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Author Topic: Private aprs on alternate frequency?  (Read 7411 times)
KI6TDB
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Posts: 2




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« on: September 12, 2012, 01:29:00 AM »

I have been using APRS for 3+ years now, but always on the public frequencies

I am building a $500 race car to enter into a local amateur race circuit in northern california, and am hoping to use APRS for telemetry. I don't want to spam the public APRS network (I hope to do 30 to 60 second updates). What's the etiquitte for picking other frequencies to do this on? Since I'm not keying it up myself, i may not be able to readily notice if other people are on those frequencies too.

Specifically, I have an argentdata opentracker 3 device in the car, connected to a 5w HT radio (I'd go lower power, but the next step down on this unit is 500mw, and wasn't reliably transmitting through the car, and I can't easily get an external antenna installed). On the receiving side, I have a tinytrack 4 connected to a laptop running xastir.

-brian
ki6tdb
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K7RBW
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Posts: 384




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« Reply #1 on: September 12, 2012, 06:20:38 AM »

As long as you don't interfere with anyone, it should not be a problem.

The question then becomes if you find an unused freq, start to use it for your activity, and another ham comes in on the same freq for a rag chew, who's interfering with whom? That said, if someone hears an APRS burst every 30 seconds, they'll probably just go to another freq.

You might also give some thought to using a freq in the 70 cm (440) band or even the 900 mhz band, where the chances of bumping into someone are even smaller (and you could also run a higher data rate).
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KA6MLE
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Posts: 77




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« Reply #2 on: September 12, 2012, 10:11:41 AM »

Well 146.52 is pretty dead in my area and available  Roll Eyes (JUST KIDDING)

If you don't have a bunch of Packet Radio activity in your area you can use those frequencies:

144.90-145.10 Weak signal and FM simplex (145.01,03,05,07,09 are widely used for packet)

Jim
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AF6OF
Member

Posts: 27




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« Reply #3 on: September 14, 2012, 07:04:47 AM »

Not only is it permissible, but operating off the National APRS frequency is the polite thing to do for a fast transmission rate. I suggest operating without a CTCSS tone to minimize the chance you are kerchunking someone's repeater, and to make sure you listen +600 KHZ and -600 KHZ to help verify that you are not hitting a carrier operated repeater. If you can, run the transmitter before the race for several days, with your e-mail in the comment field. Give anyone who is usign the frequency and might be effected by your low power station a chance to have input.

73,

Allen AF6OF
VHS
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KB9TMP
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Posts: 58


WWW

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« Reply #4 on: September 16, 2012, 01:00:23 PM »

If you look at the ARRL bandplan for 2 meters 145.5 to 145.8 is listed as miscellaneous and experimental modes. I run an EchoLink simplex link at 145.72 in Lawrence Co. Indiana. There is no one else in that area at all it's always silent. You might give that slot a listen and see if that would work for you.

Best Regards "73" from
W.W. Warren - KB9TMP, ARRL VE
EchoLink Node: 7492 KB9TMP-L
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W5LZ
Member

Posts: 477




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« Reply #5 on: September 18, 2012, 06:45:58 AM »

And just for grins...
An external antenna and 500 mw doesn't sound too unreasonable.  At the least, it would extend the time the setup could be used.  A transmission every 30 - 60 seconds can certainly add up and run down an HT's battery (assuming that's how you are powering it).
 - 'Doc
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