Comtech EF Data CDM-625 - Manual (Page 130)

CDM-625 Advanced Satellite Modem Revision 15
Front Panel Operation MN-CDM625
5–30
5.2.1.5.2 CONFIG: Clocks  Rx Buffer/Clock
Clk=Rx-Sat (Rx-Sat,TxTerr,Int(SCT),Ins)
Buffer-Size = 00016bytes(00002ms) Center
Use the ◄ ► arrow keys to set the Rx Clock (top line) or the Buffer-Size (bottom line).
On the top line – To set the Rx Clock, use the ▲▼ arrow keys to select Rx-Sat, Tx-Terr, Int
(SCT), or Ins, and then press ENTER. Note the following:
Selection Function
Rx-Sat
Sets the Receive buffer clock source to the satellite clock (the receive buffer is bypassed).
Note: This will fix the buffer size to minimum.
Tx-Terr In this timing mode, data is clocked out of the receive buffer using the external transmit clock.
Int(SCT) Data is clocked out of the buffer using the same reference that drives the modem Internal(SCT).
Ins(ert)
Available only if Rx framing is D&I and Rx interface is G.703. Sets the buffer clock to the Insert
stream.
On the bottom line – To set the Buffer-Size, use the ◄ ► arrow keys to select a digit to edit, and
then use the ▲▼ arrow keys to change that digit. Press ENTER when done.
Buffer Size indicates the size in bytes (and size in milliseconds) of the Plesiochronous
/ Doppler Buffer. The minimum buffer size and step size are usually the same, and
are dictated by the following rules:
If Framing is D&I or D&I++: Otherwise:
If D&I Type is: Step size (bytes) If data rate is: Step size (bytes)
E1 D&I @ 1920kbps 1024 1544 kbps (T1) 1158
T1-D4 24 x n or 3ms 2048 kbps (E1) 1024
T1-ESF 48 x n or 6ms 6312 kbps (T2) 1578
E1 32 x n or 4ms 8448 kbps (E2) 528
Otherwise 2, with minimum size of 16 bytes
CONFIG: Clocks  Rx Buffer/Clock  Center
Selecting Center displays the following screen:
Press ENTER to Center the Buffer
otherwise, press CLEAR
Press ENTER or CLEAR as instructed.