Архив за 30.09.2019

Weekly Brag, Image, Q&A, anything goes thread.

Beginning with this thread /r/RTLSDR will present a weekly catch all thread where your hobby related image posts, achievement brags, questions, and anything else hobby related that does not warrant its own thread should go.

This is the only space in this sub where memes are permitted, so get it out of your system here.

submitted by /u/The_Real_Catseye
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Can Meteor GIS be used in non-real time decoding of M2/M22 .s files?

For our set up to decode M2/M22 images we save the transmission from SDR# and then run the decoders manually afterwards. How do I setup Meteor GIS to process these files afterwards? Is that possible? The info we've found online seem to only set it up to decode in real time during a satellite pass.

Any help would be appreciated.

submitted by /u/FGL2_0west
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Does anyone recognise this noise on LF?

Does anyone recognise this noise on LF?

The noise has been there for as long as I can remember going to LF. It completely obliterates any signal nearby, even with the HF+ Discovery. I check my own devices and even the streetlights outside, but nothing influenced the signal. I already cut the power and it still stayed. Walking around the house changes the intensity if I was near a window, which makes me think that it comes from outside. It appears at random and mostly in the evening. In the worst case I could inform the government and they should fix it, but I don't want to waste their time if it could be something simple.

Here are some pictures from the noise:




It really sucks because it comes up when the prorogation is really great and I can receive more signals, but the noise kills my dynamic range.

submitted by /u/melvin2204
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Comment on Building An Open Source SDR Based Hydrogen Line Radio Telescope by snn47

The authors did not specify if the calculated antenna gain is referenced to dBi(sotrophic) or dbd(ipole)?
Note: while an isotropic antenna has a gain of 0 dBi, a halfwave dipole has 2.15 dBi gain. Unfortunately even many manufacterer just claim a gain in dB and do not specify if the antenna gain is referenced to dBi or dBd.

So far I have seen only one L-Band Horn antenna design built by Bendix for SSR Parrots (1030/1090 MHz). I don’t have the dimensons and remember only the gain meassured to be 15 dB? and antenna elevation width @- 3dB points was 30°.

Without meassurement however it is quite bold to claim that any antenna achieved the calculated theoretical antenna gain, because there a re many things that can go wrong.

As for Yagis take a look at “A Homebrew Yagi for 1296 MHz DX” from DJ9YW http://www.ok2kkw.com/dj9yw_dubus0601.pdf , which gives you an idea of antenna gain variation of different designs, all meassured both under dry (3 dBd variation) and wet (5 dBd variation) conditions.

While it is possible to scale 23 cm designs for 1420 MHz, I wouldn’t dare to predict if the gain of a 23 cm design meassured in the 23 cm band can be reached at 1420 MHz or not, more likely not.

KerberosSDR • Re: Kerberos Image does not boot

if you have rpi 3 available, better to try with it :-) good luck!

Statistics: Posted by Duppo — Mon Sep 30, 2019 7:42 pm

Collection of WEFAX images I received today with my homemade YouLoop and Airspy HF+ Discovery

Collection of WEFAX images I received today with my homemade YouLoop and Airspy HF+ Discovery submitted by /u/melvin2204
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Comment on New RTL-SDR Receiver App for iOS Released by Scott Harris

Thank you so much Kertesz. I have the RTL2832U dongle. I will give this software a try. Thank you so much for the advice!

KerberosSDR • Re: Kerberos Image does not boot

Is this imaging incompatible with the Raspberry Pi 4?

I have an old Pi 3 in a closet somewhere. Should I use that?

Statistics: Posted by Dougga — Mon Sep 30, 2019 6:20 pm

KerberosSDR • Kerberos Image does not boot

I've tried several times using the process that works just fine with all other .img files.
1. download the latest image(v1.4) using this link: https://drive.google.com/open?id=1shO-9 ... VCighqPg3p
2. use Win32DiskImager application to install image onto SD card
3. install SD card in Raspberry Pi 4
4. plug in monitor, keyboard, mouse into Raspberry Pi
5. plug in power cord into USB-C port

I get no response from the device.
re-imaging any other OS to the SD card provides a responsive computer.
Any thoughts? I'm so tired of following instructions on the web and getting results like these, I'm tempted to just throw away the hardware.


Statistics: Posted by Dougga — Mon Sep 30, 2019 6:16 pm

KerberosSDR • Re: direction finding of short pulses

The problem is that the code collects a chunk of samples and processes that chunk. If the chunk contains only a short pulse and mostly noise it might not get a good result.

We're working on new code now which will allow you to set the sample chunk size to anything you like, so a smaller chunk might work better for these short pulses.

I'm checking with Tamas if there is any other solution to this, but we might need to wait for some code updates.

Bear with me! just trying to learn some python along side of Kerberos.... The recommended sample rate setting is 1.0 MSPS for direction finding. Does that define the Sampling Size (1MB sample less for FIR & Decimation influences) you are referring to as data chunk? Identified also as "iq_samples" and these are pulled every quarter sec??

Statistics: Posted by myke — Mon Sep 30, 2019 6:11 pm

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