What is required to make GPS signals available indoors?












5












$begingroup$


GPS satellites don't transmit strong enough to reach indoors, through the roofs and walls of buildings, like cell phones do. GPS signals that enter buildings through windows are unreliable since they often have bounced and thus give the wrong distance measures by even hundreds of meters. Since cell phones work fine indoors, and GPS uses the same frequency, I suppose there's no need to use another frequency.



Would it suffice for today's kind of GPS satellites to orbit in low Earth orbits, such as planned communication satellites constellations like Starlink? Would it be feasible to equip them with larger solar arrays, or would nuclear generators be required?



One can imagine many commercial applications for precision indoor navigation (like more efficient robotic vacuum cleaners ;-) Just reaching through the roofs of single storage factories and shopping centers should make for a great market. The alternative today is to install radio or ultrasound beacons (or perhaps a camera system) in every room where one wants to have a location service. A single ubiquitous system that's already standard would have economic advantages.






gps radio







share|improve this question











$endgroup$












  • $begingroup$
    Not all cell phones work fine indoors and not in every building. There are metall roofs and steel construction buildings. Multi path distribution of satellite signals does harm the GPS position precision. The speed of electric waves is different in air and in solid materials ( non metallic solids ). But GPS even handles different speed of light in vacuum and air. But how to handle the much lower speed in solids?
    $endgroup$
    – Uwe
    3 hours ago


















5












$begingroup$


GPS satellites don't transmit strong enough to reach indoors, through the roofs and walls of buildings, like cell phones do. GPS signals that enter buildings through windows are unreliable since they often have bounced and thus give the wrong distance measures by even hundreds of meters. Since cell phones work fine indoors, and GPS uses the same frequency, I suppose there's no need to use another frequency.



Would it suffice for today's kind of GPS satellites to orbit in low Earth orbits, such as planned communication satellites constellations like Starlink? Would it be feasible to equip them with larger solar arrays, or would nuclear generators be required?



One can imagine many commercial applications for precision indoor navigation (like more efficient robotic vacuum cleaners ;-) Just reaching through the roofs of single storage factories and shopping centers should make for a great market. The alternative today is to install radio or ultrasound beacons (or perhaps a camera system) in every room where one wants to have a location service. A single ubiquitous system that's already standard would have economic advantages.






gps radio







share|improve this question











$endgroup$












  • $begingroup$
    Not all cell phones work fine indoors and not in every building. There are metall roofs and steel construction buildings. Multi path distribution of satellite signals does harm the GPS position precision. The speed of electric waves is different in air and in solid materials ( non metallic solids ). But GPS even handles different speed of light in vacuum and air. But how to handle the much lower speed in solids?
    $endgroup$
    – Uwe
    3 hours ago
















5












5








5





$begingroup$


GPS satellites don't transmit strong enough to reach indoors, through the roofs and walls of buildings, like cell phones do. GPS signals that enter buildings through windows are unreliable since they often have bounced and thus give the wrong distance measures by even hundreds of meters. Since cell phones work fine indoors, and GPS uses the same frequency, I suppose there's no need to use another frequency.



Would it suffice for today's kind of GPS satellites to orbit in low Earth orbits, such as planned communication satellites constellations like Starlink? Would it be feasible to equip them with larger solar arrays, or would nuclear generators be required?



One can imagine many commercial applications for precision indoor navigation (like more efficient robotic vacuum cleaners ;-) Just reaching through the roofs of single storage factories and shopping centers should make for a great market. The alternative today is to install radio or ultrasound beacons (or perhaps a camera system) in every room where one wants to have a location service. A single ubiquitous system that's already standard would have economic advantages.






gps radio







share|improve this question











$endgroup$




GPS satellites don't transmit strong enough to reach indoors, through the roofs and walls of buildings, like cell phones do. GPS signals that enter buildings through windows are unreliable since they often have bounced and thus give the wrong distance measures by even hundreds of meters. Since cell phones work fine indoors, and GPS uses the same frequency, I suppose there's no need to use another frequency.



Would it suffice for today's kind of GPS satellites to orbit in low Earth orbits, such as planned communication satellites constellations like Starlink? Would it be feasible to equip them with larger solar arrays, or would nuclear generators be required?



