Ok, a couple of people sent me captures. I'll edit and append to this post with more. And I'll edit the post to get the images in-line with the comments (haven't done that before...)
A note on the plots: It should be obvious x is frequency. Y is in dB of the raw ADC units (0 to 255). It's not calibrated to the vertical setting since we're only interested in the shape of the waveform and relative db of the peaks.
From pa3bca:
Waveform 1: 10 MHz from a Rigol DG1032Z generator
Waveform 2: 10 MHz from a GPS disciplined OCXO
Firmware version is 00.02.03.SP5, no idea abt the HW board version.
This 1074Z has NO 5us trigger issues!
Looks pretty clean to me too.
Waveform 1:
Waveform 2:
From RoTTe:
The generator is a FE5680B, the 20MHz have some DC bias (2.30Vpp), and the 60MHz is a little attenuated (2.8Vpp).
Model: DS1054Z
Software version: 00.04.02.SP3
Board Version: 0.1.1
So, this one's PLL is not locked, but the instability isn't too severe. Note the 100kHz spacing originating from the PFD, which is what we should find in all the scopes running this version.
20MHz sine (stopped):
60MHz sine (stopped):
From nuno:
Scope: DS1104Z-S , sw 00.04.00
16.wfm: 1 channel capture @ 1Gsps, source is 16.000 MHz crystal on AVR microcontroller, measured across the crystal's pins with the GND spring, channel with AC coupling (original signal has an offset)
25.wfm: 1 channel capture @ 1Gsps, source is oscilloscope's own function gen, sine @ 25MHz 1Vpp
This 1104 looks fine to me. The 16.wfm is a little noisy, but the main carrier does not appear to have any modulation in it. 25.wfm is also good, but it's probably using the same clock source internally for sampling and generation, and could have synchronized away any issues. But since 16.wfm is ok, I think it's ok.
16.wfm:
25.wfm:
From Bud:
DS2072A Hardware v2.0, Firmware 00.03.00.SP1
F=280MHz via a 280MHz bandpass filter to reduce source spurious/harmonics
Source 1: HP 8753C VNA (low phase noise)
Source 2: HP 8656B signal gen
Scope memory depth 1.4Mpts
Sampling frequency 2Gsa/S
Sergey's tests before showed anomalies dc vs ac coupling, so just in case I made two waveforms from 8753C
The 280MHz frequency choice was just because I have a good bandpass filter for that frequency. But it is also close to the 300MHz scope bandwidth limit (in fact I measured 400MHz 3dB bandwidth on that scope).
These look like there might be a tiny bit of 200kHz modulation in the clock. But I'm also noticing the close-ups of the main carrier show that there is a slight difference in the offset between the two sources which may imply it's in the source.
I'm undecided on this one.
Bud: Being a precision RF guy, you probably know these sources very well. Your comments? Have you looked at your Rigol's internal clock with a swept analyzer?
8656B_280MHz_0dBm_Dc_coupling:
8753C_280MHz_0dBm_ac_coupling:
8753C_280MHz_0dBm_dc_coupling:
8656B_280MHz_0dBm_Dc_coupling_closeup:
8753C_280MHz_0dBm_dc_coupling_closeup:
8753C_280MHz_0dBm_ac_coupling_closeup:
From leppie:
DS1054Z - beta FW, mine like poda-pie's is very bad after beta FW, jitter goes away in offset intervals of ~33us (was 10us before beta FW)
24Mhz crystal, no trigger offset
Only one capture provided. I'm not sure without comparing against a second source.
Just kidding. Wow, what can I say. It's not even centered on 24MHz. You win the award for best stegosaurus.
In measuring those modulation spikes they are 35.8kHz apart (almost 1/33us), but I'll bet they drift so the jitter offset is going to drift too.
24.wfm:
From poida_pie:
signal source: Rigol DG1022, 20MHz sine, 1v p/p into 50 ohm terminated BNC at scope.
Vertical gain 0.2V/div
DS1054Z sample rate: 1G
DS2072 sample rate: 2G
We have a runner up for instability. I don't think it's quite as bad as leppie's because the modulation peaks are a little less broad. But we're talking about the finer points of bad.
There is a different modulation frequency of 42.7kHz on this DS1054Z. This is not surprising since when the PLL isn't locked variations in the loop filter components and the PLL itself are in play. Temperature is going to matter too.
The DS2072 looks like fine with maybe a little more phase noise than the others, but that could be the source.
20Mhz_DS1054Z:
20Mhz_DS2072:
From sergey:
Oscilloscope is DS2072
Rigol DG1022A source
Set up to 5MHz, HighZ. This all together with highZ input of the scope and genuine rigol coax cable shouldn't give any reflection issues.
As with the other DS2k series, the sample clock look fine to me. 5MHz is a little low for seeing perturbations in the clock (recall that for each decade away from the sampling clock we lose 20dB), but anything major will certainly show up.
Sergey sent me a 1.4Mpt and a 56Mpt capture of the 5MHz signal. The 56Mpt capture provides resolution down to about 36Hz (and also took about a minute to process). It's overkill for what we're looking for, but I thought it was interesting to include so people can observe how increasing the number of waveform sample points used in an FFT can dramatically improve the amount of detail you can see.
10us_1.4Mpts_2MHz_span (about the same span we've been using on the others):
10us_1.4Mpts_120kHz_span:
10us_56Mpts_120kHz_span: