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MDC signalling on GMRS.


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I feel kind of stupid asking this question, but I'm genuinely not sure of the answer.

I know MDC signalling is not legal on amateur radio, because it is a proprietary (Motorola) protocol (e.g. not an open 'standard'). 

However, I can't find anything in the rules that prohibits its use on GMRS.

Legal or not legal? (cause I'd really like to use it).  I'm leaning towards it being legal but I'd really like some feedback on the topic

Thanks!

🙂

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The rules don't say that you can't use it - but I'm not aware of any Motorola radio that's type accepted for Part 95 that has MDC signalling. "Legal" has lots of angles you can view it from.

There are other brands that now offer MDC signalling.Vertex, Icom, and Kenwood all have certain models that offer it. It may not be fully compatible with all features in the MDC1200 Motorola world, but they've got it. I'm not actually sure if Motorola patents expired, or if they just decided to license it to other manufacturers at a more reasonable cost.

 

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20 hours ago, WROZ250 said:

I know MDC signalling is not legal on amateur radio, because it is a proprietary (Motorola) protocol (e.g. not an open 'standard'). 

So where in the rules does it say that ? Many folks use MDC as well as P25 and other signaling on amateur radio. Many folks use MDC on GMRS.

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4 hours ago, gortex2 said:

So where in the rules does it say that ? Many folks use MDC as well as P25 and other signaling on amateur radio. Many folks use MDC on GMRS.

My question had to do with GMRS use of MDC.

However, at the risk of getting into a debate, I'll answer your comment.

First, it has nothing to do with modulation and bandwidth, etc... 

MDC is prohibited (on ham radio) because it is not an open standard.  MDC is proprietary, Motorola created and owned, and so for every radio manufactured that includes it, that manufacturer pays a licensing fee that is (one would assume) included in the cost of each radio.

For example, were you to build your own radio and wanted to include MDC signalling, you would need to ask Motorola for the specifications of the protocol and (like their other software licensing) have to pay them for the information and the use of their technology.  Also like their software licensing, it is highly unlikely that such a request would be granted to an individual/end user.

With the above noted, because an individual cannot legally obtain access to the details of the protocol (MDC), and/or use it in a design, it cannot be used in amateur radio.

All that said, I am more than aware that there are hams using MDC signalling and that a lot of details of the protocol have leaked out over the years, to the point where one might be able to build a unit and/or write some code to make use of it.  However, to the best of my knowledge, it's remains Motorola proprietary and so would remain a closed standard.

So how are these people getting away with it? 

My opinion is that #1. when it comes to rule violations, it's a minor violation.  #2, the FCC rarely goes after serious offenders so it's unlikely something like this would ever be pursued (much like the part 90 vs part 95 radio issue).

The fundamental difference is that Ham radio and GMRS are two different radio services each with it's own intended purpose, rules and restrictions.

Hams are permitted to construct their own equipment, GMRS operates are not allowed to do this. 

Ultimately GMRS operators are, in many ways, just users and so as our equipment is manufactured, we are generally free to use whatever technologies come with those radios (rules notwithstanding).  Even then, the GMRS rules have a lot of caveats in regard to what kind of things we can put into the microphone jack so to say.

Hams have very few technical restrictions beyond ensuring bandwidth use and clean signals.

What lead to my original question was that MDC seems to still have a lot of debate going on between proponents of its use in amateur radio and those like myself whose understanding of legal operation (when it comes to Ham radio) leans to the restriction on the use of proprietary technology of any kind.  Basically, if Joe ham cannot legally build a radio that includes technology 'X', then technology 'X' cannot be used in amateur radio.  MDC is one such technology.

Many will point out that there are other protocols in use in amateur radio, some of which include technologies that are proprietary to the manufacturer, D-Star for example (Icom).  Nevertheless, those protocols and the licensing of them to end users and equipment manufacturers are available. 

