KerberosSDR Developments in 2020

[rtlsdrblog]

Can the Kerberos 4 channel board accept a clock input signal? I'm exploring the possibility of using this board in a VLBI setup since my group has access to multiple hydrogen masers. Is the only way to sync the Kerberos receiver clocks with an outside source to have a separate clock breakout board take the 10MHz maser signal and solder four of its 28.8MHz outputs to the four receivers directly? Is there another way?

Yes you can use CLK_IN, and set the jumper to SLAVE. But it will only accept a 28.8 MHz input.

[lbiffle]

For networked operation the stop-gap idea was to get this program compatible with the KerberosSDR http://www.musther.net/RDFMapper/.

But if you're happy to open source and throw your code up on GitHub i'll help test it too.

Will be definitely keen to hear about your switch experiments too. Keep in contact either here on the forums or [email protected].

Right now, the networking code is in bits and pieces for testing of various concepts. I'll open up the repo later this year.


I've very pleased with the results from the antenna switch! I've set up the software to run an auto-calibration routine upon changing frequency. Nothing got mangled in the VHF range. I'm not sure how it will translate to the upper UHF range that people seem to use in the demo videos. There's nothing I've cared to DF in the 800MHz range.
Here are some photos: https://photos.app.goo.gl/K1PndvpgotPKdeBU9

Nice PCB's where do i buy this

Hi guys. I need this to work at 1.3 GHz for adaptive polarization, and am planning an external switch solution using TE Axicom FC3-53 3 GHz SPDT relays. If we’re considering an internal switching solution, I would recommend these. If not, we’ll need a signal to control our external relays. I don’t care which way we go, as long as it works at 1.3 GHZ.

This is quite exciting, and I’m thrilled with the progress you’re making!
Les - AA5NA

[WhereAmIFlying]

@Harbinger Unfortunately I can't send you a private message, I'm either too stupid or it's just not possible. Sorry for spamming the forum...

Is there a chance a future iteration of the Kerberos could come with a five SDR board? Something that could provide an integrated listening on the same frequency as the DF function would be nice instead of using a separate dongle and tuning separately.

I have "hacked" an ZMQ export into Kerberossdr which you can use to pass data to Gnuradio on demand. Drop me a mail at [email protected] if you want to have a look at it. Depending on what you want to do, this may or may not help you.

Would you be able to release this on github etc?

I have just commited the changes to my own GitHub fork https://github.com/nuena/kerberossdr. I don't (yet) want to create a pull request because I think there should be a few tests, benchmarks and documentations before.

The changes mainly consist of a couple of extra lines in hydra_receiver.py and an added example GnuRadio flowgraph. I'm looking forward to any feedback!

[hongikwireless]

Hello.

I was interested in KerberosSDR, so I bought "KerberosSDR 4 Channel Coherent RTL-SDR For Direction Finding & Passive Radar".

I got KerberosSDR and tested the "SDR# (Windows) (Free)" program.

By the way, I want to use KerberosSDR for direction finding, but I want to know if there is a test software.

Are there any programs like Windows 10 or 7 that can be tested on Windows?

Is KerberosSDR only available for "Raspberry Pi 3 / 4" or "Tinkerboard" or "Other SBCs"?

Is there no direction detection test program in Windows OS series?

Thanks.

[joealthaus]

@rtlsdrblog - our team is trying to do some work with the KSDR that requires 2 units cascaded for 8 channels and to do beamforming. Any updates on the items below or perhaps just point us in the direction of the most recent associated commits and/or hardware versions. We are using the KDSR units that have the microUSB ports. ATM, we are having trouble getting coherent signal reception between the two units.

[*] DAQ Unit Separation - Processing performance could be significantly improved if the DAQ subsystem and DSP processing code is separated onto two different pieces of computing hardware. Presently if the DSP code is set to run too fast, the DAQ code will lose sample sync due to the CPU + OS on a single device not being able to keep up with the task switching requirements. In the long run it would be better to dedicate a Pi3/4 or other cheap SBC to the DAQ and another computing unit to the DSP. This will allow people to easily read the coherent data stream in other programs too like GNU Radio via an Ethernet network stream. For mobile DFing we will keep the option to use just one SBC.

[*] Beamforming - Once the DAQ system upgrades are completed, beamforming and listening to actual signals should be possible. Beamforming will allow you to electrically optimize an antenna array for receiving in one particular direction.

[*] Direct support for two combined KerberosSDR units - Combining two KerberosSDR's gives you 8 antenna inputs. This can improve DFing accuracy, and improve passive radar coverage.

[markahan]

I've very pleased with the results from the antenna switch! I've set up the software to run an auto-calibration routine upon changing frequency. Nothing got mangled in the VHF range. I'm not sure how it will translate to the upper UHF range that people seem to use in the demo videos. There's nothing I've cared to DF in the 800MHz range.
Here are some photos: https://photos.app.goo.gl/K1PndvpgotPKdeBU9

Hi Corey,

These switches you've used here look like an elegant solution to the programmatic disconnect-reconnect for syncing the kerberos. Sounds like it worked successfully which is great.

Can you advise the part that you've used for the switch?

Also, I see you've indicated in another post the following:

Now you're just left with the problem of syncing, which isn't reliable without a way to disconnect the antennas from the receiver. Hardware switches aren't hard to build and can be controlled with the GPIO. I have a fork of the KSDR software that can auto-sync if you have RF switches. https://github.com/ckoval7/kerberossdr/ ... witch_ctrl

Is this fork the same software you've used to control the above switches from the RPI GPIO lines?

Will be nice if a new hardware & software revision can incorporate this function natively, but it appears unclear when that might arrive.

Cheers,
Mark

[Tom_G0JSV]

Here is my home brew solution. A simple set of 4*5V relays in a metal case. There is a switch to disconnect the antennas. Runs on 3 * 1.5v AA Batteries. I calibrate using the Android software, then throw the switch to connect the antennas and it seems to give reasonable results.

P1.png (311.08 KiB) Viewed 1396 times

Here are a couple of screenshots from a local net on 145.425 this morning. 21 Jan 2021

P2.png (260.53 KiB) Viewed 1396 times

Station one to the NE.

P3.png (260.96 KiB) Viewed 1396 times

Station two to the SE.


Tom.

[ckoval7]

These switches you've used here look like an elegant solution to the programmatic disconnect-reconnect for syncing the kerberos. Sounds like it worked successfully which is great.

Can you advise the part that you've used for the switch?


Is this fork the same software you've used to control the above switches from the RPI GPIO lines?

Will be nice if a new hardware & software revision can incorporate this function natively, but it appears unclear when that might arrive.

Cheers,
Mark

If you're inclined to roll your own boards, this is the part I've used: https://www.minicircuits.com/WebStore/d ... A2-30DR%2B

If you would like to buy some, I'll be selling them through Tindie in a couple weeks. I've got most of what I need to make a significant number of these, just waiting for a few more items to show up.

You'll need that specific branch of my fork. It includes the autocal code as well as gpsd support and an expanded XML format which contains location and heading information.

[Tom_G0JSV]

OK...home brew antenna switch good on 2M. Not so good on 70cm. Back to the drawing board.

[markahan]

If you're inclined to roll your own boards, this is the part I've used: https://www.minicircuits.com/WebStore/d ... A2-30DR%2B
If you would like to buy some, I'll be selling them through Tindie in a couple weeks. I've got most of what I need to make a significant number of these, just waiting for a few more items to show up.

Fantastic - definitely interested in the finished product, so will keep an eye out for your tindie store when the time comes.
Do you have a link to your store?
Cheers,
Mark