User's Guide

80-VF329-3 Rev. C 21 QUALCOMM Confidential and Proprietary
MAY CONTAIN U.S. EXPORT CONTROLLED INFORMATION
UNDP-1 Universal Notebook Data Platform User Guide RF Integration
4.4 Shielding and interference
Shielding is an extension of the system ground and must be installed to prevent
interference between the host computer and the UNDP-1 platform. The platform is fully
shielded (Figure 4-1), in accordance with FCC regulations (see [4] listed in Table 1-2).
Figure 4-1 UNDP shields
NOTE These UNDP shields must not be removed.
The host PC is a hostile environment for RF transceivers, making the shields absolutely
necessary. Potential interference sources include the following:
■ Noise or ripple on the DC power supply voltage input lines, including transients due to
switching-mode power supplies or host operating mode changes.
■ High-speed digital logic transistions – The fast rising and falling edges include high
frequency harmonics that can fall into the UNDP Rx and/or Tx passbands. Host
circuits most likely to cause problems are the microprocessor, memory, and its
displays and display drivers.
■ Clocks – Also due to their high-speed transitions
■ Other wireless devices, whether integrated into the host PC or external, such as
WLAN (802.11) and Bluetooth devices. Transmit channels and their associated
wideband noise can jam the UNDP receivers, and even their LO frequencies, digital
logic, or clock signals can be disruptive.