While an end user likely isn't charged a licensing fee, another manufacturer would be.  That again, is the fundamental issue.  The protocol must be legally available for the end user in amateur/ham radio.  While Mototrbo (DMR) and P25 are Motorola creations, both protocols are openly obtainable, indeed published.  P25 via/through APCO and Mototrbo is based on one of the ETSI standards.

My understanding of such restrictions is based on a long career I had as an engineer with Motorola.  That said, It could be, as @Radioguy7268 mentioned, it is possible that patents have expired on MDC.  It is admittedly, a somewhat antiquated (but in its full implementation, extremely powerful) protocol.  Indeed, it may be that MDC signalling (not the full protocol) is legal because there is little in that subset of the protocol that could be considered as a way to concealing intent or otherwise be considered as a 'cypher' (encryption), which is not legal on ham or GMRS.

I don't fear the FCC, but I do like to operate legally as much as possible, and after years working in the communications field, my experience with FCC rules is that one should adhere to the most restrictive interpretation.

I don't feel my understanding is simple opinion, but take it as such if that helps. 

My original question was specific to GMRS and was answered, so I'm done with the issue and have no interest in debating it.

Indeed, for the purpose of this GMRS forum any such debate is irrelevant, because MDC is legal on GMRS!


All that said...

I do apologize if my explanation seems to carry some tone, but I am admittedly upset because I posed the same simple question on a different GMRS forum and the sysop/admin of that forum threatened another user with removal for disagreeing with him, even resorting to a personal attack before threatening removal.  Yeah, an admin, over a technical discussion!!! WTF? 

I enjoy (some) of the discussions that occur here, but really guys, if anyone feels they are personally, nevermind violently, offended because someone has a different opinion, then perhaps that person should stay out of the frey (IMHO).

So by all means continue to discuss this one if you must.  Just do it with respect and civility.

To each their own.

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It’s not that it’s too minor for the fcc to react. The restrictions in ham radio are against encryption, not proprietary technology. 
The debate seems to center around an opinion that proprietary standards amount to encryption and thus violate the spirit of ham radio. 
I thought GMRS users were also restricted from using encryption. If so, how is it different from amateur radio in allowing MDC?

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Ham radio in general is more permissive in what technologies are used for communications. The principal limitation is on bandwidth, transmissions have to fit into allowed emission masks.

Also you can’t use codes or encryption meant to obscure or hide the contents of the communications. There is an exception for satellite control ground stations for obvious reasons. 
 

The recent rule changes for GMRS in 2017, effective in 2018, encryption is now prohibited on GMRS, including the old voice inversion methods. You’ll likely find this on the older, pre rule change, radios but can no longer be used.

So even though modes such as NXDN on Ham, for example, are proprietary they are “published” so anyone can receive the signals and don’t count as encryption thus legal to use. The same would apply to many other signaling systems currently in use. If one wants to design a new signaling system, fine, but the technical details have to be publicly available to any interested party. 

On GMRS you can use modes other than FM. There are several that are permitted, such as SSB, J3E. Not likely to encounter that one but it is listed as a legal mode.

https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-95/subpart-E/section-95.1771

https://repeater-builder.com/tech-info/pdfs/fcc-emissions.pdf

So I would recommend looking over the rules to see EXACTLY what is permitted first, then examine if a particular mode/signaling system is allowed per the FCC emission masks. Then decide if its an allowed emission does it fall under the prohibition of “codes” meant to hide or obscure the communications.

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1 hour ago, Sshannon said:

It’s not that it’s too minor for the fcc to react. The restrictions in ham radio are against encryption, not proprietary technology. 
The debate seems to center around an opinion that proprietary standards amount to encryption and thus violate the spirit of ham radio. 
I thought GMRS users were also restricted from using encryption. If so, how is it different from amateur radio in allowing MDC?

Well this is where one gets into a grey area...  sort of...

But you nailed it on the head.

