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C4FM Thing of the past or of the future?

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by N7BKV, Jun 22, 2019.

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  1. W4EAE

    W4EAE Subscriber QRZ Page

    Curious. Surely there is no legal prohibition to decoding AMBE encoded audio. If such were the case, it would be completely illegal to use AMBE on amateur bands in the US anyway.
     
  2. SM0AOM

    SM0AOM Ham Member QRZ Page

    Certainly not, as long as you buy the AMBE chip with its embedded firmware.

    73/
    Karl-Arne
    SM0AOM
     
  3. K7JEM

    K7JEM Ham Member QRZ Page

    Why would you think it would be illegal?
     
  4. SM0AOM

    SM0AOM Ham Member QRZ Page

    Here is the warning in free translation from Portuguese:

    "While DSD was intended to be patent-free, mbelib describes functions that may be covered by one or more U.S. patents owned by DVSI Inc. The source code itself should not be infringing as it merely describes possible methods of implementation. Compiling or using mbelib may infringe on patents rights and/or require licensing. It is unknown if DVSI will sell licenses for software that uses mbelib.

    If you do not have a license and are in a jurisdiction protected by the DVSI patents you should not compile or use this source code"

    73/
    Karl-Arne
    SM0AOM
     
  5. W4EAE

    W4EAE Subscriber QRZ Page

    If decoding it were illegal, that would mean the equivalence of a private key at both ends: encryption; which is illegal in amateur radio.
     
  6. SM0AOM

    SM0AOM Ham Member QRZ Page

    It is obvious that most radio amateurs do not understand the difference between "encoding" and "encryption".

    This shows up in more than one thread. In the DVSI/AMBE case, the voice is encoded using a proprietary algorithm, but if you buy the chip, or a piece of equipment that contains the chip, you have the full access to the transmission contents, as long as they not have been encrypted before transmission in another piece of software and/or hardware.

    What the DVSI lawyers want to prevent is losing the sales of their chip, which is the reason that they have patented it.

    In many countries, it is not possible to patent a software algorithm, so they are instead protected as "trade secrets", but if you have the competence to reverse-engineer such an algorithm without industrial espionage, there is very little that that the IP owner can do about it.

    Encryption is a scheme to "obscure the meaning" of the transmissions.
    You cannot just pay up some money without any questions asked and get the key(s) to the encryption.

    In DMR systems for e.g. law-enforcement and military use, there is an "encryption layer" or "encryption module" which ideally are both physically and logically separated from the voice encoding parts of the radio to avoid "back-doors" or "leakage" of non-encrypted information.

    Encryption schemes worth their names go to great lengths to ensure the proper generation and handling of their cryptographic keys.

    73/
    Karl-Arne
    SM0AOM
     
    KX4O, NL7W and K7JEM like this.
  7. W4EAE

    W4EAE Subscriber QRZ Page

    I would never argue that audio encoding is encryption, simply that in result it can be equivalent to encryption. If it is not possible to legally decode it without buying a specific product from a peculiar company, that really should be a problem for all amateurs.

    Were AM, SSB, or FM ever patented?
     
  8. K7JEM

    K7JEM Ham Member QRZ Page

    https://casetext.com/case/armstrong-v-motorola-inc-2
     
    KX4O likes this.
  9. SM0AOM

    SM0AOM Ham Member QRZ Page

    Expressions like "Equivalent to encryption" or "Effectively encrypted" are "weasel words" that are especially palatable for politicians, MBA:s and lawyers.

    You should be very careful about what you wish for, because you might get it.

    73/
    Karl-Arne
    SM0AOM
     
    KX4O and K7JEM like this.
  10. W4EAE

    W4EAE Subscriber QRZ Page

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