HP 8590 E & L Series Spectrum Analyzers and HP 8591C Cable TV ...

840 !calculate the percent distortion:
850 Prcnt,distort=SQR(Summ,sqr)/Fund~amptd,v*lOO
860 GOSUB Clearscreen !clear the alpha screen:
870 !Output,data:
880 !send data to the screen of the computer:
890 OUTPUT CRT USING "7/,lX,K"; "HARMONIC DISTORTION RESULTS"
900 OUTPUT CRT USING "llX,K,DDDD.D,K";"FREQ = ";Fundamental;" MHz"
910 OUTPUT CRT USING "llX,K,DDDD.D,K";"AMP = ";Fund-amptd-dbm;" dBm"
920 OUTPUT CRT USING "llX,K,DDD.D,K";"2nd HARMONIC = -";Harmonic_dbc(2);" dBc"
930 OUTPUT CRT USING ',llX,K,DDD.D,K";"3rd HARMONIC = -";Harmonic,dbc(3);" dBc"
940 FOR I=4 TO Max-harmonic
950 OUTPUT CRT USING "lOX,DD,K,DDD.D,K";I;"th HARMONIC = -";Harmonic,dbc(I) dBc"
960 NEXT I
970 OUTPUT CRT USING "llX,K,DDD.D,K";"TOTAL DISTORTION = ";Prcnt,distort;" %"
980 !
990 LOCAL 7
1000 STOP
1010 !
1020 Clearscreen: !alpha clear subroutine
1030 !the statement below presses the "CLR SCR" key on
1040 !the keyboard:
1050 OUTPUT KBD USING "# 3" B"*255 75
1060 RETURN
1070 END
The program prompts the user to connect a source to the spectrum analyzer INPUT and enter
the source frequency. It sets the spectrum analyzer center frequency to the value of the
source, or fundamental, frequency. It measures and records the frequency and amplitude of
the fundamental, then measures and records the amplitude of the second, third, and fourth
harmonics. These values are used to compute percent of harmonic distortion. The result of the
harmonic distortion percentage computation, plus harmonic amplitudes in dBc (decibels relative
to the carrier), are displayed on the computer display. Extensive annotation has been added
(after the exclamation points) to help clarify the program.
If necessary, change the number of harmonics in line 80.
Programming Topics 3-17