Comtech EF Data SDM-650B Specifications download pdf (Page 235)

100

101

SDM-300L3 Satellite Modem Revision 0

Clocking Options MN/SDM300L3.IOM

6–9

6.3 Buffering

The purpose of a receive buffer is two reasons:

• Plesiochronous buffering of two dissimilar clock frequencies (normally the far

end transmit clock verses the local network clock). The clocks may be very close

in frequency to each other and will normally slip at a constant rate. Figure 6-6

shows plesiochronous operation for dissimilar clocks. If incoming traffic is too

fast, an occasional bit will be lost. If incoming traffic is too slow, an occasional

bit will be repeated.

• Doppler buffer of the signal of the satellite. The Doppler shift results from the

“figure 8” (Figure 6-7) station keeping movement performed by the satellite in

space over a period of one day. Doppler shift should not result in a clock slip, as

the buffer will constantly fill and empty.

If the two earth stations are configured as master/slave, then the buffer need only be

configured for Doppler operation. The buffer will then have sufficient capacity for the

Doppler shift on the outward and return paths.

A buffer set up for Doppler operation only, will typically require less depth than one

intended for both Doppler and plesiochronous operation.

1 2 ... 230 231 232 233 234 235 236 237 238 239 240 ... 433 434

Comments to this Manuals

No comments

Comtech EF Data SDM-650B Specifications Page 235

Comments to this Manuals

Related products and manuals for Networking Comtech EF Data SDM-650B