8

The simplest might be to use an app. On Android, Heavens Above, a product of the 25-year-old website of the same name, stores the orbital elements of the satellites of interest, and does the pass calculations on your phone. The app uses the GPS to find your location. It likes to get fresh elements from the Internet on startup, but it caches them, so as long ...


4

After looking through things for quite some time, and asking around, I was able to find the following, assuming that I can get a copy of the signed certificate from somewhere. There is some more information at this blog article, and this GitHub site. The log file is done in a format called GAbbI (Global Amateur Interchange). This file format is similar to ...


4

The closest I could find to a specification for FT-8 was on the Wikipedia page for WSJT. In answer to your second question. I lead an open source project that is designing an implementation of the DVB-S2 and DVB-S2X protocols for amateur terrestrial and space use. The uplink is frequency-division-multiple-access. The downlink is the time-division-...


4

The RTL-SDR interfaces to your computer via USB. The USB interface and driver will buffer the data and send it to your software at the requested sample rate on average (baring underflow due to software glitches), but with varying timing due to interface jitter. The RTL2832U USB is likely sending larger chunks of data over USB in blocks of far more than 512 ...


4

512 samples should take 256 microseconds, so your times look about right. The exact time it takes to execute those lines of code will depend on the rest of what your computer is busy with. And it's unlikely that the elapsed time counter will be accurate to better than 10 us anyway (but I may be wrong, try it yourself by timing a delay loop). Whats slightly ...


4

Actually, direwolf already supports higher data rates since 2017; it will use the G3RUH modem for a speed of 9600 or higher. As shipped it can be configured up to 40000 bps. But it's a mistake to think that 9600bps isn't making use of a 48kHz sample rate. The author has done some testing which shows that 9600bps is about the highest rate that works reliably ...


3

To track the satellites, you need the Keplerian TLE orbital coefficients. Once you have those, you can track the sats without internet access. The TLE's are accurate enough for about a week. The TLE file format is standardized and works with nearly all the tracking software, and most software either downloads them on command or can import from a file. As ...


3

I'll answer the first part of your question, Ronald. I once witnessed a blind ham (WD8PIC) operate. His solid-state transceiver had a speech synthesizer that audibly spoke the frequency when the front-panel SPEECH button was pressed. What is more, he had everything on the front and back panels memorized. It was simply amazing how much he was able to do for ...


3

Since you tagged your question with GNU Radio, I am assuming that is your SDR software package. If you look under level controllers, you will find a function block called "Power Squelch". This function: Sets the threshold (in dB) where the squelch control switches between MUTED and UNMUTED states. If Ramp is enabled, there in an ATTACK state between MUTED ...


2

"Is it possible to generate rf by directly programming a pc parallel port?" Yes, you can. In fact any "alternating current" will produce RF, and a "port" (parrallel or other) from a "computer" can do this... but... (there is always one, isn't there?) You will have to ensure that you are filtering intermodulation, harmonic's and so on so forth, before ...


2

Just use pavucontrol to redirect the audio output from gnuradio to the audio input of baudline, shouldn't take more than a minute. Creating gnuradio blocks is a mission, and that's without integrating with something like baudline, which I don't even think is possible.


2

This may not be a direct answer to the question but since a comment suggested a book, let me suggest some others that I have in my library. First, what I think is the most practical for hands-on programming: "DSP Software Development Techniques for Embedded and Real-Time Systems" by Robert Oshana and published by Newnes. My copy is copyrighted 2006 and I ...


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 ...


2

I do have the specification for JT9 if that is of interest to you. It is currently in the form of a pdf. Would you like it emailed to you? Or would you prefer I paste it on this forum as ASCII text (where the formatting is a bit strange, but...


2

$ od -txC QSOPCTDIR.dat 0000000 60 00 00 08 20 20 20 20 20 41 4c 4c 20 20 20 20 0000020 20 20 20 20 20 20 20 20 20 45 41 47 4a 44 52 32 0000040 41 55 49 20 20 20 20 20 20 20 20 20 20 20 20 08 0000060 30 20 30 00 20 08 30 20 30 00 20 08 30 19 43 00 0000100 32 30 32 30 2f 30 38 ...


2

There are accessories for some radios that provide a speech capability. Here is a link to a web site, HamRadioAndVision, that has some information. https://www.hamradioandvision.com/accessible-transceivers-vision/ Also keep in mind that a person can be legally blind but still have some sight. I believe that a person with 20/100 vision is considered to be ...


2

The real number of samples from an RTL-SDR is not available via the USB interface. The RTL2832U chip samples at 28.8 Msps, but then mixes and downsamples the internal samples to lower rate IQ samples at from 240k to about 3 Msps, to allow transport over its slower USB 2.0 bus. The front-end R820T tuner can first downconvert VHF and UHF signal to a low HF ...


2

More than one block can be read into the psd if you want a result that is averaged (thus usually smoother) over several blocks. A sample rate in Hz can be divided by 1e6 if you want a spectral plot labeled in MHz, instead Hz.


1

The number of samples to read. Probably because whoever wrote it wants the graph to read in MHz rather than Hz.


1

I don't believe FT8 has a complete specification besides the source code, which is openly available. RTTY is an option. It doesn't need much of a specification since it's so damn simple. PSK-31 is marginally less simple. ARRL hosts a specification, among others. The QPSK variant has very basic FEC. On HF, I don't know what more exists which may qualify as ...


1

The TX channels are separate from the RX channels. Hence, there will be a singkle, dual-stream RX streamer, and a single, dual-stream TX streamer. The subdev strings in your pseudocode aren't doing what you want; docs. You also don't need them – if you request a dual-stream streamer, the default behaviour is to count them ascendingly. So, if you just get ...


1

The developer introduction has an overview and links to further resources. If you can link against a C++ library, you can use TrustedQSL to deal with the signing portion, or read the code to understand the process and create a Java version of it.


1

I'm one of the TrustedQSL developers. We currently have a C library (tqsllib) that you could link against with JNI, but we don't have a Java port of it and aren't really planning to do one. Most people writing code against LoTW to use the command-line interface to TQSL, explained here: http://www.arrl.org/TrustedQSL/tQSL-help/cmdline.htm If you decide to ...


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