Talk:Software-defined radio

message: The link for SDR Forum Software Defined Radio Design Process and Tools Work Group Wiki was removed. This was a valuable link to a collaborative forum for the SDR community. I do not see this as spam.
It is a place to discuss how to design and implement SDR's. How do we get it added back in? AndrewDauman 22:02, 19 June 2007 (UTC)
replies: text: The WP:EL guideline says to avoid external links to wikis. Besides, this SDR article already has 3 sdrforum.org external links, any more would be excessive. (Requestion 22:29, 19 June 2007 (UTC)
thread_title:  External Links 

message: It appears that there are three pages for Software Defined Radio. http://en.wikipedia.org/wiki/Software_radio
http://en.wikipedia.org/wiki/Software-defined_radio
http://en.wikipedia.org/wiki/Software_defined_radio
Even though it appears as though they somehow sync-up, I suggest one be maintained and the other two deleted Jennifersteinberg 20:31, 4 June 2007 (UTC)
replies: text: Two of those are redirects to the main Software-defined radio page. Software Receiver is another redirect. Only the main page is being maintained. (Requestion 20:47, 4 June 2007 (UTC)
thread_title:  Redirects 

message: Current (2003) digital electronics is to slow to process signals from 10kHz to 2.4GHz? Might be a bit outdated.  In 2007, I think we're either there or getting there, and while we cannot receive the entire radio spectrum, projects such as HPSDR are developing hardware (the mercury board) that can directly sample the radio spectrum from 0-65MHz.  - Ryan 19:26, 15 June 2007 (UTC)
replies: text: Digital hardware is fast enough, but doing it in software is slower. Processors are getting more parallel, so you can do more and more digital signal processing in software, but still slower than in digital hardware. Maybe software-defined radio is the wrong term. Gah4 (talk) 13:38, 11 November 2015 (UTC)
thread_title: It isn't 2003 anymore

message: from the intro: SDR [uses] … the soundcard of a general purpose computer (PC), or a reconfigurable home-made piece of digital electronics. But, the military examples given don't sound like either 'a soundcard' or 'home-made digital electronics'. Should it instead say that the processing is done in a type of computer hardware known as a DSP such as what is found in soundcards? 「ѕʀʟ·✎」 06:21, 24 September 2007 (UTC)
replies: text: As SDR is used in the amateur radio market place, any DSP in the soundcard is almost irrelevant to the processing.  If there is a DSP there, it is because it is cheaper to base a soundcard on a DSP than to create a logically simpler design.  All the significant processing is actually performed on the main CPU.  The essential function of the soundcard is to do the A/D conversion, and associated anti-alias filtering.  In professional use of the the term SDR, the processing is normally done on a DSP, rather than on a general purpose processor, but that DSP is in the receiver (i.e. it is a complete SDR, not just the front end).  Essentially all the confusion here is because amateur radio mis-uses the terms, so ends up labeling things by their physical realisation, rather than their function. -- David Woolley (talk) 14:04, 22 January 2012 (UTC)
thread_title:  contradiction in definition? 

message: In the second paragraph:
"An SDR performs significant amounts of signal processing with the soundcard of a general purpose computer (PC)..."
Why soundcard? In my opinion soundcard equals to audio card. It's kind of confusing here.  —Preceding unsigned comment added by 202.40.139.171 (talk) 08:06, 4 October 2007 (UTC)
replies: text: The quote was nonsense and seems to have been corrected in the main article.  The functional component is an A/D converter.  Soundcards are the cheapest way of providing these with a typical PC.  Where they are referred to it is in terms of the physical realisation, not of the the logical structure of the system.  -- David Woolley (talk) 14:16, 22 January 2012 (UTC)
thread_title:  Why "Soundcard"? 

