Re: [time-nuts] PLL behavior

At 19-09-2012, you wrote: What we want to know is what happens if the receiver and transmitter can't run at the same time? Obviously, we have less information coming into the system (we see the uplink half the time, so right there, we have a 2:1 hit) and the ground end only sees the transmit

Re: [time-nuts] PLL behavior

In my opinion you fall in the case of disciplining with holdover... this is more like a disciplined oscillator (like a GPSDO) problem than a PLL. On Wed, Sep 19, 2012 at 1:45 AM, Jim Lux jim...@earthlink.net wrote: On 9/18/12 9:48 AM, Raj wrote: If you break the DC control chain of the PLL

Re: [time-nuts] PLL behavior

Hi Commonly this sort of thing is done with a sample and hold in the loop. No reference in / put the loop voltage in hold. You still have a phase drift and need to cope with the phase offset when the reference comes back. Bob On Sep 19, 2012, at 4:08 AM, Azelio Boriani

Re: [time-nuts] PLL behavior

On 09/19/2012 10:08 AM, Azelio Boriani wrote: In my opinion you fall in the case of disciplining with holdover... this is more like a disciplined oscillator (like a GPSDO) problem than a PLL. It is indeed very similar, However, a second of hold-over isn't all that hard, but one has to be

Re: [time-nuts] PLL behavior

On 9/19/12 1:08 AM, Azelio Boriani wrote: In my opinion you fall in the case of disciplining with holdover... this is more like a disciplined oscillator (like a GPSDO) problem than a PLL. Good point... it's like what happens when we come out of holdover.

Re: [time-nuts] PLL behavior

On 9/19/12 4:38 AM, Bob Camp wrote: Hi Commonly this sort of thing is done with a sample and hold in the loop. No reference in / put the loop voltage in hold. You still have a phase drift and need to cope with the phase offset when the reference comes back. or, in our case, we run the

Re: [time-nuts] PLL behavior

On 09/20/2012 01:55 AM, Jim Lux wrote: On 9/19/12 4:38 AM, Bob Camp wrote: Hi Commonly this sort of thing is done with a sample and hold in the loop. No reference in / put the loop voltage in hold. You still have a phase drift and need to cope with the phase offset when the reference comes

[time-nuts] PLL behavior

I'm looking for info on behavior of a PLL (with VCXO) when the reference comes and goes periodically. When the reference is gone, the PLL will flywheel according to whatever the loop filter does. (we can turn off the input to the filter, so we're not trying to track noise).. What I'm

Re: [time-nuts] PLL behavior

won't it depend almost entirely on the charge pump filter? Don Jim Lux I'm looking for info on behavior of a PLL (with VCXO) when the reference comes and goes periodically. When the reference is gone, the PLL will flywheel according to whatever the loop filter does. (we can turn off the input

Re: [time-nuts] PLL behavior

and frequency measurement Subject: [time-nuts] PLL behavior I'm looking for info on behavior of a PLL (with VCXO) when the reference comes and goes periodically. When the reference is gone, the PLL will flywheel according to whatever the loop filter does. (we can turn off the input to the filter, so we're

Re: [time-nuts] PLL behavior

Usually in a regular PLL the missing reference should pull the output at the lowest voltage: as if the input frequency is too high. It helps if the charge pump output can be disabled when the reference stops: in this case the output voltage will go down following the droop of the

Re: [time-nuts] PLL behavior

If you break the DC control chain of the PLL with a A2D and a controller and back with a D2A .. you would program the control with any kind of behavior you want. Just a thought! Raj, vu2zap At 18-09-2012, you wrote: I'm looking for info on behavior of a PLL (with VCXO) when the reference comes

Re: [time-nuts] PLL behavior

On 9/18/12 8:39 AM, Don Latham wrote: won't it depend almost entirely on the charge pump filter? Classic PLL with a mixer, not with a Phase Frequency Detector and charge pump.. But yes, it depends in large part on the loop filter, but also on the behavior of the oscillator.. (i.e. where

Re: [time-nuts] PLL behavior

On 09/18/2012 05:28 PM, Jim Lux wrote: I'm looking for info on behavior of a PLL (with VCXO) when the reference comes and goes periodically. When the reference is gone, the PLL will flywheel according to whatever the loop filter does. (we can turn off the input to the filter, so we're not trying

Re: [time-nuts] PLL behavior

On 09/18/2012 06:15 PM, Bob Camp wrote: Hi Gardner in Phaselock Techniques has figure 4.8 that is a pretty good starting point. In general, it's a really good book to read. Gardner covers this field well, and even if some of the stuff I needed wasn't in there, it was an excellent

Re: [time-nuts] PLL behavior

On 9/18/12 1:49 PM, Magnus Danielson wrote: On 09/18/2012 05:28 PM, Jim Lux wrote: I'm looking for info on behavior of a PLL (with VCXO) when the reference comes and goes periodically. When the reference is gone, the PLL will flywheel according to whatever the loop filter does. (we can turn off

Re: [time-nuts] PLL behavior

On 9/18/12 9:48 AM, Raj wrote: If you break the DC control chain of the PLL with a A2D and a controller and back with a D2A .. you would program the control with any kind of behavior you want. Just a thought! That is exactly what we do... the PLL is actually implemented digitally (DAC