start here: Software Defined Radio receivers

Posted Jul 7, 2007 12:50 UTC (Sat) by kbengston (guest, #6153)
Parent article: A green light for free-software defined radio?

SDR receivers are a good starting point for anyone interested in this stuff. Not much danger of running afoul of regulatory agencies, because they pretty much only care about radio transmitters.

A good receiver is way more difficult to design than a transmitter. There are lots of radio signals out there for which there is no SDR receiver, particularly with the worldwide move to digital modulation formats for TV, Broadcast Radio, and many mobile services.

SDR Receivers for packet-based signals like 802.11 wlan are specially difficicult because there is a very short (10s of microseconds) preamble in which the gain of the receiver needs to be set so that the Analog to Digital Converter is neither saturated nor in the noise. Most general purpose hardware platforms lack the ability to measure signal strength and set gain fast enough to be able to handle 802.11 (or similar) modulation.

start here: Software Defined Radio receivers

Posted Jul 7, 2007 15:00 UTC (Sat) by pascal.martin (guest, #2995) [Link] (3 responses)

This is somewhat true for radio and television, but there are some lagging "flag" problems with TV and the HD radio "standard" secrets are firmly protected by the DMCA.

The problem is wireless networking. A receiver-only equipment is of little use, except if all you want is to steal credit card numbers ;-)

Did you go to Best Buy lately? Wireless is taking over Ethernet in term of shelf space. You find few choices with Ethernet equipment and much more choice with wireless. In a few years, Ethernet might be relegated to a more professional market (expensive CISCO boxes...) out of range for most personal use.

Open Source could be pushed out of the home network market, smashed between the demands of the FCC and those of GPL v3. With home network there is no home computer either. Worst case, Linux could become unusable for 80% of its users. FCC is telling us that binary-only drivers might be our only way. Not much fun.

start here: Software Defined Radio receivers

Posted Jul 11, 2007 1:10 UTC (Wed) by ilmari (guest, #14175) [Link] (2 responses)

Open Source could be pushed out of the home network market, smashed between the demands of the FCC and those of GPL v3.

There's no need to worry about the GPL v3 unless you're worried about wireless support in HURD. The Linux kernel is staying GPLv2 and I doubt the BSDs would accept GPLv3 code in their kernels.

start here: Software Defined Radio receivers

Posted Jul 13, 2007 18:09 UTC (Fri) by vonbrand (subscriber, #4458) [Link]

But they already accepted CDDL code! See the ZFS on FreeBSD page...

start here: Software Defined Radio receivers

Posted Jul 20, 2007 12:58 UTC (Fri) by hazelsct (guest, #3659) [Link]

Indeed. The new Intel drivers work around this by means of a small free in-kernel driver (using DeviceScape no less) with a user-space binary blob.

As long as it is legal to use proprietary user-space software with free operating system kernels and libraries (which I'm pretty sure GPL v3 does not prevent), this approach will work fine for software-defined radio.