Category Archives: spectrum

Crowdfunding Is Now A Contract Between Company And Backer

Kickstarter is not a store. Indiegogo is not a store. Crowdfunding is not buying something — you’re merely donating some money, and you might get a reward for your pledge. Caveat emptor doesn’t apply, because there is no buyer, and no one can figure out what the correct Latin translation for ‘backer’ is. These are the realities that have kept Indiegogo and Kickstarter in business, have caused much distress in people who think otherwise, and have been the source of so, so many crowdfunding follies.

Now, finally, crowdfunding is being legally recognized as a store. The Register reports a court …read more

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Posted in indiegogo, law, spectrum, ZX Spectrum, ZX Spectrum Vega | Leave a comment

Tapping into a Ham Radio’s Potential with SDRPlay

Software-defined radios are great tools for the amateur radio operator, allowing visualization of large swaths of spectrum and letting hams quickly home in on faint signals with the click of a mouse. High-end ham radios often have this function built in, but by tapping into the RF stage of a transceiver with an SDR, even budget-conscious hams can enjoy high-end features.

With both a rugged and reliable Yaesu FT-450D and the versatile SDRPlay in his shack, UK ham [Dave (G7IYK)] looked for the best way to link the two devices. Using two separate antennas was possible but inelegant, and switching …read more

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Posted in FT-450D, ham, Omni-Rig, radio hacks, RF, sdr, sdrplay, spectrum, waterfall, yaesu | Leave a comment

Cascade LNAs and Filters for Radioastronomy with an SDR

It may not be the radio station with all the hits and the best afternoon drive show, but 1420.4058 MHz is the most popular frequency in the universe. That’s the electromagnetic spectral line of hydrogen, and it’s the always on the air. But studying the H-line is a non-trivial task unless you know how to cascade low-noise amplifiers and filters to use an SDR for radio astronomy.

Because the universe is mostly made of hydrogen, H-line emissions are abundant, and their distribution can tell us a lot about the structure of galaxies. The 21-cm emission line is so characteristic and …read more

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Posted in filter, H-line, hydrogen, LNA, microwave, misc hacks, radio hacks, radioastronomy, spectrum | Leave a comment

Making a Spectrum Analyzer the Wrong Way on an ATtiny85

Everyone’s a critic, but it’s hard to argue with success. And that’s exactly what [agp.cooper] has with his ATtiny85-based spectrum analyzer devices.

The “normal” way to build a spectrum analyzer is to collect a bunch of samples and run a Fast Fourier Transform (FFT) on them all in one shot. As the name implies, the FFT is fast, and the result is the frequency components of the sampled data. [agp.cooper]’s “wrong” way to do it takes the Goertzel algorithm, which is used for detecting the intensity of a particular frequency, and scanning across the frequency range of interest. It’s a …read more

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Posted in fft, Goertzel, spectrum, spectrum analyzer | Leave a comment