One can imagine many commercial applications for precision indoor navigation (like more efficient robotic vacuum cleaners ;-) Just reaching through the roofs of single storage factories and shopping centers should make for a great market. The alternative today is to install radio or ultrasound beacons (or perhaps a camera system) in every room where one wants to have a location service. A single ubiquitous system that's already standard would have economic advantages.






gps radio




gps radio






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 2 hours ago









Glorfindel

2111210




2111210










asked 4 hours ago









LocalFluffLocalFluff

12.9k449165




12.9k449165












  • $begingroup$
    Not all cell phones work fine indoors and not in every building. There are metall roofs and steel construction buildings. Multi path distribution of satellite signals does harm the GPS position precision. The speed of electric waves is different in air and in solid materials ( non metallic solids ). But GPS even handles different speed of light in vacuum and air. But how to handle the much lower speed in solids?
    $endgroup$
    – Uwe
    3 hours ago




















  • $begingroup$
    Not all cell phones work fine indoors and not in every building. There are metall roofs and steel construction buildings. Multi path distribution of satellite signals does harm the GPS position precision. The speed of electric waves is different in air and in solid materials ( non metallic solids ). But GPS even handles different speed of light in vacuum and air. But how to handle the much lower speed in solids?
    $endgroup$
    – Uwe
    3 hours ago


















$begingroup$
Not all cell phones work fine indoors and not in every building. There are metall roofs and steel construction buildings. Multi path distribution of satellite signals does harm the GPS position precision. The speed of electric waves is different in air and in solid materials ( non metallic solids ). But GPS even handles different speed of light in vacuum and air. But how to handle the much lower speed in solids?
$endgroup$
– Uwe
3 hours ago






$begingroup$
Not all cell phones work fine indoors and not in every building. There are metall roofs and steel construction buildings. Multi path distribution of satellite signals does harm the GPS position precision. The speed of electric waves is different in air and in solid materials ( non metallic solids ). But GPS even handles different speed of light in vacuum and air. But how to handle the much lower speed in solids?
$endgroup$
– Uwe
3 hours ago












3 Answers
3






active

oldest

votes


















5












$begingroup$

There are some big differences between GPS and cell phone signals:




  1. GPS relies on the exact timing of a signal (1 nanosecond off = 30 cm of position inaccuracy). Cell phones are much more tolerant to variations in signal timing. Basically they don't care as long as the packets arrive quickly enough not to cause a gap in the audio.


  2. GPS transmitters are 18,000 km away, cell phone towers are less than 5 km away. So a cell phone signal is much stronger at the receiver.



item 2 could be solved with a stronger transmitter, but that would make #1 worse: with a stronger signal, you get more multipathing: more reflections that are still strong enough to be picked up by the receiver.



You can't really use indoors transmitters either. Many buildings have a steel structure which reflects radio waves, so you get lots of multipathing when the transmitter is inside.






share|improve this answer









$endgroup$









  • 1




    $begingroup$
    "... with a stronger signal, you get more multipathing..." This sounds like something that's made up and not based in EE fact. Any digital radio receiver system will have automatic gain control (AGC) before the ADC. So as far as the digital signal is concerned, the multipathed reflections will have the same strength relative to the direct path signal no matter what the strength of the satellite's signal is.
    $endgroup$
    – uhoh
    2 hours ago








  • 1




    $begingroup$
    if your signal is weak to begin with, reflections can drop below the noise floor. Strong signal->more reflections make it to the receiver above the noise floor.
    $endgroup$
    – Hobbes
    2 hours ago










  • $begingroup$
    It doesn't work like that. It's not like there is a "floor" and signals below it disappear. Every signal (of a given type, e.g. L1) from every GPS satellite in the sky, plus every reflection of every signal from every satellite in the sky plus all sources of noise, all go through one single front end amplifier and then one ADC, where it is digitized into one digital stream of 1's and 0's. That stream is then copied to dozens of identical correlaters, each looking for a different Gold code from a different satellite.
    $endgroup$
    – uhoh
    2 hours ago






  • 1




    $begingroup$
    @uhoh, would need to find a reference, and is a analog artifact but was taught a potential solution for en.wikipedia.org/wiki/Ghosting_(television) where the cause was proximity to the transmitter allowing reflections to be above noise floor was adding an attenutor or just making the antenna less effective. Thinking through may have also been result of of doing AGC later in the signal path than GPS.
    $endgroup$
    – GremlinWranger
    2 hours ago






  • 1




    $begingroup$
    @uhoh, other place I've met power reduction to reduce multipathing is in Sonar, which also does not say anything useful at all about GPS and their somewhat unique receiver design so think I get to learn something today.
    $endgroup$
    – GremlinWranger
    1 hour ago



















2












$begingroup$

In general, if you need a local indoor navigation system, then you are better off implementing your own. Generally speaking these are called Indoor Positioning Systems. There isn't yet a standard, but there has been some work to making one. It would be MUCH cheaper, more accurate, and overall just better.



GPS satellites are expensive, they are all space rated atomic clocks, some of the most accurate clocks ever created, and the most accurate in orbit. Making thousands of them would be very expensive, and not really gain a lot.



