What is a blind encoder?











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7
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As I'm studying, I found that GPS has to have 5 satellites or 4 satellites with "blind encoders" to use RAIM.



What is a blind encoder and what is its purpose?










share|improve this question
























  • Can you reference the source you are learning from or provide the relevant quotes from it? Because as far as I can tell, RAIM needs 5 satellites for error detection and 6 for correction and there is no way around it. Also, I am not sure what “blind-encorder” is it talking about, but there does not seem to be anything called blind encoder around GPS.
    – Jan Hudec
    2 days ago










  • An altitude encoder used with transponder? (no cockpit display): How does radar receive Mode C information?
    – mins
    2 days ago












  • As I know, GPS knows our altitude (via blind encoder which is another point of reference for position information. Therefore we need only 4 satellite to trilaterate our position.
    – Mun Park
    2 days ago










  • Closely related. I think you may be mixing some different things here: a blind encoder is usually part of an aircraft's altimeter, which has nothing to do with RAIM.
    – Pondlife
    2 days ago






  • 1




    @MunPark GPS doesn't know your altitude. It knows the altitude of its satellites, but it has no idea what your altitude (or your position in any dimension) is. Your flight computers may know because of data from your altimeter(s), but the Global Positioning System doesn't know, as it's a transmit-only system that doesn't even know who is receiving its signals, let alone their altitudes.
    – reirab
    yesterday















up vote
7
down vote

favorite












As I'm studying, I found that GPS has to have 5 satellites or 4 satellites with "blind encoders" to use RAIM.



What is a blind encoder and what is its purpose?










share|improve this question
























  • Can you reference the source you are learning from or provide the relevant quotes from it? Because as far as I can tell, RAIM needs 5 satellites for error detection and 6 for correction and there is no way around it. Also, I am not sure what “blind-encorder” is it talking about, but there does not seem to be anything called blind encoder around GPS.
    – Jan Hudec
    2 days ago










  • An altitude encoder used with transponder? (no cockpit display): How does radar receive Mode C information?
    – mins
    2 days ago












  • As I know, GPS knows our altitude (via blind encoder which is another point of reference for position information. Therefore we need only 4 satellite to trilaterate our position.
    – Mun Park
    2 days ago










  • Closely related. I think you may be mixing some different things here: a blind encoder is usually part of an aircraft's altimeter, which has nothing to do with RAIM.
    – Pondlife
    2 days ago






  • 1




    @MunPark GPS doesn't know your altitude. It knows the altitude of its satellites, but it has no idea what your altitude (or your position in any dimension) is. Your flight computers may know because of data from your altimeter(s), but the Global Positioning System doesn't know, as it's a transmit-only system that doesn't even know who is receiving its signals, let alone their altitudes.
    – reirab
    yesterday













up vote
7
down vote

favorite









up vote
7
down vote

favorite











As I'm studying, I found that GPS has to have 5 satellites or 4 satellites with "blind encoders" to use RAIM.



What is a blind encoder and what is its purpose?










share|improve this question















As I'm studying, I found that GPS has to have 5 satellites or 4 satellites with "blind encoders" to use RAIM.



What is a blind encoder and what is its purpose?







gps raim






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 2 days ago









Pondlife

49.8k8134272




49.8k8134272










asked 2 days ago









Mun Park

563




563












  • Can you reference the source you are learning from or provide the relevant quotes from it? Because as far as I can tell, RAIM needs 5 satellites for error detection and 6 for correction and there is no way around it. Also, I am not sure what “blind-encorder” is it talking about, but there does not seem to be anything called blind encoder around GPS.
    – Jan Hudec
    2 days ago










  • An altitude encoder used with transponder? (no cockpit display): How does radar receive Mode C information?
    – mins
    2 days ago












  • As I know, GPS knows our altitude (via blind encoder which is another point of reference for position information. Therefore we need only 4 satellite to trilaterate our position.
    – Mun Park
    2 days ago










  • Closely related. I think you may be mixing some different things here: a blind encoder is usually part of an aircraft's altimeter, which has nothing to do with RAIM.
    – Pondlife
    2 days ago






  • 1




    @MunPark GPS doesn't know your altitude. It knows the altitude of its satellites, but it has no idea what your altitude (or your position in any dimension) is. Your flight computers may know because of data from your altimeter(s), but the Global Positioning System doesn't know, as it's a transmit-only system that doesn't even know who is receiving its signals, let alone their altitudes.
    – reirab
    yesterday


















