There is a lot of confusion among the ham radio community around the internet as to whether Jumbospots are counterfeits, knockoffs, etc. of legitimate open source developers’ work. Again, I’m not a lawyer and can’t give legal advice, but as an open source user and contributor for over 20 years I will give my perspective.

I had an extensive email conversation with one of the developers of the MMDVM_HS HAT. These are the people accusing the Chinese of ripping them off. From what he told me, the way this situation happened is that they developed the MMDVM_HS HAT on their own. They were themselves accused of ripping off another design and placed that designer’s name on their product in order to placate him. So, there is an extra name on their product that arguably didn’t have anything to do with actually developing it. However, they were not able to keep up with demand for their product and considered having Chinese manufacturers assemble the boards for them. They sent the designs to a Chinese manufacturer and inquired as to pricing. They got the price back and decided not to go with them. The Chinese manufacturers then began to manufacture the boards themselves, gave an attribution to the original developers, and called their product the Jumbospot.

Those familiar with open source hardware and software probably already see what has happened here. First, let’s look at one of the MMDVM_HS HAT boards: MMDVM_HS HAT board

As you can see, it is stamped with both the Open Source Hardware Association (OSHWA) logo as well as CC-BY-NC-SA. Those are two incompatible licenses. If you go to that link I just gave for the logo, it says you may only use it if you agree to the Open Source Hardware Definition. Number 8 in that definition states:

  1. No Discrimination Against Fields of Endeavor The license must not restrict anyone from making use of the work (including manufactured hardware) in a specific field of endeavor. For example, it must not restrict the hardware from being used in a business, or from being used in nuclear research.

In other words, by posting the logo on your hardware you agree that it can be used commercially. In the OSHWA article On Creative Commons and Open Source, the OSHWA specifically names the CC-BY-NC-SA license as incompatible with open source and goes as far to say:

Creative Commons also offers licenses that carry restrictions — against commercial use and/or derivative works — that are strictly incompatible with open source¹. The open source hardware definition states that a license for open source hardware “[…] shall allow for the manufacture, sale, distribution, and use of products created from the design files, the design files themselves, and derivatives thereof.” Thus, if you choose to release hardware under the banner of “open source,” that means that you agree to allow others to use your design commercially, as well as to create derivative works (and to use them commercially). Consequently, you cannot advertise your project or product as “open source” if it carries restrictions against either of those uses.

So, you have a situation where these boards appear to be created with dual licenses. Again, I’m not a lawyer, but everywhere I’ve seen dual licenses deployed, you didn’t have to comply with BOTH licenses and weren’t bound by the MOST restrictive license. If you were in compliance with the LEAST restrictive license, you are therefore entitled to use the work. By attributing the MMDVM_HS HAT, the manufacturers of the jumbospot appear to be complying with the Open Hardware license.

A similar situation arises with the firmware/software these boards run: MMDVM. It is released under GPLv2. However, the README states

This software is licensed under the GPL v2 and is intended for amateur and educational use only. Use of this software for commercial purposes is strictly forbidden.

I saw that and wrote an email to the Free Software Foundation, the group that owns the copyright to the GPL. They referred me to this document explaining the legal clauses of the GPL and specifically that section because it states:

The second sentence of GPLv2 §6 does the opposite; it bounds from the top. It prohibits any licensor along the distribution chain from placing additional restrictions on the user. In other words, no additional requirements may trump the rights and freedoms given by GPLv2.

So, it appears that you can only release your software under the GPL and restrict commercial use if the GPL itself doesn’t allow commercial use. However, the GPL grants usage to everyone, regardless of what they’re using the GPL’d software for. In the section 7.4.2 Promissory estoppel, the whole section is about how businesses would be harmed if they were no longer allowed to use software they’ve based their business around, so the person who released the software under the GPL is legally unable to revoke those rights unless the user violates the GPL.

Again, I’m not a lawyer, but as someone who uses and develops open source code, that is something we all have to accept: people may use our code in ways we do not personally agree with. However, as long as they do not violate the GPL, they are free to do so.