message: It seems that digital oscilloscopes and function-genertors are bit similar to sdr. any comments? 193.167.107.251 (talk) 19:25, 28 January 2008 (UTC)
replies: text: Seems to me that an important part of SDR is the digital mixer. I don't know if that is usual for an oscilloscope, but a digital function generator might make a transmitter, in the same way that an analog function generator makes an AM or FM signal. Gah4 (talk) 19:16, 14 September 2015 (UTC)
thread_title:  comparsion to oscope/fn-generator 

message: There are several technical inaccuracies in the section on practical receivers. The statement that digital electronics are too slow to receive signals over 40 MHz is incorrect. Remember that the Nyquist Theorem states that the sampling rate must be at least twice the bandwidth of the signal. This means that, in theory, we can sample signals anywhere in the spectrum (with some limitations depending on where the signal is located in relation to the sampling frequency). The limiting factor in actual radios is a measure called the aperture jitter, which quantifies the ability of the ADC to sample at a precise interval (assuming a jitter-free sampling clock, of course). If you are interested more in the subject a google of "undersampling" turns up several excellent references. 
The statements on recovering the phase and bit timing are also incorrect. The reason we need to recover phase and bit information is that the transmitter and receiver clocks are not in sync with each other. By recovering this information we will be able to integrate over the entire bit and thus receive the most power and improve the accuracy of the entire radio.
As far as authority goes, I am an electrical engineer who designs digital radios for a living. Roddefig (talk) 07:06, 23 May 2008 (UTC)
replies: text: Part of the idea of SDR is doing as much in the digital side as possible. But yes, if you bandpass filter before the ADC, you are essentially generating a mixer, but in the analog domain. As noted early on, in theory one wants to connect the antenna directly to the ADC, but in practice that doesn't happen. If you generate a programmable bandpass filter, you might be close enough. Gah4 (talk) 19:20, 14 September 2015 (UTC)
thread_title:  Misinterpretation of the Nyquist Theorem 

message: Can someone define radio protocol, as used several times in the article? --Abdull (talk) 12:49, 24 August 2008 (UTC)
replies: text: Radio protocols are obviously the sets of rules, parameters and conventions needed for radios to communicate. I don't think explicit definition is necessary here.  —Preceding unsigned comment added by 24.251.186.204 (talk) 22:25, 23 February 2011 (UTC)
thread_title:  Radio protocol? 

message: The part "Receivers" is copied from NXP itself.
There are more companies claiming to have a chip implementation of SDR for a handset soc. from google
217.140.96.21 (talk) 07:51, 3 April 2009 (UTC)
thread_title:  Handset soc chips 

message: In the section "SPEAKeasy phase II", at the end, it is claimed that "The time to reprogram these [FPGAs] is an issue limiting application of the radio."  This is misleading.  The time to write a program for an FPGA is significant; the time to download a stored FPGA program is around 20 milliseconds.  This means an SDR could change transmission protocols and frequencies in one fiftieth of a second, probably not an intolerable interruption for that task. 
I am speaking from my experience with Gigaoperations, the maker of the FPGA computing platform chosen by Xilinx in the 1990s. I imagine with much bigger, but faster, FPGAS today, download times are similar. Rhodesh (talk) 22:43, 10 August 2010 (UTC)
replies: text: Please change the article as you suggest. Regards, Ariconte (talk) 04:12, 11 August 2010 (UTC)

text: Thanks for the change. But 20 milliseconds (ms) are 20/1000 seconds, that is 1/50 second, not 1/5 second. It is true that FPGA got faster, but FPGA got MUCH bigger, too. I think 200 ms as download time for the FPGA configuration is a conservative value. Next, the number of downloads is limited. 1 million downloads before FPGA end-of-live give you only 5.55 hours operation at a configuration change every 20 ms. Question: is 200ms and 1/5 seond correct or 20ms and 1/50 second? AndreAdrian (talk) 14:27, 5 October 2021 (UTC)
thread_title:  FPGA programming 

