Figure 5-1. Simplest form of a network
Outbound packets from the gateway or repeater to the endpoints or other repeaters are sent a
set number of times determined by the user. The receiving transceiver, endpoint or repeater, will
accept the first packet received with the correct signature (32-bit CRC). However, the packet is
not acknowledged. On the return trip to the gateway, all packets sent are acknowledged or
retransmitted until they are acknowledged. Therefore, the return link is generally very robust.
Traditionally, a network is used in applications where data is collected from one to many data
loggers and reported back to one central site. The central site is typically a computer running
LoggerNet
, but could be a data logger. Refer to
(p. 27) for different
installation scenarios.
6. Specifications
Frequency:
902 to 928 MHz
Transmit
Output power:
10 mW to 1 W, user selectable
Range:
20 to 95 km (13 to 60 miles) assuming ideal conditions, line-of-
sight, and appropriate antenna
Note that line-of-sight obstructions, RF interference, and antenna
type will affect transmission distance. Maximum distances can be
greatly reduced by vegetation, line-of-sight obstacles, humidity
levels, and other environmental and physical factors.
Modulation:
2 level GFSK
Spreading method:
Frequency hopping
RF451/RF452 Spread Spectrum Radio
5