Software Defined GPS Receiver

Replies

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  4d1

  Re: How to Recieve GPS Signal
  
  

  omar abdalla

  how are you guys
  i want to make a final year project and i want to ask you a basic question:
  "Can i recieve GPS signal FOR FREE and make some processing on it to get the positioning data???"
  
  i will be very pleased with your help
  thanks in advance

  i think you just need a GPS receiver. GPS works anywhere on the planet where you can receive signals from the satellite. You will need a pretty clear view of the sky for GPS to work, so it won't work inside buildings, underground or even in a forest.
  
  *as far as i know ,the global positioning system is owned and operated by US department of defence. but it is available freely to anyone in the world for use.
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  omar abdalla

  Re: How to Recieve GPS Signal
  
  thank you 4d1 for ur reply
  do you mean that it is free to use a GPS satellite to get my position??
  knowing that i will make the hardware, i won't buy a ready portable GPS!!
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  Muffy

  Re: How to Recieve GPS Signal
  
  To receive signals form GPS satellites you will need a GPS module [#-Link-Snipped-#. Unless your project involves building a GPS receiver, don't try to, it will be an expensive and complicated affair. You can purchase one of those modules and interface it with whatever it is your doing.
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  omar abdalla

  Re: How to Recieve GPS Signal
  
  

  Muffy

  To receive signals form GPS satellites you will need a GPS module [#-Link-Snipped-#. Unless your project involves building a GPS receiver, don't try to, it will be an expensive and complicated affair. You can purchase one of those modules and interface it with whatever it is your doing.

  thank you Muffy for your reply
  but i will make it by software(software defined GPS receiver)
  i.e. the hardware will be only the rf front end and the RF to IF mixer and the analog to digital converter; and the rest is done by software
  is that will be expensive too??
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  gohm

  Re: How to Recieve GPS Signal
  
  I like that different approach. If you can, share more about your project. What effected your decision to go the software route? pros and cons? As already mentioned, the signals are there for your usage.
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  Ashraf HZ

  Re: How to Recieve GPS Signal
  
  Thats an interesting approach. Though, you will still find it difficult to get the same performance as a specialized GPS chip, since their receiver sensitivities are really high. I wouldn't be surprised if the costs of the hardware would be more expensive than getting a gps module itself at the moment. For sure, USRPs still cost hundreds of US dollars!
  
  However, I do encourage you to look into this more. Perhaps there is a simpler hardware set up just to get the required GPS frequencies and a decent SNR performance.
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  omar abdalla

  Re: How to Recieve GPS Signal
  
  thanks for your replies gohm and ash
  but before i start, i want to be sure that this is applicable
  i mean is it legal to use GPS signal??
  and i will use isA an FPGA instead of USRP
  so is this is much more for a final year project?!
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  Ashraf HZ

  Re: How to Recieve GPS Signal
  
  What kind of FPGA are you going to use?
  
  Yes, you can use the GPS signal legally and freely, as long as your hardware setup is only set to receive signals.
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  omar abdalla

  Re: How to Recieve GPS Signal
  
  i didn't decide yet
  but i will try to find a cheap one 😀
  thank you for your reply ash
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  Ashraf HZ

  Re: How to Recieve GPS Signal
  
  Alright, keep us updated on your progress. Keep in mind the amount of bandwidth your FPGA has to process the C/A code of the GPS. The modulation scheme states that it is around 1Mbps give or take, so your ADC will need to be this quick.
  
  Hopefully this guide can help you along: #-Link-Snipped-#
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  omar abdalla

  Re: How to Recieve GPS Signal
  
  thank you ash so much for ur help 😀
  waiting for more information from this great site 😀
• 

  Ashraf HZ

  No problemo 😀 I have changed the title of this thread for more relevance to the topic.
• 

  4d1

  Re: How to Recieve GPS Signal
  
  

  omar abdalla

  thank you 4d1 for ur reply
  do you mean that it is free to use a GPS satellite to get my position??
  knowing that i will make the hardware, i won't buy a ready portable GPS!!

  There are two kind of GPS signals,
  C/A code: which is the civilian signals and given acuracy about 8-15m
  P code - which is military signal and only US military can use that, which is more accurate.
  There are high-end civilian receivers available, called dual-frequency receivers, which uses part of P-code, not the full signal, and gives higher accuracy than single frequency receivers.