All that being said, there are a few things that can be done. The way indoor GPS typically works is by estimating your location from other means, and looking for the very low signal strength signal coming at the right time.






share|improve this answer











$endgroup$













  • $begingroup$
    Low altitude GPS satellites do have conceptual problems with time in sight and Earth's shadow. But I'm pretty sure that putting nuclear reactors on the GPS satellites to up their power (if that would be a solution) is cheaper than installing and maintaining unstandardized indoor systems in billions of buildings. Just changing the beacons' batteries or cabling them to the power grid is a pain. GPS isn't more expensive than EU, Russia, China, Japan and India all have gotten their own (redundant) positioning satellite constellations.
    $endgroup$
    – LocalFluff
    1 hour ago





















1












$begingroup$

There is existing technology for this, termed "{Active,Passive} GPS Repeater". It is composed of both an antenna outside and inside, with optionally active or passive components to forward the signal. My introduction to it was within an ocean-going vessel, and it worked fine.



http://www.terrisgps.com/how-do-gps-repeaters-work/



https://www.tri-m.com/index.php/product/tri-m/gps-networking/gps-re-radiators/l1-gps-repeater-kit



https://electronics.stackexchange.com/a/7798/216525






share|improve this answer








New contributor




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






$endgroup$









  • 2




    $begingroup$
    Note that a GPS repeater doesn't actually give you indoor navigation - everything receiving the repeated signal computes approximately the same position, that of the outside antenna. (Source: we use these repeaters to be able to do indoor testing of GPS-based equipment that we make.)
    $endgroup$
    – jasonharper
    1 hour ago










  • $begingroup$
    A cite from your first link: "It should be noted that all the repeaters in a single network will transmit the coordinates of the outdoor antenna and not the position of the repeater unit itself."
    $endgroup$
    – Uwe
    1 hour ago










  • $begingroup$
    @jasonharper If they have chosen to transmit the computed GPS position directly to the GPS receivers (so that crew and cruise passenger easily can see on their phones where they are at sea when under deck) instead of via e.g. WiFi, that speaks for the advantage of GPS, as a dominating standard, over indoor positioning systems requiring specific hardware and software.
    $endgroup$
    – LocalFluff
    1 hour ago












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3 Answers
3






active

oldest

votes








3 Answers
3






active

oldest

votes









active

oldest

votes






active

oldest

votes









5












$begingroup$

There are some big differences between GPS and cell phone signals:




  1. GPS relies on the exact timing of a signal (1 nanosecond off = 30 cm of position inaccuracy). Cell phones are much more tolerant to variations in signal timing. Basically they don't care as long as the packets arrive quickly enough not to cause a gap in the audio.


  2. GPS transmitters are 18,000 km away, cell phone towers are less than 5 km away. So a cell phone signal is much stronger at the receiver.



item 2 could be solved with a stronger transmitter, but that would make #1 worse: with a stronger signal, you get more multipathing: more reflections that are still strong enough to be picked up by the receiver.



You can't really use indoors transmitters either. Many buildings have a steel structure which reflects radio waves, so you get lots of multipathing when the transmitter is inside.






share|improve this answer









$endgroup$









  • 1




    $begingroup$
    "... with a stronger signal, you get more multipathing..." This sounds like something that's made up and not based in EE fact. Any digital radio receiver system will have automatic gain control (AGC) before the ADC. So as far as the digital signal is concerned, the multipathed reflections will have the same strength relative to the direct path signal no matter what the strength of the satellite's signal is.
    $endgroup$
    – uhoh
    2 hours ago








  • 1




    $begingroup$
    if your signal is weak to begin with, reflections can drop below the noise floor. Strong signal->more reflections make it to the receiver above the noise floor.
    $endgroup$
    – Hobbes
    2 hours ago










  • $begingroup$
    It doesn't work like that. It's not like there is a "floor" and signals below it disappear. Every signal (of a given type, e.g. L1) from every GPS satellite in the sky, plus every reflection of every signal from every satellite in the sky plus all sources of noise, all go through one single front end amplifier and then one ADC, where it is digitized into one digital stream of 1's and 0's. That stream is then copied to dozens of identical correlaters, each looking for a different Gold code from a different satellite.
    $endgroup$
    – uhoh
    2 hours ago






  • 1




    $begingroup$
    @uhoh, would need to find a reference, and is a analog artifact but was taught a potential solution for en.wikipedia.org/wiki/Ghosting_(television) where the cause was proximity to the transmitter allowing reflections to be above noise floor was adding an attenutor or just making the antenna less effective. Thinking through may have also been result of of doing AGC later in the signal path than GPS.
    $endgroup$
    – GremlinWranger
    2 hours ago






  • 1




    $begingroup$
    @uhoh, other place I've met power reduction to reduce multipathing is in Sonar, which also does not say anything useful at all about GPS and their somewhat unique receiver design so think I get to learn something today.
    $endgroup$
    – GremlinWranger
    1 hour ago
















5












$begingroup$

There are some big differences between GPS and cell phone signals:




  1. GPS relies on the exact timing of a signal (1 nanosecond off = 30 cm of position inaccuracy). Cell phones are much more tolerant to variations in signal timing. Basically they don't care as long as the packets arrive quickly enough not to cause a gap in the audio.


