vswr and rp traslate

vswr.py

## fileencoding=gbk ##
from math import *
import sys

def vswr_to_rp(vswr):
    '''Translate VSWR to Return Power'''
    rl=20*log10((vswr+1)/(vswr-1))
    rp=pout/pow(10,rl/10)
    return rp

def line_to_db(val):
    '''Translate linear value to dB'''
    return 10*log10(val)

if __name__ == '__main__':
	print(sys.argv)
	# Output power & VSWR
	pout=10
	vswr=(1.3, 1.6)
	preal=[0,0]

	# Calc return power
	preal[0] = pout - vswr_to_rp(vswr[0])
	preal[1] = pout - vswr_to_rp(vswr[1])

	# check delta
	dp=line_to_db(preal[0]/preal[1])
	dp=round(dp,2)
	print "输出功率:",pout,"W"
	print "功率差异:",dp,"dB"