Abstract:
An automated process to periodically check and ensure that earth terminal settings provide compliant EIRPSD. For example, one embodiment of the present invention provides an apparatus which queries the modem for its transmit symbol rate and the Block Up-Converter (BUC) for its RF output power. Using these two values and preprogrammed values for connection loss between the BUC and antenna, the current input power spectral density being transferred to the antenna is computed by the apparatus and compared to the preprogrammed regulatory limit for the specific antenna. If the limit is being exceeded, the apparatus sets BUC attenuation to compensate for the excess.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/533,923, filed Sep. 13, 2011. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to satellite communication systems. More particularly, the present invention relates to methods and apparatuses for mitigating satellite interference due to user error. 
     2. Description of the Related Art 
     Satellite interference is a problem that affects all satellite operators, costing them millions of dollars per year to resolve. The Satellite Users Interference Reduction Group (SUIRG) lists user error as a major cause of interference. One aspect of user error involves exceeding the effective isotropic radiated power spectral density (EIRPSD) limitations defined by the satellite operator/regulatory agency. 
     Users most often only interface with the modem, where they set parameters such as user data rate, modulation scheme, forward error correction rate, coding type and output power. These settings along with connection losses and gain stages between the modem and antenna determine the input power spectral density to the antenna which along with the antenna radiation pattern characteristics yields the EIRPSD of the terminal. 
     Currently it is up to the user to take into consideration all these factors, perform the necessary calculations and set the input power into the antenna to ensure the terminal is not being used inappropriately. 
     BRIEF SUMMARY OF THE INVENTION 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects and advantages of the invention will be apparent from the description and drawings, and from the claims. 
     The present disclosure provides an automated process to periodically check and ensure the earth terminal settings provide compliant EIRPSD. 
     According to one aspect of the disclosure, an apparatus queries the modem for its transmit symbol rate and the Block Upconverter (BUC) for its RF output power. Using these two values and preprogrammed values for connection loss between the BUC and antenna, the current power spectral density being transferred to the antenna is calculated and compared to the preprogrammed regulatory limit for the specific antenna. If the limit is being exceeded, the apparatus sets BUC attenuation to compensate for the excess. 
     According to another aspect of the disclosure, an apparatus calculates the current value of the power spectral density and compares that value with the regulatory limit. If the limit is being exceeded, the apparatus sets the modem transmit power to compensate for the excess. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic block diagram of an earth terminal including an antenna control unit, according to an embodiment of the disclosure. 
         FIG. 2  is a flowchart of a routine executed by an automated satellite interference mitigation processing unit, according to an embodiment of the disclosure. 
         FIG. 3  is a flowchart of an alternative routine executed by an automated satellite interference mitigation processing unit, according to another embodiment of the disclosure. 
         FIG. 4  is a flowchart of a another alternative routine executed by an automated satellite interference mitigation processing unit, according to additional embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein is an apparatus that automatically checks earth terminal settings and ensures compliance of the terminal&#39;s operation with satellite operator/regulatory agency restrictions on EIRPSD. 
     Abbreviations used in this description are listed in Table 1. 
     
       
         
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
             
               
                   
                 ACU 
                 Antenna Control Unit 
               
               
                   
                 ASIM 
                 Automated Satellite Interference Mitigation 
               
               
                   
                 BUC 
                 Block Upconverter 
               
               
                   
                 D 
                 Delta Attenuation (dB) 
               
               
                   
                 EIRPSD 
                 Effective Isotropic Radiated Power Spectral Density 
               
               
                   
                 LNB 
                 Low-Noise Block Downconverter 
               
               
                   
                 M&amp;C 
                 Monitor and Control 
               
               
                   
                 Po 
                 Power Output (watts) 
               
               
                   
                 PSDL 
                 Power Spectral Density Limit (dBW/Hz) 
               
               
                   
                 PSDo 
                 Power Spectral Density Output (dBW/Hz) 
               
               
                   
                 RF 
                 Radio Frequency 
               
               
                   
                 Rx 
                 Receive 
               
               
                   
                 SUIRG 
                 Satellite Users Interference Reduction Group 
               
               
                   
                 TSR 
                 Transmit Symbol Rate (symbols/s) 
               
               
                   
                 Tx 
                 Transmit 
               
               
                   
                 QPSK 
                 Quadrature Phase-Shift Keying 
               
               
                   
                   
               
             
          
         
       