  2. GPS transmitters are 18,000 km away, cell phone towers are less than 5 km away. So a cell phone signal is much stronger at the receiver.



item 2 could be solved with a stronger transmitter, but that would make #1 worse: with a stronger signal, you get more multipathing: more reflections that are still strong enough to be picked up by the receiver.



You can't really use indoors transmitters either. Many buildings have a steel structure which reflects radio waves, so you get lots of multipathing when the transmitter is inside.






share|improve this answer









$endgroup$









  • 1




    $begingroup$
    "... with a stronger signal, you get more multipathing..." This sounds like something that's made up and not based in EE fact. Any digital radio receiver system will have automatic gain control (AGC) before the ADC. So as far as the digital signal is concerned, the multipathed reflections will have the same strength relative to the direct path signal no matter what the strength of the satellite's signal is.
    $endgroup$
    – uhoh
    2 hours ago








  • 1




    $begingroup$
    if your signal is weak to begin with, reflections can drop below the noise floor. Strong signal->more reflections make it to the receiver above the noise floor.
    $endgroup$
    – Hobbes
    2 hours ago










  • $begingroup$
    It doesn't work like that. It's not like there is a "floor" and signals below it disappear. Every signal (of a given type, e.g. L1) from every GPS satellite in the sky, plus every reflection of every signal from every satellite in the sky plus all sources of noise, all go through one single front end amplifier and then one ADC, where it is digitized into one digital stream of 1's and 0's. That stream is then copied to dozens of identical correlaters, each looking for a different Gold code from a different satellite.
    $endgroup$
    – uhoh
    2 hours ago






  • 1




    $begingroup$
    @uhoh, would need to find a reference, and is a analog artifact but was taught a potential solution for en.wikipedia.org/wiki/Ghosting_(television) where the cause was proximity to the transmitter allowing reflections to be above noise floor was adding an attenutor or just making the antenna less effective. Thinking through may have also been result of of doing AGC later in the signal path than GPS.
    $endgroup$
    – GremlinWranger
    2 hours ago






  • 1




    $begingroup$
    @uhoh, other place I've met power reduction to reduce multipathing is in Sonar, which also does not say anything useful at all about GPS and their somewhat unique receiver design so think I get to learn something today.
    $endgroup$
    – GremlinWranger
    1 hour ago














5












5








5





$begingroup$

There are some big differences between GPS and cell phone signals:




  1. GPS relies on the exact timing of a signal (1 nanosecond off = 30 cm of position inaccuracy). Cell phones are much more tolerant to variations in signal timing. Basically they don't care as long as the packets arrive quickly enough not to cause a gap in the audio.


  2. GPS transmitters are 18,000 km away, cell phone towers are less than 5 km away. So a cell phone signal is much stronger at the receiver.



item 2 could be solved with a stronger transmitter, but that would make #1 worse: with a stronger signal, you get more multipathing: more reflections that are still strong enough to be picked up by the receiver.



You can't really use indoors transmitters either. Many buildings have a steel structure which reflects radio waves, so you get lots of multipathing when the transmitter is inside.






share|improve this answer









$endgroup$



There are some big differences between GPS and cell phone signals:




  1. GPS relies on the exact timing of a signal (1 nanosecond off = 30 cm of position inaccuracy). Cell phones are much more tolerant to variations in signal timing. Basically they don't care as long as the packets arrive quickly enough not to cause a gap in the audio.


  2. GPS transmitters are 18,000 km away, cell phone towers are less than 5 km away. So a cell phone signal is much stronger at the receiver.



item 2 could be solved with a stronger transmitter, but that would make #1 worse: with a stronger signal, you get more multipathing: more reflections that are still strong enough to be picked up by the receiver.



You can't really use indoors transmitters either. Many buildings have a steel structure which reflects radio waves, so you get lots of multipathing when the transmitter is inside.







share|improve this answer












share|improve this answer



share|improve this answer










answered 3 hours ago









HobbesHobbes

95.1k2267421




95.1k2267421








  • 1




    $begingroup$
    "... with a stronger signal, you get more multipathing..." This sounds like something that's made up and not based in EE fact. Any digital radio receiver system will have automatic gain control (AGC) before the ADC. So as far as the digital signal is concerned, the multipathed reflections will have the same strength relative to the direct path signal no matter what the strength of the satellite's signal is.
    $endgroup$
    – uhoh
    2 hours ago








  • 1




    $begingroup$
    if your signal is weak to begin with, reflections can drop below the noise floor. Strong signal->more reflections make it to the receiver above the noise floor.
    $endgroup$
    – Hobbes
    2 hours ago










  • $begingroup$
    It doesn't work like that. It's not like there is a "floor" and signals below it disappear. Every signal (of a given type, e.g. L1) from every GPS satellite in the sky, plus every reflection of every signal from every satellite in the sky plus all sources of noise, all go through one single front end amplifier and then one ADC, where it is digitized into one digital stream of 1's and 0's. That stream is then copied to dozens of identical correlaters, each looking for a different Gold code from a different satellite.
    $endgroup$
    – uhoh
    2 hours ago






