Hack Chat Transcript, Part 1

A event log for Software Defined Radio Hack Chat

What's in your dongle?

Dan MaloneyDan Maloney 09/18/2019 at 19:350 Comments

OK, everyone, it's noon here in the Pacific time zone, so let's get started. Today we have @Signals Everywhere/KR0SIV to talk about software-defined radio, which I can't believe we've never done a Hack Chat about.

@Signals Everywhere/KR0SIV - Welcome! Can you kick us off with a little about yourself and how you discovered SDR?

fernando.gil joined  the room.12:01 PM

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Signals Everywhere/KR0SIV12:02 PM
Sure thing @Dan Maloney

So my name is Harold Giddings although most online know me as Corrosive or my amateur callsign KR0SIV

I originally got involved with SDR when the RTL drivers were originally modified from old TV Tuners to an SDR platform.

This was years ago when I was still active on IRC and once I saw these things in action. I was officially addicted

Chip Standifer joined  the room.12:02 PM

Signals Everywhere/KR0SIV12:03 PM
I'm currently employed as a commercial radio technician and so thankfully I get to have radio fun most days even when I'm not playing with an SDR (which I still find excuses to use at work)

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RichardCollins12:05 PM
What SDRs are you using now, and what software do you use?

Signals Everywhere/KR0SIV12:05 PM
Software Defined Radio is really what got me back into radio. I take my amateur exam shortly after getting into SDR.

It was like opening an entirely new world being able to look at the radio spectrum via the waterfall rather than scanning individual channels.

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IRC12:06 PM
[Arsenijs] should work now (ignore this message)

Signals Everywhere/KR0SIV12:06 PM
@RichardCollins Currently my primary daily drive is still the RTL-SDRv3 from the blog however I have a large plethora of SDRs these days. My favorite SDR client software would have to be SDR# however, I make often use of CubicSDR and SDRConsole as well as when transmitting... SDRAngel

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RichardCollins12:07 PM
Do you have particular "targets" or frequency ranges, or just browsing generally?

Signals Everywhere/KR0SIV12:07 PM
My primary SDR for transmit has to be the PlutoSDR because it was affordable, has a good housing on it and is of course full duplex

James Finch12:08 PM
Totally awesome the visual representations of what you first hear on the radio (or maybe other sensor stimuli too)... then see in other ways to identify, qualify and quantify.

Signals Everywhere/KR0SIV12:09 PM
Frequency ranges really depend on what I'm doing. Generally I like to play around in the SW/HF bands as well as looking for digital stuff in the commercial end of the 440 MHz range as well as 800-1090 for P25/trunking/ and ADS-B

Seth12:09 PM
I can't wait until lab-grade spectrum analyzers are as cheap as SDR dongles ;)

Signals Everywhere/KR0SIV12:09 PM
Satcom is also a big thing of mine so I'll often be playing in the L-Band around 1.5ghz

Joyce joined  the room.12:09 PM

Joshua Conway12:09 PM
Have you ever come across unencrypted 'sensitive' data? If so, how did you handle it?

anfractuosity12:09 PM
for satcomms do you need a dish, also what kind of data do you pick up from them?

James Finch12:09 PM
The PlutoSDR hack looks nice, thanks for sharing that.

BSA Secure12:09 PM
I'm keeping my setup simple and cheap by using RTL-SDR's... until I've decided to extend my knowledge and play around wide bandwidth Ka-Band satellite links that and bought LimeSDR (after getting WAF .. Wife Approval Factor. Now .. everyday I'm learning from Signals Everywhere community so I can dive deeper in RF "Hacking".

Signals Everywhere/KR0SIV12:10 PM
@Joshua Conway I do sometimes come acrossed sensitive data.. The key is simply not sharing it, if I do a video that contains such data I'll blur it out (such as my decoding of a pager signal)

RichardCollins12:11 PM
The SDRs are improving, but they still have issues with comparison between different actual devices. I have two SDR V3s and they give totally different results on the same antenna.

Signals Everywhere/KR0SIV12:11 PM
@anfractuosity This depends on the satellite you are looking at, sometimes I'll be in L-Band looking at inmarsat or iridium, a dish can be helpful but a tuned panel antenna works fine. There are also UHF band satellites that have analog voice on them

Signals Everywhere/KR0SIV12:12 PM
Generally a dish is needed for Ku band / C band and other SHF

Signals Everywhere/KR0SIV12:13 PM
@BSA Secure you can still do a lot with a typical RTL based SDR

James Finch12:13 PM
@Seth I recently found another oscilloscope plugin for SDR# that I haven't verified/tried yet that isn't the one from IN3IEX:

Signals Everywhere/KR0SIV12:13 PM
for example looking at Ku band

Signals Everywhere/KR0SIV12:13 PM
You can use the LNB as a down converter, technically... that's what it is

Signals Everywhere/KR0SIV12:13 PM
You just need an external bias-t to push voltage to it for power

BSA Secure12:14 PM
@Joshua Conway, whenever you will take a look on something, you will see that you can find sensitive data. For example, military traffic is encrypted so you cannot (and shouldn't) put your hands on - but still you can notice that protocols allows you to e.g. count how many participants are on the channel - it means that by monitoring traffic you can count how many military / police units are in the area.

