Архив за 03.12.2017

RTL-SDR Discussion • Re: bypass diplexer

Hmm I'm not sure if it's actually possible to get the two ADC branches simultaneously. Though the E4000 chip does use both together so it might be possible, but it would require some investigation of the driver code.

The V3 is already set up so that the R820T signal goes into the I-branch ADC ports, and the HF signal goes into the Q-branch. There should be no need to modify the dongle. If you wanted to inject a signal directly into the Q branch, then juust remove the transformer T2 and connect to the Q-branch breakout holes in the top right.

Statistics: Posted by rtlsdrblog — Sun Dec 03, 2017 11:45 pm

rtl-sdr.com antenna kit: Orientation Matters

A lot. Official recommendation is to install antenna vertical (up-and-down), as a real man, didn't read the manual, then posted results in a recent ADS-B comparison.
Mea culpa, I was wrong, as an eagle-eyed reader pointed out:

"Orienting dipoles goes back to the signal polarization, horizontal vs vertical. It should match otherwise you'll get losses. But the way you've oriented it makes it vertical, but more like a whip. So there should be some improvement by using it in the correct orientation. TV signals are usually strong and so the bunny ears can withstand being in the wrong or random orientations."

Fair enough, so onto ADS-B testing, got an antenna kit from rtl-sdr.com for review and ordered one within minutes as it's well worth the money, then some ended up with two identical kits:

Back end is two ModMy Pi 3 Raspberries, so only variable is antenna used:

Then my jaw dropped, bunny ears configuration results:

Vertical dipole results:

No math required, more than 2x performance. Where's a stone I can hide under?

Polar plots

First of December, 21,033 Totals on vertical orientation, geographical coverage:

Bunny ears with 9,563 Totals on the same day, geographical coverage:


"RTL-SDR Blog Multipurpose Dipole Antenna Kit" works, 144 nm max range in an unamped, stock setup is simply astonishing at my location.
Would, and do recommend to grab as many as you can from the manufacturer, but others have also seen that sliced bread is better than a loaf, therefore it's sold out.

The new SDRPlay RSP1A is disruptive. A leap in value over RTL-SDRs

The new SDRPlay RSP1A is disruptive. A leap in value over RTL-SDRs submitted by /u/ve3cnu
[link] [comments]

Help setting up a SDR GPS

I am trying to set up a SDR GPS using this tutorial. I am using a V3 SDR with a bias T and a gps antenna. I use a batch file to turn on the bias T and start up the RTLSDRLIB software. Then, when I try to run the program, I receive an error.

Error: failed to open rtlsdr device #0.

Error: rcvinit

I have tried to solve this issue by following these steps.

edit lines 34 and 37 in rtlsdr.c (found under GNSS-SDRLIB-master\GNSS-SDRLIB-master\src\rcv\rtlsdr) and change: "int ret,dev_index=0;;" to "int ret,dev_index=1;;" "verbose_device_search("0")" to "verbose_device_search("1")"

So far nothing has worked for me. Any help would be much appreciated.

submitted by /u/Wess_is_Bestin
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Behind the Scenes: Photography and Building a Lightbox

RTL-SDR dongles, preamps and tools of trade are small. Here's what I came up with for little money, and why it works for me.
Tips are also applicable to small product photography, and so on.

Build a lightbox

Using one, two or three lamps results in shadows, which take aeons to remove in Photoshop, and I simply have no time. Enter a lightbox, which is a cardboard box with lamps for optimal illumination, watch Youtube videos here, here, and here for inspiration just like I did, common trait is having a box and lights on the side, the more the better, first result:

Product image wasn't bad:

1. Lights shines into camera and my eyes, and looking into thousands of lumen is not fun.
2. No reflective surfaces, less light reaching object.
3. Unacceptable shadows on the left hand side.

Improved lightbox

All light sources covered from camera, easier on me eyes:

Same with less shadows:

Being able to look at an object is worth more than more light and white speckles swimming in my vision.

Lumens and color temperature

Lumens: how much light emitted by bulb, written on packaging. Also given as W at the bottom (how much power bulb uses). The more, the better, 50 W combined from LED and fluorescents is more than enough, or 4-5000 lumens light output.

Light sources must be distributed for an even coverage and to get no shadows. I put two on top, two in the top left corner, two at bottom corners. Connections are easy-peasy, cut a hole, screw in bulb.

Sidenote: Some might say cardboard, paper and a heat source is disaster, and I totally agree. Do not use incandescent lights, floodlights or HID lights, if in doubt, test: turn off = touch with hand then hot, auch = don't use. Fluorescent and LED give more light and cooler to touch.
Color temperature: that's the number before the K on the bulb above, LED and fluorescent lights are used interchangeably, not on purpose, simply I could buy them for cheap. Most cameras are great sensing color temperature, if really skewed, can adjust in Photoshop:

Note that Auto Color (Ctrl + Shift + B) does a good job, but all image adjustments in PS should be done as adjustment layers like above. That said, for lesser images I do Ruler Tool, then Crop (C), then Ctrl - Shift - L, then B, be done.


Sony DSC HX9V, a compact point-and-shoot. Images below are straight from camera, no Photoshop.

Automatic mode does not do the job, that's the green setting, result is dismal:

Program mode, multi-AF and multi-metering with flash:

Usable, small shadow on right for depth perception, would add +25 brightness after cropping.
Smartphones: work for on-the-go images, and great for family photos, but ultimate quality is nowhere near a dedicated camera, I use a Samsung J5 2016. Shoe from a cobbler.


Don't. It's better and ultimately less time to set up a lightbox, even when you play with camera for two days to find the best settings, than to spend hours in Photoshop adjusting sliders down the line, plus it's easier to get it right the first time, taking care in - great image out, 5 minutes with an image (which is more like 30 minutes once the rush for perfection overcomes you) when a post contains 20+ images is time wasted.
Do. Before a post with images goes online, I check images on a 49" screen to find any faults, invariably, there's something to improve. Deciding what needs to be completed and knowing when I gotta wake up for work leads to compromises.

Connectors and macro photography

Must crop and do post post-processing, before and after:

Ensure background is evenly illuminated, so magic wand (W) will work efficiently. Looking closely, you'll see that grooves are not cleaned on this F-connector, Eraser tool (E) is my least favorite command.
I tend to take multiple images then choose the best one, as hand shaking, distance to subject and lighting differences will make or break the final image.

Dipole Setup for NOAA reception

Pointing the dipole. True north or magnetic north?

submitted by /u/nixon7606
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Comment on Using the RTL-SDR as a Transmitter by Billy

Not if you are a amateur radio operator!

RTL-SDR Discussion • Re: bypass diplexer

up : more explanations about my project

Statistics: Posted by royae — Sun Dec 03, 2017 7:40 pm

Is this guy talking nonsense or on the level?

Is this guy talking nonsense or on the level? submitted by /u/mosler
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RTL-SDR Discussion • Re: RTL-SDR dump1090 windows

yess, I am from Pardubice (Pardubitz) CZ. :D

Ladislav alias OK1UNL

Statistics: Posted by OK1UNL — Sun Dec 03, 2017 7:06 pm

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