2014-04-27 00:03 dos11 has quit [Ping timeout: 252 seconds] 2014-04-27 00:16 Luke-Jr has quit [Remote host closed the connection] 2014-04-27 00:16 Luke-Jr has joined #qi-hardware 2014-04-27 00:20 Luke-Jr has quit [Remote host closed the connection] 2014-04-27 00:21 Luke-Jr has joined #qi-hardware 2014-04-27 00:23 Luke-Jr has quit [Client Quit] 2014-04-27 00:23 Luke-Jr has joined #qi-hardware 2014-04-27 00:34 hkm has quit [Quit: Leaving] 2014-04-27 00:45 atommann has joined #qi-hardware 2014-04-27 01:07 dandon_ has joined #qi-hardware 2014-04-27 01:09 dandon has quit [Ping timeout: 276 seconds] 2014-04-27 01:09 dandon_ is now known as dandon 2014-04-27 03:48 Luke-Jr has quit [Remote host closed the connection] 2014-04-27 03:48 Luke-Jr has joined #qi-hardware 2014-04-27 04:58 gbraad_ has quit [Ping timeout: 265 seconds] 2014-04-27 06:32 zcrc|drunk has joined #qi-hardware 2014-04-27 06:33 zcrc|drunk is now known as pcercuei 2014-04-27 06:40 wolfspraul has joined #qi-hardware 2014-04-27 06:40 jekhor_ has joined #qi-hardware 2014-04-27 09:58 sb0 has joined #qi-hardware 2014-04-27 12:01 dos11 has joined #qi-hardware 2014-04-27 12:03 jekhor_ has quit [Read error: Connection reset by peer] 2014-04-27 12:37 nicksydney has quit [Remote host closed the connection] 2014-04-27 12:38 nicksydney has joined #qi-hardware 2014-04-27 12:43 viric has quit [Ping timeout: 240 seconds] 2014-04-27 12:48 viric has joined #qi-hardware 2014-04-27 13:32 Ornotermes has quit [Quit: leaving] 2014-04-27 13:35 Ornotermes has joined #qi-hardware 2014-04-27 14:18 jekhor has joined #qi-hardware 2014-04-27 14:30 sb0 has quit [Read error: Operation timed out] 2014-04-27 14:43 sb0 has joined #qi-hardware 2014-04-27 14:49 jekhor has quit [Read error: Operation timed out] 2014-04-27 14:55 viric has quit [Ping timeout: 240 seconds] 2014-04-27 15:00 viric has joined #qi-hardware 2014-04-27 15:54 wej has joined #qi-hardware 2014-04-27 16:04 atommann has quit [Quit: Leaving] 2014-04-27 16:12 FrankBlues has joined #qi-hardware 2014-04-27 16:17 wej has quit [Ping timeout: 260 seconds] 2014-04-27 16:21 wej has joined #qi-hardware 2014-04-27 16:32 solrize has joined #qi-hardware 2014-04-27 16:32 are there still any ben nanonotes around? 2014-04-27 16:33 I have one... kinda gathering dust atm 2014-04-27 16:33 neat 2014-04-27 16:35 I've been thinking about running emulators on it - I used to have VICE working, and I thought someone had one of the older Mac emulators working 2014-04-27 16:36 nice! i didn't know about vice 2014-04-27 16:41 newbie question but, would it be very hard to make a simple 2.4 GHz GFSK demodulator? 2014-04-27 16:41 I guess that the fact that some part of the circuit would need to handle high frequency (GHz) is what would be the big issue for DIY 2014-04-27 16:43 but if you buy some IC to do the PLL part for instance, maybe it's feasible, right? 2014-04-27 16:44 There's a Dingux port of VICE that used to run on Ben, last time I tried it had strange dependency issues that I never got around to fixing. 2014-04-27 16:49 ysionneau, i imagine something like an AM detector to get rid of the baseband, then a hardware or software PLL? but i have no idea how stuff works at those frequencies 2014-04-27 16:53 bjj 2014-04-27 16:53 I mean, as long as I have a PLL to lock on the 2.4 GHz carrier 2014-04-27 16:53 oops 2014-04-27 16:54 and then I can demodulate by mixing the input signal with the PLL locked output 2014-04-27 16:54 all of this is the "hard part" because it runs at 2.4 GHz 2014-04-27 16:54 after that, it's baseband indeed 2014-04-27 16:54 you have a 2.4 ghz pll? that's what i didn't realize was possible, at least in the dinky equipment (e.g. bluetooth) that i imagine you're dealing with 2014-04-27 16:55 how can you demodulate a bluetooth signal without a 2.4 GHz pll ? 