A comparison of my police feed before and after switching to SDR

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fireshaper

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I had been using a Bearcat 996XT to stream my local police feed, and even with an upgraded antenna I still wasn't getting the best signal. A friend suggested SDR and got me in touch with someone he knew who (like a drug dealer) gave me my first NooElec RTL SDR dongle for free. I was hooked as soon as I started playing with it. Anyway, long story short, I bought a second one and set up UniTrunker and now my police feed is powered by SDR!

I made a short video that compares the feeds from the Broadcastify archives. I couldn't believe the difference I heard with SDR. One of my dongles doesn't even have a real antenna, just a piece of copper wire.

Here's the video: https://youtu.be/N3-sUe-32Cw

I'd love to hear everyone's thoughts!
 

br0adband

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If anything I've got to say the end result your setup is producing sounds great to me, I prefer to hear a more bassy and not so heavily mid-to-high audio signal when I monitor comms myself so that sounds great. Since you say you have a 996XT which can do P25 Phase I my next question is whether or not this is supposed to be a digital system because if you didn't mix up the audio sources then what I'm hearing from the first section of the video (the 996XT I presume as stated) sounds more like a P25 Phase I data stream being decoded, at least that's what it sounds like to me given I've used Unitrunker with DSD+ to monitor some P25 Phase I traffic in my area and that's pretty much what I get as a result myself.

The second audio portion of the video, which is stated as being the RTL based reception, sounds more like what I'd expect from the 996XT myself - in all my years I've only had a few minutes of experience using an actual digital scanner (a 436HP I got to play with for a short period a few months ago) and when I plugged in my Koss KSC-75 earclips that's about how it sounded to me decoding a P25 Phase I stream here in the Las Vegas area (there's not really that much on P25 Phase I at the moment, 3-4 systems overall but DMR is catching on really fast here).

I'm not saying you made a booboo and if you're actually getting audio that clean and clear from your Unitrunker based setup with an RTL stick my advice is this: don't change a thing. :D

Aside from that, I'd be interested in knowing the setup overall you're using - the only time I get audio that sounds similar to yours in the video is by using SDR-Radio aka SDR-Console because of how Simon (the software's author) uses some nice filtering in the audio pathway and it produces great sounding output - again, to my ears it sounds like I'd want voice audio to sound, not everyone has the same ears and has different expectations and requirements obviously.

But definitely, spill the beans 'cause it sounds great. If it's a pure analog trunked system then everything I just said is moot and means nothing at all since for myself personally there's never been and probably never will be a digital comm system based on radio technology that's going to sound like pure analog does but that's also my opinion. I know there's been a serious effort to produce understandable speech using digital codecs but they still suck in major respects, every one of 'em. :D
 

fireshaper

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If anything I've got to say the end result your setup is producing sounds great to me, I prefer to hear a more bassy and not so heavily mid-to-high audio signal when I monitor comms myself so that sounds great. Since you say you have a 996XT which can do P25 Phase I my next question is whether or not this is supposed to be a digital system because if you didn't mix up the audio sources then what I'm hearing from the first section of the video (the 996XT I presume as stated) sounds more like a P25 Phase I data stream being decoded, at least that's what it sounds like to me given I've used Unitrunker with DSD+ to monitor some P25 Phase I traffic in my area and that's pretty much what I get as a result myself.

The second audio portion of the video, which is stated as being the RTL based reception, sounds more like what I'd expect from the 996XT myself - in all my years I've only had a few minutes of experience using an actual digital scanner (a 436HP I got to play with for a short period a few months ago) and when I plugged in my Koss KSC-75 earclips that's about how it sounded to me decoding a P25 Phase I stream here in the Las Vegas area (there's not really that much on P25 Phase I at the moment, 3-4 systems overall but DMR is catching on really fast here).

I'm not saying you made a booboo and if you're actually getting audio that clean and clear from your Unitrunker based setup with an RTL stick my advice is this: don't change a thing. :D

Aside from that, I'd be interested in knowing the setup overall you're using - the only time I get audio that sounds similar to yours in the video is by using SDR-Radio aka SDR-Console because of how Simon (the software's author) uses some nice filtering in the audio pathway and it produces great sounding output - again, to my ears it sounds like I'd want voice audio to sound, not everyone has the same ears and has different expectations and requirements obviously.

But definitely, spill the beans 'cause it sounds great. If it's a pure analog trunked system then everything I just said is moot and means nothing at all since for myself personally there's never been and probably never will be a digital comm system based on radio technology that's going to sound like pure analog does but that's also my opinion. I know there's been a serious effort to produce understandable speech using digital codecs but they still suck in major respects, every one of 'em. :D
I guess I should have given a bit more info on my system. It's a Motorola Type 2 system, Analog and APCO-25 Common Air Interface. So there is digital involved, but I'm not sure if they are using it. When I watch the feed it looks like all my police audio is going over analog. I've got the feeds labeled correctly and you can verify by listening to the Georgia > Richmond County feed before October 12 and after (that's when I did the switch over). Believe me, I was just as shocked as you are now when I was first testing!

Maybe I just got lucky, maybe I'm a fringe case. Maybe the radio waves are bouncing off a neighbor's satellite dish and directly into my office window. I don't know, I just know what I hear sounds so clear that it's like I'm listening to the actual police radio. I've got two NooElec RTL-SDR dongles sitting beside each other on top of my printer near my office window, one is using the stock antenna and the other is just using a piece of wire jammed into the antenna port (this was a freebie dongle that a guy gave me where he didn't have the antenna).

As for software I tried a couple of things before I settled on just using UniTrunker. I just followed the guide on rtl-sdr.com but didn't set up DSD+ since everything seemed to be analog audio. That's really it. So maybe it's just because it's all analog and my county hasn't made the switch over to digital on police feeds yet (it looks like EMS is digital but I need to play around with that some more before I add it to my set up). But I think I have a really great feed right now that I'm proud to have on Broadcastify for my listeners.

slicerwizard said:
Sounds like there is an issue with how your 996 is connected to your PC. Possibly a ground loop.
The 996 was just connected to the computer with an audio cable into the audio in port on the server.
 
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