Feature requests / development ideas

Discuss KerberosSDR - 4x Coherent RTL-SDR
rtlsdrblog
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Re: Feature requests / development ideas

Post by rtlsdrblog » Thu Sep 05, 2019 9:52 am

Yep we will definitely be adding a calculator to the GUI. You're right, it's probably better to let people entry the spacing, and let them decide if the calculated spacing factor is reasonable.

f4exb
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Re: Feature requests / development ideas

Post by f4exb » Sat Sep 07, 2019 7:23 am

Hi,

I think it would be good to add a NCO to shift the effective reception center frequency anywhere in the 2 MHz or so passband of the RTLSDRs. This is motivated mostly because if you use only the passband around zero frequency and use the RTLSDR LO to tune to the signal of interest then you have to re calibrate each time you change this frequency and this is very cumbersome. Of course the same NCO sample is applied to every channel sample to stay synchronous.

Brgds.

rtlsdrblog
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Re: Feature requests / development ideas

Post by rtlsdrblog » Mon Sep 09, 2019 6:01 am

f4exb wrote:
Sat Sep 07, 2019 7:23 am
Hi,

I think it would be good to add a NCO to shift the effective reception center frequency anywhere in the 2 MHz or so passband of the RTLSDRs. This is motivated mostly because if you use only the passband around zero frequency and use the RTLSDR LO to tune to the signal of interest then you have to re calibrate each time you change this frequency and this is very cumbersome. Of course the same NCO sample is applied to every channel sample to stay synchronous.

Brgds.
Thanks, yes this makes sense. It is planned to be added in a future version. In the future we'll probably be splitting the DoA and Passive Radar applications into separate software, which will make it easier to add tuning options for DoA.

KD7JJY
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Joined: Thu Sep 12, 2019 4:39 pm

Re: Feature requests / development ideas

Post by KD7JJY » Thu Sep 12, 2019 4:57 pm

rtlsdrblog wrote:
Sun Sep 01, 2019 3:52 am
k5cg wrote:
Sun Sep 01, 2019 2:02 am

3. Having to disconnect 4 antennas (optionally connect the terminators) to sync, zero the IQ, and then reverse all of that, is time consuming. The system would be less tedious if you could use PIN diodes to switch the antennas off (to terminators or ground) right on the PCB under software control. The user would never have to disconnect the antennas. Further, Sync and IQ zero could be automated in software.

Thanks for the great product!

Future updates will also see a streamlined one click calibration process, that just runs the steps one after another, and checks that the graphs have been zeroed itself.
I just got mine the other day, and I see a lot of possibilities going forward.

Could the calibration process be a table file (multi-point) across the Spectrum or Band. That way you only need to calibrate at startup or once in a while?

f4exb
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Re: Feature requests / development ideas

Post by f4exb » Fri Sep 13, 2019 3:07 pm

Kerberos designers can correct me if I am wrong but if I got it right this is not like a power vs frequency calibration that you put in a table and update once in a while when some external condition (temperature...) changes. The 4 receivers have a common clock so they are coherent at a certain point in time but as they are 4 independent receivers otherwise using each its own USB channel you don't know that certain point in advance yet it will not vary as long as you keep the USB link alive and some other receiver parameters like center frequency, gain, sample rate (afaik). Therefore you cannot have it in a static table that you change every so often you need to run through a calibration cycle at every power up and parameters change.

Some MIMO devices (MI for Rx part that is) like LimeSDR, BladeRF v2, XTRX... do not have this issue because the two (don't know of more than two) receivers live on the same chip so their time difference is constant by construction and can be corrected (or made null in the chip fabric) once and for all. But they don't sit in the same price range and I don't know of any with more than two receivers.

rtlsdrblog
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Re: Feature requests / development ideas

Post by rtlsdrblog » Sat Sep 14, 2019 4:13 am

f4exb wrote:
Fri Sep 13, 2019 3:07 pm
Kerberos designers can correct me if I am wrong but if I got it right this is not like a power vs frequency calibration that you put in a table and update once in a while when some external condition (temperature...) changes. The 4 receivers have a common clock so they are coherent at a certain point in time but as they are 4 independent receivers otherwise using each its own USB channel you don't know that certain point in advance yet it will not vary as long as you keep the USB link alive and some other receiver parameters like center frequency, gain, sample rate (afaik). Therefore you cannot have it in a static table that you change every so often you need to run through a calibration cycle at every power up and parameters change.

Some MIMO devices (MI for Rx part that is) like LimeSDR, BladeRF v2, XTRX... do not have this issue because the two (don't know of more than two) receivers live on the same chip so their time difference is constant by construction and can be corrected (or made null in the chip fabric) once and for all. But they don't sit in the same price range and I don't know of any with more than two receivers.
Yep that's correct, every boot the USB sample offsets are going to be different, so you cannot have just one calibration table.

Exactly, some more expensive chips are naturally coherent, but yeah much more expensive and with only 2x receivers. And if you wanted 4 receivers, I think you'd still need to end up calibrating with a noise source anyway.

pstamand
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Antenna spacing calculation on the code

Post by pstamand » Mon Sep 16, 2019 1:53 am

i would be really great to put a simple field that calculated the antenna based on the configuration screens so the value is easily referenced without having to do all the calculations. A simple calculate button the screen would show the spacing value.

Bigtwig
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Re: Feature requests / development ideas

Post by Bigtwig » Tue Sep 17, 2019 5:40 pm

Is it possible to get the schematic for the KSDR? or at the very least could you tell me the part number for U2 on the PCB? thanks.

rtlsdrblog
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Re: Feature requests / development ideas

Post by rtlsdrblog » Thu Sep 19, 2019 3:08 am

Bigtwig wrote:
Tue Sep 17, 2019 5:40 pm
Is it possible to get the schematic for the KSDR? or at the very least could you tell me the part number for U2 on the PCB? thanks.
I checked with the HW developer, and he said it's a SY8008C(AA)C.

myke
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Re: Feature requests / development ideas

Post by myke » Tue Sep 24, 2019 3:26 pm

In the DF process, as you get closer to the source it would be beneficial to insert attenuation into the Antenna system to counter increased multipath. (of course those changes would require stopping and re-calibration with any antenna changes.) What do you think about an auto increase of "Minimum Required Power" in the Android App as you DF closer to Signal origin? Also, what is the range the software will accept for 'Minimum Required Power' ?

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