[aprssig] APRS legality

Steve Dimse steve at dimse.com
Wed Jan 28 15:34:08 CST 2009

On Jan 28, 2009, at 12:12 PM, Robert Bruninga wrote:
> Yes, all applications that do not detract from others are
> welcome.

Slippery slope, Bob. "Applications that don't detract from others"...  
Who decides which applications are blessed and which are not? It seems  
you want to be the one to make that determination. My position is no  
one individual or group has the right to make that determination. It  
depends so heavily on local use and convention that I think no czar  
has the right to do this. If an area has 20 people that use 144.39  
just for one-way trackers, do you really think you have the right to  
tell them it is an unacceptable application?

> We are not arguing the devices or stations, what we
> are arguing is the definition of the APRS system.

You can define the term "APRS (TM)" any way you want, you hold the  
trademark rights to the term. That is a very different thing from  
telling people how they can use the tools that have been created for  
"APRS (TM)".

>> How can you cling to this idea that a network
>> is needed to make APRS legal in the US.
> Because without transmissions being intended for the other
> participants, (as they are in a net) then by your own claims,
> they are nothing more than blind one-way transmissions, which
> are very strictly limited by the FCC in the rules.

Oneway transmissions are limited in the rules yes, but because the one- 
way APRS transmissions are telemetry, they are fully legal within the  
limitations of those rules.

On the other hand, if you say the thing that makes APRS legal is that  
the participants are part of a net (again, something never mentioned  
in the rules), then if I am driving between two areas with networks,  
in an area without a network, I must turn off my tracker or else I am  
violating the rules. This is ridiculous at first glance!

> It is not in
> keeping with the general principles of ham radio to transmit
> blindly on a shared net, so for the health of the network, we
> need APRS operators to be sharing the experience and the channel
> and able to react to the network situation and to each other.

If you are talking about "good amateur practice", what is acceptable  
on a voice net is very different than what is acceptable on 144.39,  
just like what is good amateur practice on ATV is different from HF  
voice. Different modes, different "good practices". If you are talking  
about the rules, again, there is NO MENTION OF NET in Part 97!
>> Show me one single place in the rules where
>> the word or even the concept of network
>> appears...
> A net is a group of other licensed individuals participating in
> a two-way information exchange.

I know what a net is. What I asked is show me where it occurs in the  
rules. Can't do it, can you?
>> Again, it is a shame that the FCC felt
>> one-way was such an obvious concept
>> they did not define it. I maintain that
>> any transmission not directed at one or
>> more specific amateur stations as part of a
>> bidirectional exchange is one way.
> Great!  Finally we agree.

Wanna bet?

>  APRS is that bi-directional two-way
> communication system, with individual operators "transmitting"
> their information "directed at" the many other "specific amateur
> stations" all participating in the bi-directional exchange on
> the national APRS frequency called  APRS (the quotes are your
> words).

Again, this makes 99% of users of APRS illegal. Specific stations  
means specific stations, not anyone who is listening. If I'm on your  
beloved voice net, the communications are with net control and the  
others who have checked in. In APRS, there is no net control, there is  
no checkin list. When someone transmits, they transmit their  
information to whoever may be listening. If no one is listening they  
still transmit it. That seems like one-way communication to me.

And once more, the information will be transmitted whether someone is  
listening or not. If I want to check in on a traffic net, I'll give my  
call, location, and any traffic I have to pass. If I do that during a  
net, it is a legal, because I am communicating that information to net  
control and the other stations which have checked in. On the other  
hand, if I tune to a random clear frequency and transmit "K4HG, Cudjoe  
Key, no traffic", that is certainly a one way transmission.

If you want to say that a computer (attended or not) transmitting a  
position on 144.39 is acting like the former voice net check-in, then  
the same station transmitting in an area without anyone on the air  
MUST be violating the rules. There is no way around it, the same rule  
has to apply. Either everything is legal as one-way telemetry, or  
transmissions may be legal or illegal depending on who is listening.  
If you persist in the latter case, the only way to make APRS legal  
would be for every APRS station to send a CQ before beaconing (?APRS?  
would be good APRS CQ), and not transmit anything else until it hears  
that another station is on the air.

> We agree that there are some one-way examples also on
> APRS as noted above, from unattended remote sensors.

We do agree on that, but I maintain that ALL positions, weather  
reports, tide gauges, etc. are one-way telemetry.
> I agree completely here too.  And you notice that your words are
> now allowing for NET's in  your statement above as "one-or more
> specific stations", which is what I have claimed all along.\

I never for a second claimed nets were not allowed. What I claim is  
that whether APRS is a net or not has no impact on whether it is  
legal, because Part 97 has no mention of anything to do with nets.  
Since there is no mention of nets, the mere act of being part of net  
cannot make you legal.
> Nope, they are two-way, since they are transmitted by an
> operator to "one-or more specific stations" who are
> participating in the roundtable (net) as two-way stations.

Bob, this is a wild guess, but I'd say over the last 12 years I've  
transmitted somewhere over 100,000 packets on HF and VHF APRS. Aside  
from a tiny handful of messages (probably less than 0.001%), none were  
directed at "one or more specific stations". There were one-way  
transmission to whoever happened to be listening, and for reception  
into the APRS Internet System. Yes, Bob, we do agree that APRS  
messages are two-way. but that is all.
> We disagree here.  If the station is both sending and receiving
> on the APRS channel with all the other specific participants
> (using your words), then it is two-way communications and not
> the same as the one-way unattended transmit-only remote devices
> that clearly fit the FCC definition of one-way transmissions.

Two one-way transmissions do not make a two-way transmission! Right  
now you and I are having a two way conversation. No matter how much it  
seems to others we are just screaming at each other, each message is a  
reaction to the other person's prior message. If one message from me  
was "today is wednesday", and you sent "The sky is blue", and I sent  
"PI = 3.1415..." are we having a two way conversation? Of course not,  
we are both sending random one-way thoughts.

You send your position every 30 minutes, I send my weather every 10  
minutes, Joe sends his tide reading every 15 minutes. Is this a three- 
way conversation, or three one-way transmissions. To me, the answer is  
obvious. And yes, I know this isn't your "concept" behind APRS (TM).  
This is however, the reality of 144.39. Go ahead and encourage people  
to use APRS more like your concept. Just please do not say people do  
not have the legal right, or the Bob-given right, to use the way the  
majority use, and want to continue to use, 144.39 and its associated  
APRS (TM) tools.

Steve K4HG

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