osmocom-sdr

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906 discussions

Super Efficient SMD Schottky Barrier from Comchip Technology Corporation
by Jay Salsburg 30 Jun '12

30 Jun '12

http://beta.globalspec.com/featuredProducts/detail?id=372 <http://beta.globalspec.com/featuredProducts/detail?id=372&campid=736&exhibi tId=209851&uid=%2D249525238&uh=e8a921&md=120628&mh=221961> &campid=736&exhibitId=209851&uid=%2D249525238&uh=e8a921&md=120628&mh=221961

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RTL direct sampling
by Adam Nielsen 24 Jun '12

24 Jun '12

Hi all, I've been watching with interest Steve's commits to the direct_sampling branch of the rtl-sdr repository. I haven't seen much mentioned about it though, so I'm just wondering whether anyone knows how it's progressing, and whether it's at the point yet where I should crack open one of these devices and try it out? Thanks, Adam.

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Caputed RTL-SDR file for playing around?
by Johannes Bauer 22 Jun '12

22 Jun '12

Hi list, I've stumbled upon the rtl-sdr and am quite excited. Have already ordered a dongle, but it is going to take a while until it arrives. Since I'd like to play around with it already, is there a capture file available somewhere for download to test out the functionality (working with GnuRadio etc)? I.e. someone with a dongle doing ./rtl_sdr /tmp/capture.bin -s 1.8e6 -f 392e6 (or whatever frequency there is something audible on, preferrably something that can easily be identified like FM radio) and publishing the capture.bin file? This might also be of interest to people who consider to play around with SDR, but do not know if they should buy a dongle. Would be very cool if there was something available or somebody on the list could provide one. Best regards, Joe

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v2 Prototype issues and fixes
by Sylvain Munaut 21 Jun '12

21 Jun '12

Hi, The v2 prototype I still had a couple of issues so I'll describe them here and the corresponding fixes: - Bad TVS Diode: There is a diode that's supposed to protect against ESD near the antenna connector. Turns out that the component supplier swapped reels IIRC and so that's not a TVS diode that was mounted. My board had the rework to fix this already done. I don't know if any board shipped with the wrong part. It's the small ~ 0603 sized component near the antenna connector and it's supposed to be greenish. The result of this is a ~ 10-15 dB attenuation of the input signal. - Missing LNA bias inductor: The v2 has a LNA at the input but it's missing it's bias inductor which means it's powered off. So instead of boosting the signal by 18 dB, it actually attenuates it quite a lot. Solution is simple: Solder a 0603 bias inductor. Schematics call for a 470nH inductor and make sure to choose a good RF rated one and not random junk. - FPGA 1.2V LDO Oscillation: The output capacitor of the LP3965 regulator generating the 1.2V for the FPGA core has too low an ESR (a ceramic cap is mounted). This regulator needs a capacitor with an ESR greater than 0.5 ohm and lower than 5 ohm for it to be stable. Without this, the LDO is unstable and has high spectral content at 55 kHz and harmonics. This noise is present at the output but also leaks to the input voltage of the LDO which is the 3.3V rail that powers the LNA ... This is causing unwanted images of the signal at f +- 55kHz f+- 110 kHz ... The solution is simple: replace the cap by a tantalum one within the right ESR range. ( I used a TR3A106K016C1700 from Farnell ). This is before the fix: http://i.imgur.com/rRDDQ.png and this is after : http://i.imgur.com/VlOW7.png - Impedance mismatch between E4K output and ADC input: Ideally we'd like to imagine that the E4K IQ output have very low impedance and that the ADC input have very high impedance. Turns out that neither is true: The E4K has a ~ 500 ohm output impedance and the ADC is a track and hold type and the capacitance of the input changes when you start sampling, causing a small current flow. The combination of the 2 creates a noise at the sampling frequency on the IQ lines ... The effect of this is currently unknown and is being investigated ... it might be possible to lower the noise floor a bit and get less DC offset with this. But it certainly doesn't have as much impact as the 3 erratas above for sure. See for components location. http://i.imgur.com/M4Lvt.jpg Cheers, Sylvain

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Tuning gap between 325 and 350 MHz
by Kire Pudsje 27 May '12

27 May '12

Also posted on reddit: I measured another stick and this time I also noticed the gap between 325 and 350 MHz, as was reported earlier by Roger on reddit. http://www.reddit.com/r/RTLSDR/comments/tftz4/some_frequency_response_measu… I could trace it back to the fact that the E4K_REG_SYNTH is not set properly. I do not know why yet, but first setting a different value from the desired one seems to fix the problem. It might be the wrong solution for the wrong problem, but it seems to work for me. change this line in tuner_e4k.c:448 rc = e4k_reg_set_mask(e4k, E4K_REG_SYNTH1, 0x06, band << 1); to: uint8_t tmp = e4k_reg_read(e4k, E4K_REG_SYNTH1) & ~0x06; tmp |= (band << 1) & 0x06; e4k_reg_write(e4k, E4K_REG_SYNTH1, tmp ^ 0x06); rc = e4k_reg_write(e4k, E4K_REG_SYNTH1, tmp); Kire.

