Quantum and Evolution Series Installation and Operating Handbook
8-27
Baud Rate = (Main data rate/15) x (O/H bits allocated/32) x (Bauds per Character/9)
where:
Main data rate: The main modem data rate, eg 64000bps (/15 gives total
overhead)
O/H bits allocated:
The number of bits of the overhead allocated to the ESC, for
example if the ESC is set in P230 mode, then 20 bits (TS16 bits
1-8, TS48 bits 1-8 & TS32 bits 4-8) are available (/32 give the
proportion of the overhead allocated to the ESC)
Bauds per Character: The number of Baud periods per character (eg for async
character format 8,N there are 10 Baud periods per character:
start + 8 data bits + stop (/9 as 9
synchronous
bits are always
used for each character).
Note that if the CAS Multiframe is active
to transfer G.732 CAS
, then TS16 and TS48 are
not available. Note also that is the CAS Multiframe is active
without
CAS, i.e. to maintain
the timeslot ID for an `Odd value of N` or if RBS signalling is active, then only 7 out of 8 of
every TS16 are available for ESC, as TS16 has to carry the `CAS MF unique word` or
`pack byte` every 8th frame. In this case simply consider TS16 as providing 7 bits of
overhead not 8.
For Custom IBS modes this is unchanged unless Minimum Overhead mode is selected, in
which case the overhead will vary up or down from the standard 1/15th to accommodate
whatever Baud rate is set on the ESC Rate screen.
In all IDR modes, the ESC channel is an 8kbps synchronous channel, and if the ESC port is
set to provide an async interface the
exact
maximum continuous async rate is:
Baud Rate = 8000 x (Bauds per Character/9)
Where "Bauds per Character" is the number of Baud periods per character (eg for async
character format 8,N there are 10 Baud periods per character: start + 8 data bits + stop (/9
as 9
synchronous
bits are always used for each character). This results in a maximum of
9777Baud with 11 Baud periods per character (eg start + 8 + stop), and 8888Baud
with 10 Baud periods per character (eg start + 8 + stop), as used with Paradise M&C
protocols. So when set for [8 bits No Parity] or [7 bits with Parity] the maximum standard
Baud rate is 4800 Baud. When set for [8 bits with Parity] the maximum standard Baud rate
is 9600 Baud.
8.10.2 Closed Network Plus ESC
8.10.2.1
Overhead Rates
The following table shows example overhead rates for different async ESC Baud rates at a
variety of main channel data rates. The table was generated (using a modem) with the
async character format set for 8 bits no parity, the overhead percentages will vary slightly
for async character formats different from this.
