To get one of the big things out of the way: bandwidth. The FCC don't want anyone taking up big chunks of spectrum without using a license or service appropriate to that use. Notably, they don't want a few users to be able to chew up entire bands.
But there's a philosophical part to the discussion also. The tradeoff goes like this: hams get some really nice spectrum assignments, low fees, self-regulation, experimental modes and techniques, etc. In exchange, they can't use the amateur radio service commercially or for non-personal aims, and specifically they are expected to focus mostly on learning, community interaction, public service, experimentation, and so on. They also want amateur modes to be somewhat approachable, i.e. not requiring exotic or expensive hardware, necessarily.
Should an operator wish to use the radio spectrum for commercial or highly productive use, especially one requiring significant bandwidth, secrecy, exclusivity, etc, they are expected to use a different license / service more appropriate to those needs.
Basically:
Tinkering, chit-chat, community service, narrow bandwidths => amateur radio
Anything else => get a different license
To that end it was long the FCC's stance that high symbol rates sort of implied that you're going outside the purposes of the amateur radio service. With digital communication having developed as much as it has, though, it's reasonable that hams want to be able to do more interesting things with digital modes, which generally means higher symbol rates.
An interesting twist to the regulations is that you're not allowed to use ham radio as a substitute for cell service. I never quite understood this rule, nor how it was to be enforced; but it would seem to place some limits on the permissible chit-chat.
47 CFR 97.113 Prohibited transmissions,
(a) No amateur station shall transmit:
(5) Communications, on a regular basis, which could reasonably be furnished alternatively through other radio services.
The FCC has a perfectly good part 22 service for cell phones.
Or FCC part 73 regulates "old fashioned broadcast radio"
Per 97.1 (a) thru (e) explain the purpose of amateur radio but it boils down to something like a national park, sorta. The purpose of the service is NOT to avoid existing regulation.
"on a regular basis" means experiment as much as possible, for free, non-professionally, as a ham, but if you try to set up a formal cell phone company business for the public just like AT&T, and try to tell the FCC you prefer being regulated under part 97 and pay only $35 for a license, the FCC will be very very very mad at you, wave 47 cfr 97.113(a)(5) at you, then regulate you under part 22.
The FCC has nothing against people building broadcast radio services; but if you try to demand they regulate your public broadcast FM radio service under part 97 rules, the FCC is warning you they will absolutely insist on regulating and charging you under part 73 rules...
> Communications, on a regular basis, which could reasonably be furnished alternatively through other radio services.
I guess this was the bit I had in mind. It means that one can’t use amateur radio for what a cell phone is normally used for, doesn’t it? Like calling your ham friends to make arrangements for poker night. Or is that the wrong interpretation?
Note you can run a business on a cell phone or do financial transactions or speak swear words or all kinds of things common carriers supposedly don't care about but would be banned on ham radio. Also ham radio has no SLA or mandatory 911 access like a phone. Consider... if you are a casino operator and you're trying to book hotel rooms for these guys to play poker night at your casino, that would be forbidden under part 97 because its a business and part 97 isn't for business use.
Its definitely an intent based situation. "Fooling around with radio technology while having convos of a non-commercial personal nature to promote international goodwill and gain radio operating experience" is literally what part 97 was designed for, and fits the poker game example perfectly. "We built a nationwide cellphone network but forgot to budget for FCC licensing fees so we'll reprogram to use ham radio freqs and lie to the FCC and tell them its a part 97 ham radio, while we sell it to the general public as a cell phone" would be quite stunningly illegal because it would be perfectly reasonable to operate a commercial cell phone network under existing FCC regulations for commercial cell phone providers, and its done on a regular basis by the famous big name nationwide cell phone services every day...
Service. In the sense of serving!? My two FM episodes, 25 years apart, were service. Not for regulatory purposes. To those, we but poor wee pirates were, and remain.
I've heard this several times about ham radio, and to me as an outsider the idea of shared access to the medium is a bit off-putting to me.
Is it possible to have two-way links "in the clear" but otherwise encoded or ciphered? Is there a regulation that says all transmissions must be in English, for example, or can I transmit in Esperanto/Navajo/hex?
You can speak whatever language you want on the air so long as you identify every ten minutes and at the end of your transmission. The ITU regulations for radio call signs cover their format however and use the Latin alphabet. Call books are also public so anyone can look up the stations and know who you are.
Speaking in shorthand to be clear and concise over the radio is fine. Even using terms of art or abbreviations is likely fine. If you're explicitly coding your communication to obfuscate its meaning you're definitely going to run afoul on the ban of encryption.
