Архив за Октябрь, 2018

[Help] Meteor decode only produces a black image, even though I’ve gotten clean images before.

I wanted to know if anyone else had this problem, and knows how to fix it.

Some info: SDR: Nooelec NESDR SMArt. Software: Win 10, SDR#, Audacity, LrptRx, M2_Lrpt_Decoder. QFH antenna @ 11 meters.

I was getting good images after following this Video and this PDF. The first few images were good, then some decodes came out as a solid black picture, but some passes were still producing visible images, now all my passes are solid black.

The sample rate that works for me with NOAA is 1.024MSPS (NOAA still works btw), and that's what worked with Meteor for a while. When I kept getting black images, I tried other sample rates of 0.25, 0.9, 1.4, 1.8, 1.92, 2.048, 2.4, they all produced similar black image results.
I record the baseband and process it through two methods, LrptRx then M2LrptDecoder, and the other method of opening the baseband recording in SDR# and using the Meteor demodulator (Live decode has trouble locking on for me so I only record). I do them both, since I'm new to Meteor decoding I want to find the most efficient method for me.
Everything hardware wise has stayed the same since I was getting good images, and I still get four clean dots in LrptRx. I wanted to ask to see if anyone else had a problem like this before I reinstall programs or delete any updates since it could just be something really simple.

submitted by /u/stuffandthings54
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Уважаемые форумчане.помогите разобраться с dsd.как определить местоположение рации Открывается такая карта .что делать дальше?…


Уважаемые форумчане.помогите разобраться с dsd.как определить местоположение рации
Открывается такая карта .что делать дальше?

How to make a ferrite bar antenna for RTL-SDR?

I bought a RTL-SDR(blue one with little mcx antenna). I modified its Q branch, and can receive short wave radio with Degen 31ms antenna now. For MW, Degen 31ms antenna has a ferrite bar ant coupler to work with internal antenna of the radio. I don't have a ferrite bar antenna.

How to make a a ferrite bar antenna for RTL-SDR?

submitted by /u/slqqqq
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What is the bitrate of wav files saved with SDR#?

Hi there! In my settings I have sample rate set to 2.4 MSPS and I am recording a wav file in 8 bit PCM, 16 bit PCM, and 32 bit IEEE float. How can I find the appropriate bitrate for these newly created wav files?

submitted by /u/devil_d0c
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Comment on Comparing the Airspy HF+ And KiwiSDR on Shortwave Radio by Martin Ehrenfried

There is a flaw in this test – it’s the antenna.

Most active antennas do not provide sufficient dynamic range (the maximum signal level that can be received without unwanted distortion products relative to the antenna noise floor and the amplifier noise floor itself).

It is likely that both receivers have better performance than the antenna is capable of providing, so it would be hard to spot any differences between the two SDRs.

Differences between the two SDR’s AGC and receive bandwidth settings would also modify the results.

RTL-SDR Discussion • USA-Satcom XHRPT decoder

Hi all,
I am trying to get in contact with USA-Satcom out from Belgium via their website, however my e-mail does not get through for whatever reason.. My question : can somebody give me a hint how i can get in contact with them. I want to try out their XHRPT decoder, first on trial and in next step to buy it. As I am in Belgium , I am interested in METEOSAT 10.
Can anybody help? Thank you_ Paul - 0N5QM

Statistics: Posted by ON5QM — Wed Oct 31, 2018 5:39 pm


GOES reception — How clear does the path need to be?

My property has a TON of trees on it, mostly 80-100ft oak and maple, and some pine to the side. Luckily I found a spot on the side of the yard towards the front that has spotty foliage between 45-40 degrees or so, right where I should be pointing for GOES 16. Wondering if you guys have any experience with thin tree cover for receiving the GOES birds?

submitted by /u/bab5871
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Other SDR Devices • SDR for 802.11ac with 160 MHz channel

Hello,

Do you know any SDR devices or frontends capable of 160 MHz (or more) for RX channel bandwidth? I need to implement 802.11ac processing with all channels supported.

I've checked all popular SDR devices and frontends and they're capable of 10-54 MHz bandwidth, not more.

Thanks in advance.

Statistics: Posted by oleg_sdr — Wed Oct 31, 2018 3:58 pm


Troubleshooting Help • Re: What software to use for 100 kHz to 25 Mhz

Thanks,
I will try it out as soon as I have come to terms with gnu-radio.
H

Statistics: Posted by hakelm — Wed Oct 31, 2018 3:36 pm


Signal Hacking — Teach Me What I’m Missing — FSK Parameters.

Signal Hacking - Teach Me What I'm Missing - FSK Parameters.

So I am a mechanical engineer with limited electronics understanding (I can program an arduino).

I have a sensor that I want to use for a project, it is a ISM banded device (433MHz), however, the supplied receiver is no good and doesn't interface the way I want to the data acquisition system. Instead of finding an alternative product I decided to build my own receiver.

I purchased a cheap RTL-SDR and set to work, I had a known set of parameters to feed the sensor, plus it has a hard coded serial number, I made some assumptions about what the data might look like.

Here is where I am up to:

1) Identify carrier frequency - Check

Sniff around 433mhz (SDR#), while exciting the sensor, look for signals that might correlate. Identified something with a centre frequency of 433.885MHz that polled every 1000ms when the sensors value was changing.

2) Identify signal type - Check

Took a snapshot of the frequency and did some reading.

https://i.redd.it/oftcpq861iv11.png

(2-?)FSK.

3) Decode and demodulate the signal - Check

I did this with URH and basically ended up with an 80-bit stream/packet on 1000ms intervals.

https://i.redd.it/joclfcrg1iv11.png

in the demodulated bit stream the symbol rate appears to average at 25us, or 40kbaud.

4) Determine the packet structure - CHECK

Lots of experimenting and messing around with various encodings, looking for something reasonable. Jackpot, 4 bytes match up to the laser marked serial number.

Other bytes correlate roughly to sensor values. There is a very clear preamble and sync byte.

https://i.redd.it/m21trt342iv11.png

the last byte is a CRC for byte range 5-18.

The polynomial and the initial value were calculated by the great tool bruteforce-crc. Can now validate packet delivery. Encoding is "Manchester-II".

5) Take what SDR info and program a Ti CC1101 to receive the packet - FAIL.

So I purchased a CC debugger and a premade CC1101 programmable sub-ghz module, and connected these with Ti SmartRF studio. I was hoping that setting the carrier correctly and modulation to 2-FSK would yield at least a bitstream, this has so far been unsuccessful..

https://i.redd.it/6euatwwv3iv11.png

I am now wondering if I need to look closer at the deviation value and RX filter values (I dont think channel spacing applies in my use case).

6) Take CC1101 and register settings and attach to an arduino with an SD card....TBC

I am struggling to understand deviation and RX filter BW values, I think its a simple concept I am missing and I am sure its measurable with SDR# or similar, but I am confused by all the reading and what exactly it relates to with FSK and or how to measure it.

Ideas, thoughts and comments on my progress welcome, this is about 2 nights work, having never played with SDR or signal hacking before I think I'm doing ok...

submitted by /u/kjn260
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