  • Can you reference the source you are learning from or provide the relevant quotes from it? Because as far as I can tell, RAIM needs 5 satellites for error detection and 6 for correction and there is no way around it. Also, I am not sure what “blind-encorder” is it talking about, but there does not seem to be anything called blind encoder around GPS.
    – Jan Hudec
    2 days ago










  • An altitude encoder used with transponder? (no cockpit display): How does radar receive Mode C information?
    – mins
    2 days ago












  • As I know, GPS knows our altitude (via blind encoder which is another point of reference for position information. Therefore we need only 4 satellite to trilaterate our position.
    – Mun Park
    2 days ago










  • Closely related. I think you may be mixing some different things here: a blind encoder is usually part of an aircraft's altimeter, which has nothing to do with RAIM.
    – Pondlife
    2 days ago






  • 1




    @MunPark GPS doesn't know your altitude. It knows the altitude of its satellites, but it has no idea what your altitude (or your position in any dimension) is. Your flight computers may know because of data from your altimeter(s), but the Global Positioning System doesn't know, as it's a transmit-only system that doesn't even know who is receiving its signals, let alone their altitudes.
    – reirab
    yesterday
















Can you reference the source you are learning from or provide the relevant quotes from it? Because as far as I can tell, RAIM needs 5 satellites for error detection and 6 for correction and there is no way around it. Also, I am not sure what “blind-encorder” is it talking about, but there does not seem to be anything called blind encoder around GPS.
– Jan Hudec
2 days ago




Can you reference the source you are learning from or provide the relevant quotes from it? Because as far as I can tell, RAIM needs 5 satellites for error detection and 6 for correction and there is no way around it. Also, I am not sure what “blind-encorder” is it talking about, but there does not seem to be anything called blind encoder around GPS.
– Jan Hudec
2 days ago












An altitude encoder used with transponder? (no cockpit display): How does radar receive Mode C information?
– mins
2 days ago






An altitude encoder used with transponder? (no cockpit display): How does radar receive Mode C information?
– mins
2 days ago














As I know, GPS knows our altitude (via blind encoder which is another point of reference for position information. Therefore we need only 4 satellite to trilaterate our position.
– Mun Park
2 days ago




As I know, GPS knows our altitude (via blind encoder which is another point of reference for position information. Therefore we need only 4 satellite to trilaterate our position.
– Mun Park
2 days ago












Closely related. I think you may be mixing some different things here: a blind encoder is usually part of an aircraft's altimeter, which has nothing to do with RAIM.
– Pondlife
2 days ago




Closely related. I think you may be mixing some different things here: a blind encoder is usually part of an aircraft's altimeter, which has nothing to do with RAIM.
– Pondlife
2 days ago




1




1




@MunPark GPS doesn't know your altitude. It knows the altitude of its satellites, but it has no idea what your altitude (or your position in any dimension) is. Your flight computers may know because of data from your altimeter(s), but the Global Positioning System doesn't know, as it's a transmit-only system that doesn't even know who is receiving its signals, let alone their altitudes.
– reirab
yesterday




@MunPark GPS doesn't know your altitude. It knows the altitude of its satellites, but it has no idea what your altitude (or your position in any dimension) is. Your flight computers may know because of data from your altimeter(s), but the Global Positioning System doesn't know, as it's a transmit-only system that doesn't even know who is receiving its signals, let alone their altitudes.
– reirab
yesterday










2 Answers
2






active

oldest

votes

















up vote
19
down vote













A blind encoder is an altimeter that encodes pressure altitude and outputs it on a databus. They are "blind" in that they do not display data to the pilot. Most general aviation units use a parallel bus with Gillham encoding. More expensive units and air data computers use serial bus output, commonly ARINC 429.



Historically, the blind encoder existed to provide pressure altitude data to the transponder to enable Mode C reporting.



When it was proposed to use GPS as a primary means of navigation in the early 1990's, the FAA deemed that a means of ensuring the integrity of the signal was essential. The longer term solution was to establish WAAS which provided both augmentation and an integrity channel. The short term solution was to have the receivers include an internal monitor, which took on the name RAIM for Receiver Autonomous Integrity Monitor.



