
The Raspberry Pi 3B+ as an SDR, Without the SDR - okket
https://hackaday.com/2018/04/14/the-raspberry-pi-3b-as-an-sdr-without-the-sdr/
======
mojomark
I work for the military, in which the labyrinth of acronyms and custom-made
terms are extremely challenging to navigate. We constantly remind our peers to
define acronyms when first used in document.

As I enter the computer science (CS) field, I find increasing number of pages
(such as the subject page) riddled with acronyms that you have to search to
define. I also find a host of improper terminology usage as well as
"instructional" information that is simply incorrect.

As CS experts, trying to expand our mutual horizons, why do we torture
ourselves like this?

~~~
userbinator
It's not "torture", it's learning and efficiency. We could expand every single
acronym and abbreviation every time, but that would quickly get in the way of
understanding since it would just become needlessly verbose.

 _I also find a host of improper terminology usage as well as "instructional"
information that is simply incorrect._

That's a different issue... and one that's pretty much unavoidable if you want
freedom of speech.

~~~
jlarocco
The original poster (OP) was suggesting that acronyms should be written in
expanded form once, like I did with OP at the start of the sentence, and then
used by acronym for the rest of the article, like I did in the middle of this
sentence. That way people who don't already know the acronym don't need to go
look it up, and people who do know the acronym don't have to pause and think
about it, and it still saves time and typing by the author.

Many writing style guides, like APA [1], suggest this form.

[1]
[https://owl.english.purdue.edu/owl/resource/560/21/](https://owl.english.purdue.edu/owl/resource/560/21/)

~~~
the_jeremy
The problem lies in choosing where to draw the line. People often assume the
acronyms they use every day are well known, and don't think it's necessary to
expand them. Case in point, you don't define APA, because you (correctly)
assume I know what it means.

This article doesn't look like it was written for newcomers to the field; it
appears to be written for hobbyists interested in having yet another cheap SDR
at their disposal. The target audience knows the acronyms, so the article
doesn't bother to expand.

~~~
solidsnack9000
The criterion might reasonably be (a) acronyms that are terms of art in (b) an
article for publication.

Thus acronyms that should be known to everyone within a field would be
expanded on first use. This seems redundant but it's not actually a huge
burden.

------
kam
The author's PhD thesis on the framework he built to modify the Broadcom WiFi
firmware looks really interesting, and presents several other ways to take
advantage of the low-level control of the hardware.

[http://tuprints.ulb.tu-
darmstadt.de/7243/7/dissertation_2018...](http://tuprints.ulb.tu-
darmstadt.de/7243/7/dissertation_2018_matthias_thomas_schulz.pdf)

------
magnat
You can also use RPi as FM stereo transmitter without additional hardware -
[https://github.com/Miegl/PiFmAdv](https://github.com/Miegl/PiFmAdv)

~~~
jdietrich
You can, but you definitely shouldn't.

~~~
markovbot
Why not

~~~
caltelt
From the github repo readme:

> In most countries, transmitting radio waves without a state-issued licence
> specific to the transmission modalities (frequency, power, bandwidth, etc.)
> is illegal.

~~~
userbinator
In practice, it's more like "if you get caught if it's illegal" \--- and
depending on what you're doing, getting caught can be very easy (e.g.
broadcasting in an active band at enough power that your neighbours notice),
or pretty much impossible (e.g. if you transmit inside a Faraday cage or at
powers so low it doesn't reach the other side of the room).

Or as the old saying goes, "If no one else can hear you, they won't know
you're saying anything."

------
danmg
It might be easier to just link to the guy's github repository
([https://github.com/seemoo-
lab/mobisys2018_nexmon_software_de...](https://github.com/seemoo-
lab/mobisys2018_nexmon_software_defined_radio)) than the two click throughs to
find it.

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traverseda
A better title would be something like 'Broadcom WiFi chip hack lets you use
it as an SDR'. The raspberry pi isn't the interesting thing here, it's the raw
low-level access to a wifi DSP.

~~~
noja
The raspberry pi is the interesting bit because most people know if they have
one hanging around.

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awat
Does this mean it would be possible to use Zigbee?

~~~
Bedon292
I think so, since they are on the same frequency. Which leads to some really
interesting ideas I would like to try.

------
parvenu74
Are there SDR boards or plug-in components made specifically for Raspberry Pi?

~~~
UncleEntity
I've often wondered why someone doesn't design a daughterboard with a SDR chip
for the RPi as this would let them do away with the embedded cpu/FPGA.

Plunk an rtl-sdr chip on a RPi board and Bob's your uncle...

~~~
derefr
Perhaps the IO bandwidth between the RPi and its peripherals isn't high enough
to enable it to manage an SDR. (I don't imagine you could connect a modern
GPU, or a video capture device, to an RPi either.)

Speaking of: are there any SBCs that have PCIe-based daughterboard support? Or
Thunderbolt-3-based peripheral support?

~~~
namibj
Those based on the Zynq-7000 line from Xilinx usually have ample IO, but start
at about 100$, going up. You might need to do something in the FPGA part of
them to use the IO though.

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sjwright
I'd be extremely interested if this could be used to build a rudimentary Wi-Fi
spectrum analyser / interference scanner. It doesn't even have to be very
good—hazy and vague measurements are a million times better than no
measurements.

The commercial option is Wi-Spy, a product that is so massively overpriced
it's borderline absurd.

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genericacct
Been looking at this for a while, anyone who uses it to enable miracast on the
raspi is going to be my hero.