  • 1




    $begingroup$
    @uhoh, would need to find a reference, and is a analog artifact but was taught a potential solution for en.wikipedia.org/wiki/Ghosting_(television) where the cause was proximity to the transmitter allowing reflections to be above noise floor was adding an attenutor or just making the antenna less effective. Thinking through may have also been result of of doing AGC later in the signal path than GPS.
    $endgroup$
    – GremlinWranger
    2 hours ago






  • 1




    $begingroup$
    @uhoh, other place I've met power reduction to reduce multipathing is in Sonar, which also does not say anything useful at all about GPS and their somewhat unique receiver design so think I get to learn something today.
    $endgroup$
    – GremlinWranger
    1 hour ago














  • 1




    $begingroup$
    "... with a stronger signal, you get more multipathing..." This sounds like something that's made up and not based in EE fact. Any digital radio receiver system will have automatic gain control (AGC) before the ADC. So as far as the digital signal is concerned, the multipathed reflections will have the same strength relative to the direct path signal no matter what the strength of the satellite's signal is.
    $endgroup$
    – uhoh
    2 hours ago








  • 1




    $begingroup$
    if your signal is weak to begin with, reflections can drop below the noise floor. Strong signal->more reflections make it to the receiver above the noise floor.
    $endgroup$
    – Hobbes
    2 hours ago










  • $begingroup$
    It doesn't work like that. It's not like there is a "floor" and signals below it disappear. Every signal (of a given type, e.g. L1) from every GPS satellite in the sky, plus every reflection of every signal from every satellite in the sky plus all sources of noise, all go through one single front end amplifier and then one ADC, where it is digitized into one digital stream of 1's and 0's. That stream is then copied to dozens of identical correlaters, each looking for a different Gold code from a different satellite.
    $endgroup$
    – uhoh
    2 hours ago






  • 1




    $begingroup$
    @uhoh, would need to find a reference, and is a analog artifact but was taught a potential solution for en.wikipedia.org/wiki/Ghosting_(television) where the cause was proximity to the transmitter allowing reflections to be above noise floor was adding an attenutor or just making the antenna less effective. Thinking through may have also been result of of doing AGC later in the signal path than GPS.
    $endgroup$
    – GremlinWranger
    2 hours ago






  • 1




    $begingroup$
    @uhoh, other place I've met power reduction to reduce multipathing is in Sonar, which also does not say anything useful at all about GPS and their somewhat unique receiver design so think I get to learn something today.
    $endgroup$
    – GremlinWranger
    1 hour ago








1




1




$begingroup$
"... with a stronger signal, you get more multipathing..." This sounds like something that's made up and not based in EE fact. Any digital radio receiver system will have automatic gain control (AGC) before the ADC. So as far as the digital signal is concerned, the multipathed reflections will have the same strength relative to the direct path signal no matter what the strength of the satellite's signal is.
$endgroup$
– uhoh
2 hours ago






$begingroup$
"... with a stronger signal, you get more multipathing..." This sounds like something that's made up and not based in EE fact. Any digital radio receiver system will have automatic gain control (AGC) before the ADC. So as far as the digital signal is concerned, the multipathed reflections will have the same strength relative to the direct path signal no matter what the strength of the satellite's signal is.
$endgroup$
– uhoh
2 hours ago






1




1




$begingroup$
if your signal is weak to begin with, reflections can drop below the noise floor. Strong signal->more reflections make it to the receiver above the noise floor.
$endgroup$
– Hobbes
2 hours ago




$begingroup$
if your signal is weak to begin with, reflections can drop below the noise floor. Strong signal->more reflections make it to the receiver above the noise floor.
$endgroup$
– Hobbes
2 hours ago












$begingroup$
It doesn't work like that. It's not like there is a "floor" and signals below it disappear. Every signal (of a given type, e.g. L1) from every GPS satellite in the sky, plus every reflection of every signal from every satellite in the sky plus all sources of noise, all go through one single front end amplifier and then one ADC, where it is digitized into one digital stream of 1's and 0's. That stream is then copied to dozens of identical correlaters, each looking for a different Gold code from a different satellite.
$endgroup$
– uhoh
2 hours ago




$begingroup$
It doesn't work like that. It's not like there is a "floor" and signals below it disappear. Every signal (of a given type, e.g. L1) from every GPS satellite in the sky, plus every reflection of every signal from every satellite in the sky plus all sources of noise, all go through one single front end amplifier and then one ADC, where it is digitized into one digital stream of 1's and 0's. That stream is then copied to dozens of identical correlaters, each looking for a different Gold code from a different satellite.
$endgroup$
– uhoh
2 hours ago




1




1




$begingroup$
@uhoh, would need to find a reference, and is a analog artifact but was taught a potential solution for en.wikipedia.org/wiki/Ghosting_(television) where the cause was proximity to the transmitter allowing reflections to be above noise floor was adding an attenutor or just making the antenna less effective. Thinking through may have also been result of of doing AGC later in the signal path than GPS.
$endgroup$
– GremlinWranger
2 hours ago




