Operating Manual Vol 1 - ES Documentation

Digital ModulationSMIQ2.10.5.1 External Serial Modulation DataSerial modulation data can be fed bit-by-bit via connector DATA. For modulation types with more than1 bit/symbol, the MSB is applied first (MSB first). Either an external bit clock or symbol clock or theinternal clock can be used. The symbol clock serves as strobe to mark the LSB of a symbol. If anexternal bit clock is applied, the data at the active clock edges have to be in a stable state. With externalsymbol clock, the bit clock for reading the data is internally generated in the modulation coder (internaldata clock). The following figures show the timing at the interface. In all the cases shown, the activeclock edge is assumed to be positive.DATA (input)BIT CLOCK (input)Fig. 2-54External serial data and bit clockData change should take place only on the negative clock edge.DATA (input)SYMBOL CLOCK (input)Internal dataclockMSBLSBFig. 2-55External serial data and symbol clock, 3 bit/symbolSYMBOL CLOCK = High marks the LSB. A status change of DATA and SYMBOL CLOCKshould be performed synchronously.BIT CLOCK (output)SYMBOL CLOCK (output)DATA (input)Internal dataclockMSBLSBFig. 2-56External serial data, internal clock signalsExternal serial modulation data is selected in the menu by SOURCE-SOURCE-EXT_SER.1125.5555.03 2.96E-9