Technical Features
Sprint 2 Throughput/Efficiency
Data throughput may be easily calculated. The overhead for composite rates above 32.8Kbps
is 1600bps. For rates below 32.8Kbps, the overhead is halved. For example, a composite
rate of 28.8Kbps will yield a throughput of 28Kbps.
Link Rate (Kbps)
Efficiency (%)
Throughput (Kbps)
64
97.5
62.4
19.2
95.83
18.4
Data Format
Synchronous Data
The internally generated data channel clocks are derived from the composite link clock rate.
Each data channel has a flexible input buffer (size depends on bit rate) to allow external clock
(plesiochronous) operation.
Asynchronous Data
Asynchronous data is transmitted across the composite link as synchronous data with each
character occupying eight bits in the aggregate frame irrespective of structure. Data parity is
regenerated at the remote end. When the data channel is in idle or break condition the
aggregate is padded with one of two non-ASCII codes (0BAh and 0BBh). If these codes are
received by the data channel they are coded and appended with an escape character (0BCh) to
allow them to pass across the aggregate link.
By stripping start, stop and parity bits from data, the Sprint 2 reduces the number of data bits
transferred across the composite link. An asynchronous channel with a word structure of
81N will discard two bits and transfer eight useful characters, thus requiring 80% of the
nominal bandwidth, or 7680bps for a 9600bps channel.
In practice the composite link is allocated in 800bps slots, so this channel actually uses
8000bps. When applied across all eight channels the following combinations are possible.
