Decoding GPS using an RTL SDR Receiver

[@carlclarke1]

I rarely post comments but I just want to write that I really enjoy your channel, the topics nearly always 'click' with me making me go off and find out how it works. Well done, please keep doing it.

[@TechMindsOfficial]

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

[@winstonsmith478]

I cannot figure out HOW it took me this long to find this OUTSTANDING channel. Seriously, I stumped.

[@TechMindsOfficial]

Thanks for watching 😀

[@KalidasSagolshem]

Impressive! I really don't know the limits of RTL-SDR.. amazing! Please make next video on IMSI Catchers... That ll be interesting 👍

[@TechMindsOfficial]

Thanks, will do!

[@dominionfalls]

Love the satellite and gps videos! Your explanations are great

[@TechMindsOfficial]

Glad you like them!

[@stevesweb]

Another great video. I always keep a V3 around for this. Always looking for new ideas for SDR.

[@olivierconet7995]

Really incredible! I'm Always fascinated how it is now possible to do that sort of things, when some time ago everybody would have said: oh no, too complicated, let it to professionnals (and I am an engineer) Bye the way, too many srupid ads, thanks to Google

[@TechMindsOfficial]

Hopefully I have now removed most of the ads.. Automatically added by YT.

[@elshiftos]

I get data scrolling in the monitor window of GNSS even when no antenna is connected. With an antenna connected and RTK running, nothing is displayed. Admittedly, I don't have a proper GPS antenna, just a dipole I use for ADSB, so I guess it could just be down to s/n ratio. Thanks!

[@peterbriggs3408]

You probably need to enter a Google Maps API key to get that to work. You should be able to get a free key from Google, but last time I did this I remember it was quite complicated.

[@ronylanssiers7694]

Very much appreciated that you made this video!

[@TechMindsOfficial]

Youre welcome!

[@andreweastland9634]

If you install the ucentre software from ublox you should be able to link this to the nmea output stream to provide a full gps decode

[@kevinalgoo8996]

The gnuplots after pressing start in gnss do not pop up but the cmd windows show up. The monitor in gnss does show a similar feed as in the video. RTKplot also experiences timeout while trying to connect to localhost. I'm not too sure what's the problem, I followed the video step-by-step. Any advice?

[@acestudioscouk-Ace-G0ACE]

A complex subject very well explained. Thank-you.

[@electronicatutorial]

Is it possible to see the signal strenght of the GPS like to quantify the signal level with a SDR?

[@andypag1071]

I read an article last week about capturing data that's travelling over satellite internet connections, like from users on planes. Interesting to see how easy/hard that would be to do

[@joshuanightvision1181]

Looking like it has duel frequency capability see front end One and a option for a second front end capability very nice Now all you need I guess is a multi band antenna 📡 probably won't work as well as a dedicated device or Ublox kit but it seems like a very affordable alternative 😀 Nice video 👏.

[@juandiegotenesacaillares2338]

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.

[@darshnajagiwala3500]

Hello, Techminds. I am currently using the same hardware and software setup on Windows to log the GPS I/Q data. However, I'm encountering an issue. When I press "Start" in the GNSS SDR-LIB GUI, it doesn't seem to initiate any process. Additionally, RTK-Navi is stuck showing the "connecting" status. I would appreciate any guidance you can provide to help me resolve this problem. Thank you.

[@MrFaethonkar]

Can you use hackrf instead of rtl sdr?? Should we change something in the settings for the hackrf ??

[@KelseyBlack]

Is the software capable of setting the PC clock to Stratum-1 accuracy from the GPS? Would be a really nice solution for NTP servers.

[@TechMindsOfficial]

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

[@lmamakos]

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).

[@lmamakos]

@@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.

[@antenadx6175]

Please in the next video show how to decode mobile network signals

[@NelloSirignano.]

Dear all, I am unable to get a GPS fix with RTKNAVI. I am using Win 10, the RTL SDR V3 dongle(RTL2832U R860 TCXO+BIAS T+HF), bias tee on, GPS antenna and RTKLIB 2.4.3. Is it working for anyone? Could you kindly tell me how you managed it? I am not the only one having problems. Thank you for your attention.

[@Btl147]

No luck. I have a Nooelec Smartee SDR. When I click GNCC, change the settings per your instructions and press Start, the screen blinks but nothing else happens. Any ideas?

[@yuriytitchenko215]

Does someone know what format of "file" in input type of gnss-sdrlib? Can I use my pre recorded InPhase/Quadrature data as a source file?

[@emmettbrown1700]

Great job. Thanks for sharing

[@Drvarnick]

I cant do it and im pissed. I have three different GPS antennas, all of them working "tested with a GPS receiver". I connect the bias tee and supply 5,2VDC from a USB to the coax that goes to the antenna. The 5V are ok and measured on the antenna side. The only thing i see on Airspy when i connect the Biastee on the USB is the Threshold goes higher. Ive tryied to play with the RF Gain but there is no reception. Honestly, i don't know what else to do.

