Re: Launch Controller



2
As far as I know, there is NO frequency that allows a no-license 2-watt transmitter other than 27 MHz CB. IIRC, the 72 & 75 MHz bands are limited to 1 watt, although it depends on how it's measured - 1 watt RF output corresponds fairly closely to 2-watt DC input (P=EI) at the transmitter final stage. I don't know which way the FCC specs for RC control are written.
No-license operation, at much lower power levels, is permitted on the 49 MHz and 900 MHz bands used by wireless mikes and wireless telephone handsets.
In contrast - note that pocket size cellular phones use somewhere less than 1/2 watt of RF output. They work over longer ranges because the cell sites are on towers, of course.
FWIW: Any remote-controlled system based on simple signals or even two-tone DTMF frankly scares the crap out of me. It's far too easy to falsely or maliciously trigger the thing. I'd *really* rather not have some jerk send the firing signal when I have just armed a K motor and am still only 4 feet from the pad.
MJ WB9QLR
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We used one at the last launch, worked the first time every time. Most of the ignitors were Marty Gunnerson big fat Ignitorman brand, motors were H to L from Pro38, Ron Zeppin AP and Trailer Trash candy, it lit them with no problem. The case is fire insulated I wanted to test it, but Mike was not very enthusiastic about that! ... :-)
This page has some of the flight pictures; http://www.trailertrashaerospace.com/AHPRA_6.28.03.htm
PS: Mike who authorized you to be the "Grand Puba"?
Kevin Patterson http://www.trailertrashaerospace.com
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Are you allowed to do tone-controlling at 2 watts using 27 MHz? I know you can do voice, but can you use this freq/power for remote control. I don't want to get anyone in trouble, and I'm not bitching about this. I don't remember it being legal (does anyone have a link to FCC regulations?), and I don't want someone in out hobby to get into trouble. The product seems decent and well thought out.
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See http://a257.g.akamaitech.net/7/257/2422/14mar20010800/edocket.access.gpo .gov/cfr_2002/octqtr/47cfr95.412.htm
(Yeah, it's a long ugly government URL...watch the wrap)
27MHz is supposed to be voice communication only in CB, except in very rare instances. Encoded control tones are NOT a part of those...the CB frequencies are specified for voice communication.
--
Mike KD7PVT
NAR #70953 - Sr/HPR Level-1 ~ SeaNAR - The Seattle NAR Section #568
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On Thu, 10 Jul 2003 21:27:12 -0700, nojunk@this_address.com (Mike Pearson <see .sig>) wrote:

Makes sense...
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nojunk@this_address.com (Mike Pearson <see .sig>) wrote in message wrote:

Note that Radio Shack had thier Paging unit on 27Mhz, and that was 7 Watts output.
Now OOP, it has been on RMS before as a base for other projects, like recovery systems.
And IIRC, 27Mhz for Radio Control is set to 1 Watt, while 72&75 use is .7Watt
** mike **
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nojunk@this_address.com (Mike Pearson <see .sig>) writes:

There's still 5 or 6 of the old RC CB channels that CAN be used for applications like this. At least in areas where the truckers aren't stomping on them with KW amplifiers.
    Bob Kaplow    NAR # 18L    TRA # "Impeach the TRA BoD"         >>> To reply, remove the TRABoD! <<< Kaplow Klips & Baffle:    http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org
Save Model Rocketry from the HSA! http://www.space-rockets.com/congress.html
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ProLaunch is using the same transmitters and receivers SWT (www.spacewarptechnology.com) has used for about 4 years. The low power units should never be placed on the ground because that will definitely interfere with range. The XR4 is a 2 watt transmitter with SWT does not use because the security codes available are far less than what is available in low power. The other reason is the low power units would be much harder to monitor and to capture the code generated. The two watt transmitter can be picked up by anyone within range who wants to cause problems. The frequency is 27 MHz and is legal to use. The frequency is used in a lot of security equipment. SWT sells a different design that has proven to work in almost any terrain a rocket can be launched from. SWT even sells the units, but charges a little. The main reason for the higher price is SWT provides technical support and will replace the unit if the user fries it accidentally.
You can buy: the low power transmitter at: http://store.yahoo.com/linear-access-controls/transmitters.html . the low power receiver at: http://store.yahoo.com/linear-access-controls/sere.html . the high power at: http://store.yahoo.com/linear-access-controls/xtenradcon.html .
Arnold
"Mark Johnson" < snipped-for-privacy@lsil.com . wrote in message

no-license
encoding?)?
some
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On Fri, 11 Jul 2003 04:13:20 GMT, "Arnold Roquerre"

