[aprssig] cellphone as control link?

Jim Lux jimlux at earthlink.net
Thu Oct 20 14:06:41 CDT 2005

Jeff KT2K commented:
This raises a great discussion on putting trackers on
vehicles of non-licensed persons.

Is it legal to have a non- licensed person turn a amateur radio
on and off and can a cel phone call function as a control link?

Interesting point here..
I think everyone will agree that the control operator can control a remote 
transmitter by means of a wireline connection (historically, a leased line).

Further, you can use a control link on an appropriate frequency (220 
MHz).  The link doesn't have to be continuous, does it? (i.e. I can use a 
PTT on my control signals)

You can also control by a "virtual wireline connection" (maybe not a leased 
line, but a "nailed up" ISDN phone call across the United States, for 

What about more ephemeral controls though:?

Autoanswer and wireline phone call?
Cell phone to autoanswer phone and TT decoder?
Internet remote access (telnet?)

Two incoming phone lines at the remote site, each of which rings a 
different bell and lights a different colored light, with a trained pigeon 
who observes the light and pecks at one switch or another to turn the 
transmitter on or off.

Cellphone call to teenage daughter and have her turn on or off transmitter 
(assuming you can get through with call waiting) [one might argue the 
pigeon approach is more reliable than the teenager]

Mailing a letter to the remote station, and when the site maintenance guy 
comes through once a month, he reads the letter and flips the switch 

Clearly, at some point, the control mechanism has become either unreliable 
enough, or has sufficient latency that you're not really "controlling" anymore.

How reliable does the link need to be? If my internet access at home is 
disabled because of  DoS attack, do I need a backup control plan? What if 
my telephone is disconnected or fails?

Is there some implied requirement for a "failsafe" or "deadman" (If the 
remote doesn't receive some sort of communication within 2 hours, it shuts 
down the transmitter.)

Jim, W6RMK

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