[PD] request assistance with crackles and pops in VFOs driven by modulating accelerometer signals

Darren Kelly darren at webel.com.au
Mon Jul 28 08:25:58 CEST 2008

Thanks Marius,

Volume/amplitude in the case at hand is set globally and fixed across 
all 6 [osc~], so not a suspect.
Am stripping back my system to remove all GUI and all downstream 
processing to isolate the cause

BTW I also have a 3D amplitude modulation mode, and I do use line 
smoothing with effect there.

You've also preempted some future questions about phase modulation,


marius schebella wrote:
> Frank Barknecht wrote:
>> Hallo,
>> hard off hat gesagt: // hard off wrote:
>>> i think it is pretty safe to say that the speed of the oscillator isn't what
>>> is is causing these clicks.
>> Jumps (discontinuities) in a signal are the most nasty cause for
>> clicks, while corners are generally harmless, if they aren't too
>> sharp. Changing the frequency of an oscillator never generates a jump,
>> so it's pretty safe.
> but, if you start to control the *volume* directly from a sensor you can 
> get into trouble if your signal drops to 0 for some milliseconds. also, 
> if your volume becomes very high, you can get distortion and crackles.
> if you do phase modulation you can also get crackles, if you have high 
> jumps in your control signal. I think it is good practice to use line~ 
> for such things.
> marius.
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Darren Kelly, BSc, PhD
phone: +61 (2) 9386 0090
post: PO Box 1816, Bondi Junction, NSW 1355, Australia

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