message: It's half past 2011 at the moment and there are lots of citations.  The box should be deleted immediately.  It's pure gnome shit.
: I count about 5 out of 8 sections that have no references, and some of the others are only lightly referenced. WP:V The box is still warranted IMO.--Albany45 (talk) 20:42, 11 July 2011 (UTC)
replies: text: Perhaps it would be better to take into account the NATURE OF THE CONTENT rather than mindlessly demand some unspecified number of citations in each and every section.  For instance, READ the sections rather than just count them and then ask yourself exactly what NEEDS referencing.  You may find that the material, considered with its multiple links to wikipedia pages, defines and explains in a self sufficient manner and thus STANDS ALONE without needing any BLEEDING references.  Example: if I say black is sometimes considered white you may sensibly ask for a reference BUT WHEN I SAY FOUR IS 2 + 2, YOU CANNOT, gnome.  — Preceding unsigned comment added by 24.251.186.204 (talk) 20:46, 27 July 2011 (UTC)
thread_title:  The box at the top that complains about insufficient "in-line citations" in 2009 

message: Because of his many publications on the subject, Joseph Mitola III is sometimes called "the father of the software radio."   Joe worked, off and on, at E-Systems.  In 1984 the phrase "software radio" was defined by members of a team of E-Systems Garland Division employees to describe a large baseband receiver they designed and built.  I was a member of that team.  Joe was not.  We never saw him around and as far as I know he wasn't even cleared to enter the room. He had nothing whatsoever to do with development of the 1984 E-Systems software radio.  In the years since then it has annoyed some of us whenever Joe claims he later coined the term software radio (for instance here).
By the way "software defined radio" kind of sucks since it could (and sometimes does) just mean using a GUI to set the knobs, so to speak, on an analog receiver.   — Preceding unsigned comment added by 24.251.186.204 (talk) 18:22, 29 August 2011 (UTC)
thread_title:  Joe Mitola had nothing whatever to do with the 1984 E-Systems software radio 

message: The definition of SDR used in this article is basically that used by black box consumers in the amateur radio market.  The professional definition of SDR would actually cover nearly all modern, commercially produced, HF amateur radio equipment, and an increasing amount of VHF and UHF equipment.
An SDR is a radio that uses software for back end signal processing, what people are really referring to here are not SDRs, because they actually do not run any software, but rather RF and IF front ends, which can be combined with the A/D converter in a PC sound card, and a general purpose computer, to produce a complete system which is a software defined radio.  The definition used here refers to essentially purely analogue devices (although some integrate the A/D converter).
As used here, it is either a marketing term for a specific sub-market, or simply a misunderstanding of the terminology in that market.
-- David Woolley (talk) 12:41, 22 January 2012 (UTC)
replies: text: Huh? No idea what you are talking about. The definition at the top of the article is good enough as it stands. The only improvement needed is to drop the useless word "defined" :-)  — Preceding unsigned comment added by 24.251.186.204 (talk) 15:44, 29 March 2012 (UTC)
replies: text: The comment is partly correct, in that "SDR" is a technology that is now used in virtually all but the simplest communications receivers (and transmitters).  Any radio that is advertised with "IF DSP" is probably SDR.  The IF is digitized and processed in an embedded computer. It emerges as baseband audio through a DAC.  "Consumers" may not regard such radios as SDR, however. They may think that a separate (visible) computer backend makes it an SDR, or else they see the mysterious terms "I" and "Q". :-)  It would be helpful if the article were clearer about the widespread use of these techniques, even in radios that seem (from the outside) to be conventional.--Albany45 (talk) 02:51, 30 March 2012 (UTC)
replies: text:  So he's on about the difference between software and firmware (i.e. can the device owner can reprogram it easily himself)?  That's off topic. The scope of the definition and the whole article should just be the digital processing, not hardware implementation details, not tool chains, not amateur vs. professional or whatever.  And, bless your hearts, wikipedia is not well served by sterile editors calling for authors to try again. If you think the definition sucks you should offer a better one yourself. But it doesn't suck.  It's not awesome but it doesn't suck.  — Preceding unsigned comment added by 24.251.186.204 (talk) 16:55, 30 March 2012 (UTC)
thread_title:  Uses Consumer Defnition, not Professional One 

