RFD900x FAQ
www.rfdesign.com.au
3
Last update 06/08/2019
Question/Issue:
The range of my modems is poor:
Answer checklist.
1. Follow 1 to 3 of “My modems drop connection”
2. Confirm that the modems are being operated as line of sight as this is how the modems are
designed to be used.
3. Check the noise figure (noise R/L) from the RSSI test/logs to see if this is high (generally
greater than 85). If so, this indicates that there is significant noise on the modem band, that
could be interfering with your operation.
4. Increase the modem power to extend the range. (It is the users responsibility to know the
allowable power settings and frequencies in their area of operations.)
5. It is recommended that at least dipole antennas or RFDFlex1s are used particularly for
longer ranges. Monopoles will often perform sub-optimally as correct setup of antenna and
ground plane for maximum performance can be time consuming or impractical due to
mechanical restrictions.
6. Try to elevate the ground control antenna. This will increase the radio horizon, improve the
line of sight and lessen the ground interference. At least 2 meters is recommended.
7. Check the specification of the RF extension cable in use as this can have significant loss per
metre reducing signal power.
8. If using a long USB cable or USB extension the power drop on the cable may cause the
modem to brownout or reset during use at high power. It is recommended to use a separate
power supply of 5V and at least 1A of current. (Please note the voltage regulation is critical to
avoid damage to the modems as even 5.3V for extended periods have been seen to damage
the input regulator on the modem.)
