Graphical summary of all relevant spurs and spur-free zones
show( produces a spur graph of the
hif. The spur graph contains:
Vertical green bands, representing spur-free zones.
Horizontal colored bands, representing spurious regions.
Spur-free zones are ranges of possible IF center frequencies that are free from
intermodulation distortion. Depending on the configuration of the mixers in
hif, spur-free zones may not appear. Clicking a spur-free
zone produces a tool tip, which displays information about the spur-free zone:
Min IFCF — The minimum possible IF center frequency fIF for the corresponding spur-free zone.
Max IFCF — The maximum IF center frequency fIF for the corresponding spur-free zone.
Spurious regions contain intermodulation products from at least one mixer. The color of a spur on the spur graph indicates which mixer generates the spur, according to the legend on the spur graph. Clicking a spurious region produces a tool tip, which displays information about the spur:
RF Center Freq — The RF center frequency fRF of the mixer that generates the spur
M, N — The coefficients in the equation |MfRF – N(fRF ± fIF)| (down-conversion) or the equation |MfIF + N(fRF ± fIF)|. Injection type of the receiver determines the sign in the equations. These coefficients refer to the particular mixing product that generates the spurious region.
Spur Level — The difference in magnitude between a signal at 0 dBc and the spur. If you set
hif.SpurLevelto a number greater than this value, then
hifdoes not report the region as spurious.
Freq Range — The frequency range of the spurious region. Choosing an IF center frequency in this range causes interference with the intermodulation product corresponding to the spur.
Show Spur-Free Zones
Set up the object
h = OpenIF('IFLocation','MixerOutput');
Add two mixers to the system
IMT1 = [99 0 21 17 26; 11 0 29 29 63; ... 60 48 70 65 41; 90 89 74 68 87; 99 99 95 99 99]; addMixer(h,IMT1,2400e6,100e6,'low',50e6)
IMT2 = [99 0 9 12 15; 20 0 26 31 48; ... 55 70 51 70 53; 85 90 60 70 94; 96 95 94 93 92]; addMixer(h,IMT2,3700e6,150e6,'high',50e6)
Check for spur-free zones
hif — OpenIF object
OpenIF object, specified as an object handle.
Introduced in R2011b