2014-04-27 16:55 I thought this was mandatory 2014-04-27 16:56 sample _all_ the baseband ;) 2014-04-27 16:56 sample with 4.8 GHz ADC? 2014-04-27 16:56 and then do everything as SDR 2014-04-27 16:56 but you need very expensive electronics 2014-04-27 16:57 " i have no idea how stuff works at those frequencies" => pure speculation but i was imagining some crude LC filter made of pcb trace, then a diode detector 2014-04-27 16:58 ysionneau: there are lots of SDR platforms which allow you to sample at 2.4GHz with a limited bandwidth 2014-04-27 16:58 you should probably ask on #electronics where there might be some analog rf folks hanging out 2014-04-27 16:58 say a few MHz 2014-04-27 16:59 larsc, is that stuff big and complicated? i was presuming this is for cheap low performance gear like wifi or bluetooth 2014-04-27 16:59 larsc: I am searching for very low price solutions 2014-04-27 16:59 solrize: depends on your definition of big and complicated 2014-04-27 17:00 wej has quit [Ping timeout: 252 seconds] 2014-04-27 17:00 ysionneau: but you want the digital bt signal? 2014-04-27 17:00 ysionneau: what do you want to accomplish in the end ? build an SDR system ? receive BT ? something else 2014-04-27 17:00 receive BTLE 2014-04-27 17:00 larsc, big/complicated = you can't build it into a 5 dollar consumer gizmo 2014-04-27 17:01 the cheapest solution is probably a off the shelf bt receiver 2014-04-27 17:01 well, in fact I want to learn RF 2014-04-27 17:01 I think I will start with a simple FM demodulator 2014-04-27 17:01 then it's not going to be cheap ;) 2014-04-27 17:01 ysionneau: have you been following what i'm doing on anelok ? 2014-04-27 17:01 wpwrak_: yes :) 2014-04-27 17:01 and do you just want to receive or also send ? 2014-04-27 17:01 pretty cool stuff 2014-04-27 17:01 then you already know some chips you can use :) 2014-04-27 17:01 yes 2014-04-27 17:02 but I would like to replace the chip with home made circuitery 2014-04-27 17:02 when it's possible 2014-04-27 17:02 to learn the RF part 2014-04-27 17:02 oh, i see. ah yes, there are components for that, too. and fpgas may come in handy, too 2014-04-27 17:02 larsc this is the copyleft hardware channel, using off the shelf bt doesn't count ;-). i've been wondering about this myself because of the suspicious code blobs in all the bt processors 2014-04-27 17:03 solrize: where do you draw the line? 2014-04-27 17:03 larsc: I want to demodulate, then I get the baseband analog signal, then I can sample with cheap ADC and get the digital stream 2014-04-27 17:04 it's just for fun, no big precise goal 2014-04-27 17:04 ysionneau: pll + demodulator 2014-04-27 17:04 larsc: does it sound like a very complex project? 2014-04-27 17:04 ysionneau, this rf is kind of outside the computer zone... but there are some arrl publications? arrl.org 2014-04-27 17:05 for sure I guess I need to buy the PLL since it will operate at high frequency 2014-04-27 17:05 but the rest of the board... I guess I can drop discrete components 2014-04-27 17:05 there are also demoulators with a built-in pll 2014-04-27 17:05 ysionneau, larsc does bt gear actually use plls? 2014-04-27 17:05 solrize: http://www.ti.com/product/lmx3162 2014-04-27 17:05 does anything not use a PLL ? :) 2014-04-27 17:05 ysionneau: http://www.analog.com/en/rfif-components/modulatorsdemodulators/products/index.html#Demodulators 