In 2016 a low end, non-pro 100 KHz - 4 GHz VNA cost me $430. I thought that was a game changing deal back then: being able to buy a new working VNA for under $1000. While the NanoVNA's aren't even quite the quality of even my lowend pocketVNA they do give you a qualitative picture of what's going on for $50. That's a real game changer.
NanoVNA: Low-cost handheld 4GHz vector network analyzer
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Re: NanoVNA: Low-cost handheld 4GHz vector network analyzer
#22So what's the deal with the name "NanoVNA" being applied to like a dozen unrelated projects now?
The vector analyzer is the only one I know of...
Re: NanoVNA: Low-cost handheld 4GHz vector network analyzer
#23So does it do 4 billion measurements per second, or 8 to accurately measure a 4GHz signal?
You don't need to sample at the Nyquist rate (i.e. 2x the intended measured frequency) to detect the presence of a particular signal but instead can just measure the overall power within a narrow frequency band of interest. Practically speaking this is done by mixing the sweep frequency down to at or around DC and then either directly measuring the power or sampling at a much lower rate and computing the power digitally.
Re: NanoVNA: Low-cost handheld 4GHz vector network analyzer
#24It's a shame there are not very many devices working in audio range (sub 100khz).
You still have to scout eBay for a device from the 80s-90s and they are still expensive as hell.
Re: NanoVNA: Low-cost handheld 4GHz vector network analyzer
#25So does it do 4 billion measurements per second, or 8 to accurately measure a 4GHz signal?
What the frequency range means in vector network analyzers is that the device is capable of generating a pure tone up to 4 GHz or so, and it's internal transmission lines and parts are spec'd to not be too lossy up there. A VNA generates a pure signal of a known power, puts it out the port 1 and looks how much of that power (at that freq) is reflected back by the device attached to that port (and how much makes it to port 2 (vs frequency) if it's a two port device).
It is not doing any sampling or receiving really. And concepts like instantaneous bandwidth don't matter much.
Re: NanoVNA: Low-cost handheld 4GHz vector network analyzer
#26Make sure you read the "beware of clones" section carefully. There are some real shysters out there. Even the official UK reseller of the "lesser" sub 1GHz NanoVNA has been caught shipping cloned crap that doesn't even pass self test or work properly on multiple occasions. On to more optimistic things: these are really good. My neighbour is fairly deaf and has her television obnoxiously loud watching snooker until go…
The advice to "beware of clones" is good advice that applies to the HackRF SDR as well. Despite HackRF being open source, it doesn't mean all clones are good clones.
https://greatscottgadgets.com/2021/12-07-testing-a-hackrf-cl...
Re: NanoVNA: Low-cost handheld 4GHz vector network analyzer
#27In ELI5 terms:
What is a VNA?
What are some exemplary, common things I could do with it?
Re: NanoVNA: Low-cost handheld 4GHz vector network analyzer
#28Make sure you read the "beware of clones" section carefully. There are some real shysters out there. Even the official UK reseller of the "lesser" sub 1GHz NanoVNA has been caught shipping cloned crap that doesn't even pass self test or work properly on multiple occasions. On to more optimistic things: these are really good. My neighbour is fairly deaf and has her television obnoxiously loud watching snooker until go…
Do you realize you just admitted to a crime?
Re: NanoVNA: Low-cost handheld 4GHz vector network analyzer
#29Earlier quoted context omitted.
There's probably a market for a sub $1 "smart chip" that can be added to a design. Something that can be factory programmed with a unique serial number. To keep from being cloned, verification operation wouldn't be as simple as reading out the number. Instead, the chip would respond with some sort of hash. Similar to how Apple secures their SOCs. The security wouldn't need to be perfect. Even something simple would b…
https://octopart.com/atsha204a-sshda-t-microchip-77761819?r=... But the original would have to see it coming and put this in the design, AND maintain a registry of all the valid chip serials. No hobbyist wants that headache.
What if I buy one real device and clone the serial number? This has been solved more than a decade ago but it requires hardware with secure storage to maintain a private key. Some centralized service holds the public key and can verify the device by asking it to sign something with the private key. This is basically every cell phone, quality IoT device, etc. The private key is installed in the factory, maybe provided by a secure connection back to the centralized service. Hardware features lock that key in place preventing it from being read out without a ton of work (connections are literally burned open with overcurrent inside the IC).
Since the key is unique to the device, it can easily be disavowed in the central database if a device does become compromised. Anything less than this is probably a few hours from being completely broken. And this scheme can be broken by non-state actors, especially if the private key storage is naively or poorly implemented. Many MCUs have multiple levels of readout protection and it can be easy to misconfigure. A single mistake in memory mapping could expose information on external interfaces. And then you’re trying to do all of this in China, on the cheap. Pack a lunch.
Re: NanoVNA: Low-cost handheld 4GHz vector network analyzer
#30Whats the difference between the pro and normal version (apart fr 100$}.
It is shown in the specifications table. It looks like the Plus4 Pro has higher sweep rates (600 pts/sec) vs 200-400 on the Plus4, as well as a 10dB lower noise floor for the same amount of averaging. It seems that 6 dB comes from a tighter measurement bandwidth on the Plus4 Pro. Oddly enough, the accuracy is not stated in the spec table for any of the models. If they are the same (are they?), then it looks like you can save $100 if you can live with waiting longer to get a measurement result.