47 lines
1.2 KiB
Python
47 lines
1.2 KiB
Python
#!/usr/bin/env python3
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from fractions import Fraction
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from math import floor
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PLL_FREQ = 800.0 * 10**6
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SYMBOL_COUNT = 4
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# http://www.g4jnt.com/wspr_coding_process.pdf
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FREQ_SHIFT = Fraction(12000,8192) # What the fractional fuck?
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# 7.040000 - 7.040200
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BASE_FREQ = 7.040100 * 10**6
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# Maximum c
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MAX_DENOM = 0x0FFFFF
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def main():
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print("struct si5351_params WSPR_SYMBOLS[%d] = {" % SYMBOL_COUNT)
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for i in range(0, SYMBOL_COUNT):
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symbol_freq = Fraction(BASE_FREQ) + Fraction(i) * FREQ_SHIFT
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divider = Fraction(PLL_FREQ) / symbol_freq
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divider = divider.limit_denominator(MAX_DENOM)
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a = floor(divider.numerator / divider.denominator)
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b = divider.numerator % divider.denominator
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c = divider.denominator
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print("\t// %f: %d + %d / %d" % (symbol_freq, a, b, c))
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actual = PLL_FREQ / (a + b/c)
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print("\t// actual: %f" % actual)
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# See https://www.silabs.com/documents/public/application-notes/AN619.pdf
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p1 = 128 * a + floor(128 * b/c) - 512
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p2 = 128 * b - c * floor(128 * b/c)
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p3 = c
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print("\t{%d, %d, %d}," % (p1, p2, p3))
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print("};")
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if __name__ == '__main__':
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main()
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