SDRTrunk - How to Import MCSO

[dave3825]

Any way you could use Windows Snipping Tool for the screenshots?





Your gain is still way to high.





Should look more like this with a real low noise floor.

 

[kingshootr]

Sorry, got lazy...





And I'll be danged if I can find the gain control on this program...

 

[dave3825]

 

[kingshootr]

OK, that's flat out embarrassing...

 

[dave3825]

OK, that's flat out embarrassing..

Its all good. I run my Nooelec's at 327 and have a nice low noise floor. Either that Moonraker really pulls in or your in a real rich rf envoirment.

 

[dave3825]

What you want to do, is drop that to 0, then keep raising while watching a known signal. Raise until the signal peaks (will not go any higher), and just when the noise floor starts to rise.

 

[maus92]

Looks to me like local interference as the pattern in the waterfall is very regular. Perhaps some LED lights nearby? Or perhaps a band 14 or Verizon tower nearby?

 

[kingshootr]

Well, I'm getting somewhere, finally. So after getting the gain set correctly I am getting some calls - not all, some are digitally garbled, some clear as a bell.

Fire - Perfect



Police - Perfect


Sheriff - meh


On the sheriff it's just hit and miss. I have to believe maus92 is on to something. Antenna not high enough maybe, there is a cell tower about 1/2 mile away. All the lights in my office are fluorescents (the little incandescent spiral replacement kind). I'm going to say it's about 50-50 between good and garbled.

But HEY - you all did it! I really appreciate you taking the time to throw your expertise at this. I owe you a frosty beverage(s).

 

[qc]

That is good news. One thing about the Simulcast systems is that you can get Distortion. The only way I fixed this problem on my local system was to use a 700/800 MHz Yagi antenna and point it at one of the sites. I get 100% of the calls with no garbled transmission

 

[kingshootr]

For the yagi, does it need to be clear line of sight (above the rooftops)?

 

[maus92]

There are still some super-powerful and less-powerful signals showing in you waterfall that start transmitting at the same time. Some of the less powerful signals (shorter amplitude spikes) look typical for LMR; the super tall ones look more like an interfering signal - is there any way you can determine their frequencies by hovering over them or looking at the scale? Have you considered using a simple wire or telescoping indoor antenna for testing? Gain still looks high. OTOH, the simultaneous signals *could* be individual sites from a multicast system - that's why it would be helpful to determine their exact frequencies and look them up - or try to decode them.

 

[kingshootr]

Good morning everyone.

Here's what I have today lol...

This is a video of the system running with 2 dongles and the outside antenna:

This one is with 1 dongle, and an inside 18" whip antenna:

These are pictures of my current setup - perhaps there may be a clue to some interference. The printer is a wifi type. The USB hub is a powered type with only a mouse being the other item plugged in.

The Surface Pro pc has 8GB Ram, 1/2 TB of solid state storage, and I only run the program, not a bunch of background stuff when listening.



The antenna run is 35ft from dongles to antenna. Very straight shot, out and up. I do have a 10ga ground wire from the antenna mast/mount/stand to the ground on the house.



I put some aluminum heat sinks on the dongles. I read some peoples' are heating up significantly so I figure better safe than sorry.



So, when you are bored, or trying to fall asleep - here's a bunch of stuff that might help you!

 

[kingshootr]

I ran down a few of the channel spikes. For the 1 dongle/whip antenna test:

These all come up as: West Valley Simulcast G:
770.81875
771.86875
772.61875

No records on this one:
775.406(?)

Phoenix Fire and Public Works Simulcast B:
771.98125

These had the "MMTP" notice on top of the spike - they both came back as: Maricopa County Phoenix Simulcast
771.20625
771.53125

 

[kingshootr]

This is for the 2 dongles and outside antenna. There were several duplicates from the 1 dongle test (probably more - I was just random sampling).

771.74375 = Maricopa County Phoenix Simulcast

771.68125 = Regional Wireless Coop / Simulcast A / Phoenix PD and City Services

771.38125 = Regional Wireless Coop / Simulcast B / Phoenix PD and City Services

771.94375 = (MMTP) Northeast Mountain Simulcast

 

[maus92]

I think you need an attenuator in the line from the outdoor antenna, lol. Either your SDR gains are still too high, or you have too much antenna. The indoor antenna is suppressing adjacent channel interference because it doesn't see it, leading to a better quality decode - at least it sounds better to me.

 

[kingshootr]

This is great - thanks again for the lessons lol.

Now... what dB level of attenuator should I be looking for?

Or a set like this?

 

[maus92]

Hopefully some attenuator gurus can chime in. In your testing, did you ever run a single SDR straight to the computer without using the powered hub? Trying to eliminate a source of interference by unplugging the USB hub power supply.

 

[kingshootr]

That's how I started (a few weeks ago - that's how long I've been working with them). Easy enough to try. Will let you know.

 

[dave3825]

Just curious, your scanning the Phoenix site, right? If so, where are you in relation to the towers?

 

[kingshootr]

Yes, the "Phoenix Simulcast" is what I have set up. I'm in a great location I think:


For your viewing pleasure , more videos! I don't know if these help or are annoying...

These two are 1 and 2 dongles plugged direct into the PC, using the outdoor antenna.

Each time it's sounding better and better, at least to me. Maybe I'm (we're) beating the program into submission?