Meinberg TCR511PEX - Manual (Page 13)

13
Input impedance
The IRIG-specification doesn’t define values for the output impedance of generators or
the input impedance of receivers. This fact led to incompatibility of some modules,
because the manufacturers could choose the impedances freely. For example: if the
output impedance of the generator is high and the input impedance of the receiver low,
the signal level at the receiver input might be too low for correct decoding. Therefore the
board TCR511PEX contains a jumper to select the impedance (50
Ω, 600 Ω or 5 kΩ) of
the input for modulated codes (BNC) to comply with the requirements of several
systems.
Meinberg IRIG-generators have an output impedance of 50
Ω Ω Ω Ω Ω, to build a matched
transmission system when using a coaxial cable. If such a generator is used to synchroni-
ze TCR511PEX, the input impedance has to be set to 50
Ω accordingly (default on
delivery).
In addition to the telegram, the AFNOR-code defines the input/output impedances
also. If TCR511PEX is synchronized by this code, an input impedance of 600
Ω Ω Ω Ω Ω must be
set.
The setting „5 k
Ω“ may be necessary if the generator has a high output impedance (see
specifications of manufacturer). The driver software shows a bar chart for evaluation of
the signal level at the receiver input.
The following detail of the placeplan of TCR511PEX shows the possible jumper
setting with the related input impedance:
No jumper set: 5K Ohm
Jumper in this Position: 50 Ohm
Jumper in this Position: 600 Ohm