Thanks to my SDS2000X Plus I measured the pulses for more than an hour. You can see the statistics in the screen shot. Track 1 (yellow) is from Neo m8n.
15...20 ns may be caused by the distance of the roof antenna to my breadboard. The other neo's may be suffer from reflection and bad signals on my bench.
Hi . I might be wrong but if you are using all 4 channels on your scope there will be a slight difference due to the way the scope
divides the triggers (shares) the trigger levels .
Try to use the alternative mode where you can set the trigger reference to each channel independently .
you will find that c4 will be nearer to the others .
Also did you read my post a few up . There is a Bug in the cyclone chip its self and its not the software .
The input of the cyclone chip is failing on the xtal input . as per the manual the chip has an internal counter that's meant to control the
internal DACs stability and I think (know) these are NOT originals and putting a fast rise pulse instead of the cheap xtal that they used with a slower rise time was also just on the max .
The cyclone can be run with a 100mhz xtal on the other pin .. (forgot the number off hand) .
You can see the distortion from the pins going to the dac inputs Left & right of the cyclone .
The jitter is caused but the second internal timing dac being out of phase by 1.5deg . this was on my chip and varies as much as 5deg.
so there are 2 pulse overlaying It is also visible on the sine as well but harder to see as the rising edge of a sine is much slower than
A square or pulse . So it appears to be jitter but its not because I can see it as low as 2mhz . its hard to see as its within the width
of the scope line . Set the scope to Dots and Persistence 1s all becomes clear.
This maybe just on my FY68 and I got the Big Lemon instead of a small Lemon.
If your interested I found that Ali Express is shipping supper fast I order some stuff and it has arrive within
8 days (working) I could not believe how fast.
My Uni-T UTG962 should be here next week .. I have had it with FY . and I was not going to chance there BS Data sheet again.
I might do a comparison .. but I have a feeling it will be like comparing a
Update attached photo of the overlay that comes ns after . ..
if its not an echo that would mean the jitter is negative in time .. and so far, that's not possible yet
The dots are a tracer that I put to show the neg pulse
The second trace is appearing a few ns after the first trace out of phase . giving the appearance that's it a negative
This also visible from the cyclone output pins .
Have Fun