Re: [44net] a common vendor neutral hardware/software stack for 44net. - was Re: hardware vs. software
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.
http://www.qsl.net/kb9mwr/projects/wireless/70cm-ATV-HSMM.html
As for chewing the the band. You really have to look at it on a case by case basis, geographically.
Where I live, 70cm is pretty dead, so a 5 MHz wide signal isn't a big deal. 15 years ago a guy was playing with analog ATV and that really did rip up the band, as it had no real filtering, and at the time the band was active.
97.307 doesn't apply to FHSS or DSSS. The applicable section is 97.311.
Anyway this isn't the place to discuss rules in my opinion.
However if we keep connecting slow speed conventional radios to the amprnet, then it will continue to be what is has for the last 20+ years. I am glad to see some people thinking out of the box, and exploring different technologies.
Getting back on topic, I read there was a recent presentation titled "Providing authenticated amateur radio services on the Internet", is there a paper or video available for those of us who didn't attend?
On Sat, 6 Jul 2013 13:43:29 -0500, kb9mwr@gmail.com wrote:
97.307 doesn't apply to FHSS or DSSS. The applicable section is 97.311.
Anyway this isn't the place to discuss rules in my opinion.
I disagree. Since the rules restrict what we can do on the air and the bandwidth characteristics of the emissions involved I think it's very important for hams to understand digital communications in the context of the rules, especially since hams in the U.S. may actually be under more strictures than those in other countries.
I don't mean we should start talking about rules and what needs to change on this list but when someone raises a rule stating 100kHz is the maximum bandwidth allowed, it's important to point out that spread spectrum communications, and the applicable rules that allow it, specifically depends on bandwidths greater than that by at least three orders of magnitude.
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
SS isn't redundant error correcting code. SS is accomplished by using a pseudo-random bit sequence to chip the data stream into many smaller bits, making the resulting channel stream look like Gaussian noise. It's then de-spread at the receiving end and the baseband data is recovered.
I think your best bet might be using COTS 802.11b (DSSS) hardware at 11Mbps on 3.4 GHz. Then there is the possibility of using 802.11a hardware on that band. This would be a "simple" ;) matter of getting hands on 802.11y hardware and tuning it down from 3.7 GHz. I don't know what FCC would have to say about using 802.11a protocol on that band. There used to be a prohibition in the rules about multiple carrier signals in the same transmitter but I see no mention of it in Part 97. I also see no mention of LFSR taps or length so it looks like anything goes now. This sent me looking for my old Part 97 books but it looks like I tossed them out.
FCC has already "clarified" their stand, "if it isn't specifically prohibited, it's permitted", unless we tell you to stop. As for clarification from ARRL or FCC, you don't even want to go there. FCC has amended Part 97 to make it as broadly enabling as possible such that if they don't want you to do something it's specifically prohibited in Part 97 and if it's not prohibited it's permitted. Unless they send you a cessation order after the fact the guiding principle is to "just do it".
I see you doing a lot of complaining about what's NOT being done but you don't seem to be doing something yourself. Grab that block of IP's I allocated to you and start building. Then publish your results. That's the basis and purpose of ham radio.
-
Eric Fort -
Geoff Joy -
kb9mwr＠gmail.com