Digi-Star RF DataLink Operators Manual - Manual (Page 9)

Operators Manual
D3664 3
Fresnel Zone
The Fresnel Zone can be thought of as a football-shaped tunnel between two sites that
provides a path for RF signals.
In order to achieve the greatest range, the football-shaped path in which radio waves travel
must be free of obstructions. Buildings, trees or any other obstacles in the path will
decrease the communication range. If the antennas are mounted just barely off the ground,
over half of the Fresnel Zone ends up being obstructed by the earth resulting in significant
reduction in range. To avoid this problem, the antennas should be mounted high enough off
the ground so that the earth does not interfere with the central diameter of the Fresnel Zone.
Minimal height of base radio:
Range Distance Height
1000 ft (305 m) 15 ft (4.6 m)
1 Mile (1.61 km) 25 ft (7.6 m)
1.5 Miles (2.42 km) or more 45 ft (13.7 m)
If you do not have enough cable from the computer to the radio there are different cable
lengths that Digi-Star offers, or you would like a higher powered antenna, contact Digi-Star.
Standard length is 150 ft / 45.75 m (RS-232). Extended length is 150 ft / 45.75 m (RS-422)
or custom lengths are available (150+)
Radio Interference
There are many types of wireless networks or (WIFI) and some can interfere with the
DataLink radio. If DataLink is still showing radio interference, check the WIFI network
number. Changing this number can correct for radio interference. For further information
about WIFI, check the website of the brand of your radio. 802.11 2.4GHZ use channels 1 –
6 and 13 & 14.
Standard Range Setup
When using the standard range kit, connect the DB9 serial connector to either a serial port on
the PC or use the USB to Serial adapter included and connect the
12VDC power supply to the cable. The base radio is shipped from
Digi-Star setup for standard range. The switch settings on the
radio are set to the picture to the right: Verify this if you are not
able to communicate with the base radio