Understanding time delay estimation for GPS?

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SUMMARY

This discussion focuses on time delay estimation in GPS signal processing, specifically using cross-correlation (xcorr) techniques. The user seeks clarity on calculating time delays between transmitted and received signals, emphasizing the need for mathematical operations to derive a single real number from the xcorr output. Key steps include understanding the relationship between the lengths of input vectors and the resulting xcorr vector, as well as methods to extract the time delay from this data. The user references a helpful resource on the topic but requires foundational knowledge to proceed effectively.

PREREQUISITES
  • Understanding of GPS signal transmission and reception
  • Familiarity with cross-correlation (xcorr) in signal processing
  • Basic knowledge of MATLAB for signal analysis
  • Mathematical concepts related to vector operations
NEXT STEPS
  • Study the principles of time delay estimation in GPS systems
  • Learn how to implement cross-correlation in MATLAB
  • Explore the mathematical operations required to derive time delays from xcorr outputs
  • Investigate the impact of signal noise on time delay estimation accuracy
USEFUL FOR

This discussion is beneficial for signal processing engineers, GPS technology developers, and researchers focused on time delay estimation techniques in communication systems.

Nate Duong
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I really need help to understand these questions which is highlight, for the GPS situation, I hope anyone who has been working in this situation before, please help me to have a clear understanding about "time delay estimation":

Here is the scenario:

1. Suppose I know precisely I have transmit the signal (data), I know the sampling, I know the time correspond to the very 1st point, I can go through the sign the time every single measurement, that I just transmitted. Now, I received the signal (data), I have section of data and in there somewhere is the signal that transmitted. Unlike, as the transmit, I know the time correspond to the very 1st point in my receive data:
what would I do to get the time delay?
what steps do we follow?2.
In there, somewhere, I don’t know where exactly, but in there somewhere is transmitted the signal and I want to estimate time delay between the transmit and receive. So, I want to look at:
what you need to do that?
What math. operation do I need to use to compute that time delay?
3.If I say:"I want to compute xcorr between 2 vectors". So, this xcorr is twice sum of the length – 1:
what do I do when I have xcorr output?4.I take 2 vectors, and I compute even longer vector use xcorr, so now I compute the longer vector but I want a number, I don’t want a vector, I want a time delay estimation:
what do I do with the xcorr solved like a MATLAB?5.If I say xcorr(x,y), x has certain length and y has certain length, the result is the length of x plus length of y and minus 1. So, now I have a long vector:
what do I do then to determine the time delay?
what the signal look like and what xcorr look like?
what do I do when I have xcorr to determine the time delay?
6.I know that have xcorr with bunch of complex number but I need only one real number. The real number that I want is the time delay. I take input data, I take received signal, I compute xcorr, then I do something to help myself to get the time delay. Result to that is single real number. But these are general ideas, I need to answer those question.

7.I have read this link: http://dsp.stackexchange.com/questi...-oscilloscope-signals-using-cross-correlation . It's really help my understanding, but they way he answered very high level, I think I need to understand the basic first, then continue with this link.

Please help me for these questions.

Thank you very much, everyone
 
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Nate Duong said:
Please help me for these questions.
Hi Nate Duong:

I am not sure I understood all of your questions, but I think the following might be helpful.
There is a lot of information there that seems to be related to your questions.

Regards,
Buzz
 

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