Signal reception depends as much on receiver selectivity and sensitivity and antenna design, if not more, then raw power. That's why your 100 milliwatt cell phone is able to reach that cell site so clearly half a klick away.
Power, of and by itself, means nothing. It's the final Signal to Noise ration at the receiver that will matter in the end and this will largely be determined by the factors I mentioned above.
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I was referring to the ability of a hacker to pick up the transmission from the transmitter with the intention of using it to start launches. One always needs to consider the jerk out there, who like their virus sending counter parts out in Internet land, wants to cause trouble. A 2 watt transmitter's signal sent at ground level will be much easier to pick up 3000' - 6000' away than a transmitter at the same position sending out a signal in milliwatts.
wrote:

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Howdy,
After looking at both sites for these products, the ProLaunch (8 pad - low power $379.00) looks more functional, tough and well designed than the SWT unit.
(SWT - 8 channel - Low power $879.00...pretty cheesy lame design). And if the brain parts are the same why is SWT selling their unit for what looks like $700 over cost! That's just greedy!!! That's giving it to us where the sun don't shine!!!! No tech support is worth that price difference, especially if I can by the replacement board for $80.00 as shown in the link below, if that is what both units are using.
As for the problems related to signal grabbing inherent to all wireless systems, lets face it... if someone has the knowledge, equipment and is hell bent on grabbing a signal and using it to potentially harm others, it doesn't matter if it's low power, hi power, a million codes or 60,000 codes... It can be done. Why I don't know?
As for me... I'm sticking with my extension cord and car battery! :)
My 2 cents...
Paul

limited
still
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Well the ProLaunch design is basically a box wrapped around a receiver with relays added. The problem is the box sits on the ground and that is bad. Linear Corp. does not recommend placing their receiver on the ground besides it can get stepped on. The cheesy SWT unit has been field tested and has never failed, been stepped on. It is field repairable, uses extension cords which can be replaced immediately, uses relays rated at 40 amps and includes a power supply. The strobe can be seen from 500' to 700' away with the naked eye and further with a cheap pair of binoculars.
You must be a "liberal democrat". Government workers are Greedy. Liberal socialist who force shit down our throats and demand we be taxed even if we object to the service and/or the price (tax) are Greedy. See you don't have to buy it. Now, isn't that a neat concept! Here is another one, maybe the price is what it is worth to the owner to assemble one of these units, ship it and guarantee it for two years. Also, maybe, the owner doesn't want everyone to have access to these units and is charging the high rate to keep the unit rare. Maybe the owner doesn't want to deal with pedestrian products and the people that buy them. You know - price discrimination really does work.

2-watt
transmitter
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Arnold,
You sound like you are the owner... are you?
My expirence is that if it looks like greed, and smells like greed... it's probally greed!
Paul Runion

output
the
less
to
have
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with
Where did you see the recommendation to put it on the ground? In our tests we used a folding camp chair. The Pro Launch is very well constructed, housed in a steel box, I doubt that even your clumsiness, falling over or stepping on it would harm it.
Photos of it in use; http://www.trailertrashaerospace.com/AHPRA_6.28.03.htm
In the past we tried a 5 gal bucket to elevate it, the blast from a full L sugar motor blew it about 15' and we only managed to break a fuse.

cords
The ignitor leads are also field replaceable on the Pro Launch. The choice of battery is left up to the rocketeer as many already own their preferred power source.
Much snobby BS deleted

products
I know, being part of Trailer Trash Aerospace we are probably way to "pedestrian" for you, thank goodness.
Kevin Patterson http://www.trailertrashaerospace.com /
Not affiliated with Pro Launch, other than having the pleasure of testing their units. It sure beats lugging a couple of hundred feet of extension cord, especially when clumsy people like Arnold are around tripping over the cords!... :-)
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