MDC by default is not encrypted, but it is encoded within a proprietary protocol.  A protocol which, being proprietary and restrictively/non-published, is unavailable for use and/or arbitrary decoding (deciphering?) by, in this case, amateurs.  As I alluded to previously, MDC isn't simply PTT ID and/or private call, the full data protocol is extremely powerful and feature rich.  Antiquated or not, MDC is capable of things that few (if any) amateur digital modes, even some commercial data protocols, are capable of providing .  Perhaps that is why it has not been release as an open standard (admittedly speculating there)?.

So while it isn't technically encrypted, it effectively/practically speaking is, or might as well be.

Were Motorola to release the protocol to public domain, making it 'open' to all, there is no reason it would not be completely legal for amateur radio.  However, unless something has changed, MDC is not an open standard.

That, is how I interpret the restriction/prohibition under the Part 97 rules.

There are protocols (such as D-Star and P25) that have some proprietary features within, however, the the protocol information is not restricted, hence the availability of, for example, hot spots and dongles, most of which support open protocols such as P25, Mototrbo (DMR), D-Star and a couple others.

As far as the FCC is concerned, I do agree that under 'normal' (what's normal these days?) situations, the FCC would enforce the restriction.  The reality is they rarely enforce anything but the most serious offenses these days.  That, however, is an entirely different topic.

Again, for those who have not been paying attention, not talking about GMRS legality, only Amateur radio. 

My original question was answered where GMRS is concerned.


🙂

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2 hours ago, WROZ250 said:

Well this is where one gets into a grey area...  sort of...

But you nailed it on the head.

MDC by default is not encrypted, but it is encoded within a proprietary protocol.  A protocol which, being proprietary and restrictively/non-published, is unavailable for use and/or arbitrary decoding (deciphering?) by, in this case, amateurs.  As I alluded to previously, MDC isn't simply PTT ID and/or private call, the full data protocol is extremely powerful and feature rich.  Antiquated or not, MDC is capable of things that few (if any) amateur digital modes, even some commercial data protocols, are capable of providing .  Perhaps that is why it has not been release as an open standard (admittedly speculating there)?.

So while it isn't technically encrypted, it effectively/practically speaking is, or might as well be.

Were Motorola to release the protocol to public domain, making it 'open' to all, there is no reason it would not be completely legal for amateur radio.  However, unless something has changed, MDC is not an open standard.

That, is how I interpret the restriction/prohibition under the Part 97 rules.

There are protocols (such as D-Star and P25) that have some proprietary features within, however, the the protocol information is not restricted, hence the availability of, for example, hot spots and dongles, most of which support open protocols such as P25, Mototrbo (DMR), D-Star and a couple others.

As far as the FCC is concerned, I do agree that under 'normal' (what's normal these days?) situations, the FCC would enforce the restriction.  The reality is they rarely enforce anything but the most serious offenses these days.  That, however, is an entirely different topic.

Again, for those who have not been paying attention, not talking about GMRS legality, only Amateur radio. 

My original question was answered where GMRS is concerned.


🙂

No, I’m talking about GMRS legality. If MDC prohibited in amateur radio, it’s also prohibited in GMRS for the same reason; encoded communications are prohibited in GMRS in the same way they are in amateur radio  

You stated that MDC was legal in GMRS. If it is, then it’s legal for ham radio. It can’t go both ways. 

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1 hour ago, Sshannon said:

No, I’m talking about GMRS legality. If MDC prohibited in amateur radio, it’s also prohibited in GMRS for the same reason; encoded communications are prohibited in GMRS in the same way they are in amateur radio  

You stated that MDC was legal in GMRS. If it is, then it’s legal for ham radio. It can’t go both ways. 

That is a very valid point.

On one hand, as someone else mentioned, there appears to be no part 95 radios that have MDC in them, whereas some (not all) part 90 radios do.  Sort of the same issue for ham radios.  I don't know of any radio manufactured exclusively for amateur radio that includes MDC, yet hams are free to use part 90 radios whereas GMRS technically can't use them, even though it seems to be a common practice. 

