new to SDR

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satboy8888

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Which system are you looking to monitor? Is it encrypted?

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rivardj

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I recommend the RTL-SDR dongles from the link below:

Buy RTL-SDR Dongles (RTL2832U) - rtl-sdr.com

RTL-SDR Blog R820T2 RTL2832U 1PPM TCXO SMA Software Defined Radio with 2x Telescopic Antennas

or

RTL-SDR Blog R820T2 RTL2832U 1PPM TCXO SMA Software Defined Radio (Dongle Only) if you are going to use an outdoor antenna. If so, you will need to also order the appropriate pigtail or adapter. I would find another source for the adapters or pigtails so you can order what you need instead of the kit that contains adapters you may never use. With a quick Google search you should be able to find a source for those.

I own both the NooElec and the RTL-SDR dongles and have had much better luck with frequency stability/drift when using the RTL-SDR brand.

However, you first need to determine if you local departments are encrypted or not. If they are encrypted you will not be able to listen to their traffic. Provide location information and department/agency names to get help with that.
 

rivardj

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If you are able to monitor what you want to hear via the link you posted and you live close enough to the tower sites you should be able to listen using SDR.
 

trauts14

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rivardj, that link is the one i want to monitor. I feel like I read most SDR setups for trunked systems need 2 dongles. am familiar with analog and good with computers, but SDR is a new thing for me.
 

satboy8888

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From that page, it appears that all frequencies fall within 3mhz of each other, therefore one rtl-sdr dongle can monitor the whole system. Using unitrunker to monitor the control channel then at least one or more vco's for voice signals sending to dsd+ outputting to either your speakers or a program like trunk recorder.

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trauts14

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satboy8888 thank you. so basically i order one dongle....download the free software..attach antenna of course....learn how to use the software...and that is all? i have antennas, so all i need is the free software now and the cheap dongle. are there any common mistakes to avoid and a newbie?
 

satboy8888

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satboy8888 thank you. so basically i order one dongle....download the free software..attach antenna of course....learn how to use the software...and that is all? i have antennas, so all i need is the free software now and the cheap dongle. are there any common mistakes to avoid and a newbie?
Basically, yes. Getting a dongle with txco as already recommended will save headaches and is within a dollar or two of non txco models.

Read guides already posted and forum threads already discussed but do ask any further questions you may have. Some things may have changed since that information was current.

This image may help you follow the audio signal and voice routing via virtual audio cables within the computer.

https://goo.gl/images/I4aOFp
 

bharvey2

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I use two NooElec dongles, Unitrunker and DSD+ software to monitor a trunked P25 phase 1 system in my area. It took a bit to set up but runs pretty well. I've never tried to use just one dongle. Since they are so cheap, it wasn't worth the headache for me to try to get it working with one. For the most part, I think the reception is comparable to my PRO668 which cost me 5x the price of the two dongles.
 

satboy8888

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I use two NooElec dongles, Unitrunker and DSD+ software to monitor a trunked P25 phase 1 system in my area. It took a bit to set up but runs pretty well. I've never tried to use just one dongle. Since they are so cheap, it wasn't worth the headache for me to try to get it working with one. For the most part, I think the reception is comparable to my PRO668 which cost me 5x the price of the two dongles.
It only depends on the spread of the frequency, if it falls within the 3mhz window an rtl-sdr stick can see. If it's wider, you'll need two. One to maintain the control channel and with any vco's, voice frequencies nearby. Then the other dongle can jump around and cover another 3mhz window elsewhere in the system frequencies.

The only thing holding you back from listening to multiple transmissions simultaneously is your cpu horsepower. If you have a smoking fast computer, you could record every transmission from the system your monitoring and play them back in whatever order you want with something like trunk recorder.

It should be noted that there is another solution called OP25 I believe but I have no experience with it and cannot give an opinion for or against it. But it maybe worth investigation.
 

trauts14

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is dsd+ a part of unitrunker or do i need to do something else to utilize dsd+
 

trauts14

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go figure....the txco kit with antennas is out of stock and the dongle alone is out of stock. can anyone suggest any stateside places selling the dongle(s)?
 

bharvey2

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It only depends on the spread of the frequency, if it falls within the 3mhz window an rtl-sdr stick can see. If it's wider, you'll need two. One to maintain the control channel and with any vco's, voice frequencies nearby. Then the other dongle can jump around and cover another 3mhz window elsewhere in the system frequencies.

The only thing holding you back from listening to multiple transmissions simultaneously is your cpu horsepower. If you have a smoking fast computer, you could record every transmission from the system your monitoring and play them back in whatever order you want with something like trunk recorder.

It should be noted that there is another solution called OP25 I believe but I have no experience with it and cannot give an opinion for or against it. But it maybe worth investigation.
I was aware that it could be done. When I first started out, I was using a pretty old laptop. It was running at almost 100% CPU usage and was choking periodically. I then installed everything on a more powerful laptop and it runs like a champ. (both computers were PC based BTW) I'm not implying that anything is wrong with using one dongle. I originally needed two and continue to use two as it affords me more latitude for other systems should I desire to set up for them. Good thing that you pointed it out though, One thing I would offer though is two order the dongles with the temperature controlled oscillators so you don't need to mes with the frequency drift.
 

bharvey2

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Unitrunker and DSD+ are two different pieces of software at least with the versions I use. Perhaps they will be melded together at some point. Maybe the OP25 software that satboy8888 mentioned can following the trunking and decoding both. I don't have experience with it so I can't offer any comment on it except that I understand it can decode P25 ph2.
 

bharvey2

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go figure....the txco kit with antennas is out of stock and the dongle alone is out of stock. can anyone suggest any stateside places selling the dongle(s)?
Isn't nooelec.com in the States? I think that's where I purchased mine.
 
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