That's pretty. I'll be at the space tomorrow, and happy to lend a hand with any assembly and testing.
Would you plan to stick to this power for the most part, or crank it higher later? On Wed, Jul 2, 2014 at 5:16 PM, Guan Yang <[email protected]> wrote: > For various reasons I only have one functional board right now. > > I'll try to assemble a few more tomorrow so we can test range, frequency > deviation and data rates. I believe the default is 20 kHz deviation, which > is not very friendly, and I want to see if 5 kHz works. That should give a > total bandwidth of roughly what an FM voice channel occupies. > > I'm trying to demodulate in GNU Radio but it's a fucking nightmare to > figure out. > > On Jul 2, 2014, at 16:58, Zachary Giles <[email protected]> wrote: > > > *pant pant* > > > > On Wed, Jul 2, 2014 at 4:51 PM, Robby O'Connor <[email protected]> > wrote: > >> I wanna play with it :( > >> > >> --Rob > >> Sent from my phone...excuse any typos please! > >> > >> On Jul 2, 2014 4:12 PM, "Guan Yang" <[email protected]> wrote: > >>> > >>> yes, 30 dBm is 1W. > >>> > >>> I have an initial board based on an Atmel SAM D20 microcontroller and > >>> RFM23BP. I've attached an RTL-SDR screenshot showing it in a CW test > >>> mode. With simple heatsinking from the PCB through the pad on the > >>> bottom, it barely gets hot at maximum power. > >>> > >>> (I'm running this board at 3.3V, which limits output to 27 dBm > according > >>> to HopeRF.) > >>> > >>> On Fri, May 23, 2014, at 22:37, Robert Diamond wrote: > >>>> 30 dBm is 1W, right? > >>>> > >>>> > >>>> On Fri, May 23, 2014 at 9:13 PM, David Reeves <[email protected]> > >>>> wrote: > >>>> > >>>>> You can certainly open the squelch on your end, but at the events I > >>>>> was at > >>>>> recently, folks were able to reliably 'kerchunk' the repeater but not > >>>>> transmit audio - perhaps the transmitted audio just isn't often > enough > >>>>> under bad conditions to open the repeater squelches, and that we > can't > >>>>> change. > >>>>> > >>>>> I have been musing on the possibility of getting around the canyon > >>>>> problem > >>>>> using longer wavelengths. This > >>>>> paper<http://images.rfdesign.com/files/4/0499WARNAG36.pdf> suggests > >>>>> that a Part 15 device could theoretically easily get 10 miles at 1705 > >>>>> kHz/100mW, at least during daylight. But it's very dependent on > ground > >>>>> wave > >>>>> and noise floor, so probably it's no good for mobile stations for > >>>>> audio. > >>>>> But just maybe, with a low bandwidth digital mode, it would be enough > >>>>> for > >>>>> short texts, even if the antennas were suboptimal? I saw a video of a > >>>>> guy > >>>>> getting an urban 2 mile range with audio on medium wave AM using one > >>>>> of these > >>>>> kits <http://www.sstran.com/pages/AMT3000/overview.html>. I may get > >>>>> one > >>>>> just for experimentation purposes :) > >>>>> > >>>>> > >>>>> On Fri, May 23, 2014 at 8:34 PM, Guan Yang <[email protected]> wrote: > >>>>> > >>>>>> On Fri, May 23, 2014, at 20:10, David Reeves wrote: > >>>>>>> Ok, so is the reasoning here that some kind of direct FSK > >>>>>>> modulation > >>>>>> will > >>>>>>> suffer fewer of the propagation difficulties that we've seen with > >>>>>>> reception > >>>>>>> of voice/AFSK? > >>>>>> > >>>>>> Yes; certainly on a per-baud basis. I've found that a lot of the > time > >>>>>> under bad propagation situations you can actually hear voices if you > >>>>>> open the squelch. Something not mediated by the FM voice thing > should > >>>>>> be > >>>>>> better. > >>>>>> > >>>>>> RFM23BP has a best case RX sensitivity of -120dBm, which is well > >>>>>> below > >>>>>> the noise floor at these frequencies. Of course we will have to test > >>>>>> it. > >>>>>> But even if propagation is just as terrible as FM voice, it will be > >>>>>> easier to copy a digital transmission because we can do aggressive > >>>>>> forward error correction and easily repeat transmissions many times. > >>>>>> > >>>>>> It's frustrating to be able to hear that there's *some* voice > without > >>>>>> understanding the words. Also talking to people is horrible even > >>>>>> under > >>>>>> ideal circumstances. > >>>>>> > >>>>>>> I'd assume this would be simplex only, which has in fact been by > >>>>>>> far the > >>>>>>> most reliable over the few small-area (< 3 miles) urban nets I > >>>>>>> attended > >>>>>>> recently. If we could get up to a 10 mile range somehow with some > >>>>>>> clever > >>>>>>> digital processing, I'd think that would be very useful indeed for > >>>>>>> us > >>>>>>> canyon-dwellers - do you think that might be possible? > >>>>>> > >>>>>> We could have digipeaters. That alone would help a lot. A 2m or 70cm > >>>>>> FM > >>>>>> voice repeater is a big hassle to move around and set up. With a $50 > >>>>>> digipeater we could just plant them in various locations in the > field > >>>>>> and cross our fingers that they won't get stolen - and it won't be a > >>>>>> huge deal if they are. > >>>>>> _______________________________________________ > >>>>>> Radio mailing list [email protected] > >>>>>> https://list.hackmanhattan.com/listinfo/radio > >>>>>> > >>>>> > >>>>> > >>>>> _______________________________________________ > >>>>> Radio mailing list [email protected] > >>>>> https://list.hackmanhattan.com/listinfo/radio > >>>>> > >>>> _______________________________________________ > >>>> Radio mailing list [email protected] > >>>> https://list.hackmanhattan.com/listinfo/radio > >>> > >>> _______________________________________________ > >>> Radio mailing list [email protected] > >>> https://list.hackmanhattan.com/listinfo/radio > >> > >> > >> _______________________________________________ > >> Radio mailing list [email protected] > >> https://list.hackmanhattan.com/listinfo/radio > > > > > > > > -- > > Zach Giles > > [email protected] > > _______________________________________________ > > Radio mailing list [email protected] > > https://list.hackmanhattan.com/listinfo/radio > > _______________________________________________ > Radio mailing list [email protected] > https://list.hackmanhattan.com/listinfo/radio >
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