SDR Maximum Overdrive

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KC1UA

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For those of you wondering whether or not you want to purchase one of the $20 RTL dongles and give it a try, here's an example of what one can do. This is SDR-Radio software simultaneously monitoring 6 frequencies in the span of 854-856 MHz. 5 of these are conventional public safety freqs. The 6th is a control channel for our local zone of the MA State Police, being sent to UniTrunker for processing via Virtual Audio Cable.
 

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vince48

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Scott,
That is fantastic. This is just as good as the scanners we are buying. If only one software program that can have DDS decode the different modes was available. This reminds me of our PCR2500 days

vince48
 

mtindor

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For those of you wondering whether or not you want to purchase one of the $20 RTL dongles and give it a try, here's an example of what one can do. This is SDR-Radio software simultaneously monitoring 6 frequencies in the span of 854-856 MHz. 5 of these are conventional public safety freqs. The 6th is a control channel for our local zone of the MA State Police, being sent to UniTrunker for processing via Virtual Audio Cable.
Scott,

Have you ever had any luck decoding P25 using audio coming from SDR-Radio? I have tried probably 50 times over the life of SDR-Radio versions and can never get audio [out from SDR-Radio] that is usable for decoding a P25 signal. SDR# [with filtering unchecked] works fine. SDR-Radio, never.

If you do decode P25 that is obtained through SDR-Radio, can you clue me in on the useful tuning parameters that you've employed?

Thanks

mike
 

KC1UA

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The trick to doing so in SDR-Radio, and this is per Simon, is to set the mode to FM-W with a bandwidth of 12.5 KHz. I've tried it and it works like a champ.

Now the fun part of my picture, Vince, would be to try setting up 6 virtual audio cables sending raw audio to 6 different installs of DSD....I wonder if I could make smoke come out of the back of the PC? :D

Could be a weekend project....hmmmmm......
 

vince48

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I hope you have a rather robust CPU(s) that is allot of labor for those i5 and under. I would settle for three different systems monitoring specific groups. I have not gotten as far as you have. I have been following your Blade episode. Have you checked out rachelbythebay? Very neat setup.
I see Eric has been active again. A very smart comrade.

vince48.
 

mtindor

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The trick to doing so in SDR-Radio, and this is per Simon, is to set the mode to FM-W with a bandwidth of 12.5 KHz. I've tried it and it works like a champ.

Now the fun part of my picture, Vince, would be to try setting up 6 virtual audio cables sending raw audio to 6 different installs of DSD....I wonder if I could make smoke come out of the back of the PC? :D

Could be a weekend project....hmmmmm......
Thanks, Scott. I can't wait to try it. SDR-Radio is a brilliant piece of software, no doubt. The _only_reason I haven't used it more often is because I couldn't use it to decode P25. With that out of the way, I'm sure it'll become my defacto SDR software to use.

Mike
 

KC1UA

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I hope you have a rather robust CPU(s) that is allot of labor for those i5 and under. I would settle for three different systems monitoring specific groups. I have not gotten as far as you have. I have been following your Blade episode. Have you checked out rachelbythebay? Very neat setup.
I see Eric has been active again. A very smart comrade.
Believe it or not the i5 I'm doing this on is only running at about 7-9% CPU use with it running as shown in the screenshot.

It will be fun to try this with the bladeRF. I have a USB 3.0 card on the way that should work with Windows 8.1. In all likelihood I'll be running it on an i7 so I should be able to accomplish a lot if it works out. Once I get the HF/VHF transverter it'll be fun to run this setup on milair during exercises and be able to monitor all of the pertinent traffic simultaneously.

I'll check out rachelbythebay, and yes indeed on Eric. He is definitely an asset to the hobby.

Thanks, Scott. I can't wait to try it. SDR-Radio is a brilliant piece of software, no doubt. The _only_reason I haven't used it more often is because I couldn't use it to decode P25. With that out of the way, I'm sure it'll become my defacto SDR software to use.
Mike, it's worked superbly for me with P25, DMR, NXDN, KG-TONE, and Unitrunker; I can't see why you wouldn't have the same results. I had the exact same issue. I like SDR# very much, but I definitely prefer SDR-Radio for its features and better sounding audio, so I was very pleased when the FM-W suggestion did the trick for me.
 

br0adband

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Awesome, simply awesome, and yep, having bladeRF will make things ever more awesome overall. The one downside right now with the stereotypical RTL sticks is the limited bandwidth in terms of the spectrum visibility - 2.4 MHz isn't quite enough to do what I would like to do which is do something very similar to what Scott has just demoed with that image above which is "take it all in" and then process/record/listen as desired.

