BladeRF astronomical interferometer

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Re: BladeRF astronomical interferometer

Post by livingstone_ray » Tue Aug 29, 2017 8:22 am

hi there.

i have the comments and i am i have a coupling of questions regarding the clock and sample synchronization.

firstly, i am doing an OFDM SIMO wireless system and i am trying to perform clock synchronization and sample alignment at the 2 BladeRF RX boards to ease the burden of synchronization at the software level for my diversity combining. i have followed David's work on the configuration of master receiver and slave receiver, in my case which is only two boards, so what i am trying to do is first configure the master and slave with the scripts attached below, then i run my GNU Radio flow graphs which has osmocom Source blocks which set the gains and everything else, then with the GNU Flow graph running i fire the trigger using "trigger j71-4 rx fire" from the master console, the issue is i am receiving anything at all, so my question is when i configure the boards using the bladerf -cli first and then run GNU Radio flow graphs, does my osmocom Source blocks overwrite the settings i did before with bladerf -cli?, which could be the reason why i cant fire the trigger and i cant receive anything.

secondly, if i am correct regarding the above, how can i make the clock and sample settings using bladerf -cli and then just receive the samples as i normally would from the osmocom Source block of the receiver?, i am aware of the FIFO approach but i dont have enough memory to store temp files as i am running GNU Radio from a 30 Gb Ubuntu partition that i dual booting with windows 10 on my laptop. maybe Jon you could explain a little more about how the FIFO approach actually works if i am incorrect.


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Re: BladeRF astronomical interferometer

Post by Lavigne07 » Tue Oct 16, 2018 1:30 am

dlonard wrote:
Sat Dec 26, 2015 10:47 am
Hello Everyone,

I thought I would post some of my work on using three BladeRFs as SDR interferometers for radio astronomy. If you follow the links provided below, you can see some of the data from work that I've done at 60 MHz and 140 MHz. I haven't tried out the various approaches that are emerging to synchronize the data streams from multiple BladeRF's yet, but I am very keen to use 1 PPS synchronization. To align data right now, I am using a FFT/IFFT process to synch data in post processing. The links provide some code that I've written to do this and for using a GPU to function as a FX correlator.

There are a few kinks in my set up that occasionally leads to dropped samples, but most of the time, I am able to record data at 15 MSPS simultaneously from three radios.

If anyone else is doing any work using BladeRFs for interferometry, I would be glad to hear about your experiences.

David obtenir crédit ... ferometry/!forum ... rferometry
Good job

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