# Incoherence between oscilloscope and spectrum analyser

There seems to be an incoherence between what I see with my oscilloscope, and what I see with my spectrum analyser.

I have a signal of about 1MHz (if I'm not wrong), 5mV, from an antenna, through RG174 coaxial. It is clearly seen in the following picture of my oscilloscope screen.

Then I connect the same cable to my spectrum analyser, and see nothing like this apparently (see next picture).

Is my spectrum analyser damaged, or am I missing some point ?

OSCILLOSCOPE: AC, 50 ohm, 1ns/div, 5mv/div

SPECTRUM: 50 ohm, start frequency 500kHZ, stop frequency 15MHz, ref level 1mV, attenuation 0db, 10 db/div, set in average mode for clarity, but the same problem subsist in non average mode.

• 1ns/div, and a bit more then 1 division top to top on the waveform, isn't that nearly a GHz? – Unimportant Jan 2 '19 at 12:06
• @Unimportant is right, 1.2ns =~ 833Mhz – Damien Jan 2 '19 at 12:12
• All of these types of questions should have the instrument's model numbers listed – pipe Jan 2 '19 at 13:17

Your oscilloscope shows an oscillation with a frequency in the $$\\frac{1}{1\,\text{ns}}=1\,\text{GHz}\$$ range. (So, yes, you're wrong, that's not a 1 MHz oscillation. I'm jealous of your oscilloscope, by the way.)