So in reflection, it does beg the question of legality in both services and so perhaps I was misinformed about GMRS.  Where I saw the difference was that hams can build their own radios and GMRS users can only use manufactured (part 95 type accepted) radios.

I asked the original question because while I am certain that MDC is not permitted on ham, now I am back to questioning the legality of it on GMRS. (Oye!) 

The rules almost require a doctorate degree to understand, which leads to multiple interpretations. Combine that with the constant practice of people thumbing their noses a the rules (ham and GMRS) to the point where it becomes 'common practice', we find ourselves at the point where nobody really knows what is and is not legal.  My interpretation, where ham radio is concerned, came from a legal explanation when I was still in 'the business'.  At the time, GMRS was not not even on my mind and the conversation was specifically about the use of (commercial) digital protocols by hams.

I agree with you in that if you look at the issue from the encode angle (virtually/effectively encrypted), it would be illegal in both services, save for the fact that there is no attempt to skew or hide the main information being transmitted.  So for myself, I'm back to the 'adhere to the most restrictive interpretation of the rules' mode.

That said, like the use of part 90 radio in GMRS, I don't see either user group who currently use it, ceasing the use of MDC until/unless confronted with a violation notice.  If that happens at all.

Doesn't really bother me in either radio service, indeed I rather hear people sending a short MDC burst than a string of DTMF tones. 

Personally, however, I simply don't operate in 'grey areas' where the rules are concerned.  But that's just me and I'm not suggesting anybody stop if they do.

To each their own!

🙂

 

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In my area of the country, many GMRS repeater owners state that they want users to refrain from using MDC, Talk Permit Tones, "Roger Beeps" or any other signaling, mostly due to the noise of those signals, or to keep Motorola users from "flexing" on other users......used to a thing in the past but surplus Motorola is also a lot more common now (as is other manufacturers including MDC in their products).

On my own Spectra repeater system, I do have MDC set, so I can see which radio is keying up the repeater by its Radio ID number (just me and my family using my radio net most of the time), but that is a private repeater and I want to know when some outside person is on the net. (Usually other guest users do not have MDC set up, so I see a "1" or "0000" come through). 

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I think a good lawyer would argue that proprietary encoding is not encryption.  Encryption is intentionally done for the singular purpose of concealing the meaning of messages.  A proprietary encoding scheme makes it very easy to decode the messages; you just have to buy the interface. 
 

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I believe Motorola’s patent on MDC has expired. That would mean it’s no longer even a “proprietary” signaling system. The patents are listed at the end of the below article on Wikipedia. The technical details are known how it functions.

https://en.wikipedia.org/wiki/MDC-1200

Several of my Kenwood commercial radios have it. For example the TK-3360.

https://pdfs.kenwoodproducts.com/16/TK-2360&3360Brochure.pdf
 

The radio can be easily programmed to work on GMRS, however it’s only certified for Part 90 so it’s not strictly legal to use except on Part 90 and the Ham 70cm band.

Personally I’m more interested in seeing the FCC to allow some form of digital voice to be used. I think people favor DMR. If they allow NXDN my NX-300’s are already certified for Part 95A. I can use them on GMRS FM currently.

https://comms.kenwood.com/common/pdf/download/301_NX200-300.pdf


 

NX-300 FCC Grant - 1.pdf

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10 hours ago, Lscott said:

Personally I’m more interested in seeing the FCC to allow some form of digital voice to be used. I think people favor DMR. If they allow NXDN my NX-300’s are already certified for Part 95A. I can use them on GMRS FM currently.

I agree! 

With the limited number channels offered in GMRS.  DMR could actually (if implemented) double the number of channels due to the dual time slot capability and, still remain compatible with analog users, so nobody gets 'left out in the cold'.  I don't see the FCC doing this anytime soon (if ever), but we can hope, right?  I think the issue boils down to such technologies taking GMRS beyond the scope of what GMRS is/was intended to be, at least from the FCC perspective.

This too, is a topic for another discussion.

