Paradyne DMD15L operation manual Kbps Baud Rate Example for Standard IBS Enhanced Mode

Operation DMD15/DMD15L IBS/IDR Satellite Modem

3.20DMD15 Asynchronous Overhead Operation 3.20.1 Asynchronous Framing/Multiplexer Capability

The Asynchronous Framing/Multiplexer is capable of multiplexing a relatively low-speed overhead channel onto the terrestrial data stream resulting in a slightly higher combined or aggregate data rate through the modem. The overhead channel is recovered at the far end. This added channel is termed variously “An Overhead Channel”, ”Service Channel”, “Async Channel” or in IESS terminology an “ES to ES Data Channel.” The basic frame structure used by the multiplexer is that specified in the IESS-309 Standard, resulting in a 16/15 Aggregate to Through-Data Ratio.

For Regular Async:	(Standard IBS), the Baud Rate is approximately 1/2000
	of the Data Rate listed in Table 3-3.
For Enhanced Async:	(IBS Async.), the Baud Rate is selectable, but Data Rate
	is limited.

The maximum Baud Rate is 19,200 bps for IBS Async. Two software-controlled modes are designed into the card to best utilize the available bits; “Standard IBS” and “IBS (Async)”. The characteristics of the Channel Interface is also determined by the standard or Async mode.

The Async Channel can be set under software-control to either RS-232 or RS-485 mode. The pin assignments for both modes are shown in Table 3-3. The “RS-485” Setting controls the output into tri-state when the modem is not transmitting data, allowing multiple modem outputs to be connected together.

Table 3-3

Kbps	Baud Rate Example for	Kbps	Baud Rate Example for
	Standard IBS		Enhanced Mode
128	64	9.6	300
256	128	19.2	600
384	192	32	600
512	256	64	1200
640	320	128	2400
768	384	192	4800
896	448	256	4800
1024	512	320	9600
1152	576	384	9600
1280	640	448	9600
1408	704	512	9600
1536	768	576	9600
1664	832	640	19200
1792	896	704	19200
1920	960	768	19200
1920	960	768	19200
2048	1024	832	19200

3-24 TM051 – Rev. 5.8