Packet Radio Under Linux
My first introduction to packet was using the sound card modem driver with a hand-held 2-meter band transceiver for 1200bps packet. The audio connects from the PC sound card to the radio's microphone and speaker jacks. A signal from a serial or parallel port in conjunction with a simple (one transistor) circuit is used to control the radio's PTT (Press To Talk) circuit. This approach requires no TNC and no packet modem—if you already have a computer and sound card this costs almost nothing. Figure 1 shows a block diagram of my setup.
Configuring the system was straightforward—I just followed the detailed instructions in the AX25 HOWTO. Utility programs included with the AX25 package allow me to monitor the packets being broadcast and received, and to call and answer other packet stations.
I obtained an IP address from the local IP coordinator (the 44.x.x.x ampr.org Internet domain is assigned for packet radio) and configured my system for TCP/IP over packet. All the standard network tools then operated over packet. Assuming they are configured for TCP/IP, I can ping or finger other stations and connect to them using telnet. Similarly, I can log on to my home Linux machine over the Internet.
Next I plan to set up a simple BBS system users can log on to via packet radio. I'd also like to look at more sophisticated packet networking tools supported under Linux, such as NetRom, NOS and Rose. In the future I may even explore options for higher-speed packet such as the 56 Kbps Ottawa PI2 card.
As well as being fun, packet radio under Linux taught me a lot about networking, much of which is also applicable to Ethernet, X.25 and other network protocols.
Linux is a great platform for packet, particularly since it is fully integrated with the rest of the networking subsystem. Its reliability lets you leave a Linux system up for long periods of time without crashing (ideal for a BBS environment). As an example, one local Linux system has been on the air continuously for over 310 days without interruption. Some of the software I used was still in alpha release yet was stable enough to use. Finally, packet radio has opened up a whole new area of Linux for me to explore, ensuring that I won't run out of things to do in the foreseeable future.
Thanks go to Gord Dey, VE3PPE, for reviewing this article and adding many valuable suggestions. I also wish to thank Terry Dawson for writing the AX25 HOWTO and utilities, Alan Cox, Jonathan Naylor and others for writing the Linux packet code and Thomas Sailer for writing the sound card packet modem driver.
Practical Task Scheduling Deployment
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.View Now!
|The Firebird Project's Firebird Relational Database||Jul 29, 2016|
|Stunnel Security for Oracle||Jul 28, 2016|
|SUSE LLC's SUSE Manager||Jul 21, 2016|
|My +1 Sword of Productivity||Jul 20, 2016|
|Non-Linux FOSS: Caffeine!||Jul 19, 2016|
|Murat Yener and Onur Dundar's Expert Android Studio (Wrox)||Jul 18, 2016|
- Stunnel Security for Oracle
- The Firebird Project's Firebird Relational Database
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- SUSE LLC's SUSE Manager
- Managing Linux Using Puppet
- My +1 Sword of Productivity
- Non-Linux FOSS: Caffeine!
- Doing for User Space What We Did for Kernel Space
- SuperTuxKart 0.9.2 Released
- Google's SwiftShader Released
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide