just bought an SDR (Software Defined Radio) dongle

**MFCT** · 08-30-2017, 12:50 AM

Looks like a fun gadget you have there. I've ran out of ideas for fun gadgets to buy, so I'm glad you posted.

There's a distribution of Linux that's made especially for SDR stuff, with all the essential SDR utilities pre-installed and ready to use. You can run it in VirtualBox.

http://skywavelinux.com/

Start the video at 3:48 to see what this distribution can do.

**GFED** · 08-30-2017, 02:00 AM

Here's a playlist for you.
https://www.youtube.com/watch?v=JEQX...jTLnGoZX53H0Bw

**lezinterracial** · 08-30-2017, 11:54 AM

Thanks for links. Will be fun to see what I can do.

**lezinterracial** · 09-01-2017, 09:20 PM

Got it today. Got GQRX up and running. Was able to listen to a local FM station and the NOAA weather report frequency.

I noticed the dongle gets really hot. That me be why some people complain about theirs going bad. I will use a fan on it and try not to run it too long.

I hope to find out how to scan frequencies for activity. Like I used to do on my old police scanner.

**2MuchMark** · 09-01-2017, 09:43 PM

Originally posted by lezinterracial

just bought an SDR (Software Defined Radio) dongle
Any experience with this?
Hope to pick up local Sheriff. Maybe local PD that is now on digital radios, I don't know.

https://www.amazon.com/RTL-SDR-Blog-...4&keywords=sdr

Congrats on your purchase! I have a couple of these... here's some notes on it:

The small antenna that it comes with works pretty well for turning in planes and passenger jet talk between them and the airport tower. And if you want to do something really cool, try running this: http://www.virtualradarserver.co.uk/ it turns your SDR into a virtual radar server.

The SDR is a really wide-band radio so it would be helpful to have a wide-band antenna. One that works well is called a Planar Disk Atenna, and you can build one yourself with a couple of pizza pans. http://www.wa5vjb.com/references/PlanarDiskAntennas.pdf

For some reason I had a hard time getting anything interesting below 30Mhz. I was hoping to pickup some CB and Shortwave stuff but all I get is noise. I tried using a "Ham It Up" converter https://www.amazon.ca/NooElec-Ham-Up.../dp/B009LQT3G6 but it did nothing from what I can tell. Maybe you will have better luck.

It's a fun hobby. Enjoy!

**lezinterracial** · 09-01-2017, 09:58 PM

Originally posted by 2MuchMark

Congrats on your purchase! I have a couple of these... here's some notes on it:

It's a fun hobby. Enjoy!

Thanks for the notes man. Do you notice how hot the USB stick gets?

**MFCT** · 09-28-2017, 01:33 AM

I've not noticed if mine gets hot. But if it overheats and dies, heck, I'll just cough up another 20 bucks and buy a new one. Its a fun gadget to play with.

In my earlier post, I recommended using it with Skywave Linux in a virtual machine. A great idea in theory. But for me, try as I might, I could not get this particular USB gadget to be recognized in Virtualbox. This made Skywave Linux useless for me and I'm sorry I recommended it for use in a virtual machine. And I'm not about to go from dual boot to triple boot, just for that.

But there's a workaround. I can't help Windows people. But at least in Linux Mint, all you really need is GQRX. Its effortless to install and use. Also, DSD (Digital Speech Decoder) is a must for decoding unencrypted digital voice transmissions. Let's say, installing it is a bit more involved. But once you hear that first decoded voice, you'll be dancing for joy!

I remember 20-25 years ago, a golden age when virtually everything in the radio spectrum was in the clear. With so many digital transmissions now, DSD is a critical companion and aid that you'll want to have installed when you're using SDR.

Linux apps:

GQRX install - Install Gqrx SDR on Ubuntu Linux – Gqrx SDR
DSD compile/install guide - https://www.george-smart.co.uk/scrap...peech_decoder/

DSD is a rather involved install. During the process, you may discover that there's several required libraries you need to have installed first. You'll probably want to install those libraries correctly the first time, and not just guess. I've gotten DSD compiled, installed, tested, and working perfectly. So if anyone trying to install it runs into a roadblock, I'm happy to offer assistance.

Once you get all that installed correctly, a terminal command line you'll want to use to output GQRX > DSD > your speakers in real time, as its transmitted:

Code:

socat stdout udp-listen:7355 | padsp dsd -i - -o /dev/dsp

Good luck and have fun.

