I have not looked inside any of those devices. Do they use a standard motherboard? If so a motherboard swap could get a serious improvement in performance.
I have an older HP time interval analyzer: HP5370. Originally they were built around 6800 microprocessors. An enterprising guy worked out a transplant that replaced the CPU and memory boards with a Beaglebone black. The update got a significant increase in throughput. The jitter floor is the same (20 pS) but its still hard to get a better instrument. He sold through 50 of his upgrades in a few weeks.
I have an older HP time interval analyzer: HP5370. Originally they were built around 6800 microprocessors. An enterprising guy worked out a transplant that replaced the CPU and memory boards with a Beaglebone black. The update got a significant increase in throughput. The jitter floor is the same (20 pS) but its still hard to get a better instrument. He sold through 50 of his upgrades in a few weeks.
Yes, the motherboard looks quite standard, but I have not even looked to see what processor is in it.
Cheers,
Bob
I have not opened the box. If I read the manual, and it is something I can do without a steep learning curve to operate properly.... etc. then yes. Pls keep playing with it and see if there is anything I should look out for or focus upon.
-RM
What is conspiciously absent on the specs (unless I missed it) is CMRR over frequency. This is what separates the men from the boys in diff probe land.
The 70dB CMRR at 60 Hz is easy. I want to know what it is at 1kHz, 10kHz?
Jan
It's apparently intended only for power line measuring, so I would assume that the CMRR is much worse at higher frequencies.
CineMag makes an input transformer that has really good CMRR:
http://cinemag.biz/line_input/PDF/CMOL-2x600T2.pdf
Measured CMR at 10v rms input level:
X10 range -
100Hz = -72dB
1KHz = -72
5KHz = -65
10KHz = -63
100KHz = -61
X100 range -
100Hz = -75dB
1KHz = -75
5KHz = -74
10KHz = -72
100KHz = -70
I'll look for a trim inside (or an R that can be trimmed)
THx-RNMarsh
Thanks Richard - that's very good, I want to get one! At that price!
They should advertise that!
Jan
One little thing I do at home is adjust CMRR with the system all plugged together... cables and all from preamp to amp input. I keep talking about the System... this is one way to dial it all in together (for CMRR).
This way is a lot better than just adjusting the amp alone. It takes in the Zo of the actual preamp being used and any unbalances in distributed interfacing elements.
THx-RNMarsh
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Can someone confirm this: If the "round to eliminate leakage" option is checked in the generator, the test frequency will be an exact multiple of the frequency resolution (sample rate divided by FFT size). In this case no windowing is necessary ("Rect" window function) because each harmonic will fall exactly into the FFT's "frequency bins".
The windowing is still necessary. The benefit of setting the test in the center of the bin is better amplitude accuracy. It really easy to see the effects with the QA400. They show immediately.
The distortion is higher at the higher sample rate. Two issues, first, its just higher. Second, at 192 there may be more harmonics for it to add in.
The distortion is higher at the higher sample rate. Two issues, first, its just higher. Second, at 192 there may be more harmonics for it to add in.