Decoding SSTV From Space Station with Magnetic Mount on Linear Power Supply!

 


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Have you heard of zBITX?

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 Well, I had not heard till I read the program schedule of LARC-7 today. Most of you would be familiar with uBITX which has gone up to version 6. Some of you would be aware of sBITX, which is quite an advance over uBITX. Almost daily I am meeting a new uBITX user on the band, most of them using additional linear amplifiers. That made me join the BITX group on groups.io , where I am getting messages from uBITX and sBITX users from all sides of the globe. Still I was not aware of zBITX and that made me look around and came across two references. One was the video of a talk by VU2ESE at QRP ARCI . Another was an email in the BITX groups.io which was citing the former. zBITX is a new transceiver from VU2ESE based on Raspberry Pi Zero for 20W, having CW skimmer and FT8 modes in addition to the regular SSB mode and waterfall display which the sBITX also has. zBITX is quite small, just 3" x 3" x 1.5" in size. It is a Raspberry Pi Zero based 20 W software defined radio which h...
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What is SSDV? No, it is not a typo!

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This week, every amateur radio satellite enthusiast is busy decoding and posting SSTV (Slow Scan TV) images from International Space Station. Now what is SSDV? SSDV is the abbreviation for Slow Scan Digital TV, in contrast to SSTV which is analog and has been there for a long time. It has been mentioned that SSDV is a packetised digital form of SSTV. I heard of SSDV first when I read about the recently launched ASRTU-1 amateur radio satellite, which has a UHF SSDV in addition to the V/U transponder and 10GHz high resolution image downlink onboard. UBSEDS24 Balloon with SSDV launched from Bristol, UK sometime back had recorded nice SSDV images of the clouds from above. Lunar-OSCAR-94 which went into lunar orbit had transmitted SSDV images back to radio amateurs on Earth. WSJT JT4G was used for messages and transmissions were on 435.400 and 436.400 MHz. Transmitting power was about 2W, using VHF/UHF SDR transceivers. It was the world's smallest spacecraft to enter lunar orbit indep...
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What is a PIN diode?

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 PIN diode is a diode with an additional undoped region of intrinsic semiconductor. Usual diodes have P and N types of semiconductors meeting at a junction. For PIN diode, the I or intrinsic region is between the P and N type regions. The P and N type regions may be heavily doped and used for ohmic contacts. The intrinsic region makes a PIN diode inferior as a rectifier compared to PN diodes. But PIN diodes are suitable for attenuators, fast switches, photodetectors and high voltage power electronics applications. Intrinsic region is flooded with charge carriers from P and N regions in what is known as high level injection. PIN diodes will conduct current once the flooded electrons and holes reach an equilibrium point with equal number of electrons and holes in the intrinsic region. While the PIN diodes functions like a standard diode at low frequencies, it works almost like a perfect resistor at high frequencies even for large signals. The high frequency resistance is inversely pr...
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