Here in the Las Vegas area the predominant system is our S.N.A.C.C. system (Motorola Type II SmartZone) which comprises over a dozen agencies, 223+ talkgroups, 3300+ users/RIDs, and a lot more to come when they shift to a 700 MHz P25 Phase II situation in the next 1-2 years on a slow complicated roll-out. They do all that with over 20 frequencies spread across a full 10 MHz window from 851 to 861 (I think their highest in use frequency is about 860.9375 per the FCC license(s)) so yeah, having a lot more usable bandwidth is required to take it all in.

I have a strong interest in the Airspy which is almost ready to be launched per a post made by Youssef (think it's him, using the sdrsharp nickname in the SDR# Yahoo Group) that they're almost ready to go but they wanted to judge the final pricing of the units per the amount of interest - I'm guessing (like others) that it should be in the neighborhood of $99 to $150 or so, and if it is indeed around that ballpark I'm damned sure going to do my best to get one. The fact that it's based on the already tried and true Rafael R820T tuner (coupled with a new controller to increase the visible spectrum to 10 MHz) is going to be awesome while still being relatively inexpensive compared to the higher end devices like the bladeRF, HackRF, and the really high end stuff from Ettus, etc.

I mean, make no mistake, I'd love to have a bladeRF or HackRF definitely, it's just beyond me in terms of pricing (and I don't have a USB 3.0 port on this here laptop of mine, but I'm sure I could get one using an ExpressCard but that just adds to the expense overall).

Anyway, congrats on that current setup, Scott, it's awesome as noted. When you get that bladeRF finally up and functional it'll be like going from an dirty little apartment with a view of the building next door as your view on the world to having a penthouse with a 180 degree horizon to horizon panorama... :D

By the way, could you attach or post the full size image above, if you still have it? I can see the image, sure, but I wanted to get a native resolution shot to make out some of the finer details. I've spent a little time with SDR-Radio and found it interesting - and yes the first real thing I noticed off the bat when I got a frequency tuned was the improved (dare I say "better") sounding audio over what SDR# provides - I'm not knocking SDR# because I still think it's awesome overall (great word, awesome, really) but after playing around with SDR-Radio even for a few hours that improved audio quality was like "Wow, that sounds great right outta the box..." more or less.

Would be interested in a little more detail about how that setup is... well... "set up" actually. I honestly had no idea SDR-Radio was capable of doing what you're apparently doing which is pulling data from a single RTL stick or, are you using multiple sticks at one time? I don't have any particular trunked systems here that fit inside a 2.4 MHz spectrum but I do have a few NXDN systems that would do that, and those are a hassle to monitor properly because there's no way to decode the NXDN control channel(s) yet that I'm aware of. I watch the spectrum and waterfall and can plainly see a transmission start, see it end, then another one begins (the same conversation, of course) on a different frequency, then that transmission ends, another frequency continues, etc. It's like having a bunch of water faucets and a child is running from one to another turning it on, then off, then another one on, then off, etc.

It's hella fun though, right? :D

But seriously, I really would be more interested in some finer details of how you're managing things and just how many RTL sticks are at work in that particular setup pictured above, thanks.

Awesome... :p

EDIT:
After further looking at that image I think I was misunderstanding the setup more than likely; I don't think all that's being done with just one RTL tuner, obviously... so, spill the beans, man, I'm interested. :)

EDIT2:
I'll be damned, it IS possible with just one stick to monitor more than one frequency at a time... AWESOME!!! Obligatory screenshot of my own, one RTL stick, 3 VFOs (1 on a data burst channel, 1 on another data burst channel, and 1 on an EMS MDT data channel, at least I know these are all in the 1 MHz spectrum I'm using presently and they're consistently active). This is just for testing of course, as listening to 3 voice channels at once, even I'd have issues with that I suppose, but it's nice knowing I can record them all at the same time.



See, this is precisely the feeling that Jodi Foster's character has when she takes that wormhole trip and comes upon that magnificent spacial event in the movie version of "Contact" - wonder, awe, indescribable... "I had no idea, I had no idea... I had no idea..." and honestly I didn't even consider the possibility of doing what I'm doing right now (with extremely low CPU usage too on this older Core 2 Duo laptop of mine - could probably do the full 6 VFOs if I chose to do so and get by). Damn, this is amazing, truly.

