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7

This is very likely to be be due to overload of the receiver. A quick, rough way to tell the difference: Tune your SDR receiver so the waterfall center frequency is not the same as the transmitter's frequency. Transmit. Check whether the spurs you see are symmetric about the transmitter's frequency or the receiver's frequency. This tells you which side ...


6

Yes, you'll have to look at it. I can't go into detail about every possible modulation, because there's just too many. But typically, a look at the spectral representation gives you an idea of whether you're dealing with a straightforward single-carrier signal a spread-spectrum signal or a multicarrier signal. One place to see some examples is the Signal ...


5

The display is simple: Pass the incoming signal through two band-pass filters, one at the mark frequency and one at the space frequency. Use the two filters' outputs as the X and Y coordinates of the plot. (Since you are in the SDR domain:) Do as much as you want to make a nice-looking digital oscilloscope display of that signal. The simplest accurate way ...


5

See SigiWiki: This wiki is intended to help identify radio signals through example sounds and waterfall images. Most signals are received and recorded using a software defined radio such as the RTL-SDR, Airspy, SDRPlay, HackRF, BladeRF, Funcube Dongle, USRP or others. https://www.sigidwiki.com/


5

I'm not familiar with the behavior of the particular programs you've named, but the obvious (guessed by ear and confirmed with a spectrogram/waterfall tool) difference between these two clips is the audio bandwidth is different. The clip from SDR Console has audio occupying about 5 kHz of bandwidth, in a file with a 12 kHz sample rate. The clip from SDR# ...


5

700-900MHz is "blocked" by law in the US and a number of other countries due to a (now antiquated) law that was designed to prevent wideband communications receivers from eaves dropping on old analog cellphones, which broadcast in the clear. These days it's entirely unnecessary, but it's still on the books because regulators are lazy like that. As for ...


4

A generic search term you might use is “Software Defined Radio” or SDR (a topic which covers much more than your specific question). Equipment possibilities for your specific question includes SDR hardware that covers the frequency bands of interest and that can be connected to your PC via USB or Ethernet, SDR software compatible with the specific SDR ...


4

At 27 MHz and a distance of 1000 km, propagation will be the main determinant of the possibility of communications. Propagation will primarily be a factor of time of day and the sun spot conditions. You can get a fairly accurate estimate by using propagation prediction sites such as VOACAP. If your interest is exchanging messages between stations, one of ...


4

GNU Radio Companion (GRC) generates Python code that is something like this (not exact text). (Make sure you chose the "No GUI" option in GRC.) class my_block(gr.top_block): # ... def main(): tb = my_block() tb.run() if __name__ == '__main__': main() You can just import this as a module in your Python program (the if __name__ check will ...


4

You could call it a limitation of WebSDR, but WebSDR intends to give you demodulated audio, audio for listening to, which an IQ signal is not suitable for (even if the signal is audio-like as in SSB and CW, the 90° phase shift of the quadrature component will make for unpleasant listening). That said, you can take a SSB signal you've captured and turn it ...


4

Judging by this blog post from AI4SV and an inspection of the source code for fldigi (which supports such a scope in its RTTY mode), it's pretty simple — you just run the AF signal through two narrow filters at the mark and space frequencies (exactly as you would normally do when decoding RTTY), and then use the mark signal to drive the X axis and the space ...


4

Simply put, the LNA amplifies everything that comes into it. If you think about it, it's actually kind of amazing. It's dragging its output value up and down in response to nanosecond-by-nanosecond changes in its input, reproducing signals at every frequency up to its bandwidth limit. A good amplifier is as linear as possible (meaning its output is ...


4

If the specific device is built around the Realtek RTL2832U chip, then the rtl-sdr driver software will be able to use it as an SDR. If it uses a different chip, then that driver will not work. It might still be possible to use that hardware, but would require writing new driver software and possibly reverse-engineering (the same as the original RTL-SDR ...


4

While it is useful to have, NO single book contains everything that you want or need to know. Note that the ARRL Handbook is published every year, and each year contains different information. But even if you owned every Handbook that was ever published, inevitably something you want to know will still be missing. The last Handbook that I bought was ...