2014-04-27 17:06 PLLs are about as common in modern electronics as electrons :) 2014-04-27 17:06 ah nice , thanks larsc :) 2014-04-27 17:07 wpwrak_, i dunno, we're talking about something with a design range of a few meters and in fact typical handsfree earpieces work a lot better if you hold the phone closer than keeping it in your pocket 2014-04-27 17:07 so they are willing to throw away a lot of the signal to keep the hw small and cheap 2014-04-27 17:07 that's why i was thinking of amplitude detection 2014-04-27 17:09 solrize: well, you can build an analog radio system, sure. old school :) 2014-04-27 17:10 not sure how quickly you'll bump into regulatory limit, though. but then if your sender is weak enough, maybe nobody will notice. 2014-04-27 17:10 for GFSK I guess I don't care about the I/Q output, right? 2014-04-27 17:10 I just take one of the two 2014-04-27 17:10 I/Q is useful for QAM, no? 2014-04-27 17:11 wpwrak_, yeah i was thinking if you make it crappy enough, it doesn't need much hardware 2014-04-27 17:11 having both makes the demodulation dead easy 2014-04-27 17:11 I/Q is the output of the chip, so it's already baseband, right? 2014-04-27 17:11 so already demodulated 2014-04-27 17:11 * ysionneau newbie, sorry 2014-04-27 17:12 wej has joined #qi-hardware 2014-04-27 17:13 yes 2014-04-27 17:32 rz2k has joined #qi-hardware 2014-04-27 17:51 by trying to understand some analog circuits, I feel I'm putting a toe in an ocean of unknown stuff 2014-04-27 17:52 "what's this ... ?" + wikipedia/google , then end up with explanation which raises another "what's this ?" etc 2014-04-27 17:52 * ysionneau affraid 2014-04-27 17:54 * whitequark is completely unable to grok analog circuits 2014-04-27 17:55 >>SDR platforms which allow you to sample at 2.4GHz<< wut? 2014-04-27 17:56 unclouded has quit [Ping timeout: 245 seconds] 2014-04-27 17:57 those exist but not for bluetooth ;) 2014-04-27 17:57 they are for fancy pants mobile base stations 2014-04-27 17:58 there's some dongle which can sniff bluetooth, but it's absurdly expensive 2014-04-27 17:58 I doubt *any* SDR is sampling with 4.8Gsamples/s 2014-04-27 17:59 you always use a Local Oscillator to downbeat-mix the input to some Intermediate Frequency 2014-04-27 18:00 for <100MHz you might do primary sampling 2014-04-27 18:00 I meant the baseband pll frequency, not the sampling frequency 2014-04-27 18:00 but there are also systems that have such a sampling frequency 2014-04-27 18:02 good luck with processing that data stream in realtime X-P 2014-04-27 18:02 larsc: every hobbyist should have one of those ;-) 2014-04-27 18:03 DocScrutinizer05: you'd typically not process it on a CPU 2014-04-27 18:03 aha 2014-04-27 18:03 in realtime 2014-04-27 18:03 so where's the S in SDR then? 2014-04-27 18:03 in the FPGA 2014-04-27 18:03 sure, a FPGA easily is processing a datastream of ~10GByte/s, probably via FFT 2014-04-27 18:04 maybe you get away even with 5GB/s 2014-04-27 18:04 yeah, and then some more. ask the radiotelescope folks :-) 2014-04-27 18:04 when using 8bit samples 2014-04-27 18:08 jekhor has joined #qi-hardware 2014-04-27 18:09 ysionneau: I/Q is basically the 90° phase skewed digitized samples of the IF. All (well, most) SDR is based on that 2014-04-27 18:12 consider sampling a frequency of 2Pi with a A/D that samples (average in) windows of Pi. You'd either get a maximum output signal of +max -max +max... for frequency in phase with sampling, or a 0, 0, 0, when frequency is 90° off in phase 2014-04-27 18:13 with I and Q