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NanoVNA Saver software version 0.2.1 TDR operation

 

I have one more question regarding the NanoVNA Saver software

In the TDR display there are two traces, One Red and one blue. I understand
the red but not the blue. Would some please give me an explanation of the
blue trace?

I appreciate any responses.
*Clyde K. Spencer*
 

Clyde,

I had the same question. Maybe the author of the software or someone else will reply.

Roger
 

Reminds me of the rising edge of a square wave pulse, That's how i measure TDR using fast edge pulse from Schmitt trigger inverter and oscilloscope.

Alan W2AEW has good youtube video on it.

Worth a look, hope this helps.

Ray.
 

On Sat, Dec 7, 2019 at 09:06 PM, Clyde Spencer wrote:

In the TDR display there are two traces, One Red and one blue. I understand the red but not the blue. Would some please give me an explanation of the blue trace?
===========================================================================

You can think of the red trace as equivalent to selecting <DISPLAY-TRANSFORM-LOW PASS IMPULSE> on the NanoVNA. Where the peaks are indicative of time and distance.

The blue trace can be thought of as being equivalent to selecting <DISPLAY-TRANSFORM-LOW PASS STEP> on the NanoVNA. Where levels are indicative of impedance variations (see attachment).

- Herb

TDR.jpg

 

Hello Herb,
thank you for answering this! :-) You're absolutely right.

The impedance steps are only shown in one direction, though: Going up. I've
yet to figure out quite *why*, but I am looking into it.

--
Rune / 5Q5R

On Wed, 18 Dec 2019 at 02:17, hwalker <herbwalker2476@...> wrote:

On Sat, Dec 7, 2019 at 09:06 PM, Clyde Spencer wrote:

In the TDR display there are two traces, One Red and one blue. I
understand the red but not the blue. Would some please give me an
explanation of the blue trace?
===========================================================================

You can think of the red trace as equivalent to selecting
<DISPLAY-TRANSFORM-LOW PASS IMPULSE> on the NanoVNA. Where the peaks are
indicative of time and distance.

The blue trace can be thought of as being equivalent to selecting
<DISPLAY-TRANSFORM-LOW PASS STEP> on the NanoVNA. Where levels are
indicative of impedance variations (see attachment).

- Herb
 

Thanks Herb. That will help a lot with my understanding.
*Clyde K. Spencer*

On Wed, Dec 18, 2019 at 3:15 AM Rune Broberg <mihtjel@...> wrote:

Hello Herb,
thank you for answering this! :-) You're absolutely right.

The impedance steps are only shown in one direction, though: Going up. I've
yet to figure out quite *why*, but I am looking into it.

--
Rune / 5Q5R

On Wed, 18 Dec 2019 at 02:17, hwalker <herbwalker2476@...> wrote:

On Sat, Dec 7, 2019 at 09:06 PM, Clyde Spencer wrote:

In the TDR display there are two traces, One Red and one blue. I
understand the red but not the blue. Would some please give me an
explanation of the blue trace?
===========================================================================

You can think of the red trace as equivalent to selecting
<DISPLAY-TRANSFORM-LOW PASS IMPULSE> on the NanoVNA. Where the peaks are
indicative of time and distance.

The blue trace can be thought of as being equivalent to selecting
<DISPLAY-TRANSFORM-LOW PASS STEP> on the NanoVNA. Where levels are
indicative of impedance variations (see attachment).

- Herb
 

Rune,

Yes something is not quite right.

I used the TDR function on the NanoVNA in stand-alone mode and got impedance measurements that made sense to me. I cascaded some 50 ohm (RG58), 75 ohm (RG59) and 93 ohm (RG62) coax and could see the impedance steps.

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