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James Finch12:14 PM
@Seth this reference to SDRSharper doing a Google search from a Twitter post to find the above links and will try when I get the time:

Signals Everywhere/KR0SIV12:14 PM
@RichardCollins I'm curious what kind of differences you are seeing

Chris Capobianco12:14 PM
@Signals Everywhere/KR0SIV Do you have any experience with radio astronomy using SDRs?

Seth12:14 PM
Thanks @James Finch ! I'll check that out!

Signals Everywhere/KR0SIV12:15 PM
@Chris Capobianco I've not yet delved into radio astronomy yet although I know you can detect the Suns radiation with a typical Ku LNB, it's something I want to get into but am currently limited in places I can set up a dish

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anfractuosity12:16 PM
cheers @Signals Everywhere/KR0SIV , the data from irdium/immarsat is digital then? what kind of software do you use to decode that data?

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Chris Capobianco12:17 PM
@Signals Everywhere/KR0SIV Same here. Thanks for the information.

loengrin200012:17 PM
Hello to everybody, Anybody here has experience on electric utility remote telemetry unit signal decoding on 450MHz with RTL-SDR?

James Finch12:17 PM
@Seth Right, very welcome. This was interesting finding also in that same search as I've been wondering and thinking can so, something I've wanted to try with my TDS-520 test bed frankenscope either directly or with a pan adapter in some way:

Signals Everywhere/KR0SIV12:17 PM
@anfractuosity Inmarsat is pretty straight forward, you can use USB in SDR# (or whatever) and pipe that audio using virtual audio cables into various applications for decoding. I have a video on this here:

anfractuosity12:17 PM
cheers, will watch that!

Signals Everywhere/KR0SIV12:18 PM
Iridium I generally don't recommend playing with as all the data contains are phone calls/text messages and other private information

Signals Everywhere/KR0SIV12:18 PM
Although, there is software for this too

anfractuosity12:18 PM

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Curtis Franklin12:19 PM
@Signals Everywhere/KR0SIV are there any decent low-cost amateur SDR rigs -- the equivalent of the low-cost QRP rigs available from a number of sources?

Signals Everywhere/KR0SIV12:19 PM
Inmarsat contains all kinds of data, some public such as emergency events and weather

Signals Everywhere/KR0SIV12:19 PM
some not so public like medical calls to aircraft

Signals Everywhere/KR0SIV12:19 PM
but for those you need to compile a voice codec which is easier said than done (but doable)

RichardCollins12:19 PM
I will send you a private message with some images. Generally the gains and frequency responses are different for the same software settings. I ran a five hour comparison last night over a 200 kHz region with one peak. The shifts across all frequencies are close to the same, but the individual signals are quite different. Part is the problem of synchronizing and comparing signals from the two devices. No timestamps in any of the data. No quantitative measures in SDR#. Sliders with no numbers.

James Finch12:19 PM
@Seth Spektrum is about the best I've used as a spectrum/signal analyzer with an RTL-SDR and there is the HackRF and SDRPlay ones also I haven't tried yet. Amazing there are even protocol analyzer like apps too.

Signals Everywhere/KR0SIV12:20 PM
@Curtis Franklin The only one's I've seen are the mcHF and it's clones

BSA Secure12:20 PM
@Chris Capobianco I'm working on re-purposing Ka-band household hardware to be re-purposed for radio astronony. By using 30euros hardware you can receive (RX) Frequency 18.3 to 20.2 GHz which is still valid for radio astronomy,

RichardCollins12:21 PM
Everyone, please add LINKs to mentions of specific software. These are HUGE internet topics. Narrow us down to a click. Thanks

James Finch12:21 PM
@RichardCollins Might be something that can be developed and validated in GRC?

BSA Secure12:21 PM
and you can you RTL-SDR as its downcoverts to 300MHz - 800MHz

Yes, good idea. And keep in mind that there'll be a transcript available online after the Chat in case you want o refer to anything

Signals Everywhere/KR0SIV12:22 PM
Here are some of those decoders for inmarsat

farmboy12:22 PM
@Signals Everywhere/KR0SIV What's the least expensive SDR that could be built and deployed en masse?

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Signals Everywhere/KR0SIV12:23 PM
@farmboy this is a difficult question, it depends on what features it needs

Signals Everywhere/KR0SIV12:23 PM
I generally say it's not about which SDR is best or the cheapest, it's about what SDR best fits what you want to do

farmboy12:23 PM
900 ISM, OOK / FSK. :)

RichardCollins12:23 PM
@James Finch I do not know what GRC is? Can you provide a link? Thanks Happy to look at it.

