Re: [time-nuts] Modern signal generators

2018-12-11 Thread Bob kb8tq
Hi As I said, just how rational using these parts in a radio …. not at all clear to me. Back when I went to school, stuff that was this noisy was not in the “greatest” category. That was a *very* long time ago. Oddly enough best performance synthesizers have gotten better. (as the posted

Re: [time-nuts] Modern signal generators

2018-12-11 Thread Ulrich Rohde via time-nuts
yes    In a message dated 12/11/2018 5:29:23 PM Eastern Standard Time, k8yumdoo...@gmail.com writes:   Ulrich, Is it OK for us to forward the URL for your "Noise" paper to others outside the time-nuts group? Thanks, Dana K8YUM On Tue, Dec 11, 2018 at 9:24 AM Ulrich Rohde via time-nuts <

Re: [time-nuts] Modern signal generators

2018-12-11 Thread Bob Albert via time-nuts
You can solve the spur problem by using the signal to lock an oscillator.  Some added phase noise but the oscillator can be very pure otherwise.  Many years ago I wrote an unsuccessful proposal for a synthesizer using that idea, since the spectral purity spec was too tight to use synthesizer

Re: [time-nuts] Modern signal generators

2018-12-11 Thread Dana Whitlow
Ulrich, Is it OK for us to forward the URL for your "Noise" paper to others outside the time-nuts group? Thanks, Dana K8YUM On Tue, Dec 11, 2018 at 9:24 AM Ulrich Rohde via time-nuts < time-nuts@lists.febo.com> wrote: > >

Re: [time-nuts] Modern signal generators

2018-12-11 Thread Gerhard Hoffmann
Am 11.12.18 um 20:30 schrieb jimlux: On 12/11/18 10:23 AM, Richard (Rick) Karlquist wrote: On 12/11/2018 9:13 AM, djl wrote: Rick: I've spent some time with the dds blocks. We found them to generate lots of low level spurs, making lots of "birdies" when used as local oscillators in

Re: [time-nuts] Modern signal generators

2018-12-11 Thread Richard (Rick) Karlquist
On 12/11/2018 11:30 AM, jimlux wrote: Most of the Silabs parts are available in an  I2C programmable version rather than the factory programmed flavor. That's for clarifying that. The web site is hard to navigate. I see that the phase noise is not even close to an HP 8662 and the VCXO

Re: [time-nuts] Modern signal generators

2018-12-11 Thread jimlux
On 12/11/18 10:23 AM, Richard (Rick) Karlquist wrote: On 12/11/2018 9:13 AM, djl wrote: Rick: I've spent some time with the dds blocks. We found them to generate lots of low level spurs, making lots of "birdies" when used as local oscillators in receivers. We had better results using:

Re: [time-nuts] Modern signal generators

2018-12-11 Thread Bob kb8tq
Hi There are I2C versions that can be set to “any frequency”. That’s what people are using for synthesizers in radios. Again - one can debate just how good an idea this all is. Bob > On Dec 11, 2018, at 1:23 PM, Richard (Rick) Karlquist > wrote: > > > > On 12/11/2018 9:13 AM, djl

Re: [time-nuts] Modern signal generators

2018-12-11 Thread Richard (Rick) Karlquist
On 12/11/2018 9:13 AM, djl wrote: Rick: I've spent some time with the dds blocks. We found them to generate lots of low level spurs, making lots of "birdies" when used as local oscillators in receivers. We had better results using: https://www.silabs.com/products/timing/oscillators. I

Re: [time-nuts] Modern signal generators

2018-12-11 Thread Bob kb8tq
Hi I don’t know if it’s expected / surprising / alarming, but a lot of pretty well respected amateur transceivers have the SiLabs parts buried in the heart of their “synthesizer” section. Cost (obviously) is an issue in any design. That said, they seem to be “good enough” that the designers

Re: [time-nuts] Modern signal generators

2018-12-11 Thread djl
Rick: I've spent some time with the dds blocks. We found them to generate lots of low level spurs, making lots of "birdies" when used as local oscillators in receivers. We had better results using: https://www.silabs.com/products/timing/oscillators. These may be used with GPSDO clocks for

Re: [time-nuts] Noise in linear and non-linear circuits and systems

2018-12-11 Thread Richard (Rick) Karlquist
This will be interesting to read. Around 15 years ago, when I was working for Agilent, OEO was the "next big thing" and they invested a lot of resources in it. Then they abandoned it. I can't remember exactly what the reason was. Rick On 12/11/2018 7:17 AM, Ulrich Rohde via time-nuts wrote:

Re: [time-nuts] Modern signal generators

2018-12-11 Thread Richard (Rick) Karlquist
Another gold mine. I used to work for Agilent/Keysight so I am very familiar with their signal generators. It will be interesting to see the R viewpoint. The DDS stuff is very valuable. I have been considering using a DDS eval board with a low noise 1 GHZ reference to make a poor man's signal