Use of MDC in Amateur Service, in compliance with 14 CFR?

[W1HVN]

I am an occasional user of MDC on our club repeater system. Recently the President of the club voiced his very strong concern that MDC should not be used in Amateur Service, especially on the club funded repeaters. He noted that it was not designed for Amateur use, it is for Public Safety use ONLY and is "inappropriate" for use in our venue. Further it was mentioned that this may be "borderline" not in compliance with the FCC regulations governing Amateur Radio in 14 CFR. His position is it is not an open format designed for Amateur use.

Although in the interst of friendly Amateur operating practice I have discontinued using the signaling on the frequency (myself and at least one other user frequently used it), I have to disagree on the legality issue. The format is publicly available in properly equipped Motorola equipment available to the Amateur community. The feature has great functionality in EMCOMM applications for use in drills, special events, and actual emergencies, etc.

Does anyone know if the FCC has ever issued legal interpretation or published it's position on the use of Motorola (or Kenwood for that fact) signaling formats to include MDC1200? If so, please pass it on as I'd like to at least put the legal issue to rest given issued guidance from the agency. Also, if anyone has a good contact to submit such questions to the agency, please pass on that info as well, however the compliance and enforcement division (Riley) has been sunsetted for the Amateur Radio community.

[akardam]

If your guy is quoting any part of 14 CFR, he's way off base. Amateur radio is covered by 47 CFR 97.

As far as I know amateurs are not held to emmission types (unlike the vast majority of FCC licenses out there). Sure, there's bandplans that say where/when you can use certian modes, but these are gentleman's agreements, not codified by federal law.

MDC1200 is just another data format. Amateurs have been using data formats for years (packet, RTTY, PSK, etc). As for it being an open standard, well, not precisely, as it was a proprietary Motorola protocol for years, but I believe the patents covering it have expired (check for yourself on this). MDC1200 is available natively in many Motorola products, and becoming native in other manufacturers products (most notably Kenwood) and has been available as third party add-on products from the likes of Midian for years.

In any event, your guy needs to cite the specific subpart of 47 CFR 97 which prohibits the use of data formats like MDC1200 in the amateur service. Until he does (and I'm pretty sure it doesn't exist), my opinion would be that you're well within your rights to use it.

[W8RW]

It might also be helpful when discussing the rules to explain to the repeater owner the difference between "encoding" and "encryption" since the regulations treat these differently.

Here is a nice sound card based MDC decoder that he can use so that is it clear that you are not passing secret messages:

http://www.antistatic.org/winmdcd/

By the way, I think an exhaustive search of Title 14, Aeronautics and Space

http://ecfr.gpoaccess.gov/cgi/t/text/te ... tab_02.tpl

would not turn up anything prohibiting use of MDC on the ham bands

Of course, you could always encourage the repeater owner to buy a real radio that mutes MDC!

[rocketman]

MDC 600 or 1200 is not just for public safety. I have no idea where your club president got that hairbrained idea. Utilities use it, and regular business band users employ it also. I know where I work it keeps the horseplay off the air, as we know who is fooling around and those who fool around on the radio are dealt with as approrpriate.
MDC is not encryptioning, it is a form of identification.

Chris, who are you talking about that speaks such tomfoolery?

Dave N1OFJ

[n1das]

Anybody here remember the Kenwood TR-2600A 2m handheld back in the mid 80's? The 2600A offered an MDC-like feature and simply called it "digital coded squelch" (DCS). The DCS feature was designed for paging and selective calling and was designed to work through repeaters. You programmed in your callsign and the callsign of whom you want to call. It was a 1200 baud system and supposedly used the same modulation type as MDC1200. Although the data format was Kenwood-specific, the burst of 1200 baud data sounded EXACLTY like MDC1200. It might have been a predecessor to Kenwood's Fleetsync system, a competitor to Motorola's MDC1200.

Kenwood's DCS feature never caught on but I recall hearing it being used on the air a few times when the TR-2600A radio was popular.

[RadioSouth]

DCS is usually synonomous with DPL, just a manufacturer other than Motorola's terminology. Perhaps Motorola has a patent on 'PL' and 'DPL'
Far as MDC on Ham, sure if it has a legitimate purpose and is actually being decoded by someone. If nothings decoding it, it really amounts to just a bunch of noise, not much of a point. In many of the systems that use it an appropriate delay is built in so the MDC
gets muted and not heard by other units.

[n7maq]

Just run MODAT


Jim

[Wowbagger]

DCS is usually synonomous with DPL, just a manufacturer other than Motorola's terminology. Perhaps Motorola has a patent on 'PL' and 'DPL'

Intellectual Property Rights Law 101: Patents cover devices or methods for a period of time. Copyright covers a specific expression of an idea for a longer time. Trademarks and trade dress cover a specific term or image, used in a specific context, for as long as the holder wishes to maintain the trademark.