Did I say this is awesome and just opened up yet another entirely new world for my monitoring window (as long as it fits inside 2.4 MHz, that is) - but then again I do have 2 RTL sticks... Hrmmm... ;)

EDIT3:

Last one, I swear, 'cause I'm hijacking this thing and I don't mean to. I just set up 6 VFOs in a 2 MHz spectrum and it works great, CPU usage holds steady about 50-55% consistently so yeah, it's possible but if I were to add the second RTL stick then I'd be in trouble. :p

6 "digital-capable" receivers in a single package that can monitor things no scanner at any price can do for only $9.75 + shipping and handling and some spectacular software... who would have thought it possible?
 
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KC1UA

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I was going to say, "yep, that's just one dongle".....but you found the answer to your question before I got a chance to reply.

Pretty neat, huh? I'm doing the same right now at home with the BladeRF, and obviously I can use 6 VFO's within the bandwidth of it as well. I'm hamstrung right now until I get a working USB 3.0 card; it's on the way.

I'm on the Airspy list as well; I'll use that one as my "drop in the bag and go" SDR. Thank the Gods it's USB 2.0; the nightmares I've had and heard about with Windows 8 and USB 3.0 are legendary. Another topic for another time.

The fact that this level of sophistication can be accomplished with free software and a $20 or so item just continues to blow me away.
 

br0adband

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The fact that this level of sophistication can be accomplished with free software and a $20 or so item just continues to blow me away.
I am honestly having the same reaction right this moment, it's absolutely astonishing. I'm just sitting here trying to get myself to understand the possibilities - given the bandwidth spectrum we're working with (2.4 MHz for traditional RTL sticks, 10 MHz for the R820T-based "on steroids" design of Airspy, not even sure what the bladeRF or HackRF are capable of, maybe 20-25 MHz?) and being able to actually capture all this activity at the same time?

"My god... it's full of possibilities..." to paraphrase another popular movie reference. ;)

I thank you for sharing that image and the info because if you hadn't, even now I'd still be just thinking one frequency at a time like most all of us have for years now, even decades.

Imagine a world... where you have a somewhat powerful computer - desktop or laptop, even a tablet these days - with a USB cable attached to a USB hub with 4+ ports on it, and each port has an RTL stick attached (doesn't matter which one at this moment), and using SDR-Radio you can, and more than likely will, capture the activity on 24 or more frequencies simultaneously for whatever purposes or requirements you happen to have, recorded to compressed audio files if necessary, with logging/tagging metadata files that match up perfectly for the archival process... and you can do it all for ~$40+ using "cheap USB TV tuners" that nobody used to think twice about not long ago.

Man, I swear, I'm simply stunned at this whole new aspect of things that I simply - again - had no idea about. Geezus, it's just... awesome. :D

(sorry if I come off like the proverbial kid-in-the-candy-store presently but I really am practically giddy about this new discovery as I'm sure some - if not MANY - others are now coming to terms with based on this thread alone...)

Here's a truly funny thing: I'm on this older laptop, stuck with a 1280x800 resolution which ain't all that great for high-density apps like SDR# and most definitely SDR-Radio with all the possible configurations, and I don't have an external montior.

Having said that, an acquaintance of mine contacted me earlier today and offered me "a carload full" of old computer hardware, some desktops that need fixin' up, a lot of spare components, etc... and a Samsung Syncmaster 2693HM 25.5" 1920x1200 LCD that appears to be in working condition.

See the irony here? I just learn not an hour ago that I can use these RTL sticks to monitor more than one frequency at a time, but I'm limited on what I can view on my low-resolution (nowadays) display and someone clear outta the blue contacts me and offers me a 25.5" LCD (it's somewhat old, made in 2008) with my favorite resolution ever - 1920x1200, a proper 16:10 aspect ratio - for free.

What's not to love? :D

I see you using KG-TONE too, which I was using until just last night when I saw over at the SDR# Yahoo Group that someone created - and it really does work - a plugin that decodes CTCSS, go figure. Man this has been a better day than I'd hoped.
 
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KC1UA

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not even sure what the bladeRF or HackRF are capable of, maybe 20-25 MHz?
The bladeRF, when connected to a (working) USB 3.0 port, can display just under 40 MHz of spectrum simultaneously with a powerful enough system. So that offers some interesting possibilities with this type of setup. As I said earlier I'm looking forward to trying it with milair activity. As it stands now until the HF/VHF transverter becomes available the low end of the BladeRF is 300 MHz. Exercises in my area use frequencies both above and below 300 MHz but often within that 40 MHz or so, so being able to listen to both groups at the same time will be pretty cool.

