开云体育

On 7/27/20 11:38 PM, Rudolf Schaffer wrote:

Brandon, that's exactly what i was asking for !

I've read the Si5351 datasheet but don't find an answer.

The data sheet doesn't give the details of the PLL or other synthesizers.
SiLabs has a free program called ClockBuilder that figures out how to
program it, using your desired frequencies.


What you want is this:


which gives the equations for the PLL, Multisynth, and final dividers

foutx = fvco/(Output multisynthx * Rx)
fvco = fin * Feedback_Multisynth

Valid Multisynth divider ratios are 4, 6, 8, and any fractional value
between 8 + 1/1,048,575 and 2048.

fvco = fxtal * (A + B/C)

Thank you for your message.

Rudi



Le 27.07.2020 à 22:34, Brandon Swift a écrit :

Rudi, I think I understood your question from your first message, and
your second message did make it more clear.

For others, I think Rudi is asking "what is the smallest amount we can
increment the low-level generated tone? (and this seems to vary with
frequency)". I don't think he's asking "how do I find the step size in
the VNA sweep?"

I believe the answer ought to lie in the datasheet of the Si5351A
clock generator, the main signal source of the NanoVNA


However, I can't find that info in that datasheet right now, and can't
look at control source code effectively. Maybe someone more familiar
with the ins-and-outs of the Si5351 can provide some more insight?

On Mon, Jul 27, 2020 at 12:11 PM David Eckhardt
<davearea51a@...> wrote:

Moderators, please,....PLEASE.....place this in the Wiki as this is the
third time I've explained this.

Dave - W ?LEV

On Mon, Jul 27, 2020 at 7:10 PM David Eckhardt <davearea51a@...>
wrote:

Frequency step between measured points has more to do with FREQUENCY
SWEEP
WIDTH than absolute frequency, itself. The native NANO's offer 101
measured steps over any specified frequency sweep. So a general
formula
which gives the measured point spacing during both for cal and
measurement
is:

FS = (Upper Frequency - Lower Frequency) / 101

Where FS = Frequency Step or Frequency Spacing

A couple of examples might illustrate this. Assume one wishes to
look at
an antenna over the entire 75/80-meter band, 3.5 to 4.0 MHz. The
frequency
spacing or frequency step would then be:

FS = (4.0 MHz - 3.5 MHz) / 101 = 4.95 E-3 MHz or 4.95 kHz.

A measurement, both in cal and measurement, would be made every 4.95
kHz.
If measurement of SWR is the goal, this spacing should be adequate to
assess the fine structure of SWR behavior over the entire
75/80-meter band.

Now, assume one desires to measure an antenna over the entire 70-cm
band,
430 to 450 MHz. In this case, 200 kHz spacing between measured
points may
not be adequate to assess the fine structure of the SWR behavior
over the
entire 70-cm band.

FS = (450 MHz - 430 MHz) / 101 = 1.98 E-3 MHz or
roughly
every 200 kHz.

However, using NANOSAVER on a PC or laptop, up to 10 'segments',
each of
101 measured points can be made. One need just specify the number of
segments to obtain better resolution.

For example, if one specifies 5 segments over the entire 70-cm band,
this
would yield a measurement point spacing of:

FS = ([Upper Frequency - Lower Frequency] / 5) / 101 =
([450 MHz
- 430 MHz] / 5) / 101 =39.6 MHz or roughly every 40 kHz.

This should be adequate to assess the antenna over the entire 70-cm
band.

Dave - W?LEV





On Mon, Jul 27, 2020 at 7:46 AM Rudolf Schaffer <
rudolf.schaffer@...> wrote:

Hello,

Can somebody explain to me how to define/calculate the minimum
frequency
step versus output frequency for a NanoVNA-H4 ?

Thank you in advance.

Rudi

--
*Dave - W?LEV*
*Just Let Darwin Work*

--
*Dave - W?LEV*
*Just Let Darwin Work*

On 7/27/20 11:38 PM, Rudolf Schaffer wrote:

Brandon, that's exactly what i was asking for !

I've read the Si5351 datasheet but don't find an answer.

The data sheet doesn't give the details of the PLL or other synthesizers.
SiLabs has a free program called ClockBuilder that figures out how to program it, using your desired frequencies.


What you want is this:


which gives the equations for the PLL, Multisynth, and final dividers

foutx = fvco/(Output multisynthx * Rx)
fvco = fin * Feedback_Multisynth

Valid Multisynth divider ratios are 4, 6, 8, and any fractional value between 8 + 1/1,048,575 and 2048.

fvco = fxtal * (A + B/C)

Thank you for your message.

