*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
