Dear NanoVNA v2 users,

I'm looking to buy a NanoVNA v2 for our lab. While looking at the
NanoVNA v2 specifications
(https://nanorfe.com/nanovna-v2-user-manual.html#specifications) I was a
bit confused by the "Frequency resolution" parameter, which is given as:

Frequency resolution: 0.01MHz

What exactly is this frequency resolution? Does it mean that the minimum
distance between two points on a frequency sweep is 10 kHz?

In other words, on the low end of 50 kHz, does this mean that the best
the NanoVNA can do in a frequency sweep are 50 kHz, 60 kHz, 70 kHz...
and so on?

If so, does anyone happen to know where this limitation comes from? e.g.
is there a signal source that's only programmable in 10 kHz increments?

Thanks,
Kevin

--
Kevin Zheng
Ph.D. Candidate, Electrical Engineering and Computer Sciences
University of California, Berkeley

Hi, yes that is correct, this is due to the divisor of the fractional PLL being set to 10kHz, limited by the ADF435x maximum fractional denominator.
Thanks

Kevin,
There are firmware versions that allow better frequency resolution at lower frequencies, presumably by running the synthesizer chip in a different mode.
My NanoVNA V2 using the Ojisan firmware of Oct 4, 2020 has frequency steps of 3kHz at 1.5GHz, 0.5kHz at 100MHz, and 10Hz or less at 50kHz.
The DiSlord firmware may also offer improved step size at lower frequencies.
--John Gord

On Wed, Oct 23, 2024 at 10:29 PM, Kevin Zheng wrote:

>
> Dear NanoVNA v2 users,
>
> I'm looking to buy a NanoVNA v2 for our lab. While looking at the
> NanoVNA v2 specifications
> ( https://nanorfe.com/nanovna-v2-user-manual.html#specifications ) I was a
>
> bit confused by the "Frequency resolution" parameter, which is given as:
>
> Frequency resolution: 0.01MHz
>
> What exactly is this frequency resolution? Does it mean that the minimum
> distance between two points on a frequency sweep is 10 kHz?
>
> In other words, on the low end of 50 kHz, does this mean that the best
> the NanoVNA can do in a frequency sweep are 50 kHz, 60 kHz, 70 kHz...
> and so on?
>
> If so, does anyone happen to know where this limitation comes from? e.g.
> is there a signal source that's only programmable in 10 kHz increments?
>
> Thanks,
> Kevin
>
> --
> Kevin Zheng
> Ph.D. Candidate, Electrical Engineering and Computer Sciences
> University of California, Berkeley

Thanks all for the responses.

On 10/23/24 10:22 PM, John Gord via groups.io wrote:
> Kevin,
> There are firmware versions that allow better frequency resolution at
> lower frequencies, presumably by running the synthesizer chip in a
> different mode.
> My NanoVNA V2 using the Ojisan firmware of Oct 4, 2020 has frequency
> steps of 3kHz at 1.5GHz, 0.5kHz at 100MHz, and 10Hz or less at 50kHz.
> The DiSlord firmware may also offer improved step size at lower frequencies.

That helps. Would it be convenient for you to check what frequency step
you can achieve at 20 MHz?

Nonetheless, 500 Hz resolution below 100 MHz is much closer to what
we're looking for.

Thanks,
Kevin

--
Kevin Zheng
Ph.D. Candidate, Electrical Engineering and Computer Sciences
University of California, Berkeley

Kevin,
This is all on the original NanoVNA V2 also known as SAA-2.  I don't have any of the later versions.
At 20MHz, the Ojisan firmware gives 10 Hz step size.
At 20MHz, The DiSlord firmware v1.3.21 gives 1Hz step size.
--John Gord

On Thu, Oct 24, 2024 at 09:59 PM, Kevin Zheng wrote:

>
> Thanks all for the responses.
>
> On 10/23/24 10:22 PM, John Gord via groups.io wrote:
>
>> Kevin,
>> There are firmware versions that allow better frequency resolution at
>> lower frequencies, presumably by running the synthesizer chip in a
>> different mode.
>> My NanoVNA V2 using the Ojisan firmware of Oct 4, 2020 has frequency
>> steps of 3kHz at 1.5GHz, 0.5kHz at 100MHz, and 10Hz or less at 50kHz.
>> The DiSlord firmware may also offer improved step size at lower
>> frequencies.
>
> That helps. Would it be convenient for you to check what frequency step
> you can achieve at 20 MHz?
>
> Nonetheless, 500 Hz resolution below 100 MHz is much closer to what
> we're looking for.
>
> Thanks,
> Kevin
>
> --
> Kevin Zheng
> Ph.D. Candidate, Electrical Engineering and Computer Sciences
> University of California, Berkeley

Hi, the firmware versions *20220814* and later for V2 Plus4/VNA6000 incorporates the changes for improved SI5351 frequency resolution, which I recall is 1Hz, but I will check with engineering.

Please note that all of this only applies below 140MHz, as higher frequencies are covered by ADF435x which has the aforementioned 10kHz limitation.
You can find the latest firmware here:

https://nanorfe.com/nanovna-versions.html#versions

Thanks