osmocom-sdr

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910 discussions

Recording rtl_fm output
by Martin McCormick 14 Mar '17

14 Mar '17

Something I am doing is not quite right. The following example works almost perfectly but please read on. rtl_fm -f 88.3e6 -M wbfm -s 215000 -r 44100 - | aplay -r 44.1k -f S16_LE The audio from the sound card is nearly excellent. To record this stream, I do the following: rtl_fm -f 88.3e6 -M wbfm -s 215000 -r 44100 testfile.bin I get a file so it would appear that the following should sound just like the stream I am listening to using the pipe in the first example. aplay -r 44.1k -f S16_LE testfile.bin The pitch of the audio is fine but instead of almost dead silence between words, there is a lot of hiss and distortion. In theory, I should hear the same mostly noiseless audio I hear in the first example when playing from the file. This is really not a DSP issue but maybe I have saved the audio as unsigned and am trying to play it signed which would preserve the pitch but be a cause for a lot of distortion. Besides, it is apparently signed when piped in to aplay. I am mystified. Thanks. Martin McCormick

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Re: RTL-SDR and RTL-TCP drivers
by Andreas Eriksen 10 Mar '17

10 Mar '17

Thank you for these patches, indeed they fixed my problems with gqrx :-)

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Technical help, umm I think?
by James Clark - KC3CDV 10 Mar '17

10 Mar '17

Hello all, not sure if this will go through or if Ive to subscribe or even if this is the rite place for help like this. I am on a mac running the latest OSX updates and I am waiting for my new SDR to get to me from amazon, Ive got CubicSDR and also Gqrx on the system, well my question is will I be able to just plug and play or will I have to install macports and all that other stuff that goes over my head. Do I have to use turminal? Me trying to use that thing is like a fish trying to live out of water for a year, its vary unlikely it will happen effectivly. Also let me say rite up front please don’t post any photos because I cant see your photos. I hope this is the rite place to ask this question, thank you in advanced. May Peace Be With You. Active skywarn severe weather spotter and Community Collaborative Rain, Hail & Snow Network operative. @HomefrontHugs Volunteer for our Troops and Families

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[hari.blogscripts@gmail.com: reg. a deadlink]
by Harald Welte 01 Mar '17

01 Mar '17

FYI, this was in my personal inbox but is probably better adressed by the people on this list. Regards, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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RTLSDR IQ imbalance ???
by a c 28 Feb '17

28 Feb '17

Hello, I use RTL-FM on a raspberry pi3. I notice practically always the presence of a weak carrier accompanying the emission received in AM mode and interferences in NFM mode. When i use rtl-tcp and sdr# or sdrconsole the demodulation is perfect. I assume that IQ amplitude phase correction is involved. I saw in the source of rtlsdr: IQ estimation / compensation (en_iq_comp, en_iq_est) * / Rtlsdr_demod_write_reg (dev, 1, 0xb1, 0x1b, 1); I suppose we use an internal chipset function? Is this function good enough? I did not find anything about it in RTL-FM but I'm not a specialist. Is an improvement possible? Regards, Arnaud

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Floating point error in tuner_r82xx.c
by Steve Knoeck 27 Feb '17

27 Feb '17

Hi, I get a floating point exception when I run rtl_tcp. I traced the error with GDB to line 515 of tuner_r82xx.c if (vco_fra > (2 * pll_ref_khz / n_sdm)) I found that n_sdm was 0. I don't understand how this code work and I'm very new to this software but it sure looks like a programming bug. | 513 /* sdm calculator */|| || 514 while (vco_fra > 1) {|| || 515 if (vco_fra > (2 * pll_ref_khz / n_sdm)) {|| || 516 sdm = sdm + 32768 / (n_sdm / 2);|| || 517 vco_fra = vco_fra - 2 * pll_ref_khz / n_sdm;|| || 518 if (n_sdm >= 0x8000)|| || 519 break;|| || 520 }|| || 521 n_sdm <<= 1;|| || 522 }| If the condition on line 515 ever evaluates to false then vco_fra doesn't get updated. The loop will keep repeating with the same value of vco_fra until n_sdm becomes 0. Steve

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Fwd: How to get out the maximum from cheap sdrs
by Stefan Groißmeier 27 Feb '17

27 Feb '17

Hi All, I would like to realize an algorithm to build the best possible dvb-t sdr experience. The idea is, that no matter how many sdrs and what kind of antenna you have, the software gets the best out of your hardware. This is what I have thought: The user community of a system depends on how useful it is, how easy it is to use, build and how much money it costs. Rtl-sdrs are quite cheap, but for now a user has no benefit of having multiple sdrs in its system. That is why I'm searching a way to correlate the signals of the sdrs without hardware modification. I think everyone of you has seen the noise from the power source. Has anyone tried to build a filter to use that noise to calculate the delay between multiple dongles? I mean, they get the same noise. I don't know if it is sufficient, but it is also a good spot, to put some artificial noise in, as it can be easily accessed and does not interfere with rf circuitry when it is switched off. Is that an useful approach? Do you think this could work? Did I miss something? regards, Steve

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Request
by zainab jeragh 27 Feb '17

27 Feb '17

Hello We are doing a ADS-B reciever senior project, Can we have the building blocks in the gnu radio for that? Please help us We are using the hackrf one hardware Which is the osmocom source in the gnu radio Thanks Sent from my iPhone

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Error "No E4000 tuner found" on rtl_test -t
by Martin McGlensey 27 Feb '17

27 Feb '17

Hello, I recently purchased a NooElec nesdr mini dongle. I want to install it on Linux Mint 17.1. I have rtl-sdr installed. I have blacklisted the dvb_usb_rtl28xxu driver. When I run rtl_test it reports that the dongle is present and sending. When I run rtl_sdr -t to check the tuning range it reports no E4000 tuner found. Called NooElec for tech support. Got link for linux install but got error "page not found". Tried to get on their mailing list from their IE page. Bad gateway error 502. Looks like support may be difficult to get through NooElec. Does this error indicate a defective rtl dongle? Where can I find the install procedure for the NooElec R820T NESDR mini. All responses are appreciated. Thank you, Marty, N3MOW N3mow(a)arrl.net <mailto:N3mow@arrl.net> mmcg29440(a)frontier.net <mailto:mmcg29440@frontier.net>

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Added Bias T set / get to API
by Lucas Teske 21 Feb '17

21 Feb '17

So since there are now three radios (that I know) that has a hardware Bias T support (HackRF, RTLSDR, Airspy) I added a set_biast and get_biast methods to the default Source API. I also added Airspy and HackRF bindings to enable / disable Bias T. The RTLSDR isn't merged into mainstream, so I didn't added anything. There is also the default implementations (doing nothing for set, and returning false for get), so no breaks on the current source or current applications. -- Lucas Teske Teske Virtual System GPG: 4A90 974B ACE0 A9A6 AF09 B3B1 6C39 C1C1 6A9D A7BE

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