Part of the reason for no encryption on ham bands is there's precious little bandwidth available and unintelligible signals (intentionally obfuscated) are tantamount to interference. As a listener I can't reasonably tell if an encrypted signal is noise or a genuine call. I also can't reasonably receive a call sign so I can't know who is transmitting.
The big limitation is no encryption. So it's only a substitute for cell service if you're ok with being on a big party line with everybody else in the vicinity.
Fcc part 97.101 "General Standards" (d):
"No amateur operator shall willfully or maliciously interfere with or cause interference to any radio communication or signal."
Pitiful we have to encode "the golden rule" of treat others like you'd have them treat you into law, but here we are its in the CFR.
As of 2021 no one has a technological answer to how to avoid various wide band digital technologies from interference against, well, absolutely everything else currently in use, without forcing everyone to operate in a channelized system with massive international coordination problems. The international part is a nightmare, what if, I donno, Bulgaria refuses to channelize? Nothing will work for anyone unless everyone cooperates.
Wideband digital modes do NOT play well with others.
There are channelized bands around 5 mhz (in the usa) and the FCC does relax quite a bit on wide open microwave bands, but people are going to request turning all of 20 meters into one single user digital channel, and to hell with everyone else currently using the band, apparently into infinity. Its an eternal meme.
I guess the best analogy I can come up with, is you can zone land as a public park for people to picnic, but that doesn't mean the land is completely lawless, if you blast your music at 160 dB the police will arrest you for preventing everyone else from enjoying their picnic.
We easily right now have the technological ability to turn the 20M band into a single channel, single user, very high speed digital path at 1500 watts. But that's a terrible idea, given the zillions of current users, local and international, who would be kicked off completely unable to operate.
There's very limited bandwidth available on most of the ham radio bands and other users don't want people taking up large chunks of bandwidth with wide, high-bitrate data signals and making the bands unusable for everyone else.
Truly. I have philosophical problems with the existence of the FCC but there's a great deal of interesting and educational discussion to be had here.
At the risk of delving further into conspiracy theory I suspect that may be a reason its downvoted; because there's room for debate. There's currently a lot of feeling that once the government is involved debate must be silenced.
I didn't downvote it, but I strongly suspect it was because of the sarcasm, the meta-sarcasm, and ultimately the unwillingness to believe that interesting opposing arguments might exist. That is, the post didn't encourage interesting and educational discussion, just derision. The merit of the resulting conversation was despite the initial post, not because of it.
Presumably for the same reason that GPS time signals had (have?) pseudorandom noise added: to prevent an adversary from using your own systems to steer missiles with high precision.
PRN (Pseudorandom noise) in the context of GPS is just a coding standard - it's just CDMA (aka Spread Spectrum) and it allows all satellite to use the same frequency. A side benefit is that the signals can be below the noise floor, and when you apply the gain from decoding, it rises the signal above the noise floor (exactly like how you can pick out a voice in a crowded bar if you know what that voice sounds like).
GPS uses PN codes for the timing difference measurement, as well as allowing multiple satellites on a single channel. I believe the dithering (selective availability) was turned off years ago, thus the L2 channel ads only ionospheric correction (which can also be accomplished with local sources).
The FCC symbol rate limitation needs to go. It’s a hindrance on HAM radio. Just regulate it by bandwidth, or better yet EIRP PSD, but that would be tough to control.
Yes, Selective Availability was turned off in 2000 and will never be re-enabled. In fact, the latest generation of GPS satellites do not even support Selective Availability: https://www.gps.gov/systems/gps/modernization/sa/
But there's a philosophical part to the discussion also. The tradeoff goes like this: hams get some really nice spectrum assignments, low fees, self-regulation, experimental modes and techniques, etc. In exchange, they can't use the amateur radio service commercially or for non-personal aims, and specifically they are expected to focus mostly on learning, community interaction, public service, experimentation, and so on. They also want amateur modes to be somewhat approachable, i.e. not requiring exotic or expensive hardware, necessarily.
Should an operator wish to use the radio spectrum for commercial or highly productive use, especially one requiring significant bandwidth, secrecy, exclusivity, etc, they are expected to use a different license / service more appropriate to those needs.
Basically:
Tinkering, chit-chat, community service, narrow bandwidths => amateur radio
Anything else => get a different license
To that end it was long the FCC's stance that high symbol rates sort of implied that you're going outside the purposes of the amateur radio service. With digital communication having developed as much as it has, though, it's reasonable that hams want to be able to do more interesting things with digital modes, which generally means higher symbol rates.