Архив за 16.04.2018

Comment on Using a HackRF to Transmit To a Local Repeater by AD5NL

I have a bunch of the mini-circuits low pass filters with SMA connectors for my limesdr. They are probably not the platonic ideal of harmonic suppression (I am pretty sure though that they should give 20 or 30 db out-of-band suppression at least) but they can be bough online for cheap and even a trained monkey could use them.

It might add $20 (used) to your project but at least I can look the FCC straight in the eye and say “I tried” to be compliant.

Of course once could also probably build a super-great bandpass filter themselves with some capacitors and a little magnet wire.

Bandpass filter for NOAA, -71dB for FM

submitted by /u/machsFuel
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Recommended next steps for 868 MHz heater control

Recommended next steps for 868 MHz heater control submitted by /u/simondoc
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I made a simple interactive tribute to NOAA-15

Hi all. I figured that given how much data I've gotten from NOAA-15, I have to do something to commemorate the good times up until the partial death of its image transmission. I know this isn't directly related to SDR, but I felt you guys would appreciate it.

Just open up your favorite APT decoding software, set it up to record speaker audio (eg. Stereo Mix on Windows), manually start recording (not auto-record, for example File>Record>Manual Test in WxToImg), and then play the .wav file from this link.

Took me a little while to figure out how to do it, so I hope you all enjoy!

submitted by /u/THE_CRUSTIEST
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Comment on RTL-SDR Tests: R820T vs R820T2 Stability Tests for Radio Astronomy by JOHN McMahon

A remarkable device at such an inexpensive package. For the reception and the software already available we are truly impressed by what is available!

Please help me to identify this unknown signal

Hi all, I'm trying to identify this signal as its in the WX NOAA frequency range I'm trying to receive and it keeps getting in the way. I've recorded the baseband signal and saved it here: https://drive.google.com/open?id=1aT9zCy2WGGvgxTZxzQS9CscTG9UD2GSU Screenshot is here: https://drive.google.com/open?id=13_O4d8On48pyy5Z4Z4HoZqTL_pyOaSY9 Center frequency is approx 137.965MHz.

Also, what process do you go through when trying to identify unknown signals? And, what software tools can you use to view/replay the recorded baseband signal in retrospect?

If you have any idea what this might be, any help would be gladly received! :)

Thanks in advance, Matt

submitted by /u/mechanicalraspberry
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Comment on Hiring a Dev for Direction Finding & Passive Radar Software by DoaJC Blogger

I thought FM wasn’t suitable for passive radar and that TV pilot signals are mostly used. But I too would like to see passive radar on other SDR’s such as the SDRplay.

Strange transmission at around 170Mhz. I can’t decode it with PDW. What can it be?

Strange transmission at around 170Mhz. I can't decode it with PDW. What can it be? submitted by /u/tomekb1999
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Добрый день. Поделитесь пожалуйста проверенными схемами полосовых фильтров на различные Кв диапазоны…

Добрый день. Поделитесь пожалуйста проверенными схемами полосовых фильтров на различные Кв диапазоны

Comment on Using a HackRF to Transmit To a Local Repeater by Jake Brodsky

My primary concern is that the HACKRF One put a clean signal on the air. If I were doing this experiment, I would construct a band-pass filter to ensure that any harmonics or other spurious signals are reasonably controlled. The video made no mention of any filter or prior testing with a spectrum analyzer.

I don’t care if the receiver gets crunched. That’s your problem. I care if the transmitter puts garbage on the air. That’s EVERYONE’s problem.

73,
Jake Brodsky, AB3A

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