Rudi



Le 27.07.2020 à 22:34, Brandon Swift a écrit?:

Rudi, I think I understood your question from your first message, and
your second message did make it more clear.

For others, I think Rudi is asking "what is the smallest amount we can
increment the low-level generated tone? (and this seems to vary with
frequency)". I don't think he's asking "how do I find the step size in
the VNA sweep?"

I believe the answer ought to lie in the datasheet of the Si5351A
clock generator, the main signal source of the NanoVNA


However, I can't find that info in that datasheet right now, and can't
look at control source code effectively. Maybe someone more familiar
with the ins-and-outs of the Si5351 can provide some more insight?

On Mon, Jul 27, 2020 at 12:11 PM David Eckhardt <davearea51a@...> wrote:

Moderators, please,....PLEASE.....place this in the Wiki as this is the
third time I've explained this.

Dave - W ?LEV

On Mon, Jul 27, 2020 at 7:10 PM David Eckhardt <davearea51a@...>
wrote:

Frequency step between measured points has more to do with FREQUENCY SWEEP
WIDTH than absolute frequency, itself.? The native NANO's offer 101
measured steps over any specified frequency sweep.? So a general formula
which gives the measured point spacing during both for cal and measurement
is:

?????????? FS = (Upper Frequency - Lower Frequency) / 101

?????????? Where? FS = Frequency Step or Frequency Spacing

A couple of examples might illustrate this.? Assume one wishes to look at
an antenna over the entire 75/80-meter band, 3.5 to 4.0 MHz.? The frequency
spacing or frequency step would then be:

?????????? FS = (4.0 MHz - 3.5 MHz) / 101 = 4.95 E-3 MHz or 4.95 kHz.

A measurement, both in cal and measurement, would be made every 4.95 kHz.
If measurement of SWR is the goal, this spacing should be adequate to
assess the fine structure of SWR behavior over the entire 75/80-meter band.

Now, assume one desires to measure an antenna over the entire 70-cm band,
430 to 450 MHz.? In this case, 200 kHz spacing between measured points may
not be adequate to assess the fine structure of the SWR behavior over the
entire 70-cm band.

?????????????????? FS = (450 MHz - 430 MHz) / 101 = 1.98 E-3 MHz or roughly
every 200 kHz.

However, using NANOSAVER on a PC or laptop, up to 10 'segments', each of
101 measured points can be made.? One need just specify the number of
segments to obtain better resolution.

For example, if one specifies 5 segments over the entire 70-cm band, this
would yield a measurement point spacing of:

?????????? FS = ([Upper Frequency - Lower Frequency] / 5) / 101 = ([450 MHz
- 430 MHz] / 5) / 101 =39.6 MHz or roughly every 40 kHz.

This should be adequate to assess the antenna over the entire 70-cm band.

Dave - W?LEV





On Mon, Jul 27, 2020 at 7:46 AM Rudolf Schaffer <
rudolf.schaffer@...> wrote:

Hello,

Can somebody explain to me how to define/calculate the minimum frequency
step versus output frequency for a NanoVNA-H4 ?

Thank you in advance.

Rudi

--
*Dave - W?LEV*
*Just Let Darwin Work*

--
*Dave - W?LEV*
*Just Let Darwin Work*

OneOfEleven,

I was using the latest build of the NanoVNA_WIn 0.1.25 tonight. After I stopped the Scan and tried to enter in a new Start/Stop frequency I got the following "Access violation" error. I had to go to task manger and kill it. I was able to reproduce it. I was trying to enter in a Start frequency of 600MHz and a stop of 800MHz.

Holy cow!

From the instant I opened the well-packaged device today, I was
impressed. Very nice, professional box, fitted molded plastic tray to
hold everything, no missing parts, and a thank-you note from the seller
on eBay.

On first inspection, I see only two things I might change...

(1) I may get some foam and cut it to replace the molded plastic tray. I
think that will provide better protection.

(2) I will be somehow marking the SHORT, OPEN, and LOAD components to
make them easier to identify. Maybe some color-coded Sharpie markers. My
eyes aren't what they once were, and squinting to tell the three apart
was a real pain.

I've only "played" with the device so far using my 6m-70cm MFJ discone
(it has an SMA connector on it) and everything seems pretty
straight-forward. I do need to do a little playing to get the PC
(running Linux Mint 20) to talk to the NanoVNA vie the USB port. I
couldn't get it to connect, but I literally only plugged it in, saw it
come up in the device list as a virtual COM port, and tried to connect
with minicom. No luck on the few minutes I spent trying. Kept getting a
permission denied error despite having myself in the dialout group.I'll
have more time tomorrow to look at that.

