after power up : TFOM = 0000
Clock not synchronized after power up : TFOM = 1111
For testing purposes the output of TFOM in IEEE1344 mode can be disabled. The
segment is then set to all zeros.
Outputs
The module GEN170-TC provides modulated and unmodulated (DC-Level Shift)
outputs. The format of the time codes is illustrated "IRIG-" and "AFNOR standardfor-
mat".
AM Sine Wave Output
The amplitude-modulated carrier is available at the VG connector pin 6a. The carrier
frequency depends on the code and has a value of 1 kHz (IRIG-B). The signal amplitude
is 3V
pp
(MARK) and 1V
pp
(SPACE) into 50
Ω. The encoding is made by the number of
MARK amplitudes during ten carrier waves. The following agreements are valid:
a) binary "0" : 2 MARK amplitudes, 8 SPACE amplitudes
b) binary "1" : 5 MARK amplitudes, 5 SPACE amplitudes
c) position-identifier : 8 MARK amplitudes, 2 SPACE amplitudes
PWM DC Output
The pulse width modulated DC signals labeled "IRIG" and "AFNOR standard format"
are coexistent to the modulated output and is available at the VG connector pin 13a with
TTL level.
Technical Data
Outputs:
Unbalanced AM sine wave signal: 3V
PP
(MARK) / 1V
PP
(SPACE) into 50
Ω
PWM signal: TTL (2,5V into 50
Ω), active high