Linx Technologies EVM-915-025 - Manual (Page 7)

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Usage Guidelines for FCC Compliance
The EVM-915-025 module is provided with an FCC Modular Certification.
This certification shows that the module meets the requirements of FCC
Part 15 standards for an intentional radiator. The integrator does not need
to conduct any further testing under these rules provided that the following
guidelines are met:
• An approved antenna must be directly coupled to the module’s
RP-SMA connector.
• Alternate antennas can be used, but may require the integrator to
perform certification testing.
• The module must not be modified in any way. Coupling of external
circuitry must not bypass the provided connectors.
• End product must be externally labeled with “Contains FCC ID:
Q7V-3F090008X”.
• The end product’s user’s manual must contain an FCC statement
equivalent to that listed on page 10 of this data guide.
• The antenna used for this transceiver must not be co-located or
operating in conjunction with any other antenna or transmitter.
• The integrator must not provide any information to the end-user on
how to install or remove the module from the end-product.
Any changes or modifications not expressly approved by Linx Technologies
could void the user’s authority to operate the equipment.
Additional Testing Requirements
The modules have been tested for compliance as an intentional radiator,
but the integrator is required to perform unintentional radiator testing on
the final product per FCC sections 15.107 and 15.109. Additional product-
specific testing might be required. Please contact the FCC regarding
regulatory requirements for the application. Ultimately is it the integrator’s
responsibility to show that their product complies with the regulations
applicable to their product.
Note: The integrator is required to perform unintentional radiator testing
on the final product per FCC sections 15.107 and 15.109.
Interference Considerations
The RF spectrum is crowded and the potential for conflict with unwanted
sources of RF is very real. While all RF products are at risk from
interference, its effects can be minimized by better understanding its
characteristics.
Interference may come from internal or external sources. The first step
is to eliminate interference from noise sources on the board. This means
paying careful attention to layout, grounding, filtering and bypassing in
order to eliminate all radiated and conducted interference paths. For
many products, this is straightforward; however, products containing
components such as switching power supplies, motors, crystals and other
potential sources of noise must be approached with care. Comparing your
own design with a Linx evaluation board can help to determine if and at
what level design-specific interference is present.
External interference can manifest itself in a variety of ways. Low-level
interference produces noise and hashing on the output and reduces the
link’s overall range.
High-level interference is caused by nearby products sharing the same
frequency or from near-band high-power devices. It can even come from
your own products if more than one transmitter is active in the same area.
It is important to remember that only one transmitter at a time can occupy
a frequency, regardless of the coding of the transmitted signal. This type of
interference is less common than those mentioned previously, but in severe
cases it can prevent all useful function of the affected device.
Although technically not interference, multipath is also a factor to be
understood. Multipath is a term used to refer to the signal cancellation
effects that occur when RF waves arrive at the receiver in different phase
relationships. This effect is a particularly significant factor in interior
environments where objects provide many different signal reflection paths.
Multipath cancellation results in lowered signal levels at the receiver and
shorter useful distances for the link.