     
     In one embodiment of the invention, an Automated Satellite Interference Mitigation (ASIM) processing unit is provided which interfaces with both the BUC and modem of an earth terminal.  FIG. 1  shows a block diagram of an earth terminal  1  including ACU  10 , modem  11  and BUC  12 . The ASIM processing unit may be incorporated into the Modem or the BUC; for motorized earth terminals, the ASIM processing unit may also be incorporated into the Antenna Control Unit (ACU). In the embodiment shown in  FIG. 1 , the ASIM processing unit is incorporated into ACU  10 . ACU  10  communicates with modem  11  via link L 1 , with RF power meter  12  via link L 2 , with adjustable RF attenuator  13  via link L 3 , and with antenna  14  via link L 4 . Modem  11  transmits RF signals (e.g. data) to the antenna through BUC  15 , and receives RF signals from the antenna through LNB  16 . 
     In an embodiment, the ASIM processing unit (incorporated into ACU  10 ) periodically executes a routine with steps as shown in  FIG. 2 . ACU  10  sends a query  21 - 1  to the modem  11  for the transmit symbol rate; a query  21 - 2  to the RF power meter  12  for the RF output power of the BUC; and a query  21 - 3  to RF attenuator  13  for the RF attenuation setting of the BUC. 
     The ASIM processing unit sends query  21 - 1  to the modem  11  for its transmit symbol rate (TSR) setting in symbols per second. Alternatively, the ASIM processing unit may query the modem for several parameters (user data rate, modulation scheme, forward error correction rate, and type of coding used) from which the TSR can be calculated. The TSR is used to approximate the bandwidth containing RF energy at the output of the BUC. 
     The ASIM processing unit sends query  21 - 2  to the RF power meter  12  for the RF output power (Po) of the BUC in watts, and query  21 - 3  to the RF attenuator  13  for the attenuation setting of the BUC in dB. 
     In step  22 , the ASIM processing unit calculates the power spectral density at the output (PSDo) of the BUC in dBW/Hz, using:
 
 PSDo= 10*Log( Po/TSR )  (1)
 
     The PSDo result is compared (step  23 ) with the BUC output power spectral density limit (PDSL). In this embodiment, PSDL is a preprogrammed value that corresponds to the power spectral density limit for the terminal. The amount of necessary attenuation adjustment D in dB is calculated using
 
 D=PSDo−PSDL   (2)
 
     An example for the used PSDL value for an earth terminal operating in the USA with an antenna that is FCC 25.209 compliant and has negligible connection losses between the BUC and antenna could be −50 dBW/Hz. 
     If D&gt;0 (that is, the power spectral density output exceeds the power spectral density limit), the ASIM processing unit causes the RF attenuator  13  to increase the attenuation setting (dB) of the BUC by D to compensate for the excess (step  24 ). 
     A specific example is given to help clarify the calculations: 
     An earth terminal is set to uplink a digital carrier at a 512 Kbps data rate using QPSK modulation and Viterbi rate ¾ forward error correction; the connection losses between the BUC and antenna are negligible. 
     This results in the modem query  21 - 1  returning a TSR=349,184 symbols per second. 
     Assuming the BUC queries  21 - 2 ,  21 - 3  return:
 
 Po= 10 W
 
Attenuation=1 dB
 
     PSDo is calculated by the ASIM processing unit:
 
 PSDo=− 45.43 dBW/Hz
 
     PSDL for this terminal is specified by the satellite operator to −50 dBW/Hz. This results in D:
 
 D=− 45.43+50=4.57 dB.
 
     The ASIM adjusts the BUC attenuation setting by D:
 
New Attenuation=1+4.57=5.57 dB
 
       FIG. 3  shows a flowchart for a different routine according to another embodiment of the disclosure, where instead of using BUC attenuation to compensate for the excess in EIRPSD, the ASIM processing unit decreases the current value of the modem transmit power by the excess value. 
     ACU  10  sends a query  31 - 1  to the modem  11  for the transmit symbol rate (TSR); a query  31 - 2  to the modem  11  for the modem transmit power; and a query  31 - 3  to the RF power meter  12  for the RF output power of the BUC (Po). In step  32 , the power spectral density at the output (PSDo) of the BUC in dBW/Hz is calculated using formula (1) above. In step  33 , the result for PSDo is compared with the preprogrammed value for PSDL using formula (2) above. 
     If D&gt;0 (that is, the power spectral density output exceeds the power spectral density limit), the ASIM processing unit sets the modem transmit power to compensate for the excess (step  34 ). 
       FIG. 4  shows a flowchart for an additional routine according to yet another embodiment of the disclosure, in a case where earth terminal  1  uses an antenna with a non-circularly symmetric pattern. For this type of terminal, the PSDL may depend on the relative on-axis rotation or skew angle. 
     The ASIM processing unit sends a query  41 - 1  to the modem  11  for the transmit symbol rate (TSR); a query  41 - 2  to the RF power meter  12  for the RF output power of the BUC (Po); and a query  41 - 4  to RF attenuator  13  for the RF attenuation setting of the BUC. 
     The ASIM processing unit also sends a query  41 - 3  to the ACU to determine the skew angle of the antenna. In an embodiment, the earth terminal includes a motorized antenna, and antenna encoder readings may be obtained from the ACU. The ASIM processing unit queries the antenna&#39;s encoder skew angle that indexes into a preprogrammed look-up table to determine the PSDL for the antenna. Since this processing is contained in the ACU, the ASIM processing unit does not have to interface to an external device. 
     In step  42 , the power spectral density at the output (PSDo) of the BUC in dBW/Hz is calculated using formula (1) above. 
     In step  43 , the result for PSDo is compared with a skew angle specific value for PSDL obtained from the ACU, using formula (2) above. 
     If D&gt;0 (that is, the power spectral density output exceeds the power spectral density limit for that skew angle), the ASIM processing unit causes the RF attenuator  13  to increase the attenuation setting (dB) of the BUC by D to compensate for the excess (step  44 ). 
     One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.