User's Manual

SATELLINE-3AS

User Guide, Version 2.2

buffered data has been transmitted. When the serial interface speed is the same or slower than

the speed of the radio interface, the internal transmit buffer memory cannot overflow. However,

when the serial interface speed exceeds the speed of the radio interface, data will eventually fill

the transmit buffer memory. In this instance, it will take a moment after the terminal device has

stopped transmission of data for the radio modem to empty the buffer and before the transmitter

switches off. The maximum size of the transmit buffer memory is one kilobyte (1 kB). If the

terminal device does not follow the status of the CTS-line and transmits too much data to the

radio modem, the buffer will be emptied and the transmission is restarted.

In the receive mode, the buffer works principally in the above described way thus evening out

differences in data transfer speeds. If the terminal device transmits data to a radio modem in

receive mode, the data will go into the transmit buffer memory. Transmission will start

immediately when the radio channel is available.

5.3.2 Optional start delay in transmit mode

The radio modem can be configured to delay the beginning of a radio transmission by

1...65000 ms. This function can be used to prevent packet contention in a system, where all

substations would otherwise answer a poll of a base-station simultaneously. During this delay

data sent to the radio modem is buffered. If this function is not needed, the delay time should be

set to 0 ms.

5.4 Tests

The radio modem can be switched to the Test Mode, where it will send a test packet on the

radio channel every second. The test packet is a normal data transmission, which can be used,

for example, when directing antennas during system installation.

When the test packet transmission has been switched on using the

Programming Mode

, the

transmitting radio modem needs only a power supply and an antenna. The Test Mode can be

configured to send either short (52 characters) or long packets (988 characters).

The strength of the received signal can be monitored using the LCD-display of the receiving

radio modem or by following the voltage level of pin RSSI. Error-free reception of data can be

checked using a suitable terminal program. When the Test Mode is no longer needed it must be

switched off using the Programming Mode.

Example of a test transmission:

00 This is a testline of SATELLINE-3AS radio modem

01 This is a testline of SATELLINE-3AS radio modem

02 This is a testline of SATELLINE-3AS radio modem