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Universal Software Radio Peripheral From GnuRadio
The Universal Software Radio Peripheral for GNURadio has now gone into production and is
available for purchase for $450. It used to be insanely expensive to acquire this
technical equipment. Now the price has dropped by two orders of magnitude, to something about as expensive as a high-end graphics card. How long will it be till it's labeled a terrorist tool and banned?
It's apparently a general purpose software decoder of digital signals; decode DTV at a software level, apply software filters to analog audio, basically thru programming replicate all those arcane things done in both analog and digital radio/tv/shortwave signals.
A quick search on google revealed what this thing is.. Basically it allows you to build radio receiving equipement using software instead of traditional hardware (resistors, capacitors, transistors etc..). To quote something I just read 'getting code closer to the antenna'. Interesting idea cause it means you could theoretically write a receiver to decode digital signals (like TV) without paying for it? (Ok, perhaps a little un-realistic at the moment but this is the basic idea).
A software-defined radio (SDR) system is a radio communication system which uses software for the modulation and demodulation of radio signals.
An SDR performs significant amounts of signal processing in a general purpose computer, or a reconfigurable piece of digital electronics. The goal of this design is to produce a radio that can receive and transmit a new form of radio protocol just by running new software.
Software radios have significant utility for the military and cell phone services, both of which must serve a wide variety of changing radio protocols in real time.
The hardware of a software-defined radio typically consists of a superheterodyne RF front end which converts RF signals from and to analog IF signals, and analog to digital converter and digital to analog converters which are used to convert a digitised IF signal to and from analog form.
Software-defined radio can currently be used to implement simple radio modem technologies. In the long run, software-defined radio is expected by its proponents to become the dominant technology in radio communications. GNURadio is a project to implement software-defined radio as free software.
URL:: http://en.wikipedia.org/wiki/Software-defined_rad
Essentially this is a device to 'tune' to any of the millions of frequencies that are in the upper part of the non-visible Electromagnetic spectrum. TV and Radio are broadcast in the long wavelength low frequency part of the specturm. Pretty pictures at Nasa
t rum/index.html
(Warning: you may have to click through a stupid ad.)
Anyway, Here's a Salon Article about the polictical & technical aspects of it:
http://www.salon.com/tech/feature/2003/03/12/spec
www.rdex.net
There were quite a few pages dedicated to the advances in digital radio and SDR in Monitoring Times a few months back.
One of the biggest advantages to a true SDR radio is that the manufacturer can build one or two models of radios, and have different software loads depending on bandsplit, features, costs, etc.
Motorola tried that with their Jedi-series and XTS series of handy talkies over the past decade... biggest problem was that it is pretty simple (technologically) to take a radio with no special features (smartnet, digital modes, tone signalling, etc.) and enable the features by cloning the software load of another model.
They did smarten up to that with the MTS2000 line of radios; any attempt to force a 'codeplug' into it that didn't belong would turn the unit into a brick, and you'd have to send it back to Motorola for a costly repair (as well as a stern talking to for 'hacking' at the radio).
True software defined radios would be a lot easier to secure... on paper it would drive prices way down... in reality, as long as the radio manufacturers control the public service contracts, prices will still remain sky high.
As an aside, WiNRADiO markets a device that could *almost* be considered an SDR device... super pricey for a receiver, but neat concept.
I am looking forward to the day we see true SDR transceivers.
Is it really so hard to use tags?
Software radio or SDR - an intresting subject where mathematical formulas become radio.
See for a high level overview.
Good reading is Understanding digital Signal processing by Richard G. Lyons. Prentice Hall, 1st ed: ISBN 0201634678 (amazon.com, search). 2nd ed: ISBN 0-13-108989-7 (amazon.com, search)
VanuBose 's company Vanu Technology demonstrated a software radio based on an iPAQ with a digital radio "backpack", in May 2003. Here are some links:
Slashdot article
Linuxdevices.com
Vanu.com
Vanu.com
Here's a note on the future of software defined radio
Several relevant pointers available here
Section 5 of the FCC regulations state that any device operating must accept any harmful interference from any device that is licensed to operate at similar frequencies.
Now, that being said... because BPL advocates have much larger lobbies than amateur radio, they have managed to get the FCC to basically ignore their own regulations and all but 'stick it' to the ham operator, even though the ham is legally entitled to that slice of the pie.
The Amateur Radio Relay League site on BPL has a lot more information.
I've assembled and used a Flex Radio -- they really are pretty cool.
We actually didn't use it for a Ham radio -- we used it to build a fairly inexpensive, high-quality DRM reciever (not Digital Rights Management, it stands for Digital Radio Mondiale -- pretty cool tech).
Basically it allows you to build radio receiving equipement using software instead of traditional hardware (resistors, capacitors, transistors etc..).
Partial true, it does not eliminate, but reduces the the electronics used by do as much of the decoding (demodulation, etc.) of the RF signa l in programming hardware (FPGA) and in software (GNU Radio code itself). You still need a RF front-end typically for VHF ~100 MHz and higher (microwave signals a la Wi-Fi, GPS, DSS TV, etc.) and hardware like the USRP.
ould theoretically write a receiver to decode digital signals (like TV) without paying for it?
You can legally receive signals in the US, you cannot legally bypass copyright security measures like encryption to decode a satellite TV signal to enable to watch it. There is a moderate large hobby of people who listen or watch un-encrypted signals, we use to call them scanner listeners, but scanners evolved into Software Defined Radio devices as well. NB: There are explicit laws about listening into telephone conversations (both cordless and cellular) in ths US, AFAIK.
Why go with usb2.0 as the interface instead of pci or multiple usb2.0 connectors
Because USB2.0 was the fastest commonly available connection found on home PCs and laptops.
PCI rules out laptops, but the developers (Eric and Matt) use and demo their work on laptops.
Firewire wasn't as well developed and as well supported on all Free/Open OSes (OpenBSD in particular) when the decision was made.
The on-board ADC / DAC and FPGA will reduce the needs for most applications to something that works, such as a single HDTV ATSC signal (which is roughly 6MHz bandwidth).