🙂




 

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13 hours ago, PACNWComms said:

In my area of the country, many GMRS repeater owners state that they want users to refrain from using MDC, Talk Permit Tones, "Roger Beeps" or any other signaling, mostly due to the noise of those signals, or to keep Motorola users from "flexing" on other users......used to a thing in the past but surplus Motorola is also a lot more common now (as is other manufacturers including MDC in their products).

On my own Spectra repeater system, I do have MDC set, so I can see which radio is keying up the repeater by its Radio ID number (just me and my family using my radio net most of the time), but that is a private repeater and I want to know when some outside person is on the net. (Usually other guest users do not have MDC set up, so I see a "1" or "0000" come through). 

The Spectra was the last radio that was given to field support specialists to 'beat up on' (in real world use) in an effort to uncover any serious issues, before it became a released product.  That use to be a common practice in the Bob Galvin days of Motorola, and so the Spectra was perhaps, one of the most reliable radios ever produced.  Not saying later model radios are of lesser quality, only that the Spectra was the last radio produced when 'do it right the first time' was an actual practice within the company, and not simply a 'slogan'.

Bottom line, it was and remains a great radio!

🙂

 

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1 hour ago, WROZ250 said:

I agree! 

With the limited number channels offered in GMRS.  DMR could actually (if implemented) double the number of channels due to the dual time slot capability and, still remain compatible with analog users, so nobody gets 'left out in the cold'.  I don't see the FCC doing this anytime soon (if ever), but we can hope, right?  I think the issue boils down to such technologies taking GMRS beyond the scope of what GMRS is/was intended to be, at least from the FCC perspective.

This too, is a topic for another discussion.

🙂




 

It would nice if they did. This topic should be split off into a separate thread.

However some of the benefits might be lost along the way, increased channel capacity and lower battery drain. People are confused enough trying to figure out repeaters, offsets and tones. Now you want them to understand talk-groups, color codes and time slots? I suspect if it ever does get approved it will look more like the DMR446 license free service you see in Europe as a DMR tier 1 service. There the radios transmit on both time slots I believe from a few websites I've been too looking for info. The later might be country specific. So much for added channel capacity and lower average TX power savings. What they do for talk-groups I'm not sure.

https://kenwoodcommunications.co.uk/files/file/comms/uk/pmr446/PMR446-White-Paper-V6_18AUG2016_JT_KB.pdf

They also have dPMR446 which uses FDMA, which is very similar to NXDN. Note they have several different codecs that can be used. You can find the Chinese dPMR radios, most are really DMR (TDMA) based, while a few are FDMA but use some Chinese specific version of a codec that is not compatible with the AMBE+2 you typically see in NXDN, P25 and DMR radios from the major manufactures.

https://en.wikipedia.org/wiki/Digital_private_mobile_radio

Confused? Yes they have three different modes used on their license free service, the equivalent to our FRS radios. It seems to work for them so I don't see why it won't here.

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3 minutes ago, Lscott said:

 People are confused enough trying to figure out repeaters, offsets and tones. Now you want them to understand talk-groups, color codes and time slots?

Yeah, programming DMR radios is definitely not for the inexperienced (or the impatient). LOL!

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3 hours ago, WROZ250 said:

Yeah, programming DMR radios is definitely not for the inexperienced (or the impatient). LOL!

Yeah, when I got my DM-1701 it took a while to get it programmed with CPS and I've been using Chirp for years on my analog dual band. I had to get the DMR though because more and more racetracks are going digital instead of analog and I don't like using their headsets, I have my own and my own radio that I'll use at tracks that the com manager will allow me to. I've had a couple say no to allowing me to use my radio and that is fine. I have been getting more headset adapters over the years though and that seems to work for using my headset with their radios.