$begingroup$
@uhoh, would need to find a reference, and is a analog artifact but was taught a potential solution for en.wikipedia.org/wiki/Ghosting_(television) where the cause was proximity to the transmitter allowing reflections to be above noise floor was adding an attenutor or just making the antenna less effective. Thinking through may have also been result of of doing AGC later in the signal path than GPS.
$endgroup$
– GremlinWranger
2 hours ago




1




1




$begingroup$
@uhoh, other place I've met power reduction to reduce multipathing is in Sonar, which also does not say anything useful at all about GPS and their somewhat unique receiver design so think I get to learn something today.
$endgroup$
– GremlinWranger
1 hour ago




$begingroup$
@uhoh, other place I've met power reduction to reduce multipathing is in Sonar, which also does not say anything useful at all about GPS and their somewhat unique receiver design so think I get to learn something today.
$endgroup$
– GremlinWranger
1 hour ago











2












$begingroup$

In general, if you need a local indoor navigation system, then you are better off implementing your own. Generally speaking these are called Indoor Positioning Systems. There isn't yet a standard, but there has been some work to making one. It would be MUCH cheaper, more accurate, and overall just better.



GPS satellites are expensive, they are all space rated atomic clocks, some of the most accurate clocks ever created, and the most accurate in orbit. Making thousands of them would be very expensive, and not really gain a lot.



All that being said, there are a few things that can be done. The way indoor GPS typically works is by estimating your location from other means, and looking for the very low signal strength signal coming at the right time.






share|improve this answer











$endgroup$













  • $begingroup$
    Low altitude GPS satellites do have conceptual problems with time in sight and Earth's shadow. But I'm pretty sure that putting nuclear reactors on the GPS satellites to up their power (if that would be a solution) is cheaper than installing and maintaining unstandardized indoor systems in billions of buildings. Just changing the beacons' batteries or cabling them to the power grid is a pain. GPS isn't more expensive than EU, Russia, China, Japan and India all have gotten their own (redundant) positioning satellite constellations.
    $endgroup$
    – LocalFluff
    1 hour ago


















2












$begingroup$

In general, if you need a local indoor navigation system, then you are better off implementing your own. Generally speaking these are called Indoor Positioning Systems. There isn't yet a standard, but there has been some work to making one. It would be MUCH cheaper, more accurate, and overall just better.



GPS satellites are expensive, they are all space rated atomic clocks, some of the most accurate clocks ever created, and the most accurate in orbit. Making thousands of them would be very expensive, and not really gain a lot.



All that being said, there are a few things that can be done. The way indoor GPS typically works is by estimating your location from other means, and looking for the very low signal strength signal coming at the right time.






share|improve this answer











$endgroup$













  • $begingroup$
    Low altitude GPS satellites do have conceptual problems with time in sight and Earth's shadow. But I'm pretty sure that putting nuclear reactors on the GPS satellites to up their power (if that would be a solution) is cheaper than installing and maintaining unstandardized indoor systems in billions of buildings. Just changing the beacons' batteries or cabling them to the power grid is a pain. GPS isn't more expensive than EU, Russia, China, Japan and India all have gotten their own (redundant) positioning satellite constellations.
    $endgroup$
    – LocalFluff
    1 hour ago
















2












2








2





$begingroup$

In general, if you need a local indoor navigation system, then you are better off implementing your own. Generally speaking these are called Indoor Positioning Systems. There isn't yet a standard, but there has been some work to making one. It would be MUCH cheaper, more accurate, and overall just better.



GPS satellites are expensive, they are all space rated atomic clocks, some of the most accurate clocks ever created, and the most accurate in orbit. Making thousands of them would be very expensive, and not really gain a lot.



All that being said, there are a few things that can be done. The way indoor GPS typically works is by estimating your location from other means, and looking for the very low signal strength signal coming at the right time.






share|improve this answer











$endgroup$



In general, if you need a local indoor navigation system, then you are better off implementing your own. Generally speaking these are called Indoor Positioning Systems. There isn't yet a standard, but there has been some work to making one. It would be MUCH cheaper, more accurate, and overall just better.



GPS satellites are expensive, they are all space rated atomic clocks, some of the most accurate clocks ever created, and the most accurate in orbit. Making thousands of them would be very expensive, and not really gain a lot.



