User's Manual

EE440 Specifications manual
6.2. Battery
The power is supplied to the ESL by two replaceable Alkaline AAA size batteries.
7. Specifications
Parameter Min Typ Max Unit Remarks
Receiver sensitivity -97 -89 dBm Over the entire temp. and
operating voltage range
Nominal output power -3 4.5 7 dBm
Frequency 2405 2480 MHz Over the entire temp. and
operating voltage range
Transfer rate 250Kbit/s
RSSI range 100 dB Signal strength indication
that can be reported to the
base station
7.1. Protocol
Modified 802.15.4 (Physical layer and Media Access Control layer).
7.1.1.
The physical layer
The physical layer (PHY) provides the data transmission service, as well as the interface
to the physical layer management entity, which offers access to every layer management
function and maintains a database of information on related personal area networks.
Thus, the PHY manages the physical RF transceiver and performs channel selection and
energy and signal management functions. It operates on the above mentioned frequency
band. The PHY layer is 100% compliant and is based on direct sequence spread
spectrum (DSSS) technique with a transfer rate of 250 kbit/s.
7.1.2.
The medium access control layer
The medium access control (MAC) layer enables the transmission of MAC frames through
the use of the physical channel. Besides the data service, it offers a management
interface and itself manages access to the physical channel. It also controls frame
validation, guarantees time slots and handles node associations. Finally, it offers hook
points for secure services. The EE440 does not make use of the optional network
beaconing, instead it used a polling mechanism to increase power efficiency. Some
changes are made to the standard to allow for more efficient data frames and better
power efficiency, especially when nodes are not connected to a base station.
7.2. Security
The 802.15.4 standard 128-bit AES encryption is supported. A secure method for key
management is implemented as well. The encryption is optional though and can be
configured via the base station. By default the radio traffic is unencrypted.
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