Data Service With Compression; Introduction - Furuno Felcom 30 Operator's Manual

6.5

Data Service with Compression

Note: For dial-up with data compression, see the application:
"6.3 Mobile Data Service (RS-232)" or
"6.4 Mobile Data Service (USB)".
6.5.1

Introduction

FELCOM 30 incorporates a data compression function providing up to four times
9.6 kbps increase in the transfer speed between the mobile and shore of:
text files
web browsing
e-mail
Be aware that files that are already compressed such as jpeg, mpeg, zip files are
not compressed during the data transfer.
The compression is nondestructible.
The files transferred are completely recovered at the remote end.
However, as can be seen in the DATA TRANSFER SPEED graph, it is
recommended to leave the compression function enabled.
The FELCOM 30 satellite terminal supports the V.44 and V.42bis standards.
During "negotiation" with the terrestrial modem, FELCOM 30 announces that it
supports both these compression standards.
If the shore modem also supports V.44 then this is used in preference to V.42bis.
If V.42bis only is supported, this will be used. If the called party does not support
compression then the call will proceed without compression applied.
V.44 will typically yield a 20% improvement in compression ratio compared to
V.42bis.
FELCOM 30
Supports V.44/V.42bis via:
-USB
-RS-232A
-RS-232B/RS-422
Land
Earth
Station,
LES
Modem
PSTN
supporting
V.44/V.42bis
6-85