SDR# - how to listen to 850MHz frequencies

[my53Jubilee]

I am doing a test to be able to tune into signals in the 850Mhz range.
I am using the dipole antenna that came with my RTL SDR Blog v3 dongle. I have the 2 short elements on, fully collapsed. Using SDRTrunk, I am able to listen to local emergency voice calls. They play fine, and I can see which frequencies are playing by reading the SDRTrunk log files and looking at the waterfall.

Now...I am trying to go into SDR# and listen to them there, one at a time. I see the signals in SDR#, but all i hear is noise. Are there settings I can change in order to tune into and listen to the same signals as I am getting in SDRTrunk. If I can make this work, I think i will learn a lot about SDR#. I don't think the antenna is the issue, since I am seeing peaks in the chart in SDR#, and the same frequencies play just fine in SDRTrunk.

The attached photo shows what I see in SDR#. Again, all i hear is white noise though. I cannot adjust the settings so I can hear the actual voice calls.

Thanks!

 

[dave3825]

am using the dipole antenna that came with my RTL SDR Blog v3 dongle. I have the 2 short elements on, fully collapsed. Using SDRTrunk, I am able to listen to local emergency voice calls. They play fine,

Now...I am trying to go into SDR# and listen to them there, one at a time. I see the signals in SDR#, but all i hear is noise. Are there settings I can change in order to tune into and listen to the same signals as I am getting in SDRTrunk.

If they are digital, you need to get the digital decoded. Either use sdr# simple p25 decoder or download and install virtual audio cable, and download DSDPlus. Vac sends the signal from sdr# to DSDPlus and will decode the digital. If the freqs are convention, the simple decoder will work fine.

If its a trunked system, its best to use SDRTrunk, DSDPlus and program properly as a system. If its a P25 Phase 1 system, Unitrunker will also work. Post a link to these 800 freqs.

 

[my53Jubilee]

Thanks for the reply. A couple questions, then I will post the frequencies.

1. Since I can listen to FM broadcast radio and NOAA Weather radio in SDR#, like many of the tutorials show, does that mean those are analog signals?
2. Can you briefly explain the concept of the decoders in SDR#? Out of the box, does it use only 1, the simple decoder? And to be more specific in decoding, a plugin is required?

Here are the frequencies of the Jackson County, Missouri system. It is a trunked system, and my problem isn't hearing them (I can do that in SDRTrunk), just hearing them in SDR#. I figure if I can get this working, I can listen to many more things in SDR#

System: Metropolitan Area Regional Radio System (MARRS)

4 (4)	001 (1)	MO Kansas City	Jackson, MO	851.050c	851.325c	851.4875	851.600c	851.825	851.8625c	852.050
				852.075	852.175	852.225	852.4125	852.4375	852.5875	852.6625
				852.7375	852.875	852.9625	852.9875	853.150	853.2375	853.4875
				853.7375	854.1375	854.5875	854.7125	855.6625	856.1625

 

[dave3825]

Can you briefly explain the concept of the decoders in SDR#?

Decoders take the signal thats digital and convert it to audio that can be listened to, as long as it's not encrypted.

Jackson County, Missouri system. It is a trunked system

Phase 2 trunked system.

my problem isn't hearing them (I can do that in SDRTrunk), just hearing them in SDR#.

You can listen to voice channels in sdr but you have no way to isolate who you would be listening to. With Sdrtrunk or DSDPlus, you can select who you want to listen to.

I figure if I can get this working, I can listen to many more things in SDR#

Sdr# is good basically for conventional freqs,. Conventional can be both analog and digital. But with SDR# you need to download the plug-ins for the mode of digital

Simple P25
Simple DMR
Simple NXDN.

 

[my53Jubilee]

I will try installing the Simple P25 plugin and post the results. Thanks!

 

[my53Jubilee]

Question. How do i install the Simple P25 plugin? I clicked the link above and the download link took me to a Russian site and i didnt see anywhere to download the plugin.

 

[dave3825]

search this forum for simple p25. There should be a newer link or a Dropbox link.

