Follow up to my previous post...
You can also use the Transform option in the NanoVNA menu to do TDR measurements without connecting to a PC. From the Display menu you select a trace and set it to S11 mode and set it to Linear display. From the Transform menu select Transform On and Low pass impulse. You set the VF (in %) which is for the cable being tested. You need to look this up in the manufacturers spec or measure it using a scope and pulse generator. Be aware that the actual VF can be different by a percent or two from the nominal published spec due to manufacturing tolerances. It also varies between manufacturers for the same cable type. Below are 3 screenshots taken on a NanoVNA-H4 using a VF of 63, 64 and 65 %. The measured VF using the pulse generator/scope method was 64%. Physical cable length was 9.38 meters and using 64% VF NanoVNA calculated 9.327 meters
Roger
Roger Need
