533f9ee332
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This commit allows to synchronise multiple HackRFs with a synchronisation error **below 1 sampling period**
> WARNING: Use this at your own risk. If you don't know what you are doing you may damage your HackRF.
> The author takes no responsability for potential damages
Usage example: synchronise two HackRFs
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1. Chose the master HackRF which will send the synchronisation pulse (HackRF0). HackRF1 will represent the slave hackrf.
2. Retreive the serial number of both HackRFs using `hackrf_info`
3. Use a wire to connect `SYNC_CMD` of HackRF0 to `SYNC_IN` of HackRF0 and HackRF1
4. Run `hackrf_transfer` with the argument `-H 1` to enable hardware synchronisation:
```
$ hackrf_tranfer ... -r rec1.bin -d HackRF1_serial -H 1 | hackrf_transfer ... -r rec0.bin -d HackRF0_serial -H 1
```
rec0.bin and rec1.bin will have a time offset below 1 sampling period.
The 1PPS output of GNSS receivers can be used to synchronise HackRFs even if they are far from each other.
>DON'T APPLY INCOMPATIBLE VOLTAGE LEVELS TO THE CPLD PINS
Signal | Header |Pin | Description
-------|--------|----|------------
`SYNC_IN` | P28 | 16 | Synchronisation pulse input
`SYNC_CMD` | P28 | 15 | Synchronisation pulse output
Note:
=====
I had to remove CPLD-based decimation to use a GPIO for enabling hardware.
More info:
==========
[M. Bartolucci, J. A. Del Peral-Rosado, R. Estatuet-Castillo, J. A. Garcia-Molina, M. Crisci and G. E. Corazza, "Synchronisation of low-cost open source SDRs for navigation applications," 2016 8th ESA Workshop on Satellite Navigation Technologies and European Workshop on GNSS Signals and Signal Processing (NAVITEC), Noordwijk, 2016, pp. 1-7.](http://ieeexplore.ieee.org/document/7849328/)
[Alternative link](http://spcomnav.uab.es/docs/conferences/Bartolucci_NAVITEC_2016.pdf)
The primary firmware source code for USB HackRF devices is hackrf_usb. Most of the other directories contain firmware source code for test and development. The common directory contains source code shared by multiple HackRF firmware projects. The cpld directory contains HDL source for the CPLD. The firmware is set up for compilation with the GCC toolchain available here: https://developer.arm.com/open-source/gnu-toolchain/gnu-rm/downloads Required dependency: https://github.com/mossmann/libopencm3 If you are using git, the preferred way to install libopencm3 is to use the submodule: $ cd .. $ git submodule init $ git submodule update $ cd firmware/libopencm3 $ make To build and install a standard firmware image for HackRF One: $ cd hackrf_usb $ mkdir build $ cd build $ cmake .. $ make $ hackrf_spiflash -w hackrf_usb.bin If you have a Jawbreaker, add -DBOARD=JAWBREAKER to the cmake command. If you have a rad1o, use -DBOARD=RAD1O instead. It is possible to use a USB Device Firmware Upgrade (DFU) method to load firmware into RAM. This is normally only required to recover a device that has had faulty firmware loaded, but it can also be useful for firmware developers. For loading firmware into RAM with DFU you will need: http://dfu-util.sourceforge.net/ To start up HackRF One in DFU mode, hold down the DFU button while powering it on or while pressing and releasing the RESET button. Release the DFU button after the 3V3 LED illuminates. A .dfu file is built by default when building firmware. Alternatively you can use a known good .dfu file from a release package. Load the firmware into RAM with: $ dfu-util --device 1fc9:000c --alt 0 --download hackrf_usb.dfu