Meinberg TCR51USB - Manual (Page 8)

8
Features TCR51USB
The TCR51USB was developed for computer systems with USB connection.
TCR51USB serves to receive and decode modulated (AM) and unmodulated (DC Level
Shift) IRIG and AFNOR time codes. AM-codes are transmitted by modulating the
amplitude of a sine wave carrier, unmodulated codes by variation of the width of pulses.
Automatic gain control within the receive circuit for modulated codes allows decoding
of IRIG signals with a carrier amplitude of 600 mVpp to 8 Vpp. The input stage is
electrically insulated and has an impedance of 50
Ω, it is accessible via the SMB-jack
connector in the housing of TCR51USB.
The unmodulated time codes must be connected to the second SMB jack connector.
An onboard photocoupler insulates the internal receive circuit.
Software running on the computer can read out information regarding date, time and
status of the IRIG receiver. Access to the board is made via writing to/reading from I/O
ports. It is possible but not necessarry to let the board generate periodic hardware
interrupts on the USB Bus.
The microprocessor system of TCR51USB is equiped with a Bootstrap-Loader and a
Flash-EPROM. These features enable updating of the onboard software.