All that being said, there are a few things that can be done. The way indoor GPS typically works is by estimating your location from other means, and looking for the very low signal strength signal coming at the right time.







share|improve this answer














share|improve this answer



share|improve this answer








edited 2 hours ago

























answered 3 hours ago









PearsonArtPhoto♦PearsonArtPhoto

83.9k16242464




83.9k16242464












  • $begingroup$
    Low altitude GPS satellites do have conceptual problems with time in sight and Earth's shadow. But I'm pretty sure that putting nuclear reactors on the GPS satellites to up their power (if that would be a solution) is cheaper than installing and maintaining unstandardized indoor systems in billions of buildings. Just changing the beacons' batteries or cabling them to the power grid is a pain. GPS isn't more expensive than EU, Russia, China, Japan and India all have gotten their own (redundant) positioning satellite constellations.
    $endgroup$
    – LocalFluff
    1 hour ago




















  • $begingroup$
    Low altitude GPS satellites do have conceptual problems with time in sight and Earth's shadow. But I'm pretty sure that putting nuclear reactors on the GPS satellites to up their power (if that would be a solution) is cheaper than installing and maintaining unstandardized indoor systems in billions of buildings. Just changing the beacons' batteries or cabling them to the power grid is a pain. GPS isn't more expensive than EU, Russia, China, Japan and India all have gotten their own (redundant) positioning satellite constellations.
    $endgroup$
    – LocalFluff
    1 hour ago


















$begingroup$
Low altitude GPS satellites do have conceptual problems with time in sight and Earth's shadow. But I'm pretty sure that putting nuclear reactors on the GPS satellites to up their power (if that would be a solution) is cheaper than installing and maintaining unstandardized indoor systems in billions of buildings. Just changing the beacons' batteries or cabling them to the power grid is a pain. GPS isn't more expensive than EU, Russia, China, Japan and India all have gotten their own (redundant) positioning satellite constellations.
$endgroup$
– LocalFluff
1 hour ago






$begingroup$
Low altitude GPS satellites do have conceptual problems with time in sight and Earth's shadow. But I'm pretty sure that putting nuclear reactors on the GPS satellites to up their power (if that would be a solution) is cheaper than installing and maintaining unstandardized indoor systems in billions of buildings. Just changing the beacons' batteries or cabling them to the power grid is a pain. GPS isn't more expensive than EU, Russia, China, Japan and India all have gotten their own (redundant) positioning satellite constellations.
$endgroup$
– LocalFluff
1 hour ago













1












$begingroup$

There is existing technology for this, termed "{Active,Passive} GPS Repeater". It is composed of both an antenna outside and inside, with optionally active or passive components to forward the signal. My introduction to it was within an ocean-going vessel, and it worked fine.



http://www.terrisgps.com/how-do-gps-repeaters-work/



https://www.tri-m.com/index.php/product/tri-m/gps-networking/gps-re-radiators/l1-gps-repeater-kit



https://electronics.stackexchange.com/a/7798/216525






share|improve this answer








New contributor




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






$endgroup$









  • 2




    $begingroup$
    Note that a GPS repeater doesn't actually give you indoor navigation - everything receiving the repeated signal computes approximately the same position, that of the outside antenna. (Source: we use these repeaters to be able to do indoor testing of GPS-based equipment that we make.)
    $endgroup$
    – jasonharper
    1 hour ago










  • $begingroup$
    A cite from your first link: "It should be noted that all the repeaters in a single network will transmit the coordinates of the outdoor antenna and not the position of the repeater unit itself."
    $endgroup$
    – Uwe
    1 hour ago










  • $begingroup$
    @jasonharper If they have chosen to transmit the computed GPS position directly to the GPS receivers (so that crew and cruise passenger easily can see on their phones where they are at sea when under deck) instead of via e.g. WiFi, that speaks for the advantage of GPS, as a dominating standard, over indoor positioning systems requiring specific hardware and software.
    $endgroup$
    – LocalFluff
    1 hour ago
















1












$begingroup$

There is existing technology for this, termed "{Active,Passive} GPS Repeater". It is composed of both an antenna outside and inside, with optionally active or passive components to forward the signal. My introduction to it was within an ocean-going vessel, and it worked fine.



http://www.terrisgps.com/how-do-gps-repeaters-work/



https://www.tri-m.com/index.php/product/tri-m/gps-networking/gps-re-radiators/l1-gps-repeater-kit



https://electronics.stackexchange.com/a/7798/216525






share|improve this answer








New contributor




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






$endgroup$









  • 2




    $begingroup$
    Note that a GPS repeater doesn't actually give you indoor navigation - everything receiving the repeated signal computes approximately the same position, that of the outside antenna. (Source: we use these repeaters to be able to do indoor testing of GPS-based equipment that we make.)
    $endgroup$
    – jasonharper
    1 hour ago










  • $begingroup$
    A cite from your first link: "It should be noted that all the repeaters in a single network will transmit the coordinates of the outdoor antenna and not the position of the repeater unit itself."
    $endgroup$
    – Uwe
    1 hour ago










  • $begingroup$
    @jasonharper If they have chosen to transmit the computed GPS position directly to the GPS receivers (so that crew and cruise passenger easily can see on their phones where they are at sea when under deck) instead of via e.g. WiFi, that speaks for the advantage of GPS, as a dominating standard, over indoor positioning systems requiring specific hardware and software.
    $endgroup$
    – LocalFluff
    1 hour ago