RAIM algorithms have evolved several times over the years. Since early GPS receivers were often single or 3 channel receivers, the use of altitude as a substitute for an additional satellite was common. (Altitude is just another range in the rho-rho computation.)



Later GPS receivers moved to 6 and 12 channel receivers, thus enabling RAIM algorithms that don't need altitude data except in extreme cases.



So yes, the number of satellites needed for a RAIM calculation can be reduced by one when pressure altitude is available from a blind encoder.






share|improve this answer





















  • +1, I had no idea that there's a link between altitude encoding and RAIM. I'm not doubting your answer, but do you have any sources on the algorithms you mentioned?
    – Pondlife
    2 days ago






  • 3




    The information is in the GPS MOPS, RTCA DO-229. The basics are covered in Appendix G—REQUIREMENTS FOR BAROMETRIC ALTIMETER AIDING in DO-229C. I'm not sure if the reference is still valid in the current version DO-229E. I do know that the newer version does require the use of FDE RAIM as the algorithms have evolved.
    – Gerry
    2 days ago










  • thanks for that!
    – Pondlife
    2 days ago










  • Of course the barometric altimeter reading depends on the weather, so the position obtained with use of barometric altitude has lower accuracy. Good enough for en-route navigation, but not for approaches or anything needing RNP.
    – Jan Hudec
    2 hours ago












  • @JanHudec Certainly not CAT I or APV approaches, but a TSO C129 GPS with RAIM is capable of RNP 0.3 non-precision approaches. When combined with an FMS the same GPS sensors support LNAV/VNAV approaches. They did require pilot input of the local altimeter setting. Most of those approaches had MDAs in the 250 to 400 foot range.
    – Gerry
    1 hour ago


















up vote
0
down vote













Receiver autonomous integrity monitoring
Receiver autonomous integrity monitoring (RAIM) is a technology developed to assess the integrity of global positioning system (GPS) signals in a GPS receiver system. It is of special importance in safety-critical GPS applications, such as in aviation or marine navigation



Check out the GPS article in this FAA newsletter to start with:
http://www.faa.gov/news/safety_briefing/2010/media/JanFeb2010.pdf



RAIM prediction is what is of primary concern for Non-WAAS equipped GPSs.
If you are WAAS equipped then you are good to go without doing prediction.






share|improve this answer








New contributor




KARTIK GURNANI is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.


















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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

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    up vote
    19
    down vote













    A blind encoder is an altimeter that encodes pressure altitude and outputs it on a databus. They are "blind" in that they do not display data to the pilot. Most general aviation units use a parallel bus with Gillham encoding. More expensive units and air data computers use serial bus output, commonly ARINC 429.



    Historically, the blind encoder existed to provide pressure altitude data to the transponder to enable Mode C reporting.



    When it was proposed to use GPS as a primary means of navigation in the early 1990's, the FAA deemed that a means of ensuring the integrity of the signal was essential. The longer term solution was to establish WAAS which provided both augmentation and an integrity channel. The short term solution was to have the receivers include an internal monitor, which took on the name RAIM for Receiver Autonomous Integrity Monitor.



    RAIM algorithms have evolved several times over the years. Since early GPS receivers were often single or 3 channel receivers, the use of altitude as a substitute for an additional satellite was common. (Altitude is just another range in the rho-rho computation.)



    Later GPS receivers moved to 6 and 12 channel receivers, thus enabling RAIM algorithms that don't need altitude data except in extreme cases.



    So yes, the number of satellites needed for a RAIM calculation can be reduced by one when pressure altitude is available from a blind encoder.






    share|improve this answer





















    • +1, I had no idea that there's a link between altitude encoding and RAIM. I'm not doubting your answer, but do you have any sources on the algorithms you mentioned?
      – Pondlife
      2 days ago






    • 3




      The information is in the GPS MOPS, RTCA DO-229. The basics are covered in Appendix G—REQUIREMENTS FOR BAROMETRIC ALTIMETER AIDING in DO-229C. I'm not sure if the reference is still valid in the current version DO-229E. I do know that the newer version does require the use of FDE RAIM as the algorithms have evolved.
      – Gerry
      2 days ago










    • thanks for that!
      – Pondlife
      2 days ago










    • Of course the barometric altimeter reading depends on the weather, so the position obtained with use of barometric altitude has lower accuracy. Good enough for en-route navigation, but not for approaches or anything needing RNP.
      – Jan Hudec
      2 hours ago