sampling with a skew of 90° phase between the two A/D, you have supfficient info about your signal to do SDR on it, no matter what#s the modulation 2014-04-27 18:14 basically for AM you would do I+Q, for FM you do I-Q (simplified picture) 2014-04-27 18:16 since sampling at air frequency is simply impossible for all but the highest budget, at e.g. 2.4GHz, you first mix the input frequency with a Local Oscillator in a ring modulator that creates f(in)+f(LO) and f(in)-f(LO) as output 2014-04-27 18:17 then you usually filter out the f(in)-f(LO) band with a bandpass of a few MHz or kHz width, and then sample it or do analog decoding 2014-04-27 18:18 you also want to have a bandpass at "antenna" to avoid another input frequency sneak in, f1(in)-f(LO) == f2(in)+f(LO) 2014-04-27 18:19 that's called the mirror frequency 2014-04-27 18:20 the trick with I/Q modulators acutally is, that there is no image 2014-04-27 18:20 often SDR works with mixing down to zero, means LO frequency is (almost) equal to input frequency 2014-04-27 18:23 the cake is a lie 2014-04-27 18:26 FrankBlues has quit [Remote host closed the connection] 2014-04-27 18:32 for the LO usually PLL is used (actually an analog oscillator, a reference XTAL oscillator, and two programmable dividers feeding their output to a PLL that adjusts the analog oscillator), which you program to create a LO frequency of f(in)-$some-offset. This $some-offset is the Intermediate frequency you want to use. In shortwave receivers this IF is 455kHz usually, on FM receivers (80-200MHz) it's usually 10.7MHz 2014-04-27 18:32 so for FM the mirror freq is 2 * 10,7MHz 2014-04-27 18:32 ...off from your intended receiving frequency 2014-04-27 18:35 you want a bandpass at antenna that gives a sufficient dB attenuation for frequencies that are this far from your center freq, so even strong local transmitters at mirror freq don't interfere with your signal 2014-04-27 18:37 and you definitely don't want to build all that from discrete components for BTLE ;-) 2014-04-27 18:39 wej has quit [Ping timeout: 260 seconds] 2014-04-27 18:39 when you want to learn about that stuff, maybe RTLSDR is a good starting point 2014-04-27 18:39 the dongles are still available for a 10 to 20 bucks 2014-04-27 18:40 and some of them should even be able to reach 2.4GHz 2014-04-27 18:41 http://rtlsdr.org/ 2014-04-27 18:45 wej has joined #qi-hardware 2014-04-27 18:45 thanks for the big sum up :) 2014-04-27 18:46 yw 2014-04-27 18:46 NB that RTL dongles lack most of the filters/bandpasses I mentioned. The cheat on it 2014-04-27 18:47 they* 2014-04-27 18:48 so I/Q output of the demodulator are still signals at the carrier frequency? 2014-04-27 18:48 they don't use proper antenna bandpass so mirror frequencies may be a problem, and they don't use IF filter bandpass so the A/D for I/Q is prone to aliasing 2014-04-27 18:48 they are not located after the multiplication of the local oscillator ? 2014-04-27 18:48 no, they use a downbeat mixer tuner as described above 2014-04-27 18:49 the tuner output is some Intermediate Frequency of a few MHz which then gets digitized by the RTL2832 chip 2014-04-27 18:50 wej has quit [Ping timeout: 252 seconds] 2014-04-27 18:50 the tuner has the PLL aka LO and the mixer, and some amps 2014-04-27 18:51 the RTL2832 sends I/Q data to PC via USB 2014-04-27 18:51 ah ok so it lowers the frequency a bit, but not until baseband 2014-04-27 18:51 ok :o 2014-04-27 18:51 depends on how you program it 2014-04-27 18:52 "baseband" is not demodulated signal though. What you call "baseband" would be IF of zero 2014-04-27 18:52 and it's actually usually doing that 2014-04-27 18:52 IF = input frequency? 