Feedback on possible KerberosSDR V2 Hardware

Discuss KerberosSDR - 4x Coherent RTL-SDR
WA4OSH
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Re: Feedback on possible KerberosSDR V2 Hardware

Post by WA4OSH » Wed Dec 04, 2019 9:51 pm

The Rafael Micro R820T2 chip has been discontinued since march 2018. It will need a replacement.

https://www.rtl-sdr.com/r820t2-chip-dis ... -redesign/

--Konrad, WA4OSH

rtlsdrblog
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Re: Feedback on possible KerberosSDR V2 Hardware

Post by rtlsdrblog » Sat Dec 07, 2019 1:05 am

WA4OSH wrote:
Wed Dec 04, 2019 9:51 pm
The Rafael Micro R820T2 chip has been discontinued since march 2018. It will need a replacement.

https://www.rtl-sdr.com/r820t2-chip-dis ... -redesign/

--Konrad, WA4OSH
I think we noted in that post that the R820T2 is discontinued, but production will continue as normal. Basically, since the demand for these chips is still high we can still get them produced in custom bulk orders. They're just not continually producing them anymore, and not selling them to distributors.

rtlsdrblog
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Re: Feedback on possible KerberosSDR V2 Hardware

Post by rtlsdrblog » Sat Dec 07, 2019 1:06 am

radioMatt wrote:
Fri Nov 29, 2019 4:11 am
Whats the prospective timeline on a V2?
Still a long time away, the soonest possible would be mid-2020. Realistically, probably quarter 3/4 2020.

fresnoboy
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Joined: Thu Jun 14, 2018 4:56 pm

Re: Feedback on possible KerberosSDR V2 Hardware

Post by fresnoboy » Thu Jan 02, 2020 4:46 pm

Some comments on the wish list:

1) Definitely RF switches to enable calibration without disconnecting antennas. This would pave the way for fixed site rooftop installations, and potentially a crowdsourced RDF network. Think about these mounted on towers or rooftops, and taskable from a frequency POV! Automatic calibration would also be super useful in this context and remove a ton of complexity and friction.

2) Definitely agree for an USB-C based designed using PD, and also USB-C to talk to the compute device, preferably on 2 connectors. USB-C has come a long way in the last 2 years, especially for power distribution.

3) I agree with others, don't bundle in compute - the compute changes faster than the radios should. But it would be nice if the software were more generic in terms of platform so higher performance ZCZPU's could be used. I love my odroid N2 for these sorts of uses, and a lot faster than an RPI4.

4) A recommended set of antennas for elevated fixed installation, probably vertical dipoles.

thankls,
mike

Tom_G0JSV
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Re: Feedback on possible KerberosSDR V2 Hardware

Post by Tom_G0JSV » Sun Feb 16, 2020 9:02 pm

My bad

Just suggested a few features for v3 before finding this thread.

In my defence, we are post v2 so maybe that was OK.

More to follow..

T

rtlsdrblog
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Re: Feedback on possible KerberosSDR V2 Hardware

Post by rtlsdrblog » Fri Feb 28, 2020 4:13 am

So we've decided on working towards these features for V2 for now:
  1. Redesigned calibration network with low phase distortion switches added to the board - no more need to disconnect antennas when returning and recalibrating. As long as your antennas and cables are identical, there should be no phase distortion.
  2. USB-C on all ports. With PD power supply support.
  3. An 12V supply input. (Choose between either USB-C power, or 12V plug pack)
  4. A powered USB-C out port. If powering by 12V plug pack, there should be enough power to power the KerberosSDR and a Raspberry Pi together.
  5. Everything integrated on a single PCB. Instead of using a two board design, we should be able to move everything to one 8-layer board.
  6. An improved enclosure with less holes. Better shielding against RF interference.
  7. SMA out's arranged in a fixed circular pattern on the enclosure top. This should allow the unit to work for DFing with just 4 SMA whip antennas at some frequencies below the 0.5 spacing factor threshold. Of course you can still connect mag whips via coax cabling.
  8. Bias tee's
  9. [MAYBE] Possibility a built in cooling fan to avoid the phase distortion that occurs in warm ambient environments when the unit is in the processing of warming up and hasn't reached thermal equilibrium.
We won't be including built in computing or a screen, and it will be expected that users will use an SBC like a Pi 4 or a PC like with V1.

We'll might also be able to include a 12V supply and 4 SMA whips.

One other thing we're looking into providing is an ISM band TX remote for testing DFing. However, the challenge is that there is no universal unlicensed band within the tuning range for all countries above the 40.7 MHz frequency, and that freq is too low for a reasonably sized antenna array. So the TX remote may be restricted to certain countries only.

Tom_G0JSV
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Re: Feedback on possible KerberosSDR V2 Hardware

Post by Tom_G0JSV » Fri Feb 28, 2020 3:58 pm

Nice.

Any chance of elevating the LED's so they can be seen more clearly? Or will that compromise point 6.

Never been a fan fan. ;-) Would a bit more metal-work work instead? Point 9.

Is the 'Top' where the 40 pin header comes out? Point 7.

I like the idea of placing some distance/different plane between the antenna connections and the other connectors. I 'run' my box upside down/sideways at the moment so that when I plug/unplug the aerials, nothing else is disturbed.

Tom.

Stromeko
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Re: Feedback on possible KerberosSDR V2 Hardware

Post by Stromeko » Sun Mar 01, 2020 9:51 am

Just commenting on these four points:
rtlsdrblog wrote:
Fri Feb 28, 2020 4:13 am
  • Redesigned calibration network with low phase distortion switches added to the board - no more need to disconnect antennas when returning and recalibrating. As long as your antennas and cables are identical, there should be no phase distortion.
  • SMA out's arranged in a fixed circular pattern on the enclosure top. This should allow the unit to work for DFing with just 4 SMA whip antennas at some frequencies below the 0.5 spacing factor threshold. Of course you can still connect mag whips via coax cabling.
  • Bias tee's
  • [MAYBE] Possibility a built in cooling fan to avoid the phase distortion that occurs in warm ambient environments when the unit is in the processing of warming up and hasn't reached thermal equilibrium.
  • It would be helpful if the calibration network could be used as a general 1:4 antenna splitter. If you have RF switches anyway, there's just one more switch required to have an input that can then be multiplexed on all four channels.
  • Having the SMA on top of the units would be a major inconvenience for connecting cables, so please consider an option where the SMA pigtails can be moved to some front or back panel instead.
  • Thanks for considering Bias-Tees, would it be possible to chose the supply voltage?
  • Please no fan. Instead I would recommend using a thermal interface material mounted heat spreader to equilibrate the temperature. You might consider making the enclosure part of the heat spreder, that would also allow for more efficient cooling.

Tom_G0JSV
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Re: Feedback on possible KerberosSDR V2 Hardware

Post by Tom_G0JSV » Sun Mar 01, 2020 8:32 pm

Having the SMA on top of the units would be a major inconvenience for connecting cables, so please consider an option where the SMA pigtails can be moved to some front or back panel instead.

I agree with the above comment from Stromeko.

There is space on the back panel for the 4 SMA's (in a square/diamond) and enough room for power and other connections to the left or right of these with reasonable gap.

But... if the cost of moving the SMA connections is high, then I would suggest that these are left at the back with the power, usb and LED's moving to the front panel.


Tom.

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