As I sat fooling around with the NanoVNA, I seem to recall devices some
40 years ago that could do nearly as much. They were, of course, the
size of a small house and only countries could afford them!

I feel confident in saying that I'm gonna love this gizmo!

Take Care & 73
de KC6UFM
Charles

Software can set any frequency vs 1Hz step

But real frequency - depend from si5351

And yes need see Si5351A datasheet

Xtail is 26MHz
<100 MHz uses PLL = xtail*32 and calculate Multisynth Divider for freq
for 100MHz <= freq < 150MHz Multisynth Divider = 6, and PLL calculated for freq
for 150MHz <= freq < 300MHz Multisynth Divider = 4, and PLL calculated for freq

For higer freq use harmonic (3,5,7,9,11)

So real frequency step calculation very difficult

Software can set any frequency vs 1Hz step

But real frequency - depend from si5351

And yes need see Si5351A datasheet

Xtail is 26MHz
<100 MHz uses PLL = xtail*32 and calculate Multisynth Divider for freq
for 100MHz <= freq < 150MHz Multisynth Divider = 6, and PLL calculated for freq
for 150MHz <= freq < 300MHz Multisynth Divider = 4, and PLL calculated for freq

For higer freq use harmonic (3,5,7,9,11)

So real frequency step calculation very difficult

Rudi, I think I understood your question from your first message, and
your second message did make it more clear.

For others, I think Rudi is asking "what is the smallest amount we can
increment the low-level generated tone? (and this seems to vary with
frequency)". I don't think he's asking "how do I find the step size in
the VNA sweep?"

I believe the answer ought to lie in the datasheet of the Si5351A
clock generator, the main signal source of the NanoVNA


However, I can't find that info in that datasheet right now, and can't
look at control source code effectively. Maybe someone more familiar
with the ins-and-outs of the Si5351 can provide some more insight?

On Mon, Jul 27, 2020 at 12:11 PM David Eckhardt <davearea51a@...> wrote:

Moderators, please,....PLEASE.....place this in the Wiki as this is the
third time I've explained this.

Dave - W ?LEV

On Mon, Jul 27, 2020 at 7:10 PM David Eckhardt <davearea51a@...>
wrote:

Frequency step between measured points has more to do with FREQUENCY SWEEP
WIDTH than absolute frequency, itself. The native NANO's offer 101
measured steps over any specified frequency sweep. So a general formula
which gives the measured point spacing during both for cal and measurement
is:

FS = (Upper Frequency - Lower Frequency) / 101

Where FS = Frequency Step or Frequency Spacing

A couple of examples might illustrate this. Assume one wishes to look at
an antenna over the entire 75/80-meter band, 3.5 to 4.0 MHz. The frequency
spacing or frequency step would then be:

FS = (4.0 MHz - 3.5 MHz) / 101 = 4.95 E-3 MHz or 4.95 kHz.

A measurement, both in cal and measurement, would be made every 4.95 kHz.
If measurement of SWR is the goal, this spacing should be adequate to
assess the fine structure of SWR behavior over the entire 75/80-meter band.

Now, assume one desires to measure an antenna over the entire 70-cm band,
430 to 450 MHz. In this case, 200 kHz spacing between measured points may
not be adequate to assess the fine structure of the SWR behavior over the
entire 70-cm band.

FS = (450 MHz - 430 MHz) / 101 = 1.98 E-3 MHz or roughly
every 200 kHz.

However, using NANOSAVER on a PC or laptop, up to 10 'segments', each of
101 measured points can be made. One need just specify the number of
segments to obtain better resolution.

For example, if one specifies 5 segments over the entire 70-cm band, this
would yield a measurement point spacing of:

FS = ([Upper Frequency - Lower Frequency] / 5) / 101 = ([450 MHz
- 430 MHz] / 5) / 101 =39.6 MHz or roughly every 40 kHz.

This should be adequate to assess the antenna over the entire 70-cm band.

Dave - W?LEV





On Mon, Jul 27, 2020 at 7:46 AM Rudolf Schaffer <
rudolf.schaffer@...> wrote:

Hello,

Can somebody explain to me how to define/calculate the minimum frequency
step versus output frequency for a NanoVNA-H4 ?

Thank you in advance.

Rudi

--
*Dave - W?LEV*
*Just Let Darwin Work*

--
*Dave - W?LEV*
*Just Let Darwin Work*