Interference From Other Wireless Devices; Device-Generated Rf - Sierra Wireless MC8301V Hardware Integration Manual

CDMA and GSM / UMTS Mini Card Hardware Integration Guide
Note: Values in this guide are
taken from the appropriate
product specification documents
(PSDs) (listed in
documents
, page
case of a discrepancy between
this document and the relevant
PSD, use the value listed in the
PSD.
Note: The module can cause
interference with other devices
such as hearing aids and on-
board speakers.

Wireless devices such as the
Mini Card transmit in bursts
(pulse transients) for set
durations (RF burst frequencies).
Hearing aids and speakers
convert these burst frequencies
into audible frequencies,
resulting in audible noise.
24
In the event of a discrepancy in values between this guide and the Product Specification Document (PSD), the PSD takes precedence.
The power supply ripple limit for the module is no more than
200 mVp‐p 1 Hz to 100 kHz. This limit includes voltage ripple
due to transmitter burst activity.
Related
11) — in the

Interference from other wireless devices

Wireless devices operating inside the host device can cause
interference that affects the module.
To determine the most suitable locations for antennas on your
host device, evaluate each wireless device's radio system,
considering the following:
• Any harmonics, sub‐harmonics, or cross‐products of signals
generated by wireless devices that fall in the module's Rx
range may cause spurious response, resulting in decreased
Rx performance.
The Tx power and corresponding broadband noise of other
•
wireless devices may overload or increase the noise floor of
the module's receiver, resulting in Rx desense.
The severity of this interference depends on the closeness of
the other antennas to the module's antenna. To determine
suitable locations for each wireless device's antenna,
thoroughly evaluate your host device's design.

Device-generated RF

All electronic computing devices generate RF interference that
can negatively affect the receive sensitivity of the module.
The proximity of host electronics to the antenna in wireless

devices can contribute to decreased Rx performance. Compo‐
nents that are most likely to cause this include:
Microprocessor and memory
•
Display panel and display drivers
•
Switching‐mode power supplies
•
These and other high‐speed devices (in particular, the
processor) can decrease Rx performance because they run at
frequencies of tens of MHz. The rapid rise and fall of these
clock signals generates higher‐order harmonics that often fall
within the operating frequency band of the module, affecting
the module's receive sensitivity.
Example
On a sub‐system running at 40 MHz, the 22nd harmonic falls
at 880 MHz, which is within the cellular receive frequency
band.
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