Rohde and Schwarz AMIQ Modulation Generator Teardown(tomverbeure.github.io) |
Rohde and Schwarz AMIQ Modulation Generator Teardown(tomverbeure.github.io) |
... the multiplier is based on a classic form,
having a translinear core, supported by three
(X, Y, and Z) linearized voltage-to-current
converters, and the load driving output amplifier.
I have no clue how the thing works!
Here's a lecture by him on the translinear principle: https://youtu.be/LQNJVtcFrCc
And here's some history of his work at Tektronix (where he discovered the translinear principle): https://vintagetek.org/barrie-gilbert/
[edit]
Sound Blaster claims "up to" 130dB of dynamic range on theirs. Putting aside how much work the "up to" id doing, this would make the last 9 or 10 bits completely useless, even for undithered signals, but I was thinking of something cheaper, by one of those fly-by-night companies with names made of random letters.
There are probably only a few electrical engineers in the entire world that actually use this stuff on a day to day basis.
Another way to think about it, this would be comparable to a signal generator in the same way that an oscilloscope is comparable to a spectrum analyzer.
Your UI can be built in Python/Qt/Tk while the safety critical stuff is programmed in C running on an RTOS.
I have a PSL-3 industrial controller (well, two, but one is broken) on the shelf behind me that I'm using for the noble purpose of playing Theme Hospital in Windows 98.
You could remove the SDRAM path altogether, reverse the signal path from the connector with some PCB surgery and drive the DAC from the connector with your own digital hardware. That's one way...
There's also a hardware path from the ISA bus straight to the DAC, bypassing the SDRAM, for diagnostic purposes probably. So there might by options there too, but though it would require a ton of reverse engineering or even reprogramming the FPGAs (which are so old that the software isn't available anymore on the Altera website.)
Whether or not all of that is worth doing for a 14-bit DAC output is a matter of personal opinion.
R & S AMIQ Modulation Generator general specs is available here [1].
Fun facts, the venerable Silicon Valley was started by Hewlett-Packard (HP, then Agilent, now Keysight) that mainly supplying function/signal/waveform generator for the then booming radar and electronics industry.
HP Garage is now a designated landmark and marked with a plaque calling it the "Birthplace of 'Silicon Valley' " [2].
[1] Rohde & Schwarz – AMIQ04 I/Q Modulation Generator:
https://testworld.com/product/rohde-schwarz-amiq04-iq-modula...
[2] Hewlett-Packard:
The oscillator's model number was 200A, because even back then they understood the SV maxim "Nobody wants to buy the first version of anything."
Extremely good deals are rare and the chance that there’s something broken is very real. I often consider that a feature: fixing test equipment is a bit of a hobby, but be prepared to end up with a doorstop that cost a few hundred dollars.
Here are some examples that I bought though them:
- HP 8650E spectrum analyzer: works but intermittent shutdowns
- TDS 794D: works, but CRT is broken. A well know failure mode. Need to install a $75 LCD replacement.
- this R&S AMIQ: totally broken. Needed many days of work to revive.
It’s high risk buying these things.
Say you designed a Bluetooth transceiver chip and need to test the performance under stress conditions: noise, sample clock instability etc.
The WinIQSim software simulates such a signal and uploads it to the AMIQ, which is essentially a high quality digital analog converter.
The analog output will go to an RF signal generator and then to your chip under test.
In some cases, e.g., for IEC-62304 compliance, software is designated as various safety classes based on likelihood of causing Harm. If you can extract the more safety critical software from the rest of the system and prove that it is sufficiently segregated (e.g., by putting it on a separate processor), you can substantially reduce your Verification and documentation burden.