kalibrate ppm

I have been playing with the ‘kalibrate’ program. At the end it says: “Average absolute error: -18.056”.
What should I put on the dump1090 command line?
–ppm -18 (note the minus sign)
–ppm 18 (note no minus sign)
I know the error is neglectable and will drift, but I am just curious. (There are dongles with a temperature compensated oscillator)

1 Like

You need the minus sign.