Comtech EF Data CDM-750 - Manual (Page 89)

CDM-750 Advanced High-Speed Trunking Modem Revision 2
Front Panel Operation MN-CDM750
5–11
slaved to this fixed data rate and will change when modulation, coding, pilots or Tx frame block
size is changed. Selection of these interfaces may not be possible if the symbol rate license or
CnC license will not support the symbol rate or data rate.
(CONFIG: INTF) PIICX (G.703)
Æ ClkSource
Clock Source: ExtClock TxClock RxClock
1 MHz TXC RXS ()
Use the W X arrow keys to select ExtClock, TxClock, or RxClock, and then press ENTER. The
bottom line displays the current setting for each parameter.
(CONFIG: INTF) PIICX (G.703) Æ ClkSourceÆ ExtClock
ExtClock: 1 MHz
()
To set the expected clock rate for the external clock source located on the J8 | Ext Ref BNC
connector: Use the ST arrow keys to select 1 MHz, 2 MHz, 5 MHz, 10 MHz, 20 MHz, 34.368
MHz (E3), 44.736 MHz (T3), or 51.840 MHz (STS1), and then press ENTER.
(CONFIG: INTF) PIICX (G.703)
Æ ClkSourceÆ TxClock
Tx Clock Source: TX CLK
()
To lock the Tx symbol rate of the modulator to the appropriate clock source: Use the ST arrow
keys to select EXT CLK, RX SAT, or TX CLK, and then press ENTER.
Comtech EF Data strongly suggests that TX CLK is selected here, unless a high
stability EXT CLK is present and timing of the network requires all devices to be
locked to the EXT CLK.
(CONFIG: INTF) PIICX (G.703) Æ ClkSourceÆ RxClock
Rx Clock Source: RX CLK
()
To set the clock source by which Rx data will be clocked out of the G.703 interface to the
external baseband equipment: Use the ST arrow keys to select RX SAT, INT CLK, TX CLK, or
EXT CLK, and then press ENTER.
Comtech EF Data strongly suggests that RX CLK is selected here, unless a high
stability EXT CLK is present and timing of the network requires all devices to be
locked to the EXT CLK.