DIGITAL MODES :

Discussion in 'Survey Center' started by M0XRZ, Nov 30, 2018.

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  1. ND6M

    ND6M Ham Member QRZ Page

    Then I also have a digital light in my shack.
    Its either off or on too.
     
    W7CJD likes this.
  2. KY1K

    KY1K Ham Member QRZ Page

    Yes, if you switch it on and off to send messages, that would be a digital format. Now of you had a dimmer and changed the brightness to send the message, that would not be a digital signal. It would basically be AM.

    https://en.m.wikipedia.org/wiki/TOSLINK
     
  3. KY1K

    KY1K Ham Member QRZ Page

    I would consider the DMR radio a computer. AM can be received with just a small handful of components that a 6-year-old can assemble. These new voice modes require a microprocessor (if not several) and thousands/millions of other parts to decode the signal!
     
  4. W4EAE

    W4EAE Subscriber QRZ Page

    A DMR radio could be called a computer; but as to number of parts and the complexity of assembly, we are not talking about a dramatically different proposition. This is all about perspective and scale though. For example; I would consider an SoC to be one 'part'. This really means that about six or seven extra 'parts' would be needed over a standard FM radio.

    You are welcome to disagree for the obvious reason that the SoC is the result of manufacturing process and in it you could potentially find your 'thousands of parts' (not millions though, unless we are talking molecules). But I would remind you that copper wire is not a 'found' item. I doubt the 6-year-old is mining it from the earth and processing it.

    I am not too sure about 6-year-olds, but I know a few 8-year-olds who would have no problem assembling a computer.:)

    All that said, I will amend my statement:

    DMR, C4FM, and D-Star only require a radio capable of those specific modes. They do not require an external computer or internet connection of any kind.
     
    KY1K likes this.
  5. SM0AOM

    SM0AOM Ham Member QRZ Page

    What is "digital" or not is primarily governed by what type of message function that goes in and comes out of the system.

    DMR, C4FM and D-Star transmit analogue voice by means of digital encoding and modulation which makes them analogue end-to-end transmission systems.
    This is reflected in their ITU classification of emissions;

    6K00F7W for D-Star which means a 6 kHz necessary bandwidth (6K00),
    frequency shift modulated (GMSK) F, two channels of digitised information, one speech and one control 7, and W for the mixed case between speech and control information.

    Should we ignore the control or call set-up component of the information flow, the last character would have been E for analogue speech. It can be argued if E should be a more appropriate designator as the primary purpose of a D-Star, C4FM and DMR radio is to transmit voice.

    The modulation and coding formats for the other modes are:

    DMR: 7K60FXE where "X" is a designator for channel formats "not otherwise covered".
    If we look closer into the DMR specification ETSI TS 102 361-1 it is found that it also uses a TDMA channel access scheme which accounts for the "X" in the emission designator.

    Often, DMR products are multi-standard and/or multi-role so depending on configuration or role the following supplemental designators may be associated with the equipment:

    11K0F3E, 16K0F3E, 6K60F2D, 9K60F2D 8K10F1E, 10K10F1E, 8K10F7E, 10K0F7E, 8K10F1D, 10K10F1D, 8K10F7D, 10K0F7D

    Here, a distinction is made between the data or control information transfer and the voice transfer ("D" and "E" respectively).

    C4FM: 8K10F1E in the same manner as DMR.

    As the primary purpose of radio equipment of these types is to transfer analogue voice,
    it is somewhat of a misnomer to call them "digital modes". They use digital channel encoding and modulation, but the message functions transferred are primarily continuous and analogue.

    In my opinion, the name "digital modes" ought to be reserved for transmission systems where the actual end-to-end information transferred is digital such as text or data files.

    73/
    Karl-Arne
    SM0AOM
     
    Last edited: Apr 3, 2019
  6. W4EAE

    W4EAE Subscriber QRZ Page

    Maybe symantics, but:

    Is a text file not analogue on each end (at the actual point of typing or reading)?
     
  7. WD0BCT

    WD0BCT Premium Subscriber QRZ Page

    This argument belongs on Facebook or Twitter. That we we can get the "best" minds working on such an important issue.
     
    W7CJD likes this.
  8. SM0AOM

    SM0AOM Ham Member QRZ Page

    A very good question.

    It depends on how the creation and reading process is viewed.
    When typing, analogue signals are transferred from the brain through the nerves to the muscles, which then create key-press movements in the fingers ("digits" in Latin).

    The rest is digital, if conventional typing and file storage is assumed.

    Reading a file becomes the reverse process, light from the paper or computer screen strikes the retina and sends analogue signals to the brain.
    But, light is composed of individual photons, which actually are detectable one-by-one in the retina. Stronger light can be viewed as a stream of sensory information in Pulse Amplitude Modulation format.

    (Thanks, Prof. Lars Kristiansson [SK] for making me have the course "Information Processing in the Sensory Organs")

    73/
    Karl-Arne
    SM0AOM
     
  9. W4EAE

    W4EAE Subscriber QRZ Page

    Is anything really 'analogue' then? Anything we can possibly perceive travels from whatever organ to the brain as electrical pulses.

    Admittedly, I was assuming 'digital' to be synonymous with 'binary,' as it so often is used in the modern world.
     
  10. SM0AOM

    SM0AOM Ham Member QRZ Page

    "Digital" could have any base, but base 2 or binary is convenient from an implementation perspective.

    An example of non-binary digital coding is the 8-FSK signalling used in ALE.

    Here 3 binary digits are encoded into one symbol.

    73/
    Karl-Arne
    SM0AOM
     

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