Developers guide

Chapter 21: Wireless Local-Area Networking
Availability Of API Libraries
188 Psion Teklogix Mobile Devices SDK Developers Guide
21.2 Availability Of API Libraries
The WLAN API libraries are available as follows:
21.3 Encryption For Data Transmission
21.3.1 Wired Equivalent Privacy (WEP) Keys
Wired Equivalent Privacy (WEP) is an encryption algorithm system and part of the 802.11 stan-
dard. It is a security measure to protect wireless LANs from casual eavesdropping. WEP uses a
shared secret key to encrypt packets before transmission between wireless LAN devices, and it
monitors packets in transit to detect attempts at modification.
WEP Key Length
The length of the WEP key determines the size of the encryption key:
• A 5-character text string, or a 10-character hexadecimal string, gives a 40-bit encryption key.
• A 10-character text string, or a 26-character hexadecimal string, gives a 128-bit
encryption key.
WEP Key Index
The Mobile Devices SDK can store up to four WEP keys. The index is used to identify each key
(1 to 4) when determining which key to use.
21.4 Connection State Parameters
21.4.1 Received Signal Strength Indicator—RSSI
The RSSI status of the radio changes continuously based on a number of different environmental
factors, such as distance, interference, angle of antenna, etc. The RSSI is measured in dBm. A
perfect signal is -10 dBm. An complete absence of signal is measured as -200 dBm.
21.4.2 Transmit Power
The Mobile Devices SDK enables the transmit power of the radio to be set and queried. This level
is expressed as a percentage of the maximum transmit power of the radio. The available power
levels increase incrementally; so not all percentages are valid. If you try to set the level to a non-
valid percentage, the value is increased to the next valid percentage. Similarly, when you query the
setting, the returned value is rounded up to the next valid percentage.
The maximum transmit power of the radio is regulated by the country in which the radio is to be
used.
API Library
APIs Available On...
Summit Radio RA2040 RA2043
Mobile Devices SDK WLAN
APIs
Yes Yes Yes
Summit Client Utility
Yes No No
Wireless Zero Config
Yes Yes Yes
Odyssey Access Client
No No No