Motorola has a TRADEMARK on the terms "Private Line" and "Digital Private Line", which is what PL and DPL stand for. That is why everybody else calls them "Continuous Tone-Coded Squelch System" and "Digital Code Squelch" (CTCSS and DCS), so as to not have to pay Motorola for the right to use the trademarked terms.

If Motorola had PATENTS on those ideas, then no matter what a manufacturer called it, the manufacturer would still have to pay Motorola for the use of the patented idea.

It's a peeve of mine when people get those confused, as it leads to greater confusion about IPR in general. That confusion is part of how Disney has been able to keep extending copyright ad infinitum.

[KitN1MCC]

just get a real radio on 900mhz and join us on the guilford machine.


would this happen to be the rpt on eel hill


is this a 2m or 440 i may have to add the channels to my radios

[Grog]

I am an occasional user of MDC on our club repeater system. Recently the President of the club voiced his very strong concern that MDC should not be used in Amateur Service, especially on the club funded repeaters.

The club presidents incorrect CFR quotes and thoughts of what MDC is really used for aside.......

If a trustee of a repeater does not want you to use MDC and you use it anyway, they can always tell you to stay off permanently. Just something to keep in mind.


(not saying the president is a trustee or has absolute authority to have the trustee order you off of their repeater, but a possibility)

[RadioSouth]

Ah yes, Trademark. As I was typing 'patent' it didn't seem right but couln't remember the proper terminology.
Just happen to have a Radius manual sitting next to the computer and sure enough is mentioned right on the back cover.

[kb9suy]

This has been brought up a couple of times through out the years on the board and its perfectly legal. The biggest problem we have with keeping ham radio alive is people like that who have to herass the younger ham or the new ham that is experimenting with newer technology like PL or Repeaters. When I was younger and started using mdc I was harrassed on a repeater for running it and the guy got ignorant on the air with me even tried to tell me it messed up their repeater controller. I just laughed on the air and said you old fools don't have a clue I won't turn off my identifier I just won't use your machine. almost 10 years later I hear them using mdc on their radios. The repeaters we have up linked together on uhf it is almost rare not to hear a mdc modat or fleet sync. We use it alot for our skywarn operations and just knowing if someone else is on the system we don't know. We all have each others ids databased on our yahoo group to keep track of each other. It's sadd to see people with attitudes like that all it does is discourage hams who end turning their radio off and throwing it in the closet. We don't need that. For years and years we argued with our club to maintatin the repeater try and upgrade it we got nothing but nasty comments and looks. So we just got tired of it and coordinated a uhf machine and starting building a system. No politics to deal with no older hams to get on the air and complain. Just all a bunch of great hams hanging out having fun. Theirs probably like 30 of us we all hang out together especially the local hamfests we all setup a block long of tables and tents in the flea market and just barbaque and have fun. We all help each other out I help everybody with vehicle installs and programming the other guys are the computer gurus who help us with uprgrading our toys and then the antenna gurus. Its finnally nice to have a home in ham radio were if you want to have fun your welcomed into the family. We keep recruting our friends and adding them to the group it's nice to have a home with no bad attitudes.

[MTS2000des]

the funny part is MDC is hardly new, circa 1976, and as others have pointed out, other FSK formats have actually been introduced on ham radios in the 1980's such as Kenwood's DCS, and Yaesu had a similar format/feature for selective call at the same time. FSK is an acceptable mode on FM, and any old fart who tells you otherwise is a liar.

OTOH, any repeater owner can place whatever restrictions he/she so desires on the use of their system, and can legally request that you refrain from using it on the system and even ban you from the system altogether if so desired. If it's a club system and you are a dues paying member, bring it up at the next meeting and have the OF's cite the specific "law" prohibiting use on the amateur service. They can't. However, if you have several members who do use MDC for selective calling (and not just as a "roger beep"), you may be able to appeal to the club that you are using it for a legitimate purpose so you can keep your portable on at work or at home without disturbing others.

I have been using MDC1200 for years in Atlanta, especially on 2 meters where we've had an influx of CB convert lids who constantly kerchunk repeaters, eat their micrphones, and have mindless conversations about their CB crap. It makes for a nice quiet standby without the constant sounds of chaos...of course UHF and 900 are pretty much lid free around here (except 900 which would be a great band if not for all the QRM from ISM stuff).

