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DELAY has to be understood here as "Group Delay". It highlights the transit time of a signal through a DUT (Device Under Test) versus frequency. It is usually currently related to transmission measurement (s21).

Its calculation is the mathematical derivative of the phase with respect to frequency. If there is PHASE distortion, i.e. a breakout on its monotonous variation according to frequency, the group delay remains no more at a constant value.

Group Delay = -(1/360)*(phi2-phi1)/(f2-f1)

For the NanoVNA, (f2-f1) is the elementary frequency step (Hz) between two measurement points, which depends of FSTART, FSTOP and choosen number of measurements points (101 ... 401). It means that (phi2-phi1) is the phase value difference (Degrees), between two neighboring measurements points.

Group Delay is a relevant parameter, when for example you consider a non-sinusoidal signal passing through a filter. If Group Delay is not constant, the shape of the signal will be altered at the output of the device, due to a possible time shift on its harmonic components.

A last word about Group Delay when related to reflection measurement (s11). It's less intuitive, but we can consider this example with a DUT which is an opened coaxial cable (length 2 meters), one of my favorite educative DUT ! Here the Group Delay (around 18,2 ns, see snapshot) highlights the total transit time at Port 0 level, i.e. a round trip of the signal through the coaxial cable. From it you can calculate the electrical length of the coaxial cable, and if you know the velocity factor, its physical length.

Round trip : 300.000.000 (m/s) * 18,2 E-09 = 5,46 m
Electrical length : 5,46 / 2 = 2,73 m
Physical length : 2,73 * 0,73 = 1,99 m 0,73 is the velocity factor value for RG58A/U cable type

As advanced firmware for NanoVNA now includes automatic calculation for coaxial length (thanks to DiSlord) based on Smith chart, the previous method is not necessary the most accurate or relevant. It is just for an explanation of Group Delay in s11 measurement context.

Jean-Roger / F6EGK

Mario,
The 'classic' includes all NanoVNA models from the very 1st model (and clone) up to and including the H (but not the H4).
I'm running the latest 1.0.69 on my classic with no issues.

Which variant (if any) works with the Classic (Pre-H) VNA. This never seems completely clear from the descriptions - I think because there's no consistent way to describe the original unit.

thanks,

M

The wiki page Home has been updated by Larry Rothman <nlroth@...>.

Reason: Added document link to post on measured parameter definitions

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Joe,
Many of the questions you keep asking are in both the forum wiki and the various user guides in the forum files section.?
Please read the user guides.? start with the Absolute Beginners Guide.?


On Sun., 12 Sep. 2021 at 11:48 a.m., Joe WB9SBD<nss@...> wrote: Ok,
Good,

Now if I was to save to Save-1, how does one use save 1 in the future?

Joe WB9SBD

I have gotten some great input about this, but it remains a problem that such outputs as “real” and “imaginary” come with no documentation as to what they are. I have written a 1 pager that some moderator may want to review, edit, and add to the wiki. I don’t even know how to attach things to this group in a way that they carry through, so I will cut and paste it:

NanoVNA Output Variables



LOGMAG – For S11 measurements this is the Return Loss and is measured in dB. For passive networks it will always be negative. For S21 measurements this is the INSERTION LOSS in dB.

SWR – The Standing Wave Ratio, often also called Voltage Standing Wave Ratio (VSWR), is often used for measuring antennas. For S11 measurements an SWR of 1 is a perfect match (zero reflected power). The figure is normally quoted as a ratio (e.g. 2:1). An antenna SWR of 3:1 would normally be considered good, while lower than 2:1 would be excellent. Use of SWR for S21 measurements may be meaningless.

LINEAR – Same as LOGMAG, but expressed as a ratio. For S11; 1 would be 100% power reflected, 0 would be 0% power reflected.

PHASE – The relative phase difference or delay between the signal source voltage and received signal voltage.

SMITH – This is a chart of resistance and reactance. The (real) resistance is shown on the horizontal center line, with 0 ohms (a short circuit) at the 9 o’clock position and infinite ohms (an open circuit) at the 3 o’clock position. The center point indicates whatever normalized resistance is being used, but for the nanoVNA it is always 50 ohms. Any point above the horizontal center line indicates positive (i.e. inductive) reactance and any point below indicates negative or capacitive reactance. This output reports the capacitance (C) or inductance (L) at the marker position. Note that a transmission Smith chart, on CH1, may be meaningless.

POLAR – Same trace as the SMITH chart, but provides the voltage reflection coefficient as a complex number, as shown on marker readings. On this chart, the 9 o’clock position represents -1+j0, the 3 o’clock position is 1+j0, and the 12 and 6 o’clock positions are 0+j1 and 0-j1 respectively.

DELAY – ???