Results using p25 plug in on a trunked system will be horrendous and you won’t be able to follow any conversations. No need to post those results

 

[devicelab]

You can also download SDRTRunk which doesn't use SDR# or DSDPLUS. Just be sure to follow the initial installation instructions carefully. Once it's up and running it works good.

 

[dave3825]

Using SDRTrunk, I am able to listen to local emergency voice calls. They play fine

Jackson County, Missouri system. It is a trunked system, and my problem isn't hearing them (I can do that in SDRTrunk), just hearing them in SDR#. I figure if I can get this working, I can listen to many more things in SDR#

You can also download SDRTRunk which doesn't use SDR# or DSDPLUS.

OP has SDRTrunk and is looking to follow trunked voice channels using sdr#, which as mentioned above, will not work good at all, especially on a large system.

 

[my53Jubilee]

i think i have decided to just stay with what is working and use SDRTrunk. My next challenge will be finding the best antenna. Oddly, the one that works the best is the dipole that came with my first RTL-SDR bundle.

 

[xwarp]

i think i have decided to just stay with what is working and use SDRTrunk. My next challenge will be finding the best antenna. Oddly, the one that works the best is the dipole that came with my first RTL-SDR bundle.

For my 1st post in this forum, I've decided to share this with you as I'm listening to 850 Mhz freqs of a police dept about 30 miles away. I found the link to this antenna from somewhere related to SDR and this freq, but here you go. The antenna works very well and has a fantastic SWR in the 850Mhz range.

Yagi antenna

 

[my53Jubilee]

I have this same antenna, but couldn't see any improvement over the diploe that cane in my RTL SDR v3 blog kit. How did you attach the antenna to your SDR? Any other adapters, converters, filters inline between the antenna and your SDR? How did you mount this yagi? What cable did you use from antenna to sdr? Thank you!

 

[xwarp]

I am using 2 SDR's to cover the 851 Mhz to 853 Mhz range that Tucson police use.

CAVEAT: I am familiar with RF and receivers, just not so much with antenna and SDR's.

I've got a couple of the SMA cable extensions connected between the antenna and the SDR as a temp thing for now. The antenna is mounted horizontally facing north towards the city of Tucson about 6 feet from the ground on a patio post.

The shorter antenna that comes with the SDR will work well too, but you'll have to play with the lengths and angles of it to get the best reception. I used a NanoVNA to do this but I also added a piece of square cardboard covered in aluminum foil to help tune it.

Let me see if I can get a picture uploaded.

 

[xwarp]

The foil is not connected to anything.

 

[my53Jubilee]

Thanks for posting the picture. I need to try out the foil. What does the foil do? Block out interference or magnify signal, or both?

 

[dave3825]

I have this same antenna, but couldn't see any improvement over the diploe that cane in my RTL SDR v3 blog kit.

How did you attach the antenna to your SDR?

How can you possible state you do not notice any improvement over the dipole, when you ask how to hook the Yagi to the dongle?

A dipole is omnidirectional meaning it picks up in all directions. A Yagi is directional meaning it receives from where its pointed.

That dongle and Yagi both terminate to SMA female. I have the same Yagi and on this PC I use RG-6 with F type male connectors.
So I use,

Sma male to type F female at the dongle.
Sma male to type F female at the Yagi.

What coax do you have and what connectors are on both ends?

 

[xwarp]

Thanks for posting the picture. I need to try out the foil. What does the foil do? Block out interference or magnify signal, or both?

So I was mistaken about the foil. As stated, I'm a front receiver type, not an antenna type.

In any case, I removed the foil and then readjusted the antennas to where the antenna appears to be shaped like an L where one is vertical and the other is horizontal.

Attached is the SWR plot using a NanoVNA

 

[merlin]

I see the signals in SDR#, but all i hear is noise

Awful easy, If you see the signal in the spectrum scope, just click on the peak, it tunes to that frequency.
Not getting audio, check your squelch level, That, or the signal may not be modulated. You can see that if you open the IF display

 

[my53Jubilee]

I used the same hookup, using the coax that came with the RTL SDR v3 dongle. Used an SMA adpater to make the connection. Not sure of quality of the SMA adapter.