multi-sdr-gps-sim

multi-sdr-gps-sim generates a GPS L1 baseband signal IQ data stream, which is then transmitted by a software-defined radio (SDR) platform. Supported at the moment are HackRF, ADLAM-Pluto and binary IQ file output. The software interacts with the user through a curses based text user interface (TUI) in terminal.

Project based on work of Takuji Ebinuma and IvanKor.

Generating the GPS signal

The user is able to assign a static location directly through the command line or sends motion data through a predefined input file. In addition the simulated position can be modified in realtime by user inputs.

The user also specifies the GPS satellite constellation through a GPS broadcast ephemeris file. The daily GPS broadcast ephemeris file is a merge of the individual site navigation files into one.

These files are then used to generate the simulated pseudorange and Doppler for the GPS satellites in view. This simulated range data is then used to generate the digitized I/Q samples for the GPS signal which are then feed into ADALM-Pluto SDR to transmit the GPS L1 frequency.

The simulation start time can be specified if the corresponding set of ephemerides is available. Otherwise the first time of ephemeris in the RINEX navigation file is selected. RINEX input format 2 and 3 are supported.

Note

The SDR internal oscillator must be precise enough (frequency offset) and stable (temperature drift) for GPS signal generation. Ideally the SDR shall be clocked from either by TCXO or more expensive (but highest precision) OCXO.

Best experience with HackRF.

Build instructions

Dependencies

Build depends on libm, libpthread, libcurl4-openssl-dev, libncurses, libz and libhackrf.

You will also need the latest build and install of libhackrf, libad9361-dev and libiio-dev. The Debian packages libad9361-dev that is available up to Debian 9 (stretch) is outdated and missing a required function.

So you have to build packages from source:

The first step is to fetch the dependencies, which as of now is only libxml2. On a Debian-flavoured GNU/Linux distribution, like Ubuntu for instance:

$ sudo apt-get install libxml2 libxml2-dev bison flex libcdk5-dev cmake

Depending on the backend (how you want to attach the IIO device), you may need at least one of:

$ sudo apt-get install libaio-dev libusb-1.0-0-dev libserialport-dev libxml2-dev libavahi-client-dev doxygen graphviz

Then build in this order:

$ git clone https://github.com/analogdevicesinc/libiio.git
$ cd libiio
$ cmake ./
$ make
$ sudo make install

$ git clone https://github.com/analogdevicesinc/libad9361-iio.git
$ cd libad9361-iio
$ cmake ./
$ make
$ sudo make install

Building under Linux with GCC

$ git clone https://github.com/mictronics/multi-sdr-gps-sim
$ cd pluto-gps-sim

With HackRF support: make all HACKRFSDR=yes (depends on libhackrf)

With ADLAM-PLUTO support: make all PLUTOSDR=yes (depends on libiio and libad9361-iio)

Full SDR support: make all HACKRFSDR=yes PLUTOSDR=yes

Usage

gps-sim [options]
Options:
--nav-file          -e   RINEX navigation file for GPS ephemeris (required)
--geo-loc           -l   Latitude, Longitude, Height (static mode) e.g. 35.681298,139.766247,10.0
--start             -s   Scenario start time YYYY/MM/DD,hh:mm:ss (use 'now' for actual time)
--gain              -g   Set TX gain, HackRF: 0-47dB, Pluto: -80-0dB (default 0)
--duration          -d   Duration in seconds
--target            -t   Target distance [m], bearing [°] and height [m]
--ppb               -p   Set oscillator error in ppb (default 0)
--radio             -r   Set the SDR device type name (default none)
--uri               -U   ADLAM-Pluto URI
--network           -N   ADLAM-Pluto network IP or hostname (default pluto.local)
--motion            -m   User motion file (dynamic mode)
--iq16                  Set IQ sample size to 16 bit (default 8 bit)
--disable-iono      -I  Disable ionospheric delay for spacecraft scenario
--verbose           -v  Show verbose output and details about simulated channels
--interactive       -i  Use interactive mode
--amplifier         -a  Enable TX amplifier (default OFF)
--use-ftp           -f  Pull actual RINEX navigation file from FTP server
--rinex3            -3  Use RINEX v3 navigation data format
--disable-almanac       Disable transmission of almanac information
--help              -?  Give this help list
--usage                 Give a short usage message
--version           -V  Print program version

SDR device types (use with --radio or -r option):
    none
    iqfile
    hackrf
    plutosdr

License

Copyright © 2021 Mictronics Distributed under the MIT License.