Spectracom GSG-5 series, Руководство пользователя с руководством по SCPI

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2.5 Signal Power Level Considerations
2.5.1 Compliance: Using an Antenna
Spectracom’s GSG GNSS Simulator products meet all required regulations of the FCC and CE
Mark for operation as electronic test equipment. However, when using the GSG signal gen
erator with an RF antenna (instead of an RF cable), additional regulations controlling the radi
ation of GPS-like signals into the air must be taken into account by the user:
In the USA, the GPS spectrum is controlled by the
National Telecommunications and Inform
ation Administration (NTIA) : See Sections 8.3.28 and 8.3.29 of the Manual of Regulations
and Procedures for Federal Radio Frequency Management
(
http://www.ntia.doc.gov/osmhome/redbook/redbook.html
).
Depending on your situation, you may need authorization from the FCC to operate at or near
the level allowed by the NTIA. A Special Temporary Authorization (STA) or Experimental
License
may be required. For more information, see the FCC web site:
https://fjallfoss.fcc.gov/oetcf/els/
.
Countries other than the USA may have their own regulations or restrictions, which you should
be aware of and comply with before using the optional antenna.
2.5.2 Transmit Power Level
The U.S. agency NTIA (National Telecommunications & Information Administration) restricts the
maximum signal level to -140 dBm (24 MHz BW) as received from an isotropic antenna at a
distance of 100 feet from the building where the test is being conducted. Therefore, the max
imum power level output from the GSG Signal Generator may need to be limited to conform to
this regulation. For example, consider the following test setup:
Antenna distance to nearest exterior wall: 100 ft.
Antenna gain: 0 dB (omni antenna)
Cable loss, antenna to GSG: 0 dB (no cable used)
Using the free space loss calculation for radio propagation:
Loss (dB) = 20 log10 (4
ᴫ
* Distance /
λ
)
Where
λ
= wavelength: @ 1575 MHz= 19 cm = 0.62 ft
Distance = 200 ft total => 100 ft from antenna exterior wall + 100 ft to restricted
perimeter
Loss = 72 dB = 20 log10 (4
ᴫ
* 200/0.62)
Using the free space calculation is a worst case scenario as the wall and any other obstructions
will likely reduce the signal even more. Therefore, setting the power output of the GSG to:
-140 + 72 = -68 dBm or less will guarantee compliance.
2.5 Signal Power Level Considerations
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User Manual GSG-5/6 Series Rev. 26
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