**MrMaxwell** · 09-28-2017, 04:17 AM

I think there's software somewhere which may allow for you to decode APCO using those software radios
You can't decrypt it readily if they're actually using encryption and something about phase 1 or 2 and control channel this and some thing that
CB is just a bunch of frequencies in the 27mhz area.. channel 19 is 27.185 I believe and what is it 10khz increments so 27.195 would be nineteen and so on I suppose

**MrMaxwell** · 09-28-2017, 04:19 AM

Originally posted by lezinterracial

Got it today. Got GQRX up and running. Was able to listen to a local FM station and the NOAA weather report frequency.

I noticed the dongle gets really hot. That me be why some people complain about theirs going bad. I will use a fan on it and try not to run it too long.

I hope to find out how to scan frequencies for activity. Like I used to do on my old police scanner.

Good Lord
Don't go nuts using that on a laptop, then
Especially an older one

**MrMaxwell** · 09-28-2017, 04:34 AM

It looks like they use 200ma to 400ma and then up from there for the fancy azz ones
I wouldn't recommend using these things constantly on a laptop especially if you have other garbage plugged in
USB 2.0 laptops often struggle to keep up with half the 500 they're rated for
You should be just fine with USB 3.0 as it's supposed to be I believe 900ma but still why fuck around (if you have good expensive hardware which can handle it for sure, then, why risk fucking it up... Meanwhile if you have cheap garbage hardware it cannot handle it)
Is USB 4.0 higher power

Anyway I don't recommend using laptop USB ports as power supplies.. So don't hook these u up to them and stop charging your telephone battery from your laptops.

I'm old so don't explain to me if I am wrong

**MrMaxwell** · 09-28-2017, 04:37 AM

Originally posted by MFCT

I've not noticed if mine gets hot. But if it overheats and dies, heck, I'll just cough up another 20 bucks and buy a new one. Its a fun gadget to play with.

In my earlier post, I recommended using it with Skywave Linux in a virtual machine. A great idea in theory. But for me, try as I might, I could not get this particular USB gadget to be recognized in Virtualbox. This made Skywave Linux useless for me and I'm sorry I recommended it for use in a virtual machine. And I'm not about to go from dual boot to triple boot, just for that.

But there's a workaround. I can't help Windows people. But at least in Linux Mint, all you really need is GQRX. Its effortless to install and use. Also, DSD (Digital Speech Decoder) is a must for decoding unencrypted digital voice transmissions. Let's say, installing it is a bit more involved. But once you hear that first decoded voice, you'll be dancing for joy!

I remember 20-25 years ago, a golden age when virtually everything in the radio spectrum was in the clear. With so many digital transmissions now, DSD is a critical companion and aid that you'll want to have installed when you're using SDR.

Linux apps:

GQRX install - Install Gqrx SDR on Ubuntu Linux ? Gqrx SDR
DSD compile/install guide - https://www.george-smart.co.uk/scrap...peech_decoder/

DSD is a rather involved install. During the process, you may discover that there's several required libraries you need to have installed first. You'll probably want to install those libraries correctly the first time, and not just guess. I've gotten DSD compiled, installed, tested, and working perfectly. So if anyone trying to install it runs into a roadblock, I'm happy to offer assistance.

Once you get all that installed correctly, a terminal command line you'll want to use to output GQRX > DSD > your speakers in real time, as its transmitted:

Code:

socat stdout udp-listen:7355 | padsp dsd -i - -o /dev/dsp

Good luck and have fun.

Can that DSD listen in on APCO systems ??

**MrMaxwell** · 09-28-2017, 04:40 AM

PS: Them was the days back then in those days I use to tune in to listen to all of my neighbors on their telephones and I was what was I eleven so I learned new words and was always so interested .. good old 46mhz

Hell you could tune into 800-900 range and sit there listening to random cellular telephone calls as well

Another thing was for years after that you could keep an eye on police activity and all kinds of stuff like that
You could listen to all kinds of things
All I needed was a frequency counter and a day to waste back then

**MrMaxwell** · 09-28-2017, 04:41 AM

Those were the days back in them times that's for sure

**MrMaxwell** · 09-28-2017, 04:52 AM

Originally posted by MFCT

I've not noticed if mine gets hot. But if it overheats and dies, heck, I'll just cough up another 20 bucks and buy a new one. Its a fun gadget to play with.

