Monthly Archives: April 2014

LTSpice Parameter Sweep

While designing/ working on my APRS project, I used LTSpice IV for some simulations. For those that don’t know, LTspice IV is a high performance SPICE simulator, schematic capture and waveform viewer from Linear Technology. It is a freeware and can be downloaded from this link. Versions for my both platforms exist, Win 7.0 and Mac. …

Red and Green

This will be a very short post. And only for the blog. I have a sweet spot (call it idiosyncrasy) for stationery. I mean, some people do heroin, some do alcohol, some do Oprah. I am addicted to stationery. Put me in a stationery shop — you can leave me there all day (give or take), …

144.8 Mhz TX for APRS (3)

This is a quick update post. The road I took with this little project is slowly getting to a dead end due to what it seems to be a lack of available crystals for 144.8 (like 48.26 or 28.96 MHz, for using the third or fifth harmonic). I believe that, currently, all APRS modules are …

Simple stuff: viewDidLoad vs. viewWillAppear

I was coding today for a small project I have. A very simple iOS application that has a very simple storyboard, two different paradigms for iPhone and iPad, but very, very simple. While coding I was struck by the fact — frequently forgotten — that we tend to ignore the obvious. Ok, here’s the deal: take one …

144.8 Mhz TX for APRS (2)

More work today and yesterday on this project. Still locking on 144 MHz, but this is normal, the crystal I used is a 48 MHz overtoned, working on the third harmonic in this case, thus spot on 144.0 MHz: I managed to clean the output, at the expense of transmitted power. I used a 7-pole 2m bandpass …

Weird man

I could hardly describe the pleasure of finding my mailbox full of magazines, brochures and thick envelopes. It’s psychological mojo probably goes back in my childhood days, when I was expecting my Topolino subscription, a magazine that my mother managed to get for me with some crazy efforts and connections. For those of you who do …

144.8 Mhz TX for APRS

Been busy at work lately, but still had some time for myself. Latest idea: a low-cost APRS beacon, done with a classical 144.8 Mhz TX and a μController. AX.25 on air. Automatically. So these days I’ve been busy making this: Winding coils, soldering, measuring. Fun. The frequency is remarkable stable, given the rudimentary nature of this. For example, …