GPS to Glonass transition with RTL SDR

Main forum to discuss RTL-SDR related topics.
aroo
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Joined: Tue Jul 14, 2020 7:20 am

GPS to Glonass transition with RTL SDR

Post by aroo » Tue Jul 14, 2020 8:29 am

with the help of sdrs can we make an algorithm by which we can convert GPS to GLONASS system?

alanzfq
Posts: 134
Joined: Thu Oct 04, 2018 11:18 am

Re: GPS to Glonass transition with RTL SDR

Post by alanzfq » Wed Jul 15, 2020 8:05 am

Surely this is dependent on the firmware (and chip) used in a GPS?
Alan

rtlsdrblog
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Re: GPS to Glonass transition with RTL SDR

Post by rtlsdrblog » Thu Jul 16, 2020 4:33 am

I'm not sure what you mean by converting GPS to GLONASS? You mean decode GPS data, then restransmit as GLONASS? Not sure why you'd want to do that.

aroo
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Joined: Tue Jul 14, 2020 7:20 am

Re: GPS to Glonass transition with RTL SDR

Post by aroo » Thu Jul 16, 2020 9:31 am

no in case of GPS jamming i want to shift my constellation from GPS to GLONASS such that only we get coordinates from GLONASS. This is my project

alanzfq
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Joined: Thu Oct 04, 2018 11:18 am

Re: GPS to Glonass transition with RTL SDR

Post by alanzfq » Thu Jul 16, 2020 9:53 am

This is an option on modern GPS modules.
I've never tried it but it is done on the module's one chip suitably configured by the manufacturer's utility.
The receive section may use SDR techniques but I'm not sure if anyone has reproduced a GPS receiver.
Alan

aroo
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Joined: Tue Jul 14, 2020 7:20 am

Re: GPS to Glonass transition with RTL SDR

Post by aroo » Fri Jul 17, 2020 5:32 am

but can rtl sdr help in this conversion?

alanzfq
Posts: 134
Joined: Thu Oct 04, 2018 11:18 am

Re: GPS to Glonass transition with RTL SDR

Post by alanzfq » Fri Jul 17, 2020 7:21 am

I cannot imagine any way that it would help in any sort of conversion.
It might help if you designed a completely new system using a RTL as receiver and other chips for processing.
To me it seems a very difficult project especially when it can be done by a cheap Ebay module.
Alan

alanzfq
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Joined: Thu Oct 04, 2018 11:18 am

Re: GPS to Glonass transition with RTL SDR

Post by alanzfq » Fri Jul 17, 2020 7:46 am

And if you look at the spread spectrum frequency range covered by the satellites (I guess you have not!) the RTL is completely useless.

weathersatelite
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Joined: Tue Jan 14, 2020 4:34 am

Re: GPS to Glonass transition with RTL SDR

Post by weathersatelite » Sun Jul 19, 2020 4:03 am

i am guessing that it is useless becuse to high of frqency. use a downconverter, then use software to if it has any demadulate it, someone will have to write it if it has not been already. then use the differince in time from the satelites broadcast singnal time to your time tell how far from sat you are. use triagnlation to accompligh.

possible ways it trasmits.
1. sat id and time (program have list of sat id with location.)
2. sat id and locatoin and time.

only problem will be seeing 1 sat from another. not sure how that works. broadcast at diffrent seconds. ham radion can have 2 people brauscast on a repeater at once i read.

Aussie Susan
Posts: 48
Joined: Sun Jul 31, 2016 1:55 am

Re: GPS to Glonass transition with RTL SDR

Post by Aussie Susan » Mon Jul 20, 2020 9:46 am

Nothing to do with the frequency being too high - everything to do with the bandwidth being way too wide for the RTL-SDR.
Check of one of the many sites that come up with a Google search - I looked at:
https://www.everythingrf.com/community/ ... ency-bands
which shows this quite well.

Iy can receive multiple signals from different satellites on the same frequency because of the way the GPS signal is encoded - "... a form of Code Devision Multiple Access (CDMA)..." (http://geoconnect.com.au/gps-signals-l1-l2-l5/)

I'm not sure what you are talking about with the "...ham radio can have 2 people broadcast on a repeater...". Typically analog repeaters are FM based and FM has the characteristic that it tends to lock on the stronger signal and therefore ignores any others. I think you may be thinking about the types of repeaters used in some of the Ham radio satellites that receive a set frequency range, (often invert it) shift the frequency up (or down) and then transmit the range. In this case the range of frequencies is larger than that used by a single transmission so it can repeat several simultaneous transmission - however each is still on a separate and non-overlapping frequency.
Susan (VK3ANZ)

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