Архив за 30.01.2019

Troubleshooting Help • How to play / decipher .iq file or hex?

I want to learn to decode data from recorded .iq files (RF Analyzer Android app / 820T2 dongle). I've generated hex from an .iq file of recorded signal at 451.4 MHz (example below), using command line xxd (Linux). How to decipher / interpret hex? I know GNU radio companion somewhat, but not finding any tutorials or images on setting up blocks to play iq file, or even how to use GNU RC to decipher signals. Perhaps other software is more appropriate? Thanks in advance for direction.


00000000: 797b 857c 8585 807e 8178 6a83 7160 7e83  y{.|...~.xj.q`~.00000010: 7c89 8385 8184 7589 7d82 7b7c 8671 829a  |.....u.}.{|.q..00000020: 7f7f 8384 7d82 7e81 7f80 7e82 847d 7a81  ....}.~...~..}z.00000030: 927e 8678 7881 8081 7f82 7f80 7e80 797e  .~.xx.......~.y~00000040: 8177 8a89 837d 7f73 7b73 7286 8377 897f  .w...}.s{sr..w..00000050: 8080 7e7c 7b7b 8483 8180 8486 7e84 7c80  ..~|{{......~.|.00000060: 8483 847d 7d82 8984 8486 7b7b 9084 7e77  ...}}.....{{..~w00000070: 717b 8481 887b 8281 7e83 888b 817d 857a  q{...{..~....}.z

Statistics: Posted by p1ne — Wed Jan 30, 2019 11:47 pm

The first image I captured from NOAA-20 (JPSS-1) on 7812MHz.

The first image I captured from NOAA-20 (JPSS-1) on 7812MHz. submitted by /u/dev_arved
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What am I doing wrong?

I have the official RTL-SDR.com dongle with v dipole antennas and everything works, but when I try to receive NOAA signals they're with a really bad signal and have a lot of noise. Sometimes I have really clean moments without any noise, but most of the time it has a lot of noise and WXtoImg won't render the image properly. I use WXtrack to compensate for the doppler shift and I use a virtual audio cable to port it to WXtoImg. I am forced to use my desktop because I don't have a laptop and because of that I am forced to use the most north side of my house. The length of one antenna is 50 cm + 2 cm in the holder, the antennas are 120° apart. The antenna is pointing north (mounted to the window with the suction cup) and is connected to the dongle with the included 3 meter extension cord. The dongle is laying on a wooden surface and is connected to my pc with a usb 2 5m extension cord. I woke up at 5:30 in the morning to capture a NOAA 19 pass that was perfectly in my field of view (between 10° and 210°). In practice I should have recorded the whole pass without any buildings in the way, but sadly the best I could get was a really noise image. Only when it was right above me I got clear image, but the thermal data was completely messed up. The only things I can think of that cause the noise is the train power lines 30 meters away from the antenna (the antenna is 5 meter higher than the cable) and the cable from the antenna to the dongle.

Edit: I don't have an LNA, just this package.

Also I am thinking of making a better antenna. I've found three types of antennas: double cross dipole, turnstile antenna and the QFH antenna. I know the QFH antenna is the best, but I am not experienced with working with antennas and think it is too hard to build as I've heard that they need to be really precise or they won't work well. The DCA looks pretty easy to make and have a great signal according to someone on YouTube (which also inspired me to do this.). And I don't know much about the turnstile. So which of those is the easiest and cheapest to make while having great reception. Also a guide with metric units would be nice as I've only found guides in imperial and I don't want to have inaccuracy due to conversion errors.

And the last question: what are the correct settings for sdr# for the NOAA sats? I currently have it with these settings:


Bandwidth: 38,000

Order: 310

Shift: 0

Sample Rate: 2.4 MSPS

Sampling Mode: Quadrature

Offset Tuning on


Tuner AGC off

RF Gain: 20.7dB

Frequency correction: 0 ppm

Filter audio off

Correct IQ on

DDE tracker with WXtrack


Bad signal with V dipole configuration and the correct lengths, angle and pointing towards the north, but I have a train power line 30 meters away from the antenna.