message: I propose that Software GNSS Receiver be merged into Software-defined radio.  As an alternative we could just delete Software GNSS Receiver which is more about the technology of hardware vs software radios, than it is about something specific to GPS or GNSS. ★NealMcB★ (talk) 20:16, 24 April 2012 (UTC)
thread_title:  Merge in Software GNSS Receiver 

message: I propose to branch the ham radio SDR software to a new article. Furthermore it would be helpful to include a list of the software available on Linux, OSX, Windows as entry points for the interested reader. A list like the revision control software overview would be great. :) 2A4Fh56OSA (talk) 09:21, 29 September 2012 (UTC)
replies: text: This article is losing its way. WP is an encyclopedia. It is WP:NOTHOWTO do stuff. Why is this article recommending a RTL2832U? WP is not a directory of DIY or amateur projects. WP wants its information from reliable secondary sources -- not some self-published website or youtube video. Building an SDR is an accomplishment, but it isn't necessarily notable. I'm willing to break WP rules in many places, but WP should not become a place to advertise projects that have no concrete claim to notability. There need to be WP:RS that indicate a project is significant. Glrx (talk) 19:32, 30 September 2012 (UTC)
replies: text:  I think, gnome, that if you actually read that WP guideline on notability you will see that notability is supposed to be a criterion for the existence of a _page_, not its content. Last time I looked, the notability page had a banner or something that said in so many words don't edit content for notability. And wisely so because real people generally note more than gnomes (i.e., volunteer editors for form who imagine they don't need to be knowledgeable about content).  — Preceding unsigned comment added by 24.251.169.182 (talk) 16:40, 14 November 2012 (UTC)
thread_title:  Separate the SDR Software 

message: Does anybody really consider DSP operations to a baseband signal to be SDR? I would expect that a SDR should be able to encode or decode an AM, FM, or QAM signal by changing the software. If the input to a DSP is via a sound card, then how can the IF frequencies of 455 KHz on AM broadcast and 10.7 MHz on FM broadcast be captured? Does one mix down to a 20 KHz IF? Is it really practical to generate a 20 KHz IF that a sound card could digitize? And could any useful info be extracted from that low, low IF?
I suspect anything that uses the A/D on a sound card is merely a fancy tone control for a baseband signal. That stuff belongs in Audio filter. RastaKins (talk) 21:49, 26 October 2013 (UTC)
replies: text: I'm for removing a lot of the how-to information; does the article really care about specific devices. That said, it is possible to use a 10-kHz IF and decode many modulation schemes. Sound cards are a popular amateur technique to digitally decode many signals. Glrx (talk) 22:53, 27 October 2013 (UTC)
thread_title:  Remove all references to sound cards? 

message: Seems to me that the definition of SDR excludes the use of programmable hardware (FPGAs). Maybe this is an accident due to the history of the path leading to current technology. The important distinction should be doing radio operations, such as mixers and filters, in the programmable digital domain, not software vs. hardware. Under the ideal assumptions, you should be able to connect an ADC to an FPGA, and demodulate most radio signals up to hundreds of megahertz, with all the SDR advantages but no software. (In actual implementations, you probably need some filters, though.) Why the restriction to software? Gah4 (talk) 19:38, 14 September 2015 (UTC)
thread_title:  Programmable hardware 

message: The article says: Real analog-to-digital converters lack the dynamic range to pick up sub-microvolt, nanowatt-power radio signals. Therefore, a low-noise amplifier must precede the conversion step and this device introduces its own problems. For example, if spurious signals are present (which is typical), these compete with the desired signals within the amplifier's dynamic range. They may introduce distortion in the desired signals, or may block them completely.  It seems to me that this is mixing dynamic range and signal level. To start, microvolt and nanowatt means that the impedance is in milliohms, which is pretty low.  One can build 24 bit ADC, though maybe not at the higher speeds.  Building an amplifier with noise that low is difficult, and maybe impossible.  But the ability to pick up microvolt/nanowatt signals is often due to high power signals, such as nearby transmitters. Without that, an appropriate amplifier isn't so hard to build.  Gah4 (talk) 04:41, 1 April 2018 (UTC)
replies: text: Indeed, it's a mess.  The concept of spurious signals introducing distortion in the desired signals is probably about strong co-present signals inducing spurious signals via distortion.  These problems are harder in an ADC that's trying to digitize a wide band without a tuned front end to first reduce the co-present signals that are out of band. If you can make that ADC have enough bits and enough linearity and enough speed, then no problem.  In practice, these combinations can often be challenging. Dicklyon (talk) 05:25, 1 April 2018 (UTC)
replies: text: Yes. Good ideas are there, but they seem to mix things up that don't need to be mixed up, besides the voltage and power being wrong. And yes a strong signal causes problems with weaker signals, and yes it is hard to build good enough amplifiers. But the explanations don't seem quite right. Gah4 (talk) 06:47, 1 April 2018 (UTC)

