Specifications

MDS 05-4055A01, Rev. A MDS entraNET 900 System Guide 135
movement or changing atmospheric losses. A fade margin of 15 to 20
dB is usually sufficient in most systems.
Frame—A segment of data that adheres to a specific data protocol and
contains definite start and end points. It provides a method of synchro-
nizing transmissions.
Frequency Hopping—The spread spectrum technique used by the
transceivers, where two or more associated radios change their oper-
ating frequencies several times per second using a set pattern. Since the
pattern appears to jump around, it is said to “hop” from one frequency
to another.
Frequency Zone—The transceiver uses up to 80 discrete channels in
the 902 to 928 MHz spectrum. A group of 16 channels is referred to as
a zone; in total there are 8 zones.
Hardware Flow Control—An transceiver feature used to prevent data
buffer overruns when handling high-speed data from the connected data
communications device. When the buffer approaches overflow, the
radio drops the clear-to-send (CTS) line, that instructs the connected
device to delay further transmission until CTS again returns to the high
state.
Host Computer—The computer installed at the master station site, that
controls the collection of data from one or more remote sites.
HTTP—Hypertext Transfer Protocol
IAPP (inter-Access Point Protocol)—A protocol by which access
points share information about the stations that are connected to them.
When a station connects to an access point, the access point updates its
database. When a station leaves one access point and roams to another
access point, the new access point tells the old access point, using IAPP,
that the station has left and is now located on the new access point.
ICMP—Internet Control Message Protocol
IEEE—Institute of Electrical and Electronic Engineers
Image (File)—Data file that contains the operating system and other
essential resources for the basic operation of the transceiver’s CPU.
LAN—Local Area Network
Latency—The delay (usually expressed in milliseconds) between when
data is applied at the transmit port at one radio, until it appears at the
receive port at the other radio.
MAS—Multiple Address System. A radio system where a central
master station communicates with several Remote stations for the pur-