What is the cheapest and easiest antenna to make while still keeping a great signal? (for the 137 MHz frequency).

What are the best settings for sdr#?

Any help would be appreciated.

submitted by /u/melvin2204
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Radiosondes and sorcerer

Has anyone tried using sorcerer for radiosondes? The web page says it supports the new radiosondes, although probably not as well as a program like sondemonitor.

Any help would be appreciated.

submitted by /u/Ag8n1
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Signal Identification Help • Re: Unknown Signal, Morse code like 464Mhrz

Not sure, does appear to be some CW though.

I managed a similar decode:


TWEJ718 E !EJ718 *EJ718 E AWEJ718 IY 
EJ718 is the flight ID for a military aircraft but I've not heard of them using CW in that band.
Kinda stumped on that one.

Statistics: Posted by Corrosive — Wed Jan 30, 2019 7:56 pm

LocalRadio.app v1.18 released for macOS + RTL-SDR (streams to iPhone, Android, etc.)

LocalRadio.app v1.18 released for macOS + RTL-SDR (streams to iPhone, Android, etc.)

📻 LocalRadio 📻 is software for listening to "Software-Defined Radio" on your Mac and mobile devices. With an inexpensive RTL-SDR device plugged into the Mac's USB port, LocalRadio provides a casual listening experience for your favorite local FM broadcasts, free music, news, sports, weather, public safety and aviation scanner monitoring, etc.

LocalRadio's built-in HTTP and Icecast servers support mobile devices.

LocalRadio v1.18 adds two new features -

It replaces MP3 streaming audio format with AAC (Advanced Audio Coding), using Apple's AAC encoder included in macOS. AAC provides improved audio quality at comparable bit rates, and it is compatible with most devices, including Android systems.

This release also adds https encrypted web and audio connections, and Bonjour mDNS host names. The HTTP server uses the Bonjour host name to generate a self-signed certificate. For devices like Android that may not support Bonjour host name resolution, the existing http non-encrypted connections remain available.

Two versions of the release are available. The main release supports macOS 10.14 Mojave. The "legacy" release supports older versions of Mac OS X for older hardware, like 10.11 El Capitan.

Open-source project homepage:


LocalRadio.app release v1.18-alpha:


submitted by /u/ArkPhone
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Troubleshooting Help • Re: No Source for RTL-SDR in GNURadio [GNURadio/RTL-SDR/Windows]

I haven't tried gnuradio under windows in a while, do you have the osmocom source/sink blocks? Those are what gnuradio uses to communicate with the RTL-SDR and other osmocom supported hardware.

Here is a link with more information about the osmocom blocks, I'm not sure how to install them off hand under windows but if you installed the Windows release I believe they should be there. https://osmocom.org/projects/gr-osmosdr ... dio-Blocks

Statistics: Posted by Corrosive — Wed Jan 30, 2019 7:44 pm

Troubleshooting Help • Re: Can you run two, RTLSDR USB dongles on a PC?

You can, however different software applications may see things differently.
With HDSDR I'm not sure, I know that SDRConsole/CubicSDR and SDR# do a fine job at juggling multiple RTLs.

You might want to try changing the serial number of an RTL just be careful.
This was discussed in another thread here viewtopic.php?t=586

Statistics: Posted by Corrosive — Wed Jan 30, 2019 7:34 pm

Comment on Quick Start Guide by ubaldo dibenedetto

I have seen your video, and I would like to monitor the 20meter band in order to see the activity and the individual signal strength on a large screen.I have an ICOM 746 and a Macbook Air.
Where can I but the antenna, the dongle?
TNX and 73
Ubaldo DiBenedetto WA1TJW

HF-ULF Antennas for Ham It Up Plus

I am thinking about buying the Ham it up plus. But i am unable to find a suitable antenna for it and google wasnt too helpful either since i dont know that much about that kind of stuff yet. What options do i have for antennas to receive HF/MF/LF/VLF/ULF? Preferably high gain because i live in a rural area where there is little activity on the air.

submitted by /u/Little_Capsky
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