1












1








1





$begingroup$

There is existing technology for this, termed "{Active,Passive} GPS Repeater". It is composed of both an antenna outside and inside, with optionally active or passive components to forward the signal. My introduction to it was within an ocean-going vessel, and it worked fine.



http://www.terrisgps.com/how-do-gps-repeaters-work/



https://www.tri-m.com/index.php/product/tri-m/gps-networking/gps-re-radiators/l1-gps-repeater-kit



https://electronics.stackexchange.com/a/7798/216525






share|improve this answer








New contributor




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






$endgroup$



There is existing technology for this, termed "{Active,Passive} GPS Repeater". It is composed of both an antenna outside and inside, with optionally active or passive components to forward the signal. My introduction to it was within an ocean-going vessel, and it worked fine.



http://www.terrisgps.com/how-do-gps-repeaters-work/



https://www.tri-m.com/index.php/product/tri-m/gps-networking/gps-re-radiators/l1-gps-repeater-kit



https://electronics.stackexchange.com/a/7798/216525







share|improve this answer








New contributor




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









share|improve this answer



share|improve this answer






New contributor




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









answered 2 hours ago









Tyson HilmerTyson Hilmer

192




192




New contributor




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





New contributor





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






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








  • 2




    $begingroup$
    Note that a GPS repeater doesn't actually give you indoor navigation - everything receiving the repeated signal computes approximately the same position, that of the outside antenna. (Source: we use these repeaters to be able to do indoor testing of GPS-based equipment that we make.)
    $endgroup$
    – jasonharper
    1 hour ago










  • $begingroup$
    A cite from your first link: "It should be noted that all the repeaters in a single network will transmit the coordinates of the outdoor antenna and not the position of the repeater unit itself."
    $endgroup$
    – Uwe
    1 hour ago










  • $begingroup$
    @jasonharper If they have chosen to transmit the computed GPS position directly to the GPS receivers (so that crew and cruise passenger easily can see on their phones where they are at sea when under deck) instead of via e.g. WiFi, that speaks for the advantage of GPS, as a dominating standard, over indoor positioning systems requiring specific hardware and software.
    $endgroup$
    – LocalFluff
    1 hour ago














  • 2




    $begingroup$
    Note that a GPS repeater doesn't actually give you indoor navigation - everything receiving the repeated signal computes approximately the same position, that of the outside antenna. (Source: we use these repeaters to be able to do indoor testing of GPS-based equipment that we make.)
    $endgroup$
    – jasonharper
    1 hour ago










  • $begingroup$
    A cite from your first link: "It should be noted that all the repeaters in a single network will transmit the coordinates of the outdoor antenna and not the position of the repeater unit itself."
    $endgroup$
    – Uwe
    1 hour ago










  • $begingroup$
    @jasonharper If they have chosen to transmit the computed GPS position directly to the GPS receivers (so that crew and cruise passenger easily can see on their phones where they are at sea when under deck) instead of via e.g. WiFi, that speaks for the advantage of GPS, as a dominating standard, over indoor positioning systems requiring specific hardware and software.
    $endgroup$
    – LocalFluff
    1 hour ago








2




2




$begingroup$
Note that a GPS repeater doesn't actually give you indoor navigation - everything receiving the repeated signal computes approximately the same position, that of the outside antenna. (Source: we use these repeaters to be able to do indoor testing of GPS-based equipment that we make.)
$endgroup$
– jasonharper
1 hour ago




$begingroup$
Note that a GPS repeater doesn't actually give you indoor navigation - everything receiving the repeated signal computes approximately the same position, that of the outside antenna. (Source: we use these repeaters to be able to do indoor testing of GPS-based equipment that we make.)
$endgroup$
– jasonharper
1 hour ago












$begingroup$
A cite from your first link: "It should be noted that all the repeaters in a single network will transmit the coordinates of the outdoor antenna and not the position of the repeater unit itself."
$endgroup$
– Uwe
1 hour ago




$begingroup$
A cite from your first link: "It should be noted that all the repeaters in a single network will transmit the coordinates of the outdoor antenna and not the position of the repeater unit itself."
$endgroup$
– Uwe
1 hour ago












$begingroup$
@jasonharper If they have chosen to transmit the computed GPS position directly to the GPS receivers (so that crew and cruise passenger easily can see on their phones where they are at sea when under deck) instead of via e.g. WiFi, that speaks for the advantage of GPS, as a dominating standard, over indoor positioning systems requiring specific hardware and software.
$endgroup$
– LocalFluff
1 hour ago




$begingroup$
@jasonharper If they have chosen to transmit the computed GPS position directly to the GPS receivers (so that crew and cruise passenger easily can see on their phones where they are at sea when under deck) instead of via e.g. WiFi, that speaks for the advantage of GPS, as a dominating standard, over indoor positioning systems requiring specific hardware and software.
$endgroup$
– LocalFluff
1 hour ago


















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