72ST100 User Manual v1 Confidential & Proprietary Information
8545-0194-01 v1.0
6.1. POWER REQUIREMENTS FOR AN EXTERNAL ANTENNA TO MAINTAIN SPECIFIED EIRP
Globalstar has used complex computer simulations to establish the required link budget for Simplex devices. Globalstar link
budget calculations are used for diagnostic purposes and to establish the workable EIRP spec, referenced below.
Due to movement of the satellites, the ability to serve users from diversity links, the internetworking of rake receivers, it is
not possible to make meaningful static link budget calculations. Link budget analyses are useful for trend analysis and for
comparing various system design changes. However, they cannot be used to determine absolute performance.
The link budget varies as a function of satellite elevation angle and azimuth angle from the user to the satellite. It depends
on both the user’s specific location and the specific location of the satellite. There are multiple satellites in view, each with a
different azimuth and elevation from the user, and each satellite is often communicating with multiple gateways. Every one of
these parameters are changing minute by minute.
There are two levels of Globalstar approval available for VAM products, Globalstar Registered2 and Globalstar Certified3.
The transmitted signal EIRP must satisfy the requirements in the table below from the minimum elevation angle of 25ο to a
maximum elevation angle of 90°:
Notes:
1. The low EIRP setting value corresponds to the 25° elevation angle at which point the Globalstar gateway is required to
pick up the transmitted ST100 signals. Link closure is not required until the satellites are at the minimum elevation angle
specified by Globalstar.
2. Globalstar Registered - Globalstar Registered Products have been evaluated and have been approved for use on the
Globalstar network but may not achieve the message success rates shown on the online Globalstar Simplex coverage map.
3. Globalstar Certified – Globalstar Certified Products are evaluated and tested to ensure that their performance meets
Globalstar’s certification performance specifications. Certified Products, when transmitting according to the 30-minute
certification benchmark messaging profile, with a clear view of the sky and no local interference, will provide the message
success rates advertised on the online Simplex Coverage map (http://www.Globalstar.com).
The VAM must consider the complete gain of the antenna system to be compliant with the specified EIRP limit. Conducted
power from the ST-100 is set to 24.5 dBm. Although there is some degree of adjustment available via software, the VAM should
use this is the starting point.
Final radiated power must not exceed 23dBm. This means that as designed the unit must operate such that conducted-power
+ line- loss+ antenna- gain meets the criteria in the above table.
[1]
The low EIRP setting value corresponds to 25 deg elevation angle at which point the GWA is required to pick up the STU signals. Link closure is not required until the satellites are
at the minimum elevation angle specified by Globalstar.
6. ANTENNA TUNING GUIDANCE
EIRP
(dBm)
1
SPECIFICATION GLOBALSTAR REGISTERED
2
GLOBALSTAR CERTIFIED
3
Minimum Limit 16
[1]
dBm
meet at least the Minimum Limit for at least 85% of all
azimuth directions, at each elevation (25°, 40°, 65°, 90°)
N/A Compliance required
Average 19 dBm
meet at least the Average Gain requirement for each
frequency, when averaged over all azimuth directions and
all elevations
N/A Required
Maximum Limit 23 dBm
be at or below the Maximum Limit over 100% of all azi-
muth directions, at each elevation (25°, 40°, 65°, 90°)
Required Required
TABLE 11 - EXTERNAL ANTENNA POWER REQUIREMENTS
To Next Page