    • @JanHudec Certainly not CAT I or APV approaches, but a TSO C129 GPS with RAIM is capable of RNP 0.3 non-precision approaches. When combined with an FMS the same GPS sensors support LNAV/VNAV approaches. They did require pilot input of the local altimeter setting. Most of those approaches had MDAs in the 250 to 400 foot range.
      – Gerry
      1 hour ago















    up vote
    19
    down vote













    A blind encoder is an altimeter that encodes pressure altitude and outputs it on a databus. They are "blind" in that they do not display data to the pilot. Most general aviation units use a parallel bus with Gillham encoding. More expensive units and air data computers use serial bus output, commonly ARINC 429.



    Historically, the blind encoder existed to provide pressure altitude data to the transponder to enable Mode C reporting.



    When it was proposed to use GPS as a primary means of navigation in the early 1990's, the FAA deemed that a means of ensuring the integrity of the signal was essential. The longer term solution was to establish WAAS which provided both augmentation and an integrity channel. The short term solution was to have the receivers include an internal monitor, which took on the name RAIM for Receiver Autonomous Integrity Monitor.



    RAIM algorithms have evolved several times over the years. Since early GPS receivers were often single or 3 channel receivers, the use of altitude as a substitute for an additional satellite was common. (Altitude is just another range in the rho-rho computation.)



    Later GPS receivers moved to 6 and 12 channel receivers, thus enabling RAIM algorithms that don't need altitude data except in extreme cases.



    So yes, the number of satellites needed for a RAIM calculation can be reduced by one when pressure altitude is available from a blind encoder.






    share|improve this answer





















    • +1, I had no idea that there's a link between altitude encoding and RAIM. I'm not doubting your answer, but do you have any sources on the algorithms you mentioned?
      – Pondlife
      2 days ago






    • 3




      The information is in the GPS MOPS, RTCA DO-229. The basics are covered in Appendix G—REQUIREMENTS FOR BAROMETRIC ALTIMETER AIDING in DO-229C. I'm not sure if the reference is still valid in the current version DO-229E. I do know that the newer version does require the use of FDE RAIM as the algorithms have evolved.
      – Gerry
      2 days ago










    • thanks for that!
      – Pondlife
      2 days ago










    • Of course the barometric altimeter reading depends on the weather, so the position obtained with use of barometric altitude has lower accuracy. Good enough for en-route navigation, but not for approaches or anything needing RNP.
      – Jan Hudec
      2 hours ago












    • @JanHudec Certainly not CAT I or APV approaches, but a TSO C129 GPS with RAIM is capable of RNP 0.3 non-precision approaches. When combined with an FMS the same GPS sensors support LNAV/VNAV approaches. They did require pilot input of the local altimeter setting. Most of those approaches had MDAs in the 250 to 400 foot range.
      – Gerry
      1 hour ago













    up vote
    19
    down vote










    up vote
    19
    down vote









    A blind encoder is an altimeter that encodes pressure altitude and outputs it on a databus. They are "blind" in that they do not display data to the pilot. Most general aviation units use a parallel bus with Gillham encoding. More expensive units and air data computers use serial bus output, commonly ARINC 429.



    Historically, the blind encoder existed to provide pressure altitude data to the transponder to enable Mode C reporting.



    When it was proposed to use GPS as a primary means of navigation in the early 1990's, the FAA deemed that a means of ensuring the integrity of the signal was essential. The longer term solution was to establish WAAS which provided both augmentation and an integrity channel. The short term solution was to have the receivers include an internal monitor, which took on the name RAIM for Receiver Autonomous Integrity Monitor.



    RAIM algorithms have evolved several times over the years. Since early GPS receivers were often single or 3 channel receivers, the use of altitude as a substitute for an additional satellite was common. (Altitude is just another range in the rho-rho computation.)



    Later GPS receivers moved to 6 and 12 channel receivers, thus enabling RAIM algorithms that don't need altitude data except in extreme cases.



    So yes, the number of satellites needed for a RAIM calculation can be reduced by one when pressure altitude is available from a blind encoder.






    share|improve this answer












    A blind encoder is an altimeter that encodes pressure altitude and outputs it on a databus. They are "blind" in that they do not display data to the pilot. Most general aviation units use a parallel bus with Gillham encoding. More expensive units and air data computers use serial bus output, commonly ARINC 429.