4

The ARRL Handbook is a useful reference, but it's just that: a reference. It's not written as a text. It's useful for looking up forgotten details of stuff you almost mostly know, but it's not in a good form for learning things like electronics, antenna theory, an the like. A text aimed at self-study would be much more useful -- one written to be learned ...


3

I found the solution to my problem. It was due to running my program using Python3, while as Marcus Muller stated in my other posting "GNU Radio 3.7 is not python3 compatible". So, using Python2.7 instead was the solution.


3

Here's one from the designer of fldigi. http://www.w1hkj.com/modes/index.htm


3

I've heard that 2 days in the lab can save 2 hours of reading but in this case it turned out to be easy to test. It is the sample rate of the SDR which changes the bandwidth of the signal. Since I am using the PLUTO SDR I can't go below around 500ksps. So I tried with a symbol rate of 300 kbaud at a sample rate of 600k. Able to demod successfully. I asked ...


3

Is there dvbt/dvbt-2 receiver? Yes and no: T2 reception is too computationally hard so far. It's work in progress, but it's almost certain that your average PC can't decode full standard T2 rates in real time on its CPU. The channel coding is just too involved. Transmission is always computationally easier. See gnuradio/gr-dtv/ example flowgraphs. Why "...


2

I would say, your task is a challenging one, but not unsolvable. 27 MHz CB radio band should work similar to 10m amateur radio band. I suggest to start with simple experiments. For instance, solder a simple oscillator. In my experience Clapp oscillator is quite simple to solder, see schematic in this article https://eax.me/clapp-oscillator/ . Then add a 555 ...


2

I agree with hotpaw2 but there's an even cheaper solution. You can also use the many different webSDR's that are around the world. With those you only need an internet connection. These are some places to start: http://www.websdr.org/ https://sdr.hu/ Google will give you a ton of extra possibilities.


2

(This answer is from the perspective of GNU Radio programming; I'm not familiar with what SatNOGS is doing.) There are two problems to solve to use a given data file. First, you need to decode the file format into samples of a signal. The OGG File Source presumably solves this problem for you. Converting the file to a raw format is also an option, but not ...


2

@Hadad, maybe you are not activating your pybombs prefix by running source setup_env.sh before using gnuradio? Documentation for details: https://wiki.gnuradio.org/index.php/InstallingGR#Using_PyBOMBS Once activated you should be able to import gnuradio within a python console without errors: $ python >>> import gnuradio


2

I ended up figuring it out. I had to do three things: remove the Throttle block enable the "OK to Block" option in the audio sink ensure the amplitude of the sine wave is less than 1


2

I believe this blog post is trying to show the evolution of a good setup, rather than present a number of equally appropriate setups. You might want to first read How can I calculate the effects of an LNA, antenna gain, etc. on noise performance? Assuming the LNA is good enough to justify using, you want to: minimize losses between the LNA and the antenna,...


2

I see two main factors about the options in the blog. IMD Noise figure Option 4 is just option 2 but for a considerable cable length along with distortions and recommending to put the filter after the cable. Which is a good point for that case. Option 1 is the basis as the blog discusses the application of a filter. From there we have: a) Amplifier -> ...


2

You might consider the following two books useful in learning more about radio design and the details of various circuits used in transceivers. These two are not equal in their coverage -- the first considers the electronics of radio technology and the second is more focused on the science and mathematics governing the application of various radio circuits. ...


2

It's difficult to give an exact number, because the overall latency involves at least: Processing of the signal on the given SDR Transferring data over USB 2.0 / USB 3.0 / PCIe (depending on what is used) Latencies on USB controllers on both SDR and PC (+ USB hubs, if used) Latency caused by other USB devices (keyboard, touchpad, webcam, ...) on the bus. ...


2

The answer is that the SDR hardware devices are all very different, so is the optimization quality of the SDR code. So one pretty much needs to calibrate for their specific setup: device, current method of connection, OS, and software running. I find network latency between the SDR hardware server and the software client to be one of the biggest variables, ...


2

The data is AM modulated on the 2.4 kHz subcarrier, with 256 different levels representing a single value from 0 to 255. It's a scanline every 1/2 second from the cameras with sync and telemetry data added to the beginning and end. Each line is 2080 data points (words) long, so it broadcasts at 4160 baud. The sync lines at the beginning let you know when a ...


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