User's Manual

SATELLINE-4Pro

User Guide v0.93 DRAFT

 The maximum absolute time is always 170 ms independent from the value of the Pause

length given in the set-up.

 An increase in the Pause length increases the round trip delay of the radio link

correspondingly; this is due to the fact that the radio channel is occupied for the time of the

Pause length after each transmission (the time it takes to detect a pause). If this is not

acceptable, the TX delay setting may also be useful in special cases.

8.3.3 TX delay

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

1...65000ms. 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. Although the priority setting is "RX", radio modem is prevented

to change over to receiving mode during the period of the TX delay. If this function is not needed,

the delay time should be set to 0 ms.

8.4 Testing

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

channel. The test packet is a normal data transmission, which can be used, for example, when

directing antennas during system installation.

If the channel spacing of the radio modems is 25 kHz, it is recommended to use 38400 bps as a

sserial data speed of the receiving radio modem. In the case of 12.5 kHz channel spacing the data

speed of 19200 bps is recommended.

There are two Test Modes:

Short data block test

In this test mode the radio modem sends a short test string, which is preceded by a consecutive

number, and it ends to the line feed character. The short data block is repeated continuously after

1 s break.

Short data block test is suitable for running data communication tests. Error-free reception of data

can be monitored using a suitable terminal program.

Example of a short data blocks:

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

Long data block test

Long data block consists of character strings, which are repeated without breaks 50 s time period.

After 10 s break the test transmission is started again.

Long block data test can be used for measuring Tx output power, standing wave ratio (SWR) of the

antenna system or received signal strength at Rx stations. Using Long Block Test requires running

the modem in radio compatibility mode SATELLINE-3AS.