Re: My_Tuning_Constant
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If you take 2^32 and divide it by 125000000, you get 34.359738368, which we will call the "clock factor". The frequency you want is 7.061.8. So what we want to find is what tuning word will "make" 7.062 look like 7.061.8. If the clock was perfect, we'd have: Fout = (TW x CLKIN) / 2^32 7061.800 = (TW * 125000) / 2^32 Simplifying terms: 7061.800 = TW * 34.359738368 Therefore, the "perfect" tuning word for a clock that is exactly 125MHz is:? TW = 7061800 x?34.359738368 is your tuning word, or? TW = 242648472.354816 Unfortunately, your crystal sees Fout at 7062000, not 7061800. So, what clock factor will result in us reading 7061.800 TW = Fout ?x CLKIN / 2^32 242648472.354816 =?7061800 * ClockFactor ? Therefore: ClockFactor =?242648472.354816 / 7062000? ClockFactor = 34.36071148359002 which is your TUNINGCONSTANT. It won't be perfect, but it should be better. Jack From: "wp3dx@... [SoftwareControlledHamRadio]" To: SoftwareControlledHamRadio@... Sent: Monday, May 2, 2016 11:02 AM Subject: [SoftwareControlledHamRadio] My_Tuning_Constant Hi!
How did you find the new tuning constant ? The screen on my 49er reads 7.062.0 versus my frequency counter showing 7.061.8. I'm a bit stuck finding my new tuning constant. The formula shows FOUT =(TW x CLKIN) / 4294967296 TW= (FOUT x 2^32) /125000000 TW = (7061800 x 4294967296) / 125000000 TW = 242641600.4071424 This is were I get lost,? 242641600.4071424 = FOUT x 34.359738368 ? I currently have the default? 34.35910479585483 as my tuning constant. Any help on how to get my tuning constant or where I can learn more on this subject would be greatly appreciated. Regards Norbert |
jjpurdum