2014-04-27 18:53 well, some setups use a very low IF of some kHz or so, to get rid of the DC that sneaks in to I/Q when you mix down to exactl zero 2014-04-27 18:53 Intermediate Frequency 2014-04-27 18:53 what I call baseband is when you mix the input signal with exactly the carrier frequency (by using a PLL to obtain it, in phase) 2014-04-27 18:53 the input to the RTL2832, coming from tuner output 2014-04-27 18:54 then you should get your demodulated tone, but centered at 0 Hz 2014-04-27 18:54 instead of centered on the carrier freq 2014-04-27 18:54 well, modulation not working like this 2014-04-27 18:54 for AM you might get away with it, yes 2014-04-27 18:54 wej has joined #qi-hardware 2014-04-27 18:55 yes I think most of my "modulation" thinking is centered on QAM stuf 2014-04-27 18:55 but then it's pretty hard to filter away the LO signal from your input signal when you mix down to exact 0 to demodulate 2014-04-27 18:55 would you have some litterature to educate me on those topics ? 2014-04-27 18:56 modulation/demodulation 2014-04-27 18:56 hmm, maybe something comes to mind when I tthink a bit about it 2014-04-27 18:56 on several examples: FSK, QAM all sort of different modulation scheme 2014-04-27 18:56 right off top of my head I'm short of suggestions 2014-04-27 18:57 well, those are all already digital modulations 2014-04-27 18:57 book or website (pdf..) whatever 2014-04-27 18:57 FSK is digital FM 2014-04-27 18:57 I think I can start by digging up my old school book 2014-04-27 18:57 QAM is digital AM (more or less) 2014-04-27 18:57 yep I got that 2014-04-27 18:58 sorry, afk 2014-04-27 18:58 I'm mostly interested in digital communications 2014-04-27 18:58 np, thanks :) 2014-04-27 18:59 wej has quit [Ping timeout: 245 seconds] 2014-04-27 19:03 mth has joined #qi-hardware 2014-04-27 19:05 wpwrak_ is now known as wpwrak 2014-04-27 19:06 * wpwrak hates those *_ 2014-04-27 19:13 wej has joined #qi-hardware 2014-04-27 19:21 wej has quit [Ping timeout: 260 seconds] 2014-04-27 19:43 dandon has quit [Ping timeout: 252 seconds] 2014-04-27 19:48 dandon has joined #qi-hardware 2014-04-27 20:06 wej has joined #qi-hardware 2014-04-27 20:09 larsc, hey, do you know an internet provider in Germany that offers contracts without a minimal period? 2014-04-27 20:13 mnet 2014-04-27 20:14 that's what I use 2014-04-27 20:16 I didn't know you were into K-pop 2014-04-27 20:16 unless mnet.com is not the right website 2014-04-27 20:17 ah, .de 2014-04-27 20:17 of course 2014-04-27 20:20 I think I can refer you 2014-04-27 20:24 wej has quit [Ping timeout: 252 seconds] 2014-04-27 20:31 wej has joined #qi-hardware 2014-04-27 20:35 wej has quit [Ping timeout: 252 seconds] 2014-04-27 20:49 wej has joined #qi-hardware 2014-04-27 21:01 wolfspraul has quit [Quit: leaving] 2014-04-27 21:43 solrize has quit [Ping timeout: 276 seconds] 2014-04-27 22:16 Jay7 has quit [Read error: Connection reset by peer] 2014-04-27 22:16 Jay7 has joined #qi-hardware 2014-04-27 22:37 Ornotermes has quit [Ping timeout: 240 seconds] 2014-04-27 22:44 Ornotermes has joined #qi-hardware 2014-04-27 22:58 Ornotermes has quit [Ping timeout: 240 seconds] 2014-04-27 23:00 Ornotermes has joined #qi-hardware 2014-04-27 23:44 nicksydney has quit [Remote host closed the connection] 2014-04-27 23:45 nicksydney has joined #qi-hardware 2014-04-27 23:46 jekhor has quit [Ping timeout: 255 seconds] 2014-04-27 23:53 sb0 has quit [Quit: Leaving] 2014-04-27 23:59 rz2k has quit []