> First, does the installed TCXO have EFC capability, or not? Jeff apparently
> says not, while Gerhard
> says yes. According to the datasheet, the ABLNO can be an XO only (no
> suffix), or a VCXO ("V"
> suffix). Jeff should be able to tell which, by inspection.
The 16-bit Redpitaya I am looking
I was curious and looked up this Red Pitaya SDR thing (which I had never
heard of - I would have guessed a poisonous snake, without the
internet), and the Abracom TCXO. It's getting a little confusing to keep
up with what's going on.
First, does the installed TCXO have EFC capability, or not?
Unfortunately I don't have any control over the code being run. So it's
got to be fed with the stock Fc. Now that I think of it, there is an
offset in the config file for the application. The typical offsets are
in the 1.xNNN tweaks. But given that range, I'm wondering if I
could pull th
I'm wondering if you could feed your stable 10MHz into the RP FPGA and then
change the FPGA code to use that as the master clock source and adjust the
PLL coefficients.
On Mon, Apr 4, 2022 at 1:45 PM Bob kb8tq wrote:
> Hi
>
> That’s a massive step down from what’s in there now. How much
> that i
Hi
That’s a massive step down from what’s in there now. How much
that impacts you depends a lot on what the end use is. The plots
shown are in the vicinity of 10 MHz. If a straight multiply rule applies,
the performance at 122 MHz would be about 20 db worse. The chip
datasheet:
https://www.sky
I found a commercial programmable GPSDO that looks like it would do the
job. Based on a Si chip.
http://leobodnar.com/files/Informal%20Evaluation%20of%20a%20Leo%20Bodnar%20GPS%20Frequency%20Reference.pdf
Performance is not in the "great" category but I am guessing it would be
in the "good eno
Hi
For a variety of reasons, you will have a loop bandwidth in the > 10 Hz
to < 200 Hz region. The VCXO isn’t great close in and the GPSDO (even
after multiplication) should be as good / better. Even with some work,
the VCXO still will wander around due to temperature. Unless you go
crazy, it al
Jeff one thing to be careful of with slower (lower bandwidth) PLLs and
low VCO gains, is that you end up with loop filter capacitor values
that is microfarads.
This will require film, tantalum etc caps that are not microphonic
sensitive. this needs a bit of space. Ceramic caps make good micro
It looks like the XO version is mounted on the PCB. But there is a VCXO
version which would run about +/- 35 PPM/3.3V typical and that's
(amazingly) available.
Since this EFT is not an on-board capability, at the moment, I'm
thinking to mount the VCXO - and associated goodies to slave it to t
Hi Jeff
I know the device well (Red pittaya 122-16. Great ADC) . Have you
thought of tweaking the supply volts to the on board oscillator (which
isnt too bad at all) to shift it ? that sometimes works.
Crystek have a 122.88 MHz CVHD-950 series VCXO which you can disclipine
and it is VERY goo
On 4/3/22 5:09 PM, Bob kb8tq wrote:
Hi
Does the Abricon have an EFC input? If so, rigging up a PLL to lock
122.88 to 10 MHz is probably the best option.
Bob
And what about moving off the board - so you don't have to chase the
temperature swings.
On Apr 3, 2022, at 7:57 PM, Jeff Blaine
Hi
Does the Abricon have an EFC input? If so, rigging up a PLL to lock
122.88 to 10 MHz is probably the best option.
Bob
> On Apr 3, 2022, at 7:57 PM, Jeff Blaine wrote:
>
> I've got a couple of Red Pitaya 122-16 SDR and want to discipline them to an
> external low noise GPSDO source. Wante
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