Thermal drift in radioastronomy

Hi, I am trying to record radioastronomy noise with skypipe pro chart
recorder.
I am using a 13K C-band LNB and a smal dish, and using a totalpower setup.
I have heavy variastions in signal level due to thermal drift.

So I wonder, if I use two C-band LNB's, the first one as before on skypipe
recorder channel one and the second pointing down towards earth so that it
will only pick up ground noise on recorder channel 2.
They both will drift the same way at the same times (both are identical
make).
Could I by means of program skypipe software subtract ch2 from ch 1 and let
the result be displayed on ch3?
My thinking is then i will have a drift free recording with out temp
variastions (they should cansel one anoughter.
Allmost like taking a darkframe and subtracting if from at from the rest of
the images like we do when making photoimages of deep space.
Does this seem likly to do? Or am I off track some how?
Any thoughts about this will be welcome to me!

Jan Lustrup
Norway