On Sat, Jul 6, 2013 at 11:43 AM, kb9mwr@gmail.com wrote:
(Please trim inclusions from previous messages) _______________________________________________ I was thinking the same thing.
If it's a data transmission then yes obviously the bandwidth rules apply. If it's an image transmission then a different set of rules apply. If its a spread spectrum transmission then 97.311 applies.
The problem is defining what you are transmitting.
This really is an issue but I do wonder to what extent and some clarification would indeed be helpful here. Take a couple examples:
transmitting music is completely disallowed... or is it? If I encode music as MIDI or MP3 is it music or data? Does it change it's character if I then packetize that bitstream and route it over an IP network?
If I encode video as mp4 or mpeg and transmit that is it video or data? Does it change it's character if I then packetize that bitstream and route it over an IP network?
If I encode a multiplexed multimedia stream that contains MP3 music, MPEG2 or MPEG 4 VIDEO, teletext data, and closed captions what is it and what rules apply? is it video, or data, or music, or any number of other things? Does it change it's character if I then packetize that bitstream and route it over an IP network?
When is an emission spread spectrum and when is it really just a really good super redundant error correcting unspecified code? Spread Spectrum (SS) is defined in the US as:
emissions using bandwidth-expansion modulation emissions having designators A, C, D, F, G, H, J or R as the first symbol; X as the second symbol; X as the third symbol.
X as a symbol indicates not otherwise defined. If you look at the definitions in place for the second symbol (nature of the signals modulating the main carier) I can't really see how this would not always be a 1 for our use and if you look at the third symbol (type of information to be transmitted) W would seem to cover it as it's going to be audio, video, and data in combination moving across the links.
So by a quirky set of definitions it would seem that SS does not exist as we have a designator of ?1W covering our transmissions used in digital networking thus the second and third designators not being undefined but defined and thus can not possibly be spread spectrum even if we insert enough additional redundant error correcting coding to grow the required baud/symbol rate for a given bit rate of say 300 bits per second to where it occupies several hundred Mhz of spectrum (yes I am demonstrating absurdity by being absurd....). From a perspective of coding theory however that is exactly what spread spectrum does, it transmits bunches of extra information that can be used at the reciever to help figure out and correc tthe missing or incorrect information. The conclusion here is however admittedly absurd as for instance 802.11 is generally considered to be spread spectrum emission and spread spectrum exists by the fact of it being defined. This illustrates though that we really could use some clarification as to the intent and meaning of some of the rules we live under as radio amateurs.
Thinking that it could be helpful for maybe the ARRL, TAPR, or even the FCC to grant some guidance here. Seems to me that everything we operate within a data network would be emission ?1W
Eric AF6EP