The only place right now that my bladeRF works properly is at work, where I have a Windows 7 Pro with USB 3.0. I have no problem there with 30 MHz of spectrum at once; it's an i5 processor. I have a choice of an i5 or an i7 here; I think the USB 3.0 card is going to go in the i7 for as the title of this thread says, "Maximum Overdrive". :D

Fun stuff indeed. The future is here.
 

br0adband

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I just did some thinking about this multi-VFO/multi-tuner situation which basically dropped in my lap- THANKS SCOTT! - and realized there will be a limitation in some respects that can dampen things, and I don't mean just the 6 VFO limitation in SDR-Radio at this time. Now, since this is "all new" to me for the most part and now I'm scrambling to judge the long run potential of it, I realized this all would work perfectly for analog systems without any problems for the most part, and by that I mean the following:

While it's entirely possible to just keep adding VFOs and pulling info from the signal as required (up to the limits of whatever software happens to be in use), that seemingly limitless situation works well for analog audio 'cause you can just keep piping all those audio streams into the Windows audio subsystem and they'll all just end up mixed together in a cacophony of stuff flowing from your speakers or headphones - of course you'd need to be something like Data from Star Trek: The Next Generation to be able to actually comprehend it all at the same time.

Now, with respect to digital decoding of these signals using DSD or DSD+, that's where the limitation will come in again for the most part without some audio subsystem Tomfoolery courtesy of some more capable virtual audio cable software. VB-Audio Cable is what I myself use because I only need 1 or 2 virtual cables; there's 3 capable with that version (each cable is a separate driver entirely) and that's it, so that would mean I wouldn't be able to feed DSD+ (my digital speech decoder of choice, or DSD to a lesser degree because it's not nearly as configurable regarding input source selection) with more than 3 sources in that respect, possibly 4 if I were still able to use the Recording mixer in Windows (more Tomfoolery to get things working).

The "King of the Mountain" with respect to virtual audio cable-type software is of course the original Virtual Audio Cable itself which allows you to add more "cables" as required, and I do mean a lot of them if absolutely necessary.

Since we're talking about one decoder per frequency/VFO that could end up being quite a few I suppose as each frequency/VFO = 1 feed for DSD+ (or DSD) to decode.

Again, more things to consider if your intentions are to do this multi-VFO type of monitoring and you're targeting digital systems that need to be decoded for audible voice comms. I realized this a little bit ago when I was going to set SDR-Radio up with DSD+ to see if I can accurately monitor that NXDN system I mentioned earlier: it uses discrete control channels that never transmit voice content, and 4 or 5 others that handle the voice channels. Because of how it works - there's effectively zero hang-time to follow a conversation on the same frequency - it immediately hops to the next frequency (I'm guessing in some LCN order I don't understand just yet) so using multiple VFOs that all feed into the same instance might actually work for NXDN more so than DMR/MOTOTRBO or even P25. It's like a funnel formed by multple VFOs gathering up the signals and then feeding them all into one signal sent to one instance of DSD+ for decoding - it should work because of the fact that the conversations are singular, one at a time on this system (I never see two trails of voice content at the same time on different frequencies).

More fun, fun, fun... :D

It'll work... it'll just take more effort and tweaking. ;)
 
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br0adband

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DOH!!! Had to slow down a bit and re-read the thread for that P25 info - which solved the horrible decodes as expected - and noticed you already mentioned the separate virtual audio cables for using with digital mode decoding per frequency/voice channel. I'm getting old and missing stuff, dagnabbit. ;)

Virtual Audio Cable (the original "King of the Mountain" version) supports up to (gasp) 256 cables... I think the author stated that Windows itself has a 32 "device" limit in that respect. Even so, it's still simply awesome thinking about what's possible...
 

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Scott,

Thanks for the WFM tip. Works beautifully. Now all I need to do is graduate from a 17" laptop screen to huge desktop screen. With all that is avaiable in SDR-Radio, one really needs at least one huge monitor, or a couple. I'm loving it.

Mike
 

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This is bad ***, thanks for the tip.

I'm using it now to listen to multiple lowband freqs at once with the DVB-T stick.
 

pdeveau2010

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please explain

hi , Could you please explain how to do mulitple vfo's and multiple audio connections, I have set up the vfo's
but haven't a clue as how to set up multiple dsd+ with the vfos, this ones got me confused.

thanks
Paul
 
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