P440 Data Sheet / User Guide
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transfer switch directly into the receiver. In fact, energy received on the transmit antenna will also
leak through the transfer switch directly into the receiver. Normally this is not an issue, but the user
is advised that the isolation of the transfer switch is approximately 20 dB.
When connecting the port to an SMA cable or antenna, be careful not to overtighten the connection.
This can cause damage to the board. Beware of loose connections as these can degrade performance.
As long as the connectors are “finger-tight,” the system will work well. To insure an optimal
connection, the user should use a calibrated SMA torque wrench. These are generally available and
cost about $100.
The P440 is intended to be used with Time Domain’s Broadspec antenna. Using any other antenna
will require recertification to confirm compliance with the relevant emissions regulations. However,
it is possible to add passive extension cables between the antenna port and the antenna. Be aware that
using alternate UWB antennas, additional fixed attenuators, additional cabling and/or connectors will
change the RF time-of-flight electrical distance between the antenna port and the phase center of the
antenna. Failure to account for such changes will result in an offset or bias error in range
measurements.
4.7 RF Transmit and Receive Characteristics
Two versions of the P440 are available, one which is compliant with the US FCC transmission mask
as described in FCC Part 15.519 and one which is compliant with the EU ETSI EN 302 065 mask.
The major difference between these two versions is in the nature of the transmitted pulse. The band
edges on the EU mask are much more severe than for the FCC mask and as a result they require more
severe filtering. The EU waveform is therefore more narrow in frequency and longer in time
(contains more lobes) than the FCC version.
The receive characteristics of the EU and FCC devices are identical. Both devices use a pair of
identical bandpass filters arranged in a bandpass/LNA architecture. The characteristics of a single
bandpass filter are shown below in
Figure 24.
Fig. 24: Characteristics of a single bandpass filter
4.8 Optional Power Amplifier
The P440 can be provided with an optional power amplifier which boosts the transit power by
approximately 16 db. In some cases, this can be valuable for evaluation or research activities.
However, this option is provided with two very important caveats.