REAL – This is simply the real part of the reflection coefficient gamma (i.e. the number on the Polar chart).

IMAGINARY – This is the imaginary part of the reflection coeff. gamma (i.e. the number on the Polar chart).

RESISTANCE – This is the resistance encountered in the DUT, as shown on the Smith chart.

REACTANCE – This is the reactance of the DUT, as shown on the Smith chart.

On Sun, Sep 12, 2021 at 08:19 AM, Qrp Gaijin wrote:

I recently joined the club and bought a NanoVNA, which I think is a "classic"
version clone (no case, no shielding). It is currently running NanoVNA-H
firmware 0.4.5-1-efbbceca. My current goal is to measure crystal parameters
for building crystal filters.

I think you will find this video by W2AEW on measuring crystals with a NanoVNA interesting. His videos are technically accurate, easy to follow and quite informative. He uses an earlier version of DiSlord firmware and compares several methods of measurement.



Roger

So far what I have is

CONFIG, SAVE saves:
Touch screen cal
Grid color
Trace color
Flip display

CALIBRATE, SAVE# saves (per #):
Frequency range
Sweep points
Calibration
Error Correction
Trace settings
Marker settings
Domain mode settings
Electrical delay

On Sun, Sep 12, 2021 at 08:13 AM, Joe WB9SBD wrote:

When you do a calibrate.
Open
Short
Load,

And then Save, I usually save 1

What is this saving actually doing? Can you retrieve this Save for
future use?

Joe,

I suggest you read the Absolute Beginners Guide to the NanoVNA. Your question and many others that new users ask are described in detail. It is in the files section of this group.

/g/nanovna-users/files/Absolute%20Beginner%20Guide%20to%20The%20NanoVNA/Absolute_Beginner_Guide_NanoVNA_v1_6.pdf

Roger

Same answer to both questions: yes, saving in 0, 1, 2, 3, or 4 lets you open that calibration any time using the RECALL command. And if you set up all the traces you want during a calibration, and then save, those traces will be the ones that come up when you recall that memory. I chose to divide my range of interest into 4 sub-ranges, and calibrate each in memories 1 - 4.

Thanks!
Now does this recall all the stuff including the calibration etc.?

Joe WB9SBD

Recall menu
Allow recall saved calibration slot

I add this feature for all H/H4/V2/V2Plus in my last v1.0.69
See Marker->Measure menu

Unpack and use firmware for your device variant
/g/nanovna-users/files/Dislord%27s%20Nanovna%20-H%20Firmware/NanoVNA%20v1.0.69%20fw%20pack.zip

Joe,

The prior save-1 action will keep 1 as you set it up. That is all cals, freq range, display etc... But, if you decide that you do not like some item in 1... as long as you do not significantly change the freq range... no issue. However, if for some reason you wish to change details that impact CAL. Then you will have to recal.

Ok,
Good,

Now if I was to save to Save-1, how does one use save 1 in the future?

Joe WB9SBD

Save to location zero everything like cal and displays will boot to all saved items. You can do the same with all other locations. But, requires a recall after turned on.

Hi Joe , you have to save 0 .
When you turn on the nanovna , by default the register number 0 is recalled.
Maurizio Iz1MDJ

I recently joined the club and bought a NanoVNA, which I think is a "classic" version clone (no case, no shielding). It is currently running NanoVNA-H firmware 0.4.5-1-efbbceca. My current goal is to measure crystal parameters for building crystal filters.

For NanoVNA-V2, there is a special "ojisan" firmware that has easy-to-use menu options for measuring crystal parameters; see , section "LC, Crystal series resonant measurement". Through a series of measurements, the firmware then computes and displays the crystal parameters as shown in the below sample:

Fs= 7.997345 MHz
Fp= 8.0130 MHz
Ls= 13.5 mH
Cs= 29.3 fF
Cp= 7.47 pF
Rs= 17.5 Ω
Q= 38791

Unfortunately, this firmware does not work on my classic NanoVNA.

Is there a similar firmware for the classic NanoVNA or NanoVNA-H that allows easy measurement of crystal parameters?

When you do a calibrate.
Open
Short
Load,

And then Save, I usually save 1

What is this saving actually doing? Can you retrieve this Save for future use?

Speaking of a save.

say you make changes to the traces, One I never ever use, so I have to shut it off every time.? and one I have to change from port 2 to 1 and then make it be a SWR trace.

Can this be saved and made like a new default? So i don't have to make all those changes every time I want to make a SWR measurement?

Joe WB9SBD

Interesting how a little DX35 with its small output tube would provide a similar set of L taps
for the pi net as a pair of big bottle 3-500 Z's. Apparently the ratio of plate V to plate I and the
fact that 2 tubes in the SB220 are in parallel provide nearly the same plate Z.