    Historically, the blind encoder existed to provide pressure altitude data to the transponder to enable Mode C reporting.



    When it was proposed to use GPS as a primary means of navigation in the early 1990's, the FAA deemed that a means of ensuring the integrity of the signal was essential. The longer term solution was to establish WAAS which provided both augmentation and an integrity channel. The short term solution was to have the receivers include an internal monitor, which took on the name RAIM for Receiver Autonomous Integrity Monitor.



    RAIM algorithms have evolved several times over the years. Since early GPS receivers were often single or 3 channel receivers, the use of altitude as a substitute for an additional satellite was common. (Altitude is just another range in the rho-rho computation.)



    Later GPS receivers moved to 6 and 12 channel receivers, thus enabling RAIM algorithms that don't need altitude data except in extreme cases.



    So yes, the number of satellites needed for a RAIM calculation can be reduced by one when pressure altitude is available from a blind encoder.







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 2 days ago









    Gerry

    10.1k12949




    10.1k12949












    • +1, I had no idea that there's a link between altitude encoding and RAIM. I'm not doubting your answer, but do you have any sources on the algorithms you mentioned?
      – Pondlife
      2 days ago






    • 3




      The information is in the GPS MOPS, RTCA DO-229. The basics are covered in Appendix G—REQUIREMENTS FOR BAROMETRIC ALTIMETER AIDING in DO-229C. I'm not sure if the reference is still valid in the current version DO-229E. I do know that the newer version does require the use of FDE RAIM as the algorithms have evolved.
      – Gerry
      2 days ago










    • thanks for that!
      – Pondlife
      2 days ago










    • Of course the barometric altimeter reading depends on the weather, so the position obtained with use of barometric altitude has lower accuracy. Good enough for en-route navigation, but not for approaches or anything needing RNP.
      – Jan Hudec
      2 hours ago












    • @JanHudec Certainly not CAT I or APV approaches, but a TSO C129 GPS with RAIM is capable of RNP 0.3 non-precision approaches. When combined with an FMS the same GPS sensors support LNAV/VNAV approaches. They did require pilot input of the local altimeter setting. Most of those approaches had MDAs in the 250 to 400 foot range.
      – Gerry
      1 hour ago


















    • +1, I had no idea that there's a link between altitude encoding and RAIM. I'm not doubting your answer, but do you have any sources on the algorithms you mentioned?
      – Pondlife
      2 days ago






    • 3




      The information is in the GPS MOPS, RTCA DO-229. The basics are covered in Appendix G—REQUIREMENTS FOR BAROMETRIC ALTIMETER AIDING in DO-229C. I'm not sure if the reference is still valid in the current version DO-229E. I do know that the newer version does require the use of FDE RAIM as the algorithms have evolved.
      – Gerry
      2 days ago










    • thanks for that!
      – Pondlife
      2 days ago










    • Of course the barometric altimeter reading depends on the weather, so the position obtained with use of barometric altitude has lower accuracy. Good enough for en-route navigation, but not for approaches or anything needing RNP.
      – Jan Hudec
      2 hours ago












    • @JanHudec Certainly not CAT I or APV approaches, but a TSO C129 GPS with RAIM is capable of RNP 0.3 non-precision approaches. When combined with an FMS the same GPS sensors support LNAV/VNAV approaches. They did require pilot input of the local altimeter setting. Most of those approaches had MDAs in the 250 to 400 foot range.
      – Gerry
      1 hour ago
















    +1, I had no idea that there's a link between altitude encoding and RAIM. I'm not doubting your answer, but do you have any sources on the algorithms you mentioned?
    – Pondlife
    2 days ago




    +1, I had no idea that there's a link between altitude encoding and RAIM. I'm not doubting your answer, but do you have any sources on the algorithms you mentioned?
    – Pondlife
    2 days ago




    3




    3




    The information is in the GPS MOPS, RTCA DO-229. The basics are covered in Appendix G—REQUIREMENTS FOR BAROMETRIC ALTIMETER AIDING in DO-229C. I'm not sure if the reference is still valid in the current version DO-229E. I do know that the newer version does require the use of FDE RAIM as the algorithms have evolved.
    – Gerry
    2 days ago




