Return link design for PSD limited mobile satellite communication systems
First Claim
1. A method of determining a power spectral density (PSD) of a radio frequency (RF) wave signal from a mobile platform having a communications system in communication with a space-based transponder, said method comprising:
- using a controller to receive and determine a signal quality value of said RF signal transponded from a transmitter of said space-based transponder;
assuming that said signal quality value of said RF signal received by said controller is approximately identical to a signal quality value of an RF signal emanating from an output of said space-based transponder;
determining an effective isotropic radiated power (EIRP) value of an RF signal from an antenna of said mobile platform being received by said space-based transponder, as a function of said signal quality value of said RF signal being received by said controller, and denoting said EIRP value as a target EIRP;
using said target EIRP to determine an actual EIRP of said RF signal reaching a GEO arc within which said space-based transponder resides; and
using said controller to determine, from said actual EIRP reaching said GEO arc, said PSD of said RF signal reaching said GEO arc.
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Abstract
A system and method for managing access to a satellite-based transponder by a plurality of aircraft each having a mobile radio frequency (RF) system. The system employs a ground-based, central control system for managing access to the satellite-based transponder so that the aggregate power spectral density (PSD) of the RF signals of all the mobile systems does not exceed, at any time, limits established by regulatory agencies to prevent interference between satellite systems. This is accomplished by a dual control loop arrangement for monitoring the signal-to-noise ratio (Eb/No) of the RF signal transmitted by the satellite-based transponder. A ground-based control loop is used whereby a ground-based central controller monitors the Eb/No and transmits commands to the aircraft (via the satellite transponder) to maintain the Eb/No of the transmitted signal within a predetermined range. A fast scan angle compensation is used by the mobile system of the aircraft to implement another control loop to further adjust the transmit power. This control loop maintains the Eb/No of the signal transmitted to the satellite-based transponder at the commanded level inbetween updates from the ground-based central controller.
89 Citations
20 Claims
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1. A method of determining a power spectral density (PSD) of a radio frequency (RF) wave signal from a mobile platform having a communications system in communication with a space-based transponder, said method comprising:
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using a controller to receive and determine a signal quality value of said RF signal transponded from a transmitter of said space-based transponder; assuming that said signal quality value of said RF signal received by said controller is approximately identical to a signal quality value of an RF signal emanating from an output of said space-based transponder; determining an effective isotropic radiated power (EIRP) value of an RF signal from an antenna of said mobile platform being received by said space-based transponder, as a function of said signal quality value of said RF signal being received by said controller, and denoting said EIRP value as a target EIRP; using said target EIRP to determine an actual EIRP of said RF signal reaching a GEO arc within which said space-based transponder resides; and using said controller to determine, from said actual EIRP reaching said GEO arc, said PSD of said RF signal reaching said GEO arc. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of determining a power spectral density (PSD) of a radio frequency (RF) wave signal from a mobile platform reaching a geostationary orbit plane of a satellite transponder with which the mobile platform is using to form a communication link with a remotely located central controller, said method comprising:
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causing said mobile platform to transmit an RF signal to said satellite transponder which is transponded to a remotely located central controller; using said central controller to determine a signal quality of said RF signal being transponded from an output of said satellite transponder, and received by said central controller, wherein said signal quality is represented by a Eb/No (energy per bit/noise spectral density) value of the RF signal; assuming that said Eb/No value of said RF signal received at said central controller is approximately identical to a Eb/No value of said RF signal as said RF signal emanates from said output of said satellite transponder; determining an effective isotropic radiated power (EIRP) value of said RF signal from an antenna of said mobile platform being received by said satellite transponder, as a function of said Eb/No of said RF signal being received by said central controller, and denoting said EIRP value as a target EIRP; using said target EIRP to determine an actual EIRP of said RF signal reaching a geostationary orbit plane in which said satellite transponder is orbiting; and using said controller to determine, from said actual EIRP of said RF signal reaching said geostationary orbit plane, said PSD of said RF signal reaching said geostationary orbit plane. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method for remotely determining an effective isotropic radiated power (EIRP) of a radio frequency (RF) signal being radiated by an antenna of a mobile platform to a geostationary orbit plane of a satellite transponder, wherein the RF signal is being transponded by said satellite transponder to a remotely located controller, the method comprising:
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using a central controller to determine an Eb/No value for said RF signal as said RF signal is being received by said controller; using said Eb/No value to determine an approximate Eb/No value for said RF signal when said RF signal is being transmitted from said satellite transponder; using said controller to determine, from said Eb/No value, an EIRP value for said RF signal being received by said satellite transponder, and denoting said EIRP value as a target EIRP value; and using said controller to determine, from said Eb/No value, an actual EIRP value for said RF signal reaching said geostationary orbit plane. - View Dependent Claims (18, 19, 20)
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Specification