All Your Modem Are Belong to Us

http://www.rowetel.com/blog/?p=4629

by zdw • 11 years ago

128 35 11 years ago

rowetel.com

nikanj• 11 years ago

Lost me at the Windows bit. I thought we were more adult than that by now.

angersock3• 11 years ago

Then you did yourself a disservice, because the rest of the writeup is kind of interesting.

Besides, for modern software development work, vanilla Windows is pretty terrible compared with any of the 'nix variants.

pjmlp2• 11 years ago

Only for those that prefer AT&T to Xerox PARC.

TeMPOraL3• 11 years ago

Totally agree here.

There is a problem that happens with some hobbies like radios and electronics - a lot of software and techniques was developed by people who were domain-specialists first and programmers second. This means they were disproportionally using Windows, and thus this platform has a lot of de-facto standard software written for the Microsoft's OS. On the other hand, today hobbyist programmers predominantly use Linux/MacOS, so when they want to start writing software for domains mentioned above, they hit a wall.

And yes, Windows is pretty terrible for programming compared with Unixes - and I say that as a person who grew up with Windows, spent most of his programming life in it, and had to code under it for current and previous job. When you get used to working in terminal and to all little small utilities and features, it becomes really annoying to have to code under Windows. Personally, I usually paper over it a bit by using Emacs on both platforms, but sooner or later I always hit a toolchain problem.

The solution isn't to bitch about Windows. It's a very good operating system, especially for everything that is not software development. Which means it's good for radio and electronics. Since software devs used to work under Linux like the myriads of "little things" they get from it, the only thing is for them is to sit down and just port the apps they need. Or port their favourite tools to Windows. Or both.

brianberns• 11 years ago

Really? Visual Studio is widely recognized as one of the best IDEs available, and the .NET platform is leaps and bounds better than, say, vanilla Java at this point. I'd like to know what sort of "modern software development" you do that is so "terrible" on Windows.

gambiting• 11 years ago

Vanilla Windows + Visual Studio is hands down the best development solution for writing C++ code. For any Web stuff - absolutely, I would go with a Mac or a Linux machine any day. For C++, it's incredibly hard to beat Visual Studio.

arm• 11 years ago

Going into the article, I was expecting some huge Windows insult, but all I found was this quip:

“Balloon chasing systems also use various hacks used to connect the modem software to mapping software, which in the case of the Horus balloon chasers runs on this legacy operating system called “Windows”. Yeah I’ve never heard of it either. Used to be popular apparently, and I’m told it’s good for games. However it would be nice to do everything in Open Source.”

Honestly, that seems pretty tame to me. Certainly not enough for me to stop reading the article. Perhaps that may just be because I don’t have as much sympathy for Microsoft anymore though, after they released Windows 10.

aselzer• 11 years ago

You are offended because he makes fun of a proprietary operating system that probably fits the task really badly and himself creates an open implementation?

I could not agree more with the author. From the text:

Closed source and proprietary chipsets are nasty, a glaring problem in a cool geeky field that is otherwise open source. It’s got to be fixed.

admax88q• 11 years ago

I thought we were adult enough to not throw out and entire detailed and interesting article because of one sentence we didn't like.

chrissnell3• 11 years ago

I've been working on open-source balloon control software [1] for my own balloon project that I've been building on/off for about six years. I am hoping to use a software modem to bridge between the RF and my AX.25 packet reader/writer [2] because I wanted to save weight. Payload weight is the name of the game in the balloon hobby--the lighter your payload, the less you have to inflate your balloon and the higher it will fly before it bursts. Even an ounce matters and the competitive altitude record balloons are invariably tiny, single-board, all-in-one payloads that are built around a single low-power microcontroller.

