46 lines
1.4 KiB
Python
46 lines
1.4 KiB
Python
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#!/usr/bin/env python3
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import math
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# Adapt these constants to the step attenuator
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BITS_OF_ATTENUATION = 7
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LSB_ATTENUATOR_DB = 0.25
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NUMBER_LINEAR_ATTENUATION_STEPS = 128
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file = open("AMdepth.dat", "w")
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def bindigits(n, bits):
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s = bin(n & int("1"*bits, 2))[2:]
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return ("{0:0>%s}" % (bits)).format(s)
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for i in range(NUMBER_LINEAR_ATTENUATION_STEPS):
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# calculate percentage of attenuation
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percent = float(i) / (NUMBER_LINEAR_ATTENUATION_STEPS - 1)
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# calculate attenuation in dB
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if percent < 1:
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required_dB = -20*math.log10(1 - percent)
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else:
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required_dB = 999
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# round to attenuator steps
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attenuator_dB = round(required_dB / LSB_ATTENUATOR_DB) * LSB_ATTENUATOR_DB
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# convert to digital attenuator value
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attenuator_step = int(attenuator_dB / LSB_ATTENUATOR_DB)
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# constrain
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if attenuator_step < 0:
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attenuator_step = 0
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elif attenuator_step >= pow(2, BITS_OF_ATTENUATION):
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attenuator_step = pow(2, BITS_OF_ATTENUATION) - 1
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output = bindigits(attenuator_step, BITS_OF_ATTENUATION)
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file.write(output+"\n")
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# Calculate actual attenuation
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actual_dB = attenuator_step * LSB_ATTENUATOR_DB
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actual_percent = 1 - pow(10, -actual_dB/20)
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percent_desired = round(percent*100, 2)
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percent_actual = round(actual_percent*100, 2)
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print(f'Target modulation: {percent_desired:.2f}, target dB: {required_dB:.2f}, attenuator setting: {attenuator_step}, achieved dB: {actual_dB}, achieved modulation: {percent_actual:.2f}')
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file.close()
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