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Someone check my math, please? I'm using
a program called "Cool Edit Pro" which can give me very accurate readings of tone levels coming from my FT-857D into my soundcard. I'm trying to develop my own way of evaluating my new vertical's (Cushcraft R7000) performance compared to my dipole. I'm starting by tuning 700 hz off of WWV's 10 mhz carrier and recording the tone I get in USB mode with my AGC off. I switched antennas during the recording and took 2 samples: 1st example Cushcraft R7000 Noise @ 2k = -39.27db Signal @ .7k = -7.26db S/N differance = 32.01db S/n Ratio = 14.662 2nd example 40m ladderline fed dipole Noise @ 2k = -30.11db Signal @ .7k = -8.864db S/N differance = 21.246db S/n Ratio = 10.622 For some reason my program gives me the back- ground and signal levels in negative DB. I used this formula to come up with a S/N ratio: S/N = 20 log10(-dbs/-dbn) Can someone check my math? My guess is that my R7000 is better at WWV for this test. -- 73's es gd dx de Ken KGØWX Grid EM17ip, Flying Pigs #1055, Digital On Six #350, List Owner, Yahoo! E-groups: VX-2R & FT-857 |
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