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22 — HCM rate adaption
22-8 2902 MainStreet Technical Practices
90-2906-01 May 2002
Oversampling
Asynchronous rates of up to 2400 b/s that are not listed in Table 22-1 can be
supported by oversampling. To oversample:
1 Set the device mode to synchronous (see the device mode section in the
appropriate data module chapter).
2 Multiply the asynchronous rate you wish to support by 16.
3 Enter the next highest synchronous interface speed listed in Table 22-1.
For example, to support 110 b/s (asynchronous), set the device mode to synchronous
and the interface speed to 2400 b/s (16 x 110 b/s = 1760 b/s; 2400 b/s is the next
highest synchronous rate supported).
For interface speeds of 2400 b/s or less, 2.4 kb/s of bandwidth is allocated
(represented by three D bits).
Procedure 22-5 To set the interface speed
where
pp is 1 or 9, and c is 1 or 2, or A or B
interface speed is in b/s
22.7 Data position
The data position parameter specifies the location of the first data element, or D bit
(see Figure 22-1). When signaling is turned on, the S bit appears in the element
immediately before the first data bit. signaling is turned on by default, therefore the
default data bit position is F0-B5.
You need to change the data position if you are subrate multiplexing an HCM
rate-adapted circuit with another HCM rate-adapted circuit (so that the S and D bits
for the two circuits do not overlap).
If you select a data position that is incompatible with transport position, transport
bandwidth and signaling settings, an error message appears on the display.
Note —
The tolerance for overspeed and underspeed is ±2.5% for
asynchronous devices.
I/F_SPEED
< interface speed >
↵
CONFIG — CIRCUIT — < pp-c >
↵
— FUNCTION — RATE_ADAPT
SK000523