SATEL-TR49
Integration Guide, V 1.7
33
8.2
Receiver
The sensitivity of the receiver depends on the channel spacing of the radio modem, selected
modulation level and on the mode of the FEC (error correction).
The radio modem measures the received signal strength (RSSI) of the receiver constantly. The
setting determines the received signal level above which the search for the radio messages is
active. It is recommended that values given in the table above are used as a basis. If the
threshold is set too low, it is possible that the receiver is trying to synchronise itself with noise.
In such a case the actual data transmission might remain unnoticed. If the threshold is set too
high, the weak data transmissions will be rejected although they could be otherwise receivable.
Signal threshold should only be changed for a reason - for example in the following cases:
Continuous interference is present, and the desired signal is strong. In this case the signal
threshold can be increased to prevent the modem from synchronising to the interfering signal(s)
and /or possible noise.
Maximum sensitivity should be achieved, and the desired signal is very weak. In this case the
sensitivity could increase by decreasing Signal threshold. This type of situation is usually a sign
of a poorly constructed radio network / contact. Bit errors and momentary loss of signals can be
expected in this kind of a situation. Some data might be successfully transferred.
The RSSI can be requested also locally by using a special SL command (SL@R?). The RSSI value
is available 7s after the receiving the message. After that the value is returned to zero.
Signal Threshold value range: -
80 …
-118 dBm
Default value: -118 dBm
Note that the feature is OFF in case the value is -118 dBm.
The feature works only in the following compatibility modes of TR49: SATELLINE-3AS
8.3
Encryption
Data security is often a concern when using radio communication. In SATEL radio products,
strong AES128-bit encryption (CTR-mode) on the air interface ensures privacy in the radio
network. The principle of encryption in the radio path is to collect a certain amount of data to a
shift register and manipulate it according to a certain rule. Every data packet is encrypted
individually. The process of encryption adds 5 to10 ms (depending on encryption mode) to each
sent data packet (<5 characters) and must be avoided in the cases where low latency is the most
important requirement.
AES is open source software from public domain. Author: Brian Gladman (U.K). The CTR-mode is
SATEL’s in
-house implementation.
The product models that support the encryption for the RF interface can be viewed in SATEL WEB
sites at
The radio models that doesn’t support the encryption feature