Filter
Top Products
P300H P300 Series Modem Installation and Operating Handbook Page 146
8.6 DETERMINING EXACT MAXIMUM ESC BAUD RATES
Should you wish to determine the exact maximum ESC Baud rates, in order to change the overhead
allocation to achieve specific ESC rates with specific overheads, then the following section may be useful.
For Standard IBS the exact maximum continuous rate is:
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 , ie 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 + parity + stop), and 8888Baud with 10 Baud periods per character (eg start + 8 + stop), as used
with Paradise & SA-bus M&C protocols (SA-bus is start + 7 + parity + stop = 10 Baud periods per
character). 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.