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Adapting the LiteVNA for SAR?

 

Folks,
Using the NanoVNA as a signal source for Ground Penetrating Radar (GPR) was discussed a couple of years ago. Today on Hacker News, there is an article about a home-built Synthetic Aperture Radar (SAR) unit using a freq around 6GHz.



The article discusses theory and the problem of finding a suitable Rcv A/D. The LiteVNA has the freq range, is capable of resolving nS time (to a certain amount), can measure phase and is programmable.

The big issue is probably the switching time of the generator/reflection ICs in the front-end of the LiteVNA. As for the A/D spec, would the heterodyne method and DSP used be a limiting factor?

So - might it be feasible to make use of the LiteVNA in a simplified radar setup using an external controller and appropriate antennas?
Could the TDR routines be adapted?
Could the LiteVNA be used with a TinSA-Ultra and a controller for something?

Just thinking out of the box here. In my 60+ years of Tech, I have always looked at repurposing stuff. So, instead of "not possible" answers, I would rather hear what might need to be changed (electronics /software) to achieve a minimal proof of concept. Thinking caps on....

... Larry
 

Hi Larry

I have worked on several GPR projects.? One is currently looking for land mines in SE Asia.
A LOT of loss going though dirt.??? And a big impedance bump at the air/dirt interface.?

They really need much more power than the Nano puts out.?? And since the same port is Tx and Rec, an amp will not be simple.????? But lots of neat stuff down there.?? Kent

On Monday, February 17, 2025 at 10:17:28 AM CST, Larry Rothman via groups.io <nlroth@...> wrote:

Folks,
Using the NanoVNA as a signal source for Ground Penetrating Radar (GPR) was discussed a couple of years ago. Today on Hacker News, there is an article about a home-built Synthetic Aperture Radar (SAR) unit using a freq around 6GHz.



The article discusses theory and the problem of finding a suitable Rcv A/D. The LiteVNA has the freq range, is capable of resolving nS time (to a certain amount), can measure phase and is programmable.

The big issue is probably the switching time of the generator/reflection ICs in the front-end of the LiteVNA. As for the A/D spec, would the heterodyne method and DSP used be a limiting factor?

So - might it be feasible to make use of the LiteVNA in a simplified radar setup using an external controller and appropriate antennas?
Could the TDR routines be adapted?
Could the LiteVNA be used with a TinSA-Ultra and a controller for something?

Just thinking out of the box here. In my 60+ years of Tech, I have always looked at repurposing stuff. So, instead of "not possible" answers, I would rather hear what might need to be changed (electronics /software) to achieve a minimal proof of concept. Thinking caps on....

... Larry
 

Thanks, Kent.
I'm more interested in using signals through air.
The front-end of the LiteVNA was described here:
/g/liteVNA/topic/99749985#msg1054

I see I made a mistake in my 1st post. The liteVNA doesn't use a similar DSP to the nanoVNA but uses the uP's internal DSP and several switches.
However, all the switches can be statically set: reflect=open, Rx/tx synth set to ADF4350, rcv & ecal connected to ports.
Then control Tx & Rx from external controller.
 

? Use S21 mode with an amplifier.

People have been using VNAs as radars for years.
The NanoVNA just makes it easier.

Dealing with the big first reflection is tricky. One way is to use a separate cancellation path that is adjusted to null the first reflection. ?That’s what we did for the FINDER victim detection radar.

FINDER: Radar for Locating Disaster Victims ( )
jpl.nasa.gov ( )

( )


On Feb 17, 2025, at 08:51, KENT BRITAIN <WA5VJB@...> wrote:


? Hi Larry

I have worked on several GPR projects.? One is currently looking for land
mines in SE Asia.
A LOT of loss going though dirt.??? And a big impedance bump at the
air/dirt interface.

They really need much more power than the Nano puts out.?? And since the
same port is Tx and Rec, an amp will not be simple.????? But lots of neat
stuff down there.?? Kent

On Monday, February 17, 2025 at 10:17:28 AM CST, Larry Rothman via
groups.io <nlroth@...> wrote:

Folks,
Using the NanoVNA as a signal source for Ground Penetrating Radar (GPR)
was discussed a couple of years ago. Today on Hacker News, there is an
article about a home-built Synthetic Aperture Radar (SAR) unit using a
freq around 6GHz.




The article discusses theory and the problem of finding a suitable Rcv
A/D. The LiteVNA has the freq range, is capable of resolving nS time (to a
certain amount), can measure phase and is programmable.

The big issue is probably the switching time of the generator/reflection
ICs in the front-end of the LiteVNA. As for the A/D spec, would the
heterodyne method and DSP used be a limiting factor?

So - might it be feasible to make use of the LiteVNA in a simplified radar
setup using an external controller and appropriate antennas?
Could the TDR routines be adapted?
Could the LiteVNA be used with a TinSA-Ultra and a controller for
something?

Just thinking out of the box here. In my 60+ years of Tech, I have always
looked at repurposing stuff. So, instead of "not possible" answers, I
would rather hear what might need to be changed (electronics /software) to
achieve a minimal proof of concept. Thinking caps on....

... Larry












multimediathumbsFINDER20130925-640.jpg

 

All of this begs a simple question.
Use the NanoVNA as a Field Strength Meter.
Why - Just built a new antenna using the NanoVNA to adjust it to the operational Frequency and adjusted the impedance for a match now it would be nice to be able to have some form of active display of the radiated signal, without blowing up the front end the NanoVNA
While I cause a simple diode detector and a meter using the NanoVNA is another possible use.
Any suggestions on how or how not to do it.
Thanks
 

Use S21 mode with an amplifier.

People have been using VNAs as radars for years.
The NanoVNA just makes it easier.

Dealing with the big first reflection is tricky. One way is to use a separate cancellation path that is adjusted to null the first reflection. ?That’s what we did for the FINDER victim detection radar.

FINDER: Radar for Locating Disaster Victims ( )
jpl.nasa.gov ( )

( )


On Feb 17, 2025, at 08:51, KENT BRITAIN <WA5VJB@...> wrote:


? Hi Larry

I have worked on several GPR projects.? One is currently looking for land
mines in SE Asia.
A LOT of loss going though dirt.??? And a big impedance bump at the
air/dirt interface.

They really need much more power than the Nano puts out.?? And since the
same port is Tx and Rec, an amp will not be simple.????? But lots of neat
stuff down there.?? Kent

On Monday, February 17, 2025 at 10:17:28 AM CST, Larry Rothman via
groups.io <nlroth@...> wrote:

Folks,
Using the NanoVNA as a signal source for Ground Penetrating Radar (GPR)
was discussed a couple of years ago. Today on Hacker News, there is an
article about a home-built Synthetic Aperture Radar (SAR) unit using a
freq around 6GHz.




The article discusses theory and the problem of finding a suitable Rcv
A/D. The LiteVNA has the freq range, is capable of resolving nS time (to a
certain amount), can measure phase and is programmable.

The big issue is probably the switching time of the generator/reflection
ICs in the front-end of the LiteVNA. As for the A/D spec, would the
heterodyne method and DSP used be a limiting factor?

So - might it be feasible to make use of the LiteVNA in a simplified radar
setup using an external controller and appropriate antennas?
Could the TDR routines be adapted?
Could the LiteVNA be used with a TinSA-Ultra and a controller for
something?

Just thinking out of the box here. In my 60+ years of Tech, I have always
looked at repurposing stuff. So, instead of "not possible" answers, I
would rather hear what might need to be changed (electronics /software) to
achieve a minimal proof of concept. Thinking caps on....

... Larry












multimediathumbsFINDER20130925-640.jpg

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