Always ask for the specific code section or case law being cited. That usually ends the argument or the OF reverts to "well we just don't think it is appropriate on our repeater" which is perfectly ok- just don't spread the misinformation that using MDC outright is illegal in the amateur service which is clearly not the case.

[techie]

We have an OO here in the SF bay area who has made accusations that the users of our repeater system, and one user in particular, have been jamming on the system that he lives on.

The basis of this accusation? the jammer was kerchunking with MDC, and we have some users who use MDC on our system. He didn't stop to consider that the system being jammed is on 2m, and most, if not all of the users of MDC on our system are on 440 (although we do have 6m, 2m, and 900 linked in as well).

Most of our users, including the one specifically named, refuse to have anything to do with the other system, which seems to be populated with newbies, idiots, and at least one control freak.. we refer to it as "the learning channel", and ignore them.

[Pj]

W1HVN-

What repeater is this? I am back in CT often, and wouldn't mind throwing out a "FFFF" here or there. I know when I got into the hobby I was using a Saber 3 with MDC1200 on Soapstone, and that caused a very small dizzy, but it dissapeared quickly.

[Mike B]

I think if you use the MDC paging feature where an unattended radio will automatically answer/acknowledge a MDC page, you are not in compliance because MDC data has no way to embed a HAM call sign in it. You would have to modify the unattended radio to also give a recorded voice or CW call sign after the MDC automatic reply. You could also have problems with rules about unattended transmitter remote control issues. However, if the transmitter is attended, all the operator needs to do is identify and there is no problem.

I have found fellow HAMs that know the least about rules and regulations are the very ones most likely to have unshakable, totally wrong, fantasy based opinions about what is legal. A little knowledge mixed with lots of fantasy is an extremely irritating thing to be exposed to and they do expose themselves .

MDC 1200 is simple fast frequency shift keying (FFSK) where there is a 1.5 times difference between the mark and space frequencies. Its similar to the Bell 202 1200 baud FSK modulation used for packet. If FSK modulation is a legal modulation mode and the bandwidth limitations are complied with, MDC modulation is every bit as legal as packet modulation.

[W2MB]

For what it's worth, Part 97 - Amateur Radio Service, Subpart D - Technical Standards

97.309(b) Where authorized by 97.305(c) [specifies emission types authorized on which frequencies/bands] and 97.307(f) [specifes technical standards and emission limitations such as symbol rate, frequency shift keying mark/space and bandwidth] of the Part, a station may transmit a RTTY or data emission using an unspecified digital code, except to a station in a country with which the United States does not have an agreement permitting the code to be used. RTTY and data emissions using unspecified digital codes must not be transmitted for the purpose of obscuring the meaning of any communication. When deemed necessary by and EIC [FCC Engineer In Charge] to assure compliance with the FCC Rules, a station must:
(1) Cease the transmission using the unspecified digital code;
(2) Restrict transmissions of any digital code to the extent instructed;
(3) Maintain a record, convertible to the original information, of all digital communcations transmitted.

[MTS2000des]

We have an OO here in the SF bay area who has made accusations that the users of our repeater system, and one user in particular, have been jamming on the system that he lives on.

The basis of this accusation? the jammer was kerchunking with MDC, and we have some users who use MDC on our system. He didn't stop to consider that the system being jammed is on 2m, and most, if not all of the users of MDC on our system are on 440 (although we do have 6m, 2m, and 900 linked in as well).

Most of our users, including the one specifically named, refuse to have anything to do with the other system, which seems to be populated with newbies, idiots, and at least one control freak.. we refer to it as "the learning channel", and ignore them.

OO's...don't get me started. If there ever is a group of wanna-be's right off the page from Hamsexy. I wonder when the league will start handing out badges?

the bottom line is MDC is an accepted emission type. If a repeater owner or club doesn't want it, that is well within their right but this does not mean it is "illegal" to use outright. It is no more "illegal" than discussing certain subjects on repeaters- when you put up your own system you can pretty much dictate what goes and what does not, so long as it falls within the limits of the FCC rules which MDC certainly does.

[RADIO]

the bottom line is MDC is an accepted emission type. If a repeater owner or club doesn't want it, that is well within their right but this does not mean it is "illegal" to use outright. It is no more "illegal" than discussing certain subjects on repeaters- when you put up your own system you can pretty much dictate what goes and what does not, so long as it falls within the limits of the FCC rules which MDC certainly does.

mts2000des i agree with you there are a couple of local repeaters that have asked what i was running and thought it was DTMF and i told them nope its a commercial radio running MDC but i have never been told to turn it off or stay off a machine i guess it all depends on the people you are talking to, even some of the old timers don't mind it to much

[Note, check your quote tags by using preview before you post - akardam]