Signals Everywhere/KR0SIV12:23 PM
Then you'd be fine with even the bottom of the barrel RTL on eBay honestly @farmboy but I'd still recommend at least the RTL-SDR v3

James Finch12:24 PM

Great Scott Gadgets GRC Tutorial:

Signals Everywhere/KR0SIV12:24 PM
@RichardCollins GRC is a format used by GNURadio

farmboy12:24 PM
What's the top of the barrel?

Max-Felix Müller12:24 PM
@Signals Everywhere/KR0SIV Do you have a sort of checklist for what devices fit what needs?

Signals Everywhere/KR0SIV12:24 PM
I do have a basic comparison chat that's still a WiP

Boian Mitov12:24 PM
Hello everyone :-)

Sheridan-Tech12:25 PM
@Signals Everywhere/KR0SIV How do you transmit with a RTL-SDR? Are there other transmit/receive chipsets you would recommend? I am a Computer Engineer and have thought about prototyping my own.

Signals Everywhere/KR0SIV12:25 PM
@Sheridan-Tech You don't "technically" transmit with an RTL-SDR, there have been some that have managed to modulate data using a leaky LO but for a real transmit capable SDR I'd recommend the PlutoSDR at around $130 it's the cheapest SDR based option

James Finch12:25 PM
@RichardCollins Your welcome, I'm trying to find some references I made on reddit and FB regarding the windows installation of GRC since can be a, what reminds me of a Java app programming and program installation nuances, pain.

Signals Everywhere/KR0SIV12:25 PM
There are also those cheap VGA adapaters that could be used to transmit cheaper

@Signals Everywhere/KR0SIV - Mind if I ask a little about your day job? What's new and exciting in public service radio these days? Everything is digital now I suppose.

Signals Everywhere/KR0SIV12:26 PM


Search Results vga

Osmocom are some of the people behind the original discovery and development of the RTL-SDR (in particular Steve M), and today it looks like they have done it again by releasing exciting news of a way to turn a commodity $5 USB to VGA adapter into a TX-only capable SDR. They call their discovery 'osmo-fl2k', as the magic chip that makes it all happen is a Fresco Logic FL2000.

Read this on Rtl-sdr

Joshua Conway12:26 PM
What's your take on RPi 3 and Rpitx lib?

lryindra12:26 PM

BSA Secure12:26 PM
@Sheridan-Tech What about RaspiTX ? You can transmit using FL2000 chip or raspberry pi .

Sheridan-Tech12:26 PM
*Mind blown*

RichardCollins12:27 PM
@BSA Secure Can you provide a link to what you are doing? I tried to find you before to get specifics to try that but could not find enough info to reproduce what you did. I want to look up to 40 GHz, but downconverters for the 1-20 GHz seem to be available --- IF one can connect them to the SDR. It is not the money - it is the time to reproduce what someone else tried. Saving a few hundred dollars on hardware then spending three weeks to get it to working is false economics.

Signals Everywhere/KR0SIV12:27 PM
@Dan Maloney Most things are digital, most of the time our commercial customers get DMR Capacity Plus and Linked Capacity plus. Most of our police departments are on the state MARCS IP system which is Phase 1 P25

BSA Secure12:27 PM
After adding filters (I'm bothering @Signals Everywhere/KR0SIV to prepare simple how to build filters)

Signals Everywhere/KR0SIV12:27 PM
@Joshua Conway the RPITx library is great! I need to use it more, keeping in mind it's low power and very dirty... it's still great to learn and probably one of the cheapest methods to transmit

Signals Everywhere/KR0SIV12:28 PM
Yes very correct @BSA Secure a filter should ALWAYS be used when transmitting anything that will go more than a couple feet

Sheridan-Tech12:28 PM
Thank you all. I was looking forward to this chat since it was posted. Now I have quite a bit to go on.

Signals Everywhere/KR0SIV12:28 PM
You don't want to cause interference

James Finch12:29 PM
@RichardCollins I first started with this crude reference that didn't cause me any issues.

For Windows 10 I had issues... so wrote something up somewhere I guess like I was thinking on FB and Reddit...

Yeah, not only digital but encrypted, or at least that's what I'm seeing. Used to avidly listen to local law enforcement on the state trunking system, but they encrypted everything last year. Bummer

Signals Everywhere/KR0SIV12:30 PM
There is no encryption in use for the most part in our state, generally this is because of the high cost to encrypt but also to public backlash about the fact that we should be able to "monitor the monitors" if you will.

Chris Capobianco12:30 PM
@BSA Secure I was planning on the 1.4 GHz range for neutral hydrogen, is there a LNB for that range?

Signals Everywhere/KR0SIV12:30 PM
I have a few RTL-SDRs set up at work and use it to monitor the system, it's funny because you can tell if someone i