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RC11XXHP-RC232
2009 Radiocrafts AS RC11XXHP-RC232 Data Sheet (rev. 1.00) Page 10 of 24
Radiocrafts
Embedded Wireless Solutions
For more details on changing the RF channel, output power or data rate, refer to the description
of the configuration commands.
The use of RF frequencies, maximum allowed RF power and duty-cycles are limited by national
regulations. The RC1180HP-RC232 is complying with the applicable directives within the
European Union when used within these limitations. The RC1170HP-RC232 is complying with the
applicable directives in India when used within the local regulations for India.
Multi-channel usage
All modules from Radiocrafts embed a high performance transceiver which can transmit and
receive on one out of several channels. It is clear that other transmitters present on the same
channel at the same time can cause interference (from bit errors until no detection of the wanted
signal) if they have a higher signal level from the non-friendly transmitter than the wanted signal
present at the receiver. To avoid this, configure the radio to use the channel with least
interference. At 868 MHz, radios are allowed to transmit only short bursts before leaving the
channel free for other radios, thus the interference can be expected to be of short duration.
Co-located radios
Precautions have to be taken in a so-called co-location (also named collocation) operation of
transceivers. This means reception and transmission at different channels at the same time with
the intention that the two channels shall be able to operate without disturbing each other.
As indicated in the figure above a module B is receiving a message from A on channel X while
another module C is transmitting at the same time on another channel Y (a message intended
for module D). As any radio device has a limited suppression of signals at any other channel,
some power of the signal at the other frequency will enter into the receiver B. Normally, the
suppression increases versus the frequency separation between the two channels. The phrase
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apart. The ability of a receiver to reject any out-of-band interferer is named ACR, adjacent
channel rejection.
Friis formula and empirical adaptations of this predicts the path loss between a transmitter and a
receiver. The path loss increases (1/R)n where R is the radius and n is between 2 and 5 and
heavily depending on the surroundings. Knowing the TX output power, the path loss between A-B
decides the amount of power entering the receiver B as well as the path loss between B-C
decides the amount of interferer power entering the same receiver. If we assume there is identical