CR-SEH
Introduction
The CR-SEH family of products from Cirronet
Incorporated provides wireless Ethernet connectivity
between networks located more than 5 miles apart. Built around the WIT2411 frequency hopping spread
spectrum data modem, CR-SEH products provide a 10/100BaseT connection to Ethernet networks. CR-
SEH products operate in a point-to-point mode or a point-to-multipoint mode using a star configuration.
The center of the “star” is the Master device and the remote CR-SEHs are Slave devices. Peer-to-peer
communication is accomplished by using the master CR-SEH device to relay datagrams from one slave
CR-SEH device to another slave CR-SEH device.
Contained in a DIN Rail enclosure, CR-SEH is designed for factory and industrial applications. The CR-
SEHX features a remote radio in a NEMA 4X/IP66 rated enclosure that can be mounted outdoors up to
300 feet from the network connection. Communication between CR-SEH products is performed using the
WIT2411 over-the-air protocol. Thus the CR-SEH products are 802.3 compatible but not 802.11
compatible and provides over 1Mbs data throughput. Certified by the FCC and ETSI, and CE marked,
CR-SEH products can be deployed license-free around the world.
The CR-SEHs enjoy the same benefits of frequency-hopping spread spectrum technology that the
WIT2411s do. Namely, the immunity to multipath fading and resistance to jamming that is provided by
changing frequency every few milliseconds. Operating in the 2.4GHz ISM band, CR-SEHs can be used
license-free worldwide and are not subject to the congestion in the 900MHz band caused by cordless
telephones.
The radios in CR-SEH products include a robust over-the-air protocol. This protocol insures error-free
data through the use of a 24-bit CRC and ARQ to detect errors and to automatically request a
retransmission. All of this is transparent to the network which just sees complete error-free data.
2000- 2004 Cirronet
Inc
1
M-2411-0013 Rev A
