[time-nuts] AM vs PM noise of signal sources

Magnus Danielson magnus at rubidium.dyndns.org
Sat Jan 6 17:29:42 EST 2018



On 01/06/2018 10:31 PM, Joseph Gwinn wrote:
>> ------------------------------
>>
>> Message: 2
>> Date: Sat, 6 Jan 2018 09:19:31 -0500
>> From: Bob kb8tq <kb8tq at n1k.org>
>> To: Discussion of precise time and frequency measurement
>> 	<time-nuts at febo.com>
>> Subject: Re: [time-nuts] AM vs PM noise of signal sources
>> Message-ID: <DDEF34DD-AD21-44C6-9612-D877881078E5 at n1k.org>
>> Content-Type: text/plain;	charset=utf-8
>>
>> Hi
>>
>> The key point missing is the fact that any real oscillator must have 
>> a limiter
>> in the loop. Otherwise it will “create one” by going over the max 
>> output of this or
>> that amplifier. To the degree that the limiter has issues (limits 
>> poorly) you will get 
>> AM noise.
> 
> Hmm.  Not strictly true.  One can also use an AGC loop, like a wein 
> bridge oscillator.  That said, some kind of softish limiter is commonly 
> used.

Regardless what non-linear mechanism in play, this remains a non-linear
mechanism that achieves the goal. Choose wisely.

Cheers,
Magnus



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