Need Some Help in Specific 121.5 Mhz Application

Discuss KerberosSDR - 4x Coherent RTL-SDR
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sdreecs
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Joined: Mon Feb 15, 2021 8:49 pm

Need Some Help in Specific 121.5 Mhz Application

Post by sdreecs » Mon Feb 15, 2021 9:11 pm

Hey all, noob here...

I'm working on a project with a team of engineers to create an autonomous homing robot specifically designed to target emergency distress signals.

After quite a bit of research, we purchased a KerberosSDR as it seemed the latest and greatest in RTL tech for our needs and budget.

That said, I now have a fancy custom board connecting 4 SDRs on the same clock, but was a bit concerned when I started digging further into the software. It seemed to me that the promoted software is really designed to be used exactly as is with multiple devices needed (pc, android) and a dedicated pi running the img file.

What I was hoping for however was something a bit more modular as we don't need the majority of the cool, but overly complex software for our particular needs.

That said, I would love it if someone could point me in the right direction and save me some time in prioritizing my research.

Here are some ideas of what I think we need admittingly based on my lack of knowledge and experience:

1. The ability to strip away most of the customization options and even hard code and optimize based on 1 frequency (121.5 Mhz to start, we can create separate img files for other emergency frequencies)

2. The ability to gather either the raw IQ data from the KSDR or better yet and ideally the directional data after it has been processed.

3. I believe I have found the ability to set all of the settings normally handled in the browser as constants in the software and I assume this will work but am unsure of any drawbacks or if this is even the right approach/mindset.

4. I notice it is said to keep the antenna disconnected while "calibrating" and then attach them and proceed. Is this a requirement if we have all of the settings hardcoded for one signal? IN other words, if we calibrated everything we are able to reboot with everything attached and have it work with maybe just a few software commands?

5. Is there a different software package that would be more ideal for this purpose?

6. Lastly, if we were to basically strip apart and rebuild the KSDR to meet our one specific need... What parts of the codebase should we be focused on understanding and which parts would become irrelevant?

Please keep in mind that our overall idea is to keep all of this data and direction-finding completely internalized within the PI. Other than perhaps logging data, we do not have any need for external communication with the machine while it is in the process via wifi, hotspots, Bluetooth, or the like as the robot would, in fact, be completely autonomous in its driving capabilities.

ckoval7
Posts: 90
Joined: Fri Sep 27, 2019 8:54 pm

Re: Need Some Help in Specific 121.5 Mhz Application

Post by ckoval7 » Tue Feb 16, 2021 2:28 pm

hydra_receiver.py and hydra_signal_processor.py along with the C files you havr to compile the first time you pull the source code are really the core components of the program. hydra_main_window.py is sort of the glue that holds it all together and is what hosts the GUI. Writing your own version of that file without the GUI and without a lot of the "fluff" is possible, but will be a lot of work. I've wanted to do something like that, but haven't done so because there's a new version of the KSDR software coming out soon.

Disconnecting the antennas for the calibration step is very important. Every time you start the software or change a receiver parameter the USB devices are initialized in a random order. The calibration step synchronizes the software with the order the computer is receiving the IQ data. If you're receiving a signal while calibrating, the phase of the signal will become your "zero", therefore throwing off your DOA results. Every time you power up your robot you'll need to run the calibration step. You can use solid state RF switches to electronically disconnect the antennas.

What you want to do is very possible using what's already provided plus some custom python code.

sdreecs
Posts: 4
Joined: Mon Feb 15, 2021 8:49 pm

Re: Need Some Help in Specific 121.5 Mhz Application

Post by sdreecs » Fri Feb 19, 2021 12:19 am

Thanks @kcova17 ... I think we are on the right track then as those are the same files I have been working to digest.

Currently, however, I can't seem to get the sim.py to function on my Ubuntu box which is where we had hoped to do most of the code modifications which we could then push to the pi for real-world testing.

Right now I am using the branch which states it is for Ubuntu and I made some minor mods to get the program to run as it seemed some imports were not matching packages.

So I can effectively get the GUI to pop up however it seems to be all static data and I also have no python serve running on the localhost, or at least I can't see it from the browser via the IP it states.

I will keep tinkering but if anyone has suggestions, I am all ears. Thanks again for the help!

Maginux
Posts: 19
Joined: Sun Apr 21, 2019 9:27 am

Re: Need Some Help in Specific 121.5 Mhz Application

Post by Maginux » Sat Feb 20, 2021 3:53 pm

sdreecs wrote:
Mon Feb 15, 2021 9:11 pm
That said, I would love it if someone could point me in the right direction and save me some time in prioritizing my research.
Wouldn't you be part of an Adrasec, by pure chance ? :roll:

sdreecs
Posts: 4
Joined: Mon Feb 15, 2021 8:49 pm

Re: Need Some Help in Specific 121.5 Mhz Application

Post by sdreecs » Tue Feb 23, 2021 9:10 pm

lol, nope... just a team of students at Berkeley trying to make a badass autonomous search and rescue watercraft. :D

sdreecs
Posts: 4
Joined: Mon Feb 15, 2021 8:49 pm

Re: Need Some Help in Specific 121.5 Mhz Application

Post by sdreecs » Tue Feb 23, 2021 9:17 pm

We are currently working on a fork of the kerborossdr software. We are decoupling the GUI and server-based software in order to access the data and subsequent calculations programmatically. This way we can run the software on a pi, without human interaction.

Although our primary concern for this project is simply the DOA functionality, we are excited to take on the challenge of decoupling all of the functionality and create a sort of kerberossdr light package with a simple API which we think will be helpful for many in the community with similar needs.

With that in place, it should be easy for others to create bolt-on web/os based GUI's or other expanded capabilities.

Lastly, we have our electrical team looking into a lightweight diy rf switch so that we can change settings and handle calibrations on the fly should the need arise.

ckoval7
Posts: 90
Joined: Fri Sep 27, 2019 8:54 pm

Re: Need Some Help in Specific 121.5 Mhz Application

Post by ckoval7 » Tue Feb 23, 2021 9:40 pm

sdreecs wrote:
Tue Feb 23, 2021 9:17 pm
Lastly, we have our electrical team looking into a lightweight diy rf switch so that we can change settings and handle calibrations on the fly should the need arise.
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