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5.0 Installation
Fade Margin
When all radio path numbers are being considered and hardware assumptions are being
made, another factor to consider is the ‘fade margin’ of the overall system. the fade margin is
the difference between the anticipated receive signal level and the minimum acceptable re-
ceive level (receive sensitivity). Being that the Pico Series performs to exacting specifica-
tions, the overall deployment should be such that the modems may be utilized to their full po-
tential to provide a reliable and robust communications link. A typical desired fade margin is
in the order of 20dB, however oftentimes a 10dB fade margin is acceptable.
Frequency
The frequency ranges supported are not effected by rain to any significant degree, and is also
able to penetrate through foliage and ‘around obstacles’ to a certain degree. This being the
case, some may choose to scrimp on the physical deployment, particularly when it comes to
antenna (tower) heights. Path calculations provide results which specify ‘required’ antenna
heights. For cost savings and in taking advantage of the characteristics of the frequency
range, sometimes the height requirements are not adhered to: this may result in unreliable
communications.
Power Requirements
The Pico Series may be integrated into a system (Development Board, or custom) which ac-
cepts a range of DC input voltages (supply current requirements must also be met). In some
deployments, power consumption is critical. A number of features related to minimizing
power consumption are available with the P2400 such the ability to operate at lower transmit
power given the receive sensitivity of the distant modem.
Interference
The frequency hopping spread spectrum (FHSS) operation of the Pico Series most often al-
lows it to work well in an environment within which there may be sources of in-band interfer-
ence. Frequency Restriction (Hopping Zones) is a built-in feature which may be utilized to
avoid specific frequencies or ranges of frequencies; the Spectrum Analyzer function may be
used to identify areas of potential interference. Cavity filters are also available if required:
contact Microhard Systems Inc. for further information.
