User guide

SATELLINE-3AS NMS / NMS Epic / NMS 869 / VHF
User Guide, Version 1.0
53
of 25 kHz channels available: 869.4125, 869.4375, 869.4625, 869.4875, 869.5125,
869.5375, 869.5625, 869.5875, 869.6125 and 869.6375 MHz.
When calculating the radiated power, antenna cable attenuation and antenna gain must be
taken into account. For example: when the antenna gain is 10 dBd and the antenna feeder
cable attenuation is –3dB, the maximum allowed transmission power is 100 mW (+20 dBm). It
should be noticed that by increasing the gain of the antennas, connection distance can be
increased. This is due to the fact that the transmitting power remains constant, but the added
antenna gain in the receiving end enables reception of weaker signals than otherwise possible.
System designers must also take into account that at the frequency range of 869.4…869.65
MHz the allowed transmitter duty cycle is 10% of the time (transmitter can be ON for up to 10%
of the cycle time, maximum continuous transmitting time is 36 s).
Whether this limit is exceeded or not, depends on the protocol used.
Currently, the default settings of SATELLINE-3AS(d) 869 are:
• Output power = 500 mW
• Low limits of frequency bands 1 and 2 = 869.4125 MHz
• High limits of frequency bands 1 and 2 = 869.6375 MHz
• Centre frequency = 869.0125 MHz
• Operating frequency = 869.4125 MHz