On Wed, Dec 1, 2021 at 01:27 AM, DiSlord wrote:
CABLE - this cable measure util, need calibrate nanoVNA and connect cable
(there should be nothing on the other end of the cable)
NanoVNA measure cable wave impedance, length (need setup correct velocity
factor) and cable lost in marker position (this just S11 logmag / 2)
wave impedance measured - search first frequency then it rotate on 180 degree,
divide this frequency on 2 and measure reactance at this point.
1.2.5.3 CABLE S11
Choose a frequency range such that the cable length is ~1/4 of the wavelength in the middle of the range. This feature uses velocity of propagation. It automatically measures the length, characteristic impedance, and loss at the point of the active marker. Choose the range so that the Smith trace crosses near R=0 between ¡Àj. The shorter the cable, the higher the frequency range needed for analysis. Example: Assuming the signal must go out and back on a 10 m length of coax, multiply c * VoP and divide by 4X the coax length. (3e8 m/s * 0.67) / 40m ~= 5 MHz. A range of 5-15 MHz would cover this.
This is what I am attempting to do with the user manual. There are many other ways to use this feature, but this addresses the basic requirements. Theoretically, any licensed ham will be able to adapt this description to other activities.
--
~R~
72/73 de Rich NE1EE
The Dusty Key
On the banks of the Piscataqua
Rich NE1EE