Comtech EF Data SLM-5650A - Manual (Page 352)

SLM-5650A Satellite Modem Revision 8
Appendix B
B–18
B.4.1.3 Frame / Multiframe Length
The depth of the receive buffer required is applicable to all unframed data.
When the data is framed (such as 2048 kbps G732 or 1544 kbps G733), it is desirable to provide
slips in predefined locations. The advantage of organized slip locations (in relation to the frame) is
that multiplexing equipment does not lose sync and outages on any channel are kept to a minimum.
A 2048 kbps frame structure commonly used is G732. This has a frame length of 256 bits with 16
frames per multiframe (4096 bits total, or 2 ms).
B.4.1.3.1 Multiples of the Frame Length
If this setting is set to NONE, the user can choose any buffer depth.
B.4.1.4 Total Buffer Length
T1 and E1 framing structure under G.704 are available. When this is selected, the buffer length is
restricted to the size of the buffer. Using the examples from the three previous sections, the total
buffer depth (end to end) will be:
Doppler + Plesiochronous (rounded up to the nearest multiframe)
1.15 ms + 6.98 ms = 8.13 ms
If the frame length is 2 ms, then the nearest multiframe will be 10 ms, or 20,480 bits.
B.4.1.4.1 Converting Between Bits and Seconds
Bits to Seconds 1/Data Rate x Bits = Seconds
Seconds to Bits Data Rate x Seconds = Bit