Aeronetworks sro - Airborne Linux

The L-Band is carved up for many services and the 1690 to 1710 MHz Space to Earth band is shared with 4G cell phone services, with several geo stationary and polar orbit earth observation satellites operating at 1702.5 and 1707 MHz .  Since I recently made an ADS-B 1090 MHz patch I decided to make one for this higher frequency band, while I am still in the swing of things with my mad antenna carving skillz . This Right Hand Circular polarized antenna is carved from Rogers RO4350B low loss PCB and after a couple days of meticulous cutting and measuring it is spot on. It is amazing what one can make if one has enough coffee, chocolate and patience! Rogers 4350B copper clad circuit board has the following RF parameters: Permittivity Dk = 3.66 Loss Df = 0.0031 Dielectric width Dw = 0.508 mm Cu 1 Oz = 36 um This Joint Polar Satellite Service (JPSS) antenna has the following dimensions: Base: 69 x 54.6 mm Patch: 53.3 x 43.4 mm Corners: 12 x 12 mm Slots: 5 x 8 mm Feed: 1.1 x 7.5 mm...

Minikits in Australia ( https://www.minikits.com.au/ ) makes a nifty little low noise RF amplifier for a VHF weather satellite receiver, such as the Meteor satellite on 137 MHz.   Note that SatDump is very much improved now - it is all the software you need to see that it is raining outside, without the stress of looking out the window. Some careful soldering is required, but it is not difficult to build. When I test an RF circuit, I run it from a 12V sealed battery - my noise free power supply . Once tuned up carefully with a nylon screwdriver ( the little spatula that you get with epoxy glue! ), it can provide up to 20 dB gain, but on average over the band, expect about 5 to 10 dB.  With some patience I eventually managed to eek out 7.6 dB at 137 MHz .  This may not sound like a lot, but a radio receiver is more dependent on the Signal to Noise and Distortion Ratio ( SINAD ), than the actual signal level. The LNA is a tuned single transistor amplifier with a li...

In a moment of boredom/inspiration, I thought about making a patch antenna for my ADS-B aircraft tracking system, which is part of ADS-B Exchange .  One can make one-off patch antennas from garden variety glass/epoxy FR4 board, but the result will have relatively high loss and it will not be repeatable.  In order to simply order high quality batches of antennas from any PCB factory, one needs to use low loss, controlled impedance board stock . With this antenna, the ADS-B receiver simply sits on my window sill and picks up aircraft 200 km away. Cut Corners The design is a typical rectangular patch antenna, with circular polarization.  A circular polarized antenna allows more mounting options for a conformal antenna. Slots The side slots in this design increases the bandwidth, but it also reduces the operating frequency, so slots can be used to tune a patch antenna design. Board Type There are a variety of RF boards made by various manufacturers ( Rogers , Isola , P...

I reclined in the winter garten nursing my back and watched a gaggle of geese and aircraft soar overhead, which made me realize that it's been a while since I made an Air Traffic Control (ATC) antenna, so I dug in my Junque Bochs for an old Raspberry Pi v3, a RTL-SDR dongle and a tripod telescopic test antenna , downloaded the latest ADS-B ( Automatic Dependent Surveillance-Broadcast ) decoder image from https://www.adsbexchange.com/ and went to work play. The last time I worked with ADS-B transponders was maybe five years ago, when I used a RTL-SDR to test a Sagetech Mode-S ATC transponder and the free decoder software has improved dramatically since then.  It took about an hour to set the system up and I could immediately see a handful of aircraft, as far away as 80 nautical miles (150 km), using a wonky little telescopic antenna on my office window sill. After a while I captured an Emirates A380, a USAF Galaxy and a Slovak AF LET 410 Turbojet from the military airport nearby ...

As most would know, the Kernighan and Ritchie C Programming Language is an improved version of B, which is a simplified version of BCPL, which is derived from ALGOL, which is the Ur computer language that started the whole madness, when Adam needed an operating system for his Abacus, to count Eve's apples in the garden of Eden in Iraq.  The result is that C is my favourite, most hated computer language , which I use for everything. At university, I learned FORTRAN with punch cards on a Sperry-Univac, in order to run SPICE, to simulate an operational amplifier.  Computers rapidly lost their glamour after that era! Nobody taught me C.  I bought the book and figured it out myself. Over time, I wrote a couple of assemblers, a linker-locator, various low level debuggers and schedulers and I even fixed a bug in a C compiler - not because I wanted to, but because I had to, to get the job done!   Much of my software work was down in the weeds with DSP and radio modems...