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Building with autotools - missing -lpthreads
by Joschi Brauchle 26 May '12

26 May '12

Hello all, when trying to build with autotools, I get an compile error stating that there is a: ---- undefined reference to symbol 'pthread_create@@GLIBC_2.2.5' ---- This seems to be due to "-lpthreads" is missing when using autotools1 -- Dipl.-Ing. Joschi Brauchle, M.Sc. Institute for Communications Engineering (LNT) Technische Universitaet Muenchen (TUM) 80290 Munich, Germany Tel (work): +49 89 289-23474 Fax (work): +49 89 289-23490 E-mail: joschi.brauchle(a)tum.de Web: http://www.lnt.ei.tum.de/

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Octave wrapper for rtl-sdr
by Kire Pudsje 25 May '12

25 May '12

I wrote for myself an octave wrapper for all functions in the header file of the rtl-sdr library. Even the async routine generates a callback to octave functions. The whole is a 1-to-1 mapping of the functions, I tried to stay as close as possible to the C-library. I do not know if it just me using octave, but if there is any interest in this code, I could place it somewhere. sample code: pkg load rtlsdr if rtlsdr_get_device_count()>0 dev = rtlsdr_open(0); samprate=2048e3; nsamples=2048; rtlsdr_set_sample_rate(dev, samprate); rtlsdr_set_center_freq(dev, 100e6); rtlsdr_set_tuner_gain_mode(dev, 0); rtlsdr_reset_buffer(dev); buf = rtlsdr_read_sync(dev, nsamples * 2); d = (double(buf) - 128) / 128.0; d = d(1:2:end) + 1i * d(2:2:end); f = (-.5:1/nsamples:.5-1/nsamples) * samprate; plot(f, 20*log10(abs(fftshift(fft(d .* blackman(nsamples)') / nsamples)))); rtlsdr_close(dev); end

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PATCH: Silence warning about int/socklen_t signedness
by Christian Vogel 25 May '12

25 May '12

There's only one warning for me when compiling rtl-sdr, which is about the signedness of the third (size) argument in accept(). On linux it's socklen_t* and I *think* (google...) that windows does not have socklen_t at all. In accept it uses int. ftp://ftp.microsoft.com/bussys/winsock/winsock2/winsock2.h WINSOCK_API_LINKAGE SOCKET WSAAPI accept( IN SOCKET s, OUT struct sockaddr FAR * addr, IN OUT int FAR * addrlen ); Can someone please check if it compiles on windows with the attached patch?

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[PATCH] Silence warning about socklen_t/int sign.
by Christian Vogel 25 May '12

25 May '12

rtl_tcp.c:457:57: warning: pointer types point to integer types with different sign passing 'int *', expected 'socklen_t *' [-Wpointer-sign] --- src/rtl_tcp.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/src/rtl_tcp.c b/src/rtl_tcp.c index 8b2cf44..849192b 100644 --- a/src/rtl_tcp.c +++ b/src/rtl_tcp.c @@ -42,6 +42,9 @@ #ifdef _WIN32 #pragma comment(lib, "ws2_32.lib") + +typedef int socklen_t; + #else #define closesocket close #define SOCKADDR struct sockaddr @@ -453,8 +456,10 @@ int main(int argc, char **argv) if(do_exit) { goto out; } else if(r) { - r=sizeof(remote); - s = accept(listensocket,(struct sockaddr *)&remote, &r); + socklen_t rlen; + + rlen=sizeof(remote); + s = accept(listensocket,(struct sockaddr *)&remote, &rlen); break; } } -- 1.7.0.4 --Nq2Wo0NMKNjxTN9z--

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[PATCH] FC0012 doc and fixes
by Michael Karcher 24 May '12

