[aprssig] APRS-B?

Scott Miller scott at opentrac.org
Mon Jun 24 17:00:58 CDT 2013

I think the RFM12B code for the OTUSB is already published to SVN.  I 
don't mind sharing that at all.  I don't remember what's different about 
the RFM22 modules, but I'd prefer to stick with whatever is most flexible.


On 6/24/2013 2:31 PM, John Wiseman wrote:
> I posted a message about 6 months ago about experiments with the RFM22B
> (100 mW) and RFM23BP (1 Watt modules). I also obtained a couple of the
> RFM12B (500 mw) units, but I found the interface much more difficult,
> and would recommend the 22/23 modules. I made a board for the Raspberry
> PI, and it seemed to work pretty well. and at $25 seems reasonable, but
> for a simple dig function the code could probalby run on the PIC.
> As I do a lot of sailing in the summer, the project has been put on hold
> till the Autumn, but if anyone is interested in preogressing the ideas,
> I can publish the board design and code.
> To save you trawling throught the archive, I'vr repeated the message below.
> 73, John G8BPQ
> A while ago (22 September) Bob posted a message about the RFM22 modules.
> I was working on a TNC for the Raspberry PI at the time, so decided to
> try building a TNC round these modules. There is a photo of the result here
> _https://dl.dropbox.com/u/31910649/RMF22BTNC.png_
> The board is the same size as the PI (about the same as a credit card).
> This one is fitted with the RFM22B module, with 100 mW output, but the
> board will also take the 1 Watt RFM23BP. Although designed to work with
> the PI, it also has a header for a serial to USB converter, so it can be
> used as a standalone KISS TNC.
> To test as a tracker I lashed up a board to connect the Adafruit
> Ultimate GPS Breakout board. Photo here:
> _https://dl.dropbox.com/u/31910649/S1360001.jpg_
> I've now got them running, and just completed my first tests. On the
> first trial with the 100mW version I achieved a range of just under a
> mile, with a
> 5/8 over 5/8 70cms whip on the car, and a far from ideal Marine Band
> whip at base (The 70 cms colinear I bought for the test turned out to
> have an infinite SWR!).
> Although very much a work in progress, I thought I'd share results so
> far - if anyone else is working with these modules I'd be interested to
> hear from them.
> BTW, the GPS module is pretty neat as well - it is about an inch square,
> and includes a data logger - _https://www.adafruit.com/products/746_
> 73, John G8BPQ
> ------------------------------------------------------------------------
> *From:* aprssig-bounces at tapr.org [mailto:aprssig-bounces at tapr.org] *On
> Behalf Of *Robert Bruninga
> *Sent:* 24 June 2013 13:55
> *To:* aprssig at tapr.org
> *Subject:* [aprssig] APRS-B?
> I’m impressed with the 500 mw transceivers on 433 MHz costing $20 or so
> and operating at 9600 baud.
> Why don’t we call this APRS-B (plan B).  And start paralleling our
> network with these devices.
> Then instead of only 5% of hams having APRS capability, we could get
> more people in the clubs to own a device and also to put one up at home
> so we have a backup data channel as well?
> Maybe lots of you are doing this alrady and I am the last one to the
> party.  But whatever we do, lets standardize on something so we are all
> headed in the same direction.
> These are wideband devices, so they are not compatible with any existing
> APRS or other ham FM radios.  That is why it is a fresh start.  What is
> the sync and key up time?
> Sure the range of 500mw is small, but at only 10% of the cost of a digi
> we can put them at more and closer places and even solar power them.
> Bob, WB4APR
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