I had some off brand garbage cable modem back in the day with roadrunner uncapped service and it was faster than any other modem but the one chip would get hot enough to burn the sun
You can make a free heatsink with some thermal paste and a couple or pre 1982 pennies and some aluminum foil
Even flopping a single penny on there would at least give it something to soak up some heat for awhile

**lezinterracial** · 09-28-2017, 06:18 AM

Originally posted by MrMaxwell

Hell you could tune into 800-900 range and sit there listening to random cellular telephone calls as well
0

I remember that. You could listen in on a call to a cell tower. You only got one side of the conversation.

I also remember when a couple picked up a Newt Gingrich call about Hillary. They recorded it and gave it to the media. That was the end of that.

**MrMaxwell** · 09-28-2017, 06:39 AM

Back when everything was analog I use to hear both sides of cellular calls but some would just be one side
I can't remember how that worked exactly
It seems like it was some thing about which idiot initiated the call or whatever it was

On your cordless telephones you just would tune into 46.xxx to hear both sides back then

**MFCT** · 09-28-2017, 09:54 AM

There are Windows binaries for DSD, found here. https://www.dsdplus.com/

As for APCO, I'm not really familiar with all the digital formats. But if I understand correctly, APCO is aka P25, which DSD does decode.

Here's a rundown of the formats DSD 1.7 supports: (source https://github.com/szechyjs/dsd/wiki/Supported-formats)

Code:

P25 Phase 1

Widely deployed radio standard used in public safety and amateur radio.

Support includes decoding and synthesis of speech, display of all link control info, and the ability to save and replay .imb data files
ProVoice

EDACS Digital voice format used by public safety and amateur radio.

Support includes decoding and synthesis of speech and the ability to save and replay .imb data files.

Note: not enabled by default, use -fp to enable.
X2-TDMA

Two slot TDMA system currently being deployed by several public safety organizations. Based on the DMR standard with extensions for P25 style signaling.

Support includes decoding and synthesis of speech, display of all link control info, and the ability to save and replay .amb data files
DMR/MOTOTRBO

"Digital Mobile Radio" Eurpoean two slot TDMA standard. MOTOTRBO is a popular implementation of this standard.

Support includes decoding and synthesis of speech and the ability to save and replay .amb data files.
NXDN

Digital radio standard used by NEXEDGE and IDAS brands. Supports both 9600 baud (12.5 kHz) and 4800 baud (6.25 kHz) digital voice.

Support includes decoding and synthesis of speech and the ability to save and replay .amb data files.
D-STAR

Amateur radio digital voice standard

This is an earlier version of the AMBE codec than the one used by most of the protocols. Support for this was added by various developers.
Unsupported formats considered for future development:
P25 Phase 2

This is not yet a published standard. Full support is expected once the standard is published and there are systems operating to test against. Phase 2 will use a vocoder supported by mbelib.
OpenSKY

It is possible that the four slot version uses a vocoder supported by mbelib. The two slot version does not.
Supported demodulation optimizations:
C4FM

Continuous envelope 2 or 4 level FSK with relatively sharp transitions between symbols. Used by most P25 systems.

Optimizations include calibrating decision points only during sync, 4/10 sample window per symbol, and symbol edge timing calibration.
GFSK

Continuous envelope 2 or 4 level FSK with a narrower Gaussian/"raised cosine" filter that affects transitions between symbols. Used by DMR/MOTOTRBO, NXDN and many others. Noisy C4FM signals may be detected as GFSK

but this is ok, the optimization changes will help with noisy signals.

Optimizations are similar to C4FM except symbol transitions are only kept out of the middle 4 samples and only the middle two samples are used.
QPSK

Quadrature Phase Shift Keying (and variants) used in some P25 systems and all known X2-TDMA systems. May be advertised under the marketing term "LSM"

Optimizations include continuous decision point calibration, using middle two samples, and using the symbol midpoint "spike" for symbol timing.

**MrMaxwell** · 10-04-2017, 12:02 AM

Cool.
I could charge money for that if I was in the city.
I guess I wouldn't want to be involved in doing something like that these days .. though .
But it would be exciting

**MFCT** · 10-21-2017, 02:13 PM

For those wanting to try an outdoor antenna for better reception, there's no need to drill a hole in your wall or leave a wire hanging through an open window. I recently discovered this nifty little gadget that I never even knew existed.

This is "Ghost Wire Flat RG6 Coax Jumper Cable Extreme Slim Flat Window Cable". You can put it in a window sill, close it completely, lock it, and you're good to go. It costs about $10 at Amazon. I recommend using quad-shield RG6 to connect to this gadget to your outdoor antenna.

