Thursday, August 30, 2007

Linux Repeater Contoller

Some of the early software repeater controllers were far from ideal. But that was many moons ago, back in the days of DOS. Since then, stable operating systems link Linux have come along. So have embedded computers such as mini-ITX mother boards. The physical hard drives that were prone to failure can also be replaced with flash media.

I see two viable ways to go if you need a controller and want to save a bundle.
-The IRLP Repeater Controller Project
-Asterisk with the app_rpt project.

Asterisk with app_rpt provides the following for Amateur Radio stations and systems: A Full Function Repeater Controller, Touch Tone Command and Control, Autopatch - Reverse and VOX Operation, CTCSS Decode/Encode Functions, A SIP Telephone Exchange, Voice Mail and Announcements, Contact Closure Telemetry, Non-Proprietary Software and Hardware, PC/Linux Operating System Based, Remote Base Client, Fully Configurable and Programmable Communications Solution

The IRLP controller program is a simple controller that provides hangtime, DTMF muting, activity controller ID, and controllable courtesy tones. Intelligent CW repeater ID. You can adjust; The hangtime in milliseconds, the shortkey timer in milliseconds (COS time required for hangtime activation), the alligator timer in seconds (COS timeout), toggle DTMF mute on/off, the DTMF mute duration in milliseconds, the ID interval in seconds (time between IDs), the courtesy tone frequency.

Thursday, August 16, 2007

What is ham radio?

1912 marked the beginning of the amateur radio service. It should be noted that there were many radio experimenters or radio amateurs before this time that lead to the discovery of radio. Even after 1912 many important discoveries where made in radio by radio amateurs.

The FCC's section 97.1 defined the basis and purpose of ham radio:

(a) Recognition and enhancement of the value of the amateur service to the public as a voluntary noncommercial communication service, particularly with respect to providing emergency communications.

(b) Continuation and extension of the amateur's proven ability to contribute to the advancement of the radio art.

(c) Encouragement and improvement of the amateur service through rules which provide for advancing skills in both the communications and technical phases of the art.

(d) Expansion of the existing reservoir within the amateur radio service of trained operators, technicians, and electronics experts.

(e) Continuation and extension of the amateur's unique ability to enhance international goodwill.

As you can see the emergency communications part that usually is the first thing to stand out in our minds is actually only a small part of what we are supposed to be. We exist and have access to a very valuable resource (the radio spectrum) because of or contributions, discoveries and experimentation.

Now lets look at that radio spectrum that we are so graciously given...

Amateur Allocations - Little known fact - Did you know in the US amateurs have access to approximately:
3.75 MHz of HF (160m-10m) spectrum
67 MHz of VHF/UHF (6m-33cm) spectrum
24.095 GHz of microwave (23cm-300GHz) spectrum

I hope you can see where our largest frequency allocations are. These are also unfortunately ham radios least actively used allocations. Yet, these higher frequency allocations are typically the ones most actively targeted by companies putting pressure on the FCC. There is little commercial interest in HF frequencies. Companies want to allow unlicensed operations over a wider frequency range (some moneymaking operations like PCS cell phones are actually Part 15 unlicensed transmitters). There is much more amateur spectrum to lose if we don’t use it more actively.

By the way; these truths are the point of my blog.