text: Reminds me, I had the idea some time ago about digitizing the whole AM band, which would allow one to change stations, and then back up to the beginning of a program or song.  S/N does complicated it if you are near a high powered station. Otherwise, it might work, and the data rate isn't all that high.  A little harder to do the whole FM band, but maybe not impossible. Gah4 (talk) 06:47, 1 April 2018 (UTC)
thread_title:  dynamic range? 

message: It seems to me that, as described, SDR is for digital receivers of analog radio signals.  That is, traditional modulation systems such as AM, FM, PM, or SSB. But more and more, radio systems are going digital.  In other words, there is no ADC in the receiver, but most often some type of spread spectrum system. Programmable digital receivers are now common in, for example, cell phones which need to be able to be used with different cell systems. Only in the case where one needs a receiver for an existing system, such as broadcast AM or FM, or ones such as marine or aviation radio. As I understand it, aviation radio uses AM, as it allows for emergency override, where when two are transmitting on the same frequency, the receiver gets some of each.  I suspect, though, that for military applications, they are going digital more and more. Gah4 (talk) 23:14, 3 March 2020 (UTC)
thread_title:  analog 

message: KiwiSDR is similar to WebSDR (which can use any SDR radio) but it uses a specific piece of hardware that allows individual 0-30 MHz tuning for each user.
Link to website: http://www.kiwisdr.com/  — Preceding unsigned comment added by 194.193.212.24 (talk) 05:16, 17 October 2020 (UTC)
thread_title:  KiwiSDR 

message: There is a very interesting GS1299 single chip FM radio receiver. The data sheet doesn't give much details, but it goes from antenna with a fixed LC filter on one side, to stereo audio outputs, able to drive headphones, on the other side. The only tuned circuit is a 32768Hz crystal oscillator. I don't see any mention or reason for software, though. It does say CMOS, and much of the processing can be done in digital CMOS hardware without any software. It is fixed for the FM band, so no software programming needed. As far as I know, though, there is no article on non-software digital receivers for analog radio signals. In any case, I assembled a kit with this chip, and it works just fine. Gah4 (talk) 02:18, 24 February 2021 (UTC)
thread_title:  [https://datasheetspdf.com/pdf-file/769456/GUANGSHIMEI/GS1299/1 GS1299] 

message: Hi. "The" GNU Radio: I was the head maintainer for GNU Radio, nobody uses it with the "the" article; it's a software project, just like "the libreoffice".
I also been a Support Engineer for Ettus for nearly a decade. There's several separate USRP models, but none correctly match the technical data given in the section.
The only forgivable sin here is that GNU Radio used to be predominantly used with USRP hardware. That isn't as strongly the case anymore, since better integration of other SDR hardware has arrived.
I'm hence reworking that section. Marcusmueller ettus (talk) 12:09, 3 January 2023 (UTC)
thread_title:  Complete USRP section is gibberish 

message: There's absolutely no need to bring a bullet list of arbitrarily chosen waveforms to say "SDR enables usage of different waveforms"; it actively makes the article worse.
I'm removing that list, it has no business being in this article. A link to Modulation serves the same purpose, just better! Marcusmueller ettus (talk) 12:24, 3 January 2023 (UTC)
thread_title:  Introductory section meanders, badly