There are a couple of good open source options for software-based AFSK APRS modem/TNCs:

Dire Wolf: https://github.com/wb2osz/direwolf minimodem: https://github.com/kamalmostafa/minimodem

You'll still need a USB sound card though, which adds weight and cabling. I would love to see some open-source SBC hardware a la Beaglebone Black or RasPi that had a high-quality sound card built onto the board and wired through a Molex-type plug that was suitable to the bumps and bounces of flying.

[1] https://github.com/chrissnell/GoBalloon -- This was my first project in Go and while it works well, it now looks pretty ugly to me with a year and a half of Go experience under my belt.

[2] https://github.com/chrissnell/GoBalloon/blob/master/ax25/dec...

Sanddancer• 11 years ago

What about using one of the i2s daughterboards for the pi, instead of a usb sound card? The Pi has all-in-one shields that work out of the box, but the bbb will need a tiny bit of wiring to make it work.

j_s• 11 years ago

There are some tiny USB sound cards these days! (Not sure if the quality meets the requirements though.)

http://plugable.com/2014/09/23/plugable-usb-external-audio-w...

http://www.audioquest.com/usb_digital_analog_converter/drago...

normaldotcom2• 11 years ago

I've been working on a balloon controller as well, although mine is incredibly bare-bones [1]. It only reports position, altitude, and temperature; but since it's so minimal it only weighs around 2 grams.

For your use case, you might want to consider a small external microcontroller that handles TNC functionality, this /might/ be smaller and more lightweight than a USB sound card.

Your payload controller software looks pretty awesome--nearly makes me want to launch a balloon with a full Linux single-board computer!

[1] http://protofusion.org/wordpress/2015/10/featherhab-2-gram-h...

chrissnell3• 11 years ago

I've tested my code with the TNC-Black from Coastal Chipworks and it works well. Weight isn't a huge issue on my flight; I'm focused on high altitude photography. It's just more fun for me to do things in software whenever possible. I'd really love to do the mod/de-mod in pure Go. There is an interesting example of a modem in Go but I have much more learning to do before I could write one of these for AFSK:

http://bemasher.github.io/rtlamr/

chrissnell3• 11 years ago

Awesome tracker, by the way! I'm super jealous of guys like you with actual engineering skills that can put together a custom integrated package on a PCB like that. Would you consider putting up your schematics and Eagle files on Github or similar?

jws• 11 years ago

It's nice living in 2015 when you can code your modem in Octave, an interpreted numerical computation language, and not put an appreciable dent in your available CPU.

He approaches the problem at a higher level than a typical modem, for instance, he uses predictable data in the packets as framing instead of the deficient framing provided by the bit level protocol. When confronted with a corrupted packet he also tries to guess the true content by doing a "what if" analysis on the marginal bits to see if flipping them the other way fixes it.

unoti2• 11 years ago

For those that don't know-- although Octave is interpreted, the interpreted part acts as an interface to highly optimized vector operations under the covers. Signal processing and a lot of other tasks come down to manipulating large arrays of data using similar operations across the entire array. Although Octave is interpreted, these kinds of operations execute very nicely inside Octave. Octave also lets you write those kinds of operations at a very high level, like a = b * c, and under the covers it's doing millions of operations.

If you'd like to give Octave a try and learn about Machine Learning at the same time, try this excellent and fun free course! https://www.coursera.org/learn/machine-learning

One of the later lessons in that class is a mind-blowing signal processing thing. In that exercise, they show how you can put multiple mics in a room, with multiple people talking over each other, and the computer separates out the different sources of sounds, and outputs a clean wav file for each sound source with the sounds isolated from each other. It blew my mind, and was implemented in Octave. And they teach you exactly how to do it yourself.

All the above concepts can, of course, be done in C++ or NumPy or whatever, they just use Octave to teach the course.

brudgers4• 11 years ago

If that's not cool enough, GNU Octave is available for Android devices.

https://play.google.com/store/apps/details?id=com.gnuroot.oc...

drudru11• 11 years ago

I don't believe that exercise is part of the course anymore.

All Your Modem Are Belong to Us

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