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[aprssig] poor man's blue tooth

wes at johnston.net wes at johnston.net
Wed Aug 4 21:23:54 UTC 2004


I don't mean to quote too much... but here's what I read in your link....

§97.305 Authorized emission types.
 (a) An amateur station may transmit a CW emission on any frequency authorized to
the control operator. 

(b) A station may transmit a test emission on any frequency authorized to the
control operator for brief periods for experimental purposes, except that no
pulse modulation emission may be transmitted on any frequency where pulse is not
specifically authorized and no SS modulation emission may be transmitted on any
frequency where SS is not specifically authorized. 

(c) A station may transmit the following emission types on the frequencies
indicated, as authorized to the control operator, subject to the standards
specified in §97.307(f) of this part. 
--snip--
UHF:
70 cm
Entire band
MCW, phone, image, RTTY, data, SS, test (6), (8)
--snip--
(6) A RTTY, data or multiplexed emission using a specified digital code listed in
§97.309(a) of this Part may be transmitted. The symbol rate must not exceed 56
kilobauds. A RTTY, data or multiplexed emission using an unspecified digital code
under the limitations listed in §97.309(b) of this Part also may be transmitted.
The authorized bandwidth is 100 kHz.
 
(8) A RTTY or data emission having designators with A, B, C, D, E, F, G, H, J or
R as the first symbol; 1, 2, 7 or 9 as the second symbol; and D or W as the third
symbol is also authorized. 

--snip--
§97.309 RTTY and data emission codes.
 (a) Where authorized by §97.305(c) and 97.307(f) of this Part, an amateur
station may transmit a RTTY or data emission using the following specified
digital codes: 
--snip--
(4) An amateur station transmitting a RTTY or data emission using a digital code
specified in this paragraph may use any technique whose technical characteristics
have been documented publicly, such as CLOVER, G-TOR, or PacTOR, for the purpose
of facilitating communications. 
--end quote--

Since this is 433mhz, it can be operated under part 97 with proper ID cycle. 
According to (4) above, we can use any code that is publicly documented... I bet
these little transmitters are using a publicly known modulation.

Thanks for the info about 10% duty cycle on the part 15.  I had no idea.  We'll
have to make the GPS only send GPRMC to satisfy that requirement.  

Wes





On Wed, 4 Aug 2004 13:46:21 -0500, David wrote:

> 
> One thing that needs to be looked for legality at is the legality of  
> using these modules for streamed data.  It's been a while since i last  
> looked at the rules, but as I recall, Part 15 unlicensed operation  
> requires that the transmission cycle be no more than 1/10 of the time;  
> it's meant for short burst communuication and not continuous streams of  
> data.
> 
> Now, if you meant to use these as amateur transmitters, it'll need the  
> 10 minute idenfication as well as a reduction from 8-bit ASCII to 7-bit  
> ASCII (according to  
> http://www.arrl.org/FandES/field/regulations/news/part97/d- 
> 305.html#309, only 7-bit ASCII is permitted), both of which will  
> require more smarts than just RS232 level translation.
> 
> --david
> 
> ------------------------------------------------------------------------ 
> --
> Message: 4
> Date: Tue, 03 Aug 2004 15:32:33 -0400 (EDT)
> From: wes at johnston.net
> Subject: [aprssig] poor man's blue tooth
> To: aprssig at lists.tapr.org
> Message-ID:
> 	<20040803123233.22322.h016.c000.wm at mail.johnston.net.criticalpath.net>
> Content-Type: text/plain; charset=iso-8859-1
> 
> Although one of the arguements against blue tooth enabled GPS units is  
> that you
> just have that many more batteries to replace... consider this...
> 
> I'm thinking of two uses..
> 1)I have a GPS unit in my car and want to stream the GPS data to a  
> laptop without
> having to have a tangle of wires.  My GPS is already wired to a d700.
> 
> 2)In an emergency comms bus, I want to have the ability to share GPS  
> and TNC data
> with other users.  I don't need them to be able to talk back, just to  
> see what's
> going on around them.
> 
> I think a neat "one to many" solution is Linx Technologies LC 433mhz rf  
> modules.
> The modules are simple 433mhz radios with serial in / serial out.  The  
> TX module
> is $5.60 in onesies, RX module is $11.80.  These modules TX at 5kbps at  
> a range
> of 300 feet.  All we need is to add them to a PCB with will do the  
> rs232/ttl
> level conversions and Y GPS data and TNC data together (on the TX  
> side).  Give
> each person/laptop you want to beable to see what is going on a RX  
> module with
> rs232 or they have a rs232 to USB module for $10.  Now you can "stream"  
> data out
> of the em comm bus to a public display (in the case of a publicity show  
> and tell)
> or even share a GPS between two cars which are following each other....  
> or pass a
> laptop around the inside of car w/o wires.
> 
> http://www.linxtechnologies.com
> 
> Wes
> 
> 
> I have seen the village...
>     and I don't want it raising my children.
> 
> 
> 
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I have seen the village...
   and I don't want it raising my children.




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