National Instruments NI 9467, Начало работы, Страница: 8 / 13

between -135 dBm and -120 dBm at the NI-9467 SMA input. GPS signal strength on
the Earth’s surface is typically -130 dBm. Targeting a signal strength of -125 dBm at
the SMA input, you can compute the maximum cable length as:
■
Max_cable_loss = -130 dBm + antenna_gain - (-125 dBm)
■
Max_cable_length = Max_cable_loss / (loss_per_unit_of_distance)
For example, if you use an active antenna with gain of 28 dB and RG-58 cable, which
has a rated loss at 1.5 GHz of about 0.8 dB/m (24.5 dB/100 ft), the maximum cable
length you could use is:
■
Max_cable_loss = -130 dBm + 28 dB - (-125 dBm) = 23 dB
■
Max_cable_length = 23 dB / (0.8 dB/m) ≈ 29 m
Sleep Mode
This module supports a low-power sleep mode. Support for sleep mode at the
system level depends on the chassis the module is plugged into. Refer to the chassis
manual for information about support for sleep mode. If the chassis supports sleep
mode, refer to the software help for information about enabling sleep mode. Visit
ni.com/info and enter cseriesdoc for information about C Series documentation.
Typically, when a system is in sleep mode, you cannot communicate with the
modules. In sleep mode, the system consumes minimal power and may dissipate
less heat than it does in normal mode. Refer to the Specifications section for more
information about power consumption and thermal dissipation.
Notice that when the NI-9467 is in sleep mode, the GPS receiver is not powered and
stops tracking satellites. When the module exits sleep mode and power to the GPS
receiver is restored, the module goes through the normal power-up process, which
includes the ephemeris/almanac data acquisition and self-survey process.
Therefore, it can take approximately 30 seconds before usable timing and location
signaling can be generated. Refer to Start-Up Behavior for more information.
NI-9467 Specifications
The following specifications are typical for the range -40 °C to 70 °C unless otherwise
noted.
ni.com
8
NI-9467 Getting Started