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Pertaining to the discussion of MDC being a form of 'encryption'  It's really not.  FCC specifies that it's illegal to modify the transmission 'to obscure the meaning of the communication'  MDC doesn't obscure anything.  And even being 'proprietary' doesn't hold water.  I don't own a fusion radio or a DStar radio.  So since I can't hear it, is it being specifically obscured so I can't hear it as a ham operator, and is it being done specifically so I CAN'T hear it?  Of course the answer is no.  And if you were to program up a GMRS radio with MDC status messages and broadcast them, are you obscuring the meaning?  Not unless you specifically will NOT allow others to know what those status messages are.  If you were to set up 16 status messages in MDC and then POST them here on the board, they aren't obscured.  If you are only using MDC as unit ID's for your radios, nothing is being obscured, it's your radio ID.  And MDC is limited to what it can send.  It's not packet of another digital mode where you are shipping text messages with it.  The status messages are assigned a specific number that is universal to the protocol.  If STS16 is 'A$$CLOWN on repeater" then it's not obscured if posted. And it's universally STS16 message on the MDC protocol.  Now I can' have STS16 as "I Love You' to be sent to my wife.  It's still STS16.  Of course if you have it as something else, then your radio will display something different.  But again, I am using it to communicate with my wife and you are using it to warn others of shenanigans on the repeater.   But they are BOTH STS16 in MDC. 

Now, if a number of us were to get on the repeater and start speaking Russian, is THAT 'encryption'.  If we are doing it do others CAN'T understand what we are talking about, then yes, that's encryption, not because we are using the Russian language, but because we are SPECIFICALLY using it to obscure the meaning on purpose so others CAN'T understand the meaning of the communications.  But if we have a Wednesday night net to keep our multi-lingual skills up to par and speak Russian for most all of the net then it's perfectly legal.  It all goes back to intent.

I honestly believe the only reason that we aren't allowed ANY form of encryption on ham specifically, even on WiFi links is the FCC doen't want to field the telephone calls about it from the old farts that would be raising hell about it because they can hear it on their old tube radios.  I have no doubt that when VHF went to FM the old codgers were mad because their AM VHF radios wouldn't hear it.  And it was gonna be the downfall of ham radio.

Now I am not saying GMRS should be allowed P25 C4FM modulation and AES256 encryption.  But DMR and building a nationwide network with IPSC (Ip site connect) would be nice, but also not really needed. 

So I really think it's about intent at the end of the day.  But I will also say this about MDC.  One of the features with MDC is Radio Stun.  Which enables you to send a command to a radio with an MDC ID to basically turn it off.  It's used commercially to disable rouge radios and stolen radios that pop up on the system.  And it's pretty effective.  Yes, you have to have a radio or console that will transmit that command, but that stuff IS out there in the wild. 

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GMRS rules used to specifically mention that any Non-English conversations still needed to ID in English (or CWID). I'm not sure if the newer version of the rules still says that, but I can tell you that my family regularly uses non-English on the repeater, and allows the CWID to take care of identifying. I don't really care if A$$C10WN gets upset about that.

 

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18 minutes ago, Radioguy7268 said:

GMRS rules used to specifically mention that any Non-English conversations still needed to ID in English (or CWID). I'm not sure if the newer version of the rules still says that, but I can tell you that my family regularly uses non-English on the repeater, and allows the CWID to take care of identifying. I don't really care if A$$C10WN gets upset about that.

 

As long as the ID is made by the rules who cares what language is spoken on the repeater. You’re not trying to hide or obscure the communications so it shouldn’t matter to anyone else.

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1 hour ago, Lscott said:

As long as the ID is made by the rules who cares what language is spoken on the repeater. You’re not trying to hide or obscure the communications so it shouldn’t matter to anyone else.

Exactly.  And all I was getting at was if you are speaking spanish because you want to then your legal.  If you are doing it to obscure the message content then technically it's a problem.  But there again, you do it all the time.  So the only one that would know what the motivation was for speaking another language is you.  And that gets into the whole 'no duty to self incriminate' so again you are covered. 

My other point was using MDC isn't encryption if it's not specifically being used to mask meaning.  And simply sending a radio ID is certainly NOT masking anything.

 

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