Decoding GPS using an RTL SDR Receiver 

Thank you so much for watching and taking the time to comment, I appreciate it! thanks!

Thanks for watching 😀

Glad you like them!

Thanks, will do!

Youre welcome!

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Help, I'm from Ecuador. I'm having the issue that I'm getting the graphs of the correlation output vs code offset, but the Monitor doesn't give me the ID. Only peak, code, and frequency show up. Thanks.

Bonjour Monsieur il ne fonctionne que l'oncle et RTL SDR pas encore sdrplay

@@alexandregaspar5571 thank you for answering! But Google translate is very poor in French. So i can just imagine you say it is not working. It is very pity, because i have sdrplay :(

I'm in the same situation.Help, I'm from Ecuador. I'm having the issue that I'm getting the graphs of the correlation output vs code offset, but the Monitor doesn't give me the ID. Only peak, code, and frequency show up. Thanks.

I am a research student currently doing my master in global navigation satellite systems. These are extremely useful for people like us.

If the output stream contains the GPS time then I guess it could be done.

You're barking up the wrong tree. A GPS receiver has to solve for 4 variables, including what the current time is. And this just bugs me in this video; you don't "decode" your location from the GPS signals. You compute your location from the pseduo-range that you measure to each spacecraft. The software can do this by first solving for the current time from the various signals while trying to recover the navigation messages that convey the orbital elements of the spacecraft. When you know the orbits, you can compute exactly where in space each spacecraft is at a point in time. You can then figure out how far you are from the spacecraft because you can measure the offset in the pseudorandom bit sequence broadcast by the spacecraft. But you have to do all this at once, solving for 4 unknowns (time, X, Y, Z) using 3 or 4 spacecraft. Ideally, you have a very high quality clock with low jitter and high enough precision. Does the WIndoze OS have timekeeping that good? Ultimately, the quality of the location determination is directly related to the stability of the the GPS receiver clock. As it jitters around, the computed pseudorange distances to each spacecraft change, and this also results in the location determination bouncing around. Likely some of that wander is due to clock jitter. A stratum 1 NTP clock ought to have accuracy from it's reference measure in tens or hundreds of microseconds; that's trivially achievable by a quality GPS receiver with a good, low-jitter clock. Plus, the Windoze OS is preempting the programing running, and it's got to precisely measure when the radio signals are decoded into messages and those boundaries. You're running in a real-time OS with good bounds on scheduling latency. Me, I'd just spend $50 to get a real GPS receiver module optimized from time and frequency application (with so-called "position-hold" mode to optimize for TDOP - time accuracy not HDOP or VDOP (horizontal or vertical dilution of position).

@@TechMindsOfficial The "output stream" from the spacecraft contains neither absolute GPS time or position. It tells you time the message was sent from the spacecraft, and you need to figure out how far away the spacecraft is to understand what time it is where you are. Computing the time is part of the computation done to compute your position. This is why you need multiple spacecraft in view to figure this out.

Hello, I now have the same problem. Were you able to solve it? Thank you.

L1: 1575.42 MHz L2: 1227.60 MHz L3: 1381.05 MHz L4: 1379.9133.. MHz L5: 1176.45 MHz en.wikipedia.org/wiki/GPS_signals#Overview_of_frequencies

As a starting point, you'd need a second SDR. No idea if the software does L2 or L5.

I would most likely think this issue is with your antenna. Maybe it needs to be higher, outside or specifically tuned for the NOAA frequency.

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Do you have an RTL based SDR you can test with also?

@@TechMindsOfficial im using this exact device images.app.goo.gl/CTyvY9KPYvRVbzZB6 the highest frequency that i did a demodulation, was at 1090 for ADS-B. I had an old rtlsdr with E4000 that made it to receive EMEA using a JRC FBB 250 from it's LBand output. But i dont have this dongle anymore.

Same😢😢😢 u managed to solve ?

If so can you help me by explaining what should i do

I'm in the same situation.Help, I'm from Ecuador. I'm having the issue that I'm getting the graphs of the correlation output vs code offset, but the Monitor doesn't give me the ID. Only peak, code, and frequency show up. Thanks

Not with this setup. It is thereotically possible with other equipment, but further research would be required

It kinda depends on what frequency the car tracker is sending data on. I would assume most of them these days are GSM, through the mobile data network.

Quel GPS je peux utiliser Oakley RTL SDR pour capter un satellite de gps parce que ton gps que tu as programmer ne fonctionne pas en France malheureusement si tu peux nous donner à qui se situe pour tous les pays de l'Europe à satellite de GPS qu'on peut utiliser.