Honeywell International Inc. HD-128 Manuale Utente

Pagina di 104
CONFIDENTIALITY STATEMENT 
This document contains information that is private and Confidential, and is supplied on the express condition that it is not to be 
used for any purpose other than the purpose for which it was issued, nor is it to be copied or communicated in whole or in part, to 
any third party other than the recipient organization, without the prior written permission of EMS Technologies Canada, Ltd. 
Copyright © EMS Technologies Canada, Ltd.
 
User’s Guide EMS-MN-1110-10048 
13 
Performance considerations of satellite ISDN  
The transmission of data over satellite networks differs 
from land-based ISDN applications. Satellite 
communications experience factors such as transit delay 
and bit errors caused by signal fading and blockages.  
ISDN protocols are designed specifically for ground-based 
ISDN networks. Performance of different ISDN protocols 
varies depending on the properties of each application.  
Because of these challenges, it is sometimes necessary to 
optimize the system to achieve peak performance over the 
satellite network.  
Optimizing ISDN protocols for satellite networks 
ISDN protocols are not designed specifically for use over 
satellite communication networks. To improve data transfer 
rates most ISDN protocols require minor adjustments.  
For best results, consider how the ISDN protocol you intend 
on using sends data over the network and adjust the 
configuration taking into account the unique operating 
environment of satellite network communication. 
As examples, consider the ISDN protocols TCP/IP over 
PPP and V.120.  
As a basic protocol, PPP is typically operated under the 
networking protocol TCP/IP. PPP has error checking 
properties but does not offer flow control. TCP/IP is 
flexible and designed to run over different networks 
including the Internet which like satellite networks 
experiences high transit delays. Used together, PPP and 
TCP/IP protocols perform well over the Inmarsat ISDN 
service. 
The protocol V.120 includes error correction and flow 
control applications. Flow control limits or fixes the amount 
of data that can be in transit at any one time and waits for 
acknowledgment of receipt from the other end of the 
connection before sending more data.