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  #1 (permalink)  
Old 09-11-2018, 3:26 PM
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Default Rtl sdr

Hi everyone I am new to rtl sdr dongles. I just recently watched a video that someone sent me to get it all set up. I did the walk through exactly as shown. Everything was decoding I couldn't here it though. I could see it in dsd plus now however, I get a message that says " mono audio decoding initiated." Or i get no sync. I saw the decoding working but with no sound. Then it comes up with those two error at different times. Any help would be great. Ps here is what software I'm using
Airspy
Dsd plus
V audio
Windows 10
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Old 09-12-2018, 8:52 PM
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I've read through your other thread on your sdr previously, and I'm glad to see you've gotten to this point! I have also purchased a rtl-sdr recently, and managed to get it working in the way you're looking for. Personally, I'm using UniTrunker instead of airspy, the rest is the same.

First and foremost is the antenna. Are you using the antenna that came with the kit, or are you using something else? If you're using the one with the kit(assuming the current kit available), then we get to play around a bit here. It helps to know your control frequency, as it's going to be key for this. The antenna that comes in the kit is essentially just a beginner antenna. You can do some pretty amazing stuff with it nonetheless, but it requires a bit of tuning. The following assumes you are using the current kit available.

https://www.rtl-sdr.com/dipole

Scroll down to the part labeled "Choosing the Antenna Element Length"

There is a cheat sheet that tells you the roundabout length for certain frequencies. You can use this as a rough guide instead of flying blind. Additionally, there is a link to a dipole calculator. Input your control frequency, select "One Side" and click "Calculate." This will give you the recommended length of each of the antenna. Just extend them to the measurement calculated! The next step is configuration and orientation. Going back to the link above, the next section is labeled "Using the Mounts" For the current purposes, having the antenna in a line, and vertical, is what I'd recommend.

With the kit antenna, I found placement to play a big part as well. This will apply to any antenna as well if I understand correctly. Is it close to metal? The wall? Is it inside or outside? For me, my drywall isn't healthy for the signal, neither is metal. UniTrunker has a handy "health status", which basically gives you an idea how good of a signal you're getting. The one window, and apologies for not recalling what it's called, shows bars at the top left. They will change from red, to yellow, to green, depending how good the application thinks your reception is. This can help you determine where to place your antenna. I'm also in an apartment, so it can get pretty tricky. Having that visual representation helps a lot.

Another issue could be calibration. Unfortunately, I don't understand it enough to give you a good explanation or how-to, so google "rtl sdr ppm correction" and read what pops up on the forums here. My device, miraculously, has no need to be corrected. This correction applies in SDR# and UniTrunker(if you decide to use it)

One plus side of UniTrunker is the ability to switch around frequencies(to extent), as well as perform lockouts on talkgroups. Additionally, you can name your talkgroups in accordance with the database here on radio reference. The one part that [i]really[/u] solved it for me was it telling me what talkgroup I was hearing. In UniTrunker, the frequency being broadcast to DSD+ gets highlighted in green(I think it's default color), as well as the talkgroup transmitting. I found most of the dead air, or "junk" I got was just encrypted channels. The database here has info on if a talkgroup is encrypted. For me, DSD+ tells me it's muting the audio tho when it's being converted, so if you don't get a message, your issue may be reception, or elsewhere.

A handy device I learned about, that could be of use for you, is a low noise amplifier. This is useful if you're in a more rural area and the towers are far away. Of course, it can't beat good antenna placement.

Here are two links that helped me get UniTrunker working, which I'd highly recommend you use. The program looks complicated, but it really isn't. I was able to get it all working within 2 hours of getting my kit and after troubleshooting a bit. I'm able to get a usable signal most of the time, tho I have a slight lack of unencrypted channels.

https://www.youtube.com/watch?v=pN9-1unOsu0
https://www.rtl-sdr.com/rtl-sdr-tuto...io-unitrunker/ (scroll to "Monitoring with only One Dongle" if only one rtl-sdr. The section after tells you how to set it up to pipe to DSD+)


I hope this all helps! Go through the antenna setup first, and then UniTracker and let me know your results!
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Old 09-13-2018, 4:54 PM
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Thank you for taking the time to explain all that . I have one question I didnt think about asking.is it possible to get p25 on one rtl?
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Old 09-14-2018, 9:19 AM
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Yes you sure can:https://www.youtube.com/watch?v=g9KJrtIO8_4
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Old 09-14-2018, 11:28 AM
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Quote:
Originally Posted by N9JCQ View Post
Nice you guys have helped me so much thank you.ill follow that video when I have time. My weekend is crammed full with very little time to myself.
Btw I am trying to follow 155.82000in pinal county as which is p25
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Old 09-14-2018, 11:38 AM
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Here is an idea I have that I forgot to add. I'm thinking about mirriong my phone to my computer after I get this all set up. If this works I'm thinking that's a really cheap mobile p25 scanner lol.
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Old 09-16-2018, 3:48 PM
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Quote:
Originally Posted by N9JCQ View Post
Still not able to pick up p25 I am getting the rest of analog though
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Old 09-16-2018, 4:19 PM
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Quote:
Originally Posted by azduststorm View Post
Still not able to pick up p25 I am getting the rest of analog though
So, you're able to get some communications, but not others? Looking at the database, I can take only 2 guesses. The first is whatever you're hearing is encrypted, and it's not marked in the database. The second is their P25 is running phase 2. I saw pinal county has a phase 2 system, and I think dsd+ and unitrunker cant decode it yet. I believe I read op25 does, but I never tried it out as it requires linux(and I'm lazy!). Hopefully someone with knowledge of the area can guide you further.
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Old 09-16-2018, 5:34 PM
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So here is what's going on now. I heard dispatch one time for three seconds and it went back to digital sounds. Everything with dsd is looking fine . I'm trying to listen to florence pd And they are right down the street. Dsd is picking up p25 nac 114which I am almost certain that's like a phone number on the radio side of communications. I really appreciate all your help
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Old 10-04-2018, 12:27 AM
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I went out today and got a bran new computer. Hooked it all up and I can finally hear them. All this time and it was the computer I was using.
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Old 10-21-2018, 8:01 PM
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Now i am wondering how to hook up blue tooth with dsd plus. every time i try I cant hear p25. I can hear analog just fine Ps. I am able to hear everything I almost have ever frequency programmed into the sdr in the state of Arizona.
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