taint.org: Justin Mason’s Weblog

Software: a nifty trick in this Slashdot comment:

… This reminds me of an old trick we developed to use on the Amiga on a public-access cable channel. The software was under development and crashed occasionally, so rather than having a flashing guru meditation up on a local TV channel until it was rebooted the next day, we came up with a plan, that would probably work on a Windows machine as well (or just about any other system)

The idea was that while the software application was running, it drove a continuous 1khz tone out the audio port that kept a relay energized (that kept the signal on-air). When the system crashed, the audio output stopped, which meant the relay was no longer energized = video signal switched back to a stock SMPTE bars signal from a test generator.

Nowadays, I’d probably pay the money for a hardware watchdog timer. But this is a good, cheap way to implement a dead man’s switch. Very clever!

Tags: amiga, cable, channel, comment, relay, signal, slashdot, software, system, trick

GNU Radio, which (as noted on Boing Boing) has just released screenshots of a successfully-decoded HDTV signal, is a totally new way to receive (and possibly, in the future, send) radio-frequency signals. The FCC ponder the implications:

The emergence of the low-cost, generally available SDR which can be configured with … open software will present a new issue for regulators. What will be placed in the hands of the public entrepreneurs, amateurs, and even those with malicious intent will be machines which in principal can emulate, send, and receive any radio signal on any band. …

Then, with the world-wide availability of software that can even be modified if needed, any radio transmitter or receiver can be emulated. Bans on receiver types will be circumventable with ease. Mandates such as the proposed ATSC broadcast flag will be hard to enforce (and may even fail in the presence of a single web-connected noncompliant receiver). And, although not generally an issue for the Commission, it will be possible to implement proprietary systems without the benefit of any license from the patent holder. Because the software is open, as a practical matter virtually all mandated restrictions will be at risk (except for total power output which remains a classical hardware issue). …

In the GNU SDR environment, we have the makings of a powerful new technology that has the potential of solving the spectrum management problem, but we may also have other people in the world writing and distributing software with their own agenda.

Wow. That’s a brave new world. I wish I knew enough about radio tech to really get a handle on this stuff…

Tags: boing, gnu, hdtv, issue, radio, receiver, sdr, signal, software, world