[@TechMindsOfficial]

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

[@Drvarnick]

@@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.

[@aajeev]

Can this antenna be used to work with imersat and Iridium sat?

[@linuxuser1234]

My rtl sdr blog v3 is unable to receive noaa weather radio I have been changing db and sampling rate and changing to different modes but no luck however I can somewhat receive tv signals using my dipole antenna kit

[@TechMindsOfficial]

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.

[@yuriytitchenko215]

What is the difference between GNSS-SDRLIB and GNSS-SDR?

[@Greatfulone]

Thank you so much for the informative video.

[@copycarvers]

Hello, I have done everything as explained in the video but still not getting those multiple windows when I hit start. I am using the same rtl sdr dongle but I have a bit different antenna

[@juandiegotenesacaillares2338]

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

[@glenwoofit]

Interesting video as always but the advertising like the rest of KZbin is ruining it. Do you upload to any other platforms? KZbin is really pissing me off with advertising every few minutes.

[@TechMindsOfficial]

KZbin forms part of my household income, I'm a single parent raising my disabled son alone, so any monies earned from youtube ads help us out quite a lot, therefore I dont want to disable them. Although, I do think KZbin has started automatically adding more. From my settings, there should only be one at the start and one at the end of the video.

[@TechMindsOfficial]

Hopefully I have now removed most of the ads.. Automatically added by YT.

[@glenwoofit]

@@TechMindsOfficial I don't mind adds at the beginning and end and if it's a long video one in the middle But KZbin is adding them all over the place.

[@prepperminded5732]

@@glenwoofit I feel your pain. I hate ads just as much, especially political ones.

[@justinschmitz9833]

I use Brave web browser, it blocks all advertising on youtube

[@BritishBeachcomber]

Great video, but I'm struggling to see what use it could be, when everything has built-in GPS without the hassle.

[@copycarvers]

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

[@yoppindia]

Can you talk about gps encoding, modulation

[@yuriytitchenko215]

Thank you for this video! Very clear explanation. Will GNSS-SDRLIB work with SDRplay, hackRF and others?

[@alexandregaspar5571]

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

[@yuriytitchenko215]

@@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 :(

[@donkelly36]

Great video! Was able to open GNSS-SDRLIB and get it to stream data to the monitor, but no sats show up in the RTKNAVI window. Not getting any of the plots either. I tried the RTL-SDR.COM, and two NESDR dongles. I'm using a high-end GPS antenna, and I tried both the internal bias-tee and an external bias-tee. I searched on the RTL-SDR site and it looks like others have had this same issue, but not been able to resolve. Any suggestions? Thanks!

[@juandiegotenesacaillares2338]

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.

[@roba2440]

Very good video. Which link from the RTKLIB.com site did you use?

[@Nono-hk3is]

What do all those settings mean?

[@Nono-hk3is]

What frequencies are the GPS transmitters on?

[@IanTester]

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

[@LucaInnocenti1971]

this method works with L1 signal or it's possible to have L1+L2 ?? Thanks

[@peterbriggs3408]

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

[@georgianaalexandra8343]

I am using the same configuration like yours. But in my case it didn't work. The windows are opening and closing but i can't see any gnuplot. I only saw once from one satellite but from then i can't see anything. I am new in this field and i don't know so many things. Can someone help me and tell me which may be the problem? Thanks in advance

[@syahirahzahari1110]

Same😢😢😢 u managed to solve ?

[@syahirahzahari1110]

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

[@juandiegotenesacaillares2338]

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

[@catalinalb1722]

Hey! That´s really COOL! :) I just set up everything and started for the first time using an Outernet Patch antenna, the LONA amplifyer from NooElec and the RTL-SDR v3. I can only see two sattelits G06 and G07 (here in Germany) and after one min or so their signal runns away. :( Would be nice if it would work with VBAudio Cable and SDRUno. Will have to play with this a little more. Thank´s for the video! 73! DE1CTL :)

[@oblevion28]

Thankyou quite helpfull

[@Itsmesam99]

This video is awesome thank you for this :).. Can you please tell me how to spoof a GPS signal with low cost hardware that would be great help :) Thanks before.

[@MsFred58]

Nope. Too hard for me. You sir are very smart.

[@alexandregaspar5571]

bonjour ca ne marche pas la zone francais.

[@alexandregaspar5571]

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.

[@JA-yy6bd]

Would you be able to detect a car tracker on a vehicle with this set up ? Please don’t say yes if you can’t explain set up procedure.

[@AvroVulcanXH607]

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

[@TechMindsOfficial]

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.

[@MKhanfar-MWK]

👍👍🍻