User's Manual

INSTALLATION AND MAINTENANCE MANUAL
LYNX.sc E1 FAMILY
SPREAD SPECTRUM RADIOS
SEPTEMBER 1999
PAGE 3-8 SECTION 3: INSTALLATION & ADJUSTMENTS
3.3.6 Frequency Plan Determination
When configuring radios in a hub or repeater configuration, careful engineering of the LYNX.sc radio
frequency plans and antenna locations should be performed in order to minimize potential
interference between the nearby radios. As a rule of thumb, do not place identical frequency plan
radios (e.g. two “A” channel radios) at the same site. In most cases, it is desirable to use a different
frequency plan (e.g. A versus B). However, with careful engineering, placing more than one radio of
the same frequency channel plan at the same site can be accomplished. In fact, the LYNX.sc
frequency plan is designed to allow complex hub configurations that may require re-using the same
frequency plan. When designing these types of configurations, antenna size and antenna location
are critical. If identical channel plans must be used at the same site, the same radio channel (e.g.
A1 and A1) should be used at a site to minimize interference. Using alternate channels (e.g. A1 and
A2) is less likely to be successful (and therefore not recommended) due to the high level of
transmitter to receiver isolation required from the antenna system.
Sometimes it is required to locate the LYNX.sc radio nearby a transmitter that is the same as, or
close to the LYNX.sc receive or transmit frequencies. In this case, the LYNX.sc terminal that
should be placed closest to this interfering transmitter should be the specific terminal with the
receive frequency which is furthest from this unwanted transmitted frequency. This approach
minimizes the potential of interference. While interference conditions are rare when using the
LYNX.sc radios, cases of interference may be overcome by exchanging the radios from end to end
or simply reinstalling the filter unit, as described in Section 4.2 (thus swapping the frequencies of
both ends of the radio link). In some cases, changing frequency plans (e.g. from A to B) can also
help mitigate any interference.
Section 4.8 of this manual describes interference
countermeasures in further detail.