To connect your SDR to the ghost wire, I recommend something like "SMA to F Adapter SMA Male to F Type Male RF Coaxial Connector Cable Extension" also at Amazon for about $8. Its important to have an adapter with a wire between the ends. Otherwise, undue stress might be put on the SDR's connector and could possibly damage it.

I hope you found this post helpful. Good luck and have fun with your SDR.

Edit: having an external antenna improved my reception significantly.

**2MuchMark** · 10-21-2017, 09:58 PM

Originally posted by MFCT

To connect your SDR to the ghost wire, I recommend something like "SMA to F Adapter SMA Male to F Type Male RF Coaxial Connector Cable Extension" also at Amazon for about $8. Its important to have an adapter with a wire between the ends. Otherwise, undue stress might be put on the SDR's connector and could possibly damage it.

I hope you found this post helpful. Good luck and have fun with your SDR.

This is a good tip. For some reason these SDR's come only with SMA connectors, which nobody seems to sell. I finally found some at an electronics store (Addisons in Montreal) but they were expensive at about $1.00 each, and SUCKED. You couldn't solder the wires in place, you just had to push it up against this flat connector, etc etc. Total shit.

Anyway, getting an adapter like this is highly recommended.

Originally posted by MFCT

Edit: having an external antenna improved my reception significantly.

What kind of Antenna did you put outside? I was told by my better half that I was in no way allowed to install anything ugly outside, so I was just thinking about running a wire between my house and a pole at the edge of my fence.

Do you happen to know if I can use my inside AC box as a ground? Or do I need to get a proper ground installed outside?

**MFCT** · 10-22-2017, 08:04 PM

Originally posted by 2MuchMark

This is a good tip. For some reason these SDR's come only with SMA connectors, which nobody seems to sell. I finally found some at an electronics store (Addisons in Montreal) but they were expensive at about $1.00 each, and SUCKED. You couldn't solder the wires in place, you just had to push it up against this flat connector, etc etc. Total shit.

Anyway, getting an adapter like this is highly recommended.

What kind of Antenna did you put outside? I was told by my better half that I was in no way allowed to install anything ugly outside, so I was just thinking about running a wire between my house and a pole at the edge of my fence.

Do you happen to know if I can use my inside AC box as a ground? Or do I need to get a proper ground installed outside?

Yeah, SMA must be something newer. I couldn't find anything SMA locally, but its not surprising to hear that the quality of what you were able to find is sketchy. That's where Amazon comes in as such a reliable source for stuff like this.

As for the antenna, a long wire antenna isn't a good idea for receiving the frequencies that the SDR unit receives. Plus it would have to be placed vertically to receive those frequencies. Your best bet would be to get an antenna designed for scanners.

The one I'm using now is a temporary that I'd dug out of storage. I'll use it until I can get a better one. Its a 25mhz-1296mhz telescoping whip, similar to this one.

Its a decent antenna that does the job, with decent reviews. But its not ideal, and this particular model wasn't really designed as an outdoor antenna. I'll get something much better eventually.

Its placement also isn't ideal, and its also temporary until I can place an antenna up much higher. But its functioning decently already where it is now. I have it clamped to the side of a wooden porch column, which makes it pretty much invisible from the street and to neighbors. Someone may be able to see a bit of coax cable, but they won't know why its there or what its for.

As for the ideal antenna, from my research the best ever scanner antenna hands-down, much better than any discone, is the AntennaCraft ST2. (Not to be confused with the Magnum Dynalab ST-2 FM Antenna.) And for a price of about $40, its a steal. Although it is is ugly.

Only problem is, they've been discontinued. I think due to the bankruptcy of their parent company, RadioShack. You can't find them anywhere, except maybe Ebay with the price jacked up hundreds and hundreds of dollars. I'll pass on that.

As for grounding, I don't know much about it or how to go about doing it properly. Back in the day, I just mounted a discone on the roof and took my chances with lightning. Bad idea, I know, but I was lucky.

My understanding is grounding has no effect on antenna reception. Its only for lightning protection. But where mine is currently located, grounding isn't really an issue for now. I'll look into grounding when I can obtain an antenna I'm happy with, and mount it up high properly.

Good luck to you.

just bought an SDR (Software Defined Radio) dongle

Tech just bought an SDR (Software Defined Radio) dongle

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