    The information is in the GPS MOPS, RTCA DO-229. The basics are covered in Appendix G—REQUIREMENTS FOR BAROMETRIC ALTIMETER AIDING in DO-229C. I'm not sure if the reference is still valid in the current version DO-229E. I do know that the newer version does require the use of FDE RAIM as the algorithms have evolved.
    – Gerry
    2 days ago












    thanks for that!
    – Pondlife
    2 days ago




    thanks for that!
    – Pondlife
    2 days ago












    Of course the barometric altimeter reading depends on the weather, so the position obtained with use of barometric altitude has lower accuracy. Good enough for en-route navigation, but not for approaches or anything needing RNP.
    – Jan Hudec
    2 hours ago






    Of course the barometric altimeter reading depends on the weather, so the position obtained with use of barometric altitude has lower accuracy. Good enough for en-route navigation, but not for approaches or anything needing RNP.
    – Jan Hudec
    2 hours ago














    @JanHudec Certainly not CAT I or APV approaches, but a TSO C129 GPS with RAIM is capable of RNP 0.3 non-precision approaches. When combined with an FMS the same GPS sensors support LNAV/VNAV approaches. They did require pilot input of the local altimeter setting. Most of those approaches had MDAs in the 250 to 400 foot range.
    – Gerry
    1 hour ago




    @JanHudec Certainly not CAT I or APV approaches, but a TSO C129 GPS with RAIM is capable of RNP 0.3 non-precision approaches. When combined with an FMS the same GPS sensors support LNAV/VNAV approaches. They did require pilot input of the local altimeter setting. Most of those approaches had MDAs in the 250 to 400 foot range.
    – Gerry
    1 hour ago










    up vote
    0
    down vote













    Receiver autonomous integrity monitoring
    Receiver autonomous integrity monitoring (RAIM) is a technology developed to assess the integrity of global positioning system (GPS) signals in a GPS receiver system. It is of special importance in safety-critical GPS applications, such as in aviation or marine navigation



    Check out the GPS article in this FAA newsletter to start with:
    http://www.faa.gov/news/safety_briefing/2010/media/JanFeb2010.pdf



    RAIM prediction is what is of primary concern for Non-WAAS equipped GPSs.
    If you are WAAS equipped then you are good to go without doing prediction.






    share|improve this answer








    New contributor




    KARTIK GURNANI is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.






















      up vote
      0
      down vote













      Receiver autonomous integrity monitoring
      Receiver autonomous integrity monitoring (RAIM) is a technology developed to assess the integrity of global positioning system (GPS) signals in a GPS receiver system. It is of special importance in safety-critical GPS applications, such as in aviation or marine navigation



      Check out the GPS article in this FAA newsletter to start with:
      http://www.faa.gov/news/safety_briefing/2010/media/JanFeb2010.pdf



      RAIM prediction is what is of primary concern for Non-WAAS equipped GPSs.
      If you are WAAS equipped then you are good to go without doing prediction.






      share|improve this answer








      New contributor




      KARTIK GURNANI is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.




















        up vote
        0
        down vote










        up vote
        0
        down vote









        Receiver autonomous integrity monitoring
        Receiver autonomous integrity monitoring (RAIM) is a technology developed to assess the integrity of global positioning system (GPS) signals in a GPS receiver system. It is of special importance in safety-critical GPS applications, such as in aviation or marine navigation



        Check out the GPS article in this FAA newsletter to start with:
        http://www.faa.gov/news/safety_briefing/2010/media/JanFeb2010.pdf



        RAIM prediction is what is of primary concern for Non-WAAS equipped GPSs.
        If you are WAAS equipped then you are good to go without doing prediction.






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        Receiver autonomous integrity monitoring
        Receiver autonomous integrity monitoring (RAIM) is a technology developed to assess the integrity of global positioning system (GPS) signals in a GPS receiver system. It is of special importance in safety-critical GPS applications, such as in aviation or marine navigation



        Check out the GPS article in this FAA newsletter to start with:
        http://www.faa.gov/news/safety_briefing/2010/media/JanFeb2010.pdf



        RAIM prediction is what is of primary concern for Non-WAAS equipped GPSs.
        If you are WAAS equipped then you are good to go without doing prediction.







        share|improve this answer








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        KARTIK GURNANI is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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        share|improve this answer



        share|improve this answer






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        answered yesterday









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