24 May '12

Fix selection of VCO band (needed for example to get to 166 MHz) for the FC0012 tuner, and add a lot of register descriptions. Signed-Off-by: Michael Karcher <osmosdr(a)mkarcher.dialup.fu-berlin.de> --- src/tuner_fc0012.c | 49 +++++++++++++++++++++++++++++++++---------------- 1 file changed, 33 insertions(+), 16 deletions(-) diff --git a/src/tuner_fc0012.c b/src/tuner_fc0012.c index 104a4f7..2d66f3c 100644 --- a/src/tuner_fc0012.c +++ b/src/tuner_fc0012.c @@ -20,21 +20,35 @@ /* Incomplete list of register settings: * * Name Reg Bits Desc + * CHIP_ID 0x00 0-7 Chip ID (constant 0xA1) + * RF_A 0x01 0-3 Number of count-to-9 cycles in RF + * divider (suggested: 2..9) + * RF_M 0x02 0-7 Total number of cycles (to-8 and to-9) + * in RF divider + * RF_K_HIGH 0x03 0-6 Bits 8..14 of fractional divider + * RF_K_LOW 0x04 0-7 Bits 0..7 of fractional RF divider + * RF_OUTDIV_A 0x05 3-7 Power of two required? * LNA_POWER_DOWN 0x06 0 Set to 1 to switch off low noise amp - * VCO_SPEED 0x06 3 Set the speed of the VCO. example - * driver hardcodes to 1 for some reason + * RF_OUTDIV_B 0x06 1 Set to select 3 instead of 2 for the + * RF output divider + * VCO_SPEED 0x06 3 Select tuning range of VCO: + * 0 = Low range, (ca. 1.1 - 1.5GHz) + * 1 = High range (ca. 1.4 - 1.8GHz) * BANDWIDTH 0x06 6-7 Set bandwidth. 6MHz = 0x80, 7MHz=0x40 * 8MHz=0x00 * XTAL_SPEED 0x07 5 Set to 1 for 28.8MHz Crystal input * or 0 for 36MHz + * <agc params> 0x08 0-7 * EN_CAL_RSSI 0x09 4 Enable calibrate RSSI * (Receive Signal Strength Indicator) * LNA_FORCE 0x0d 0 * AGC_FORCE 0x0d ? - * LNA_GAIN 0x13 0-4 Low noise amp gain + * LNA_GAIN 0x13 3-4 Low noise amp gain * LNA_COMPS 0x15 3 ? * VCO_CALIB 0x0e 7 Set high then low to calibrate VCO - * + * (fast lock?) + * VCO_VOLTAGE 0x0e 0-6 Read Control voltage of VCO + * (big value -> low freq) */ /* glue functions to rtl-sdr code */ @@ -99,12 +113,11 @@ void FC0012_Dump_Registers() DEBUGF("LNA Force:\t%s\n", (regBuf & 0x1) ? "Forced" : "Not Forced"); FC0012_Read(pTuner, 0x13, &regBuf); DEBUGF("LNA Gain:\t"); - switch (regBuf) { - case (0x10): DEBUGF("19.7dB\n"); break; - case (0x17): DEBUGF("17.9dB\n"); break; - case (0x08): DEBUGF("7.1dB\n"); break; - case (0x02): DEBUGF("-9.9dB\n"); break; - default: DEBUGF("unknown gain value 0x02x\n"); + switch (regBuf & 0x18) { + case (0x00): DEBUGF("Low\n"); break; + case (0x08): DEBUGF("Middle\n"); break; + case (0x10): DEBUGF("High\n"); break; + default: DEBUGF("unknown gain value 0x18\n"); } #endif } @@ -173,7 +186,7 @@ void FC0012_Frequency_Control(unsigned int Frequency, unsigned short Bandwidth) int FC0012_SetFrequency(void *pTuner, unsigned long Frequency, unsigned short Bandwidth) { - int VCO1 = 0; + int VCO_band = 0; unsigned long doubleVCO; unsigned short xin, xdiv; unsigned char reg[21], am, pm, multi; @@ -230,7 +243,7 @@ int FC0012_SetFrequency(void *pTuner, unsigned long Frequency, unsigned short Ba doubleVCO = Frequency * multi; reg[6] = reg[6] | 0x08; - VCO1 = 1; + VCO_band = 1; xdiv = (unsigned short)(doubleVCO / (CrystalFreqKhz / 2)); if( (doubleVCO - xdiv * (CrystalFreqKhz / 2)) >= (CrystalFreqKhz / 4) ) xdiv = xdiv + 1; @@ -269,7 +282,6 @@ int FC0012_SetFrequency(void *pTuner, unsigned long Frequency, unsigned short Ba if (FC0012_Write(pTuner, 0x03, reg[3])) return -1; if (FC0012_Write(pTuner, 0x04, reg[4])) return -1; //reg[5] = reg[5] | 0x07; // This is really not cool. Why is it there? - // Same with hardcoding VCO=1 if (FC0012_Write(pTuner, 0x05, reg[5])) return -1; if (FC0012_Write(pTuner, 0x06, reg[6])) return -1; @@ -277,16 +289,19 @@ int FC0012_SetFrequency(void *pTuner, unsigned long Frequency, unsigned short Ba if (FC0012_Write(pTuner, 0x0E, 0x80)) return -1; if (FC0012_Write(pTuner, 0x0E, 0x00)) return -1; - // VCO Re-Calibration if needed + // Read resulting VCO control voltage if (FC0012_Write(pTuner, 0x0E, 0x00)) return -1; if (FC0012_Read(pTuner, 0x0E, &read_byte)) return -1; reg[14] = 0x3F & read_byte; - if (VCO1) + // Adjust VCO range if control voltage is at the limit + if (VCO_band) { + // high-band VCO hitting low frequency bound if (reg[14] > 0x3C) { - reg[6] = 0x08 | reg[6]; + // select low-band VCO + reg[6] = ~0x08 & reg[6]; if (FC0012_Write(pTuner, 0x06, reg[6])) return -1; if (FC0012_Write(pTuner, 0x0E, 0x80)) return -1; @@ -295,7 +310,9 @@ int FC0012_SetFrequency(void *pTuner, unsigned long Frequency, unsigned short Ba } else { + // low-band VCO hitting high frequency bound if (reg[14] < 0x02) { + // select high-band VCO reg[6] = 0x08 | reg[6]; if (FC0012_Write(pTuner, 0x06, reg[6])) return -1; -- 1.7.10

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