User's Manual
Table Of Contents
- IMPORTANT NOTICE
- RESTRICTIONS ON USE
- PRODUCT CONFORMITY
- WARRANTY AND SAFETY INSTRUCTIONS
- TABLE OF CONTENTS
- INTRODUCTION
- 1 TECHNICAL SPECIFICATIONS
- 2 OPERATING VOLTAGE
- 3 SERIAL INTERFACE
- 4 USER INTERFACE
- 5 RF INTERFACE
- 5.1 Transmitter
- 5.2 Receiver
- 5.3 Priority RX/TX
- 5.4 Error correction
- 5.5 Error checking
- 5.6 User data whitening
- 5.7 Pacific Crest and TRIMTALK compatibility
- 6 TRANSPARENT DATA TRANSMISSION
- 7 SETTINGS
- 8 SW-RELATED COMMANDS AND OPTIONS
- 9 ACCESSORIES
- 10 APPENDIX A
- 11 APPENDIX B
SATELLINE-M3-TR1
User Guide, Version 3.0
21
5.2 Receiver
The sensitivity of the receiver depends on the channel spacing of the radio modem (=data
speed of the radio interface) and on the mode of the FEC (error correction) according to the
table below:
FEC OFF
FEC ON
25 kHz
-108 dBm
-111 dBm
20 kHz
-111 dBm
-114 dBm
12.5 kHz
-111 dBm
-114 dBm
The Signal Threshold Level setting of the receiver determines a level above which the search for
the actual data transfer signal is active. If the Signal Threshold Level setting is set too low, it is
possible that the receiver is trying to synchronise itself with noise, in which case, the actual data
transmission might remain unnoticed. Alternatively, weak data transmissions will be rejected,
even though they would be otherwise acceptable.
5.3 Priority RX/TX
SATELLINE-M3-TR1_xx offers a Priority setting, which selects the priority between reception and
transmission. The setting can be changed in Programming Mode. By default, transmission has
higher priority than reception i.e. the default value is Priority TX.
Priority TX means that a terminal device attached to a radio modem decides the timing of the
transmission. The transmitter is immediately switched on when the terminal device starts to
output data. Should reception be in progress, the radio modem will stop it and change to a
transmit state. There is no need to use any handshaking for the control of timing.
Priority RX means, that a radio modem tries to receive all data currently in the air. If a terminal
outputs data to be transmitted (or an SL command) it will buffered. The radio modem will wait
until the reception has stopped before transmitting the buffered data. This will result in timing
slacks to the system, but decreases the number of collisions on the air; this is particularly useful
in systems based on multiple random accesses.
If the Repeater Function has been set on, priority setting is automatically switched to RX mode.
5.4 Error correction
Forward Error Correction (FEC) -function is switched ON (or OFF) by using the Programming
Mode. When activated, the FEC-function will automatically add additional error correction
information, which increases the amount of transmitted data by 30 %. It is used by the receiving
radio modem to correct erroneous bits - as long as the ratio of correct and erroneous bits is
reasonable.