Products > Test Equipment
Copper Mountain Technologies VNA
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G0HZU:
I agree it would make sense to adopt the LAN method but this is banned at work for various reasons and I prefer to adopt the same rules here at home.

With this in mind, it does actually make sense to store to the VNA internal HDD as well as to a USB stick because I get a fairly safe (temporary?) copy for free on the VNA HDD and if something happens to the integrity of the USB stick  (data corruption?) it means that I don't have to repeat the measurements again.

I might take a dozen s2p measurements in maybe 30 minutes at various operating points or drive levels and saving each one to the internal HDD first is the best thing to do as I know (within reason) that the data has been saved reliably without having to verify on my desktop PC.

In other words, a typical session for me would involve me making 10-50 measurements and I'd save each one to the HDD as an SnP file as I go along. At the end of the session I transfer all of these files to the desktop PC via a USB stick. Obviously, this is a far from ideal way to do it but it's the way I've done it for many years and I've not lost any data yet. I used to do this stuff via GPIB on my first VNA but I now also need to save other things apart from s-parameter files and I want to preserve the original Agilent file format. Also, my main desktop PC is in the opposite corner to the VNA in my workroom now. So any cable routing would be a pain.

Networking it all is the obvious answer, but this is banned at work for various security reasons and I've adopted the same rules here.


--- Quote ---Nobody ever thinks to back up those drives
--- End quote ---
I do back up the VNA drive data quite regularly including the original system restore (ghost?) files put on there by Agilent and the options *.lic file.



joeqsmith:
If I saddled my home hobbies with work procedures,  it would strip away the fun and I would not get much done.   It's better for me to keep the two separate. 

In the case of the LAN, for me that's the natural way to run tests anyway so all of my equipment is on it.  It's not just how I save data but how I automate any experiments I run.   For GPIB, the interface is on the LAN.   I can walk outside of the house and have access to the entire lab at my finger tips.  I could even open up to the WAN and let you run it from your home.   

For backup, I could just save the data twice from the VNA like you mention, but once it is on the PC, I back that all up frequently anyway to multiple devices.
virtualparticles:

--- Quote from: G0HZU on August 03, 2023, 02:10:32 pm ---In that sense, I'd like to have a USB based VNA. However, I'd be concerned about the long term stability of some of the USB based VNAs from various manufacturers. A component measurement session might take me quite a while as I have to change the bias conditions maybe 50 times. I need to rely on a VNA that can hold its calibration for the whole time.

--- End quote ---

This is a very valid concern. A poorly made VNA may drift over time and the calibration would become invalid. All VNAs do drift a tiny bit of course. I've tested this a number of times on a CMT VNA and measured around 0.03 to 0.05 dB drift on the S21 measurement of a 15 dB attenuator over a 24 hour period.
virtualparticles:

--- Quote from: joeqsmith on August 03, 2023, 02:27:49 pm ---Why wouldn't you just link it to your LAN with Ethernet and store the data direct to the PC?

--- End quote ---

Hi Joe!

Mounting the VNA over the LAN is definitely better than running around with a flash drive stick. My only concern would be that if the OS in the VNA is older, it will be vulnerable to all the old exploits. We had a VNA that got hacked (at a prior company) and it was the base for getting into everything else in the building.
tomud:

--- Quote from: virtualparticles on August 03, 2023, 06:34:11 pm ---Mounting the VNA over the LAN is definitely better than running around with a flash drive stick. My only concern would be that if the OS in the VNA is older, it will be vulnerable to all the old exploits.

--- End quote ---

It's more of a company security policy issue. What is the difference whether a remote or local vulnerability will be used, e.g. using a flash drive.
With a good security policy implemented, a dedicated VLAN, such a thing can be minimized. Although it is known that it will never be eliminated, because here sometimes there is user stupidity (in general, the most common problem of hacking into the network).

As for the VNAs described here, I'd rather see sample measurements than opinions. With a description of what calibrators, test leads, etc. were used.
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