I need some information regarding the sampling frequency of the raw gps samples provided by the Emlid Reach module. I need to know the rate at which the Reach device sampled the analog GPS signals to provide the RAW digital samples.
Also I need to write a program to use the Digital Raw GPS Data to extract timing information, Please any help on this would be greatly appreciated.
14Hz maximum sample speed with only the GPS constellation enabled. Adding more constellations causes more processing overhead, so the maximum sample speed is reduced in that case.
The raw data comes out as a .UBX file which is Ublox’s binary format. You can then use open-source RTKLIB software to convert it to RINEX format, which is human-readable and will be easier to process. Someone correct me if I am wrong, but I believe is is a lossless conversion, so all your important timing data should still be present.
Thank you so much for you reply, I actually needed this information for research purposes. You see I actually needed the C/A and more importantly the encrpyted P/Y code which are encoded on the L1 carrier, at a rate of 1.023MHz and 10.23MHz respectively. I know the P/Y code is meaningless to us because it is encrypted, but I needed its unique pattern to detect spoofing attacks on other compromised receivers. For this I would need a very high frequency sampled raw gps data, at the rate of 5Mhz preferably. I was hoping the reach could provide sampled data at a reasonable rate, but obviously at 14Hz It is not of use to me.
Thank you again for helping out,
Don’t write off the usability of Reach quite yet.
I am not 100% on this, but if you dig into it, I think you may find that the kind of data you need can be harvested from the Ublox chip. The Reach module contains a Ublox chip and it is accessible and configurable.
So, you could just buy a Ublox chip with USB connector and antenna from another vendor and that would let you work directly from your laptop. Or you could buy either a Reach or Reach RS which will also let you take advantage of:
- 2GB storage capacity
- Intel Edison processor
- WiFi / Bluetooth / USB / and optional wired ethernet (with USB adapter)
- Linux operating system
- root access (to install scripts or software)
- standalone operation
Thank you so much once again for taking the time to help out. I would look into the Ublox chip and see if what you say is possible.
I read through the data sheet of the UBLOX LEA-M8T, but it does not clarify at what sampling rate the raw data is provided from the ADC, if you could direct me to a module you think works, would be really helpful. Thanks
Yes, unfortunately the ublox M8T does not support P/Y code as shown below.
Even though the Ublox chip can emit raw data, the maximum published rate is 10Hz and Emlid pushes it up to 14Hz, but this is navigation data and it is not quite as raw as you seem to need for your project. If what you need is the codes (bare demodulated RF?), then software defined radio comes to mind. You can really do anything imaginable with them. Here is a start: http://gnss-sdr.org/requirements (see the heading: Radio frequency front-ends)
And good luck on your search!
Thanks, that was always the backup plan, I was hoping to find a dedicated chip if possible.
Thanks for clarifying.
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