Hi Bob and all: This is interesting, because I suspect this frequency source is for an Ettus Research USRP. A little further downtimeline I will be faced with this problem as well. The SDR is designed already and requires a 64 MHz clock, especially as this clock is used for the microwave transmit and receive front ends. I had planned a synthesizer filtered... The oscillator that is in the USRP that I have is good only to about 1 part in 10^8 or so for accuracy, better in stability. maybe the existing osc. can be injection locked, or temp controlled in place. Don
Bob Camp > Hi > > With most SDR's a spur on the clock creates a spur in the radio. No matter > how you do your multiply, you will wind up with some sub-harmonics running > around. Much better / easier / quicker to start at 64 or 65 MHz. > > Bob > > > On Feb 9, 2010, at 8:32 PM, Bruce Griffiths wrote: > >> Thats not very useful when you want the 4th harmonic as its amplitude is >> zero fro a 25% duty cycle. >> Using a duty cycle of 1/8, 3/8 or 5/8 will maximise the amplitude of the >> 4th harmonic. >> >> see: >> http://www.wenzel.com/pdffiles1/pdfs/choose.pdf >> >> Bruce >> >> Max Robinson wrote: >>> If you start with a square wave odd order is all you can get but if you >>> start with a pulse with a 25% duty cycle you can get even order. It's >>> best to optimize the pulse width for the harmonic you want. >>> >>> Regards. >>> >>> Max. K 4 O D S. >>> >>> Email: m...@maxsmusicplace.com >>> >>> Transistor site http://www.funwithtransistors.net >>> Vacuum tube site: http://www.funwithtubes.net >>> Music site: http://www.maxsmusicplace.com >>> >>> To subscribe to the fun with transistors group send an email to. >>> funwithtransistors-subscr...@yahoogroups.com >>> >>> To subscribe to the fun with tubes group send an email to, >>> funwithtubes-subscr...@yahoogroups.com >>> >>> ----- Original Message ----- From: "Nick Foster" >>> <bistro...@hotmail.com> >>> To: <time-nuts@febo.com> >>> Sent: Tuesday, February 09, 2010 6:35 PM >>> Subject: Re: [time-nuts] Low phase noise VCO >>> >>> >>>> >>>>> From: b...@iaxs.net >>>>> To: time-nuts@febo.com >>>>> Date: Tue, 9 Feb 2010 18:24:39 -0600 >>>>> Subject: Re: [time-nuts] Low phase noise VCO >>>>> >>>>> Which leads me to ask a novice question: >>>>> >>>>> Why not pull a 16 MHz crystal and multiply to 64 MHz? >>>>> >>>>> If you count down from 64 to 10 MHz, isn't the multiplication inside >>>>> the >>>>> PLL? >>>>> >>>>> Perhaps the noise is multiplied by 4, but would it work for the >>>>> intended >>>>> purpose? >>>>> >>>>> Bill Hawkins >>>> >>>> Can you do x4 multipliers? I thought odd-order harmonics were usually >>>> used for multipliers. I'd be happy to be wrong! >>>> >>>> Nick >>>> >> >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
