Spectrum analyser waveform capturing

Sir

i captured the spectrum analyser window in matlab

but the y axis looks not correct it is a double sided values where as in spectrum minus values are there and the scale is dbm.

how to caputre the waveform correctly ? am using FORM:REAL 32, Trace:Trace? and binblocked (mx,'int32);

the data is comming as

-1.00000

-2.14573

1.00000

2.00000

where spectrum value is -80dBm