Welcome to Jens David's Homepage
This is the homepage of Jens David, DG1KJD.
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+49 163 6 32768 3 (mobile, O2)
+49 351 3201118 (landline, Arcor)
email@example.com (primary now)
firstname.lastname@example.org (whenever it works...)
Sorry for the simple layout of this page. I try to concentrate on development,
not creating fancy web pages. Sorry again, no German version available.
Here are some of my projects and publications (in no particular order) which might
be of public interest, feel free to download and distribute all of them,
software is usually GPL'ed, hardware descriptions and documentation can be freely
distributed. However, there is NO WARRANTY for anything. It might even
eat your harddisk, blow up your house or kill your cat.
- Linux Kernel AX.25
- Here you will find stuff related to Linux Kernel AX.25. In particular
patches implementing the AX.25 protocol stack (the protocol stack that comes
with the original Linus kernel tree is years old, broken by design and by now fucked beyond
repair (FBR) [TM]), some fixes and new device drivers. This patch was previously
(until 2.2.19) maintained by me but due to QRL-related issues I don't have
time to do this any more.
- AO-40 satellite telemetry project
- Some stuff developed as part of my diploma thesis. A Ptolemy model of a telemetry demodulator,
a KDE2 application which performs the same task and a decoder/viewer for the data. STP and Internet
- PCISCC-4: Four-port PCI compatible SCC card
- These are the official PCISCC-4 information pages including
construction data. PCISCC-4 is a four-port PCI compatible SCC (Serial
Communication Controller) plugin card for connection of synchronous
serial network devices, typically ham-radio modems or WAN transceivers.
- Realtek RTL-8139 driver for Linux 2.2
- This is a patchset that updates support for Realtek RTL-8139 based local area network
interface cards in Linux 2.2. The original driver by Donald Becker is unfortunately quiete
unuseable and -readable (not to say broken). The version 0.9.22-2.2
of this driver for Linux-2.2.20 can be downloaded above and applied to the
vanilla kernel. Linux-2.2.21 and later do -- as I was told -- NOT include
this version, but an older, broken one although this version (with completely
reworked TX code) was submitted a couple of times without any reaction.
I honestly do not know what is going on, please patch manually.
- Ptolemy model of a AO-40 telemetry demodulator
- This archive contains a AMSAT-OSCAR 40 (aka Phase-3D) 400bps BPSK telemetry demodulator.
A costas-loop downconverter, an AGC galaxy, a symbol timing
recovery and sampling galaxy and a decision feedback equalizer star as well as
some documentation. Makes nice learning material.
- Backstein-TV Professional
- This is a project which helps Philips-MediaBox users to watch digital
TV (mostly in Germany) without having a subscription card. The hack uses
a MicroChip PIC16C84 or PIC16F84 (or a smart card containing these chips
respectively). It can only be used with SECA compilant systems, not with the
system in use by Premiere/DF1 in Germany. It will not work with encrypted
channels either, just free-to-air.
- Soundmodem Intern (Paper, German)
- This is the paper presented at the 15th International Packet Radio
Symposium at Darmstadt Technical University (TUD) about the Linux
soundmodem implementation and error correcting codes (ECC). Only German
- AIRS - Amateur IP Routing System
- Here you will get the current version of AIRS. Note that I will not
spend a lot of time maintaining this since kernel AX.25 is a much better
aproach. The idea behind AIRS was to create a userland solution for routing
IP traffic via ham radio packet radio network, pretty similar to what
Win/FlexNet does now. However, AIRS only ran on Linux and OS/2. The OS/2
tree is included but no more maintained. It should still work though.
- IRCGATE - a perl script
- This is a little perl script which can be used to connect an IRC
(Internet Relay Chat) server to a ham-like convers system. The idea behind
it is to allow the users to use a standard IRC client for conversation. This
is also a nice example of how to use Linux' AX.25 sockets from within a perl
- SPIProg - a SPI EEPROM Programmer
- This is a little programmer for SPI (Serial Periphery Interconnect)
EEPROMs such as, but not limited to, Xicor X25640, X25650; Atmel AT25080,
AT25160, AT25320 and AT25640. The package includes the software and building
instructions for a parallel port programming adapter consisting of a D-sub
connector, three resistors, some wire and an IC socket.
- CardCrypt - a Cryptographic tool with smartcard support
- This is the result from a university project. The task was to
write a program which had to run on Windows 95 that enables the user to
apply asymetric cryptographic algorithms to data. The keys can be read from
disk or a smart card. The program is pretty neat and uses the graphical user
interface of windows to present a cool integrated crypto environment to the
user. It's a lot of work in there. However, the assignment's idea was stupid
(unfortunately I had no influence on that). Maybe it is of interest for somebody else.
- An introduction into Field Effect Transistors (Paper, English, stupid)
- This is a small paper I had to write for a seminar.
- An introduction into the principles of modern soundcards (Paper, German, stupid)
- This is a small paper I had to write for another seminar.
- DCF-77 decoder
- This is the result from a school project on grammar school, years ago.
The aim (which was reached) was to write a DCF-77 decoder in Pascal
and document it. It might be of interest for those who want to know how
created by Jens David, DG1KJD - last update 2010-07-20