SDRTrunk SDRTrunk Control Frequency Question

[benmmaddog]

SDRTrunk v6.1
RTL-SDR v3 Dongle
Outside antenna
Win 10 Pro
Had a question about the control Freq. I had been banging my head against the wall , trying to get my trunking set up
The DB had 773.03125 and 773.28125 as the control Freq. (Missouri Statewide Wireless Interoperable Network (MOSWIN))
When I would try those nothing happened , even went as far as got the subscription, have SDRT set it up for me , still nothing , tried a v4 dongle on a different machine and was getting the same results
was trying different programs to see if it was me, software,hardware and stumble across this "This page will not always be spot on. The actual control channel at the moment (they change it sometimes) is 857.2625. To find the control channel if you don’t know which one it is just open a program like GQRX and look and listen for the control channel. It will sound like digital noise. And the signal will be a constant spike." (OP25 For Dummies - Or how to build a police scanner for $30 (Part 1))
So I did just that and found 773.0325 and 773.07 . I placed them in the playlist editor , and boom I finally got something , and now it show 773.03125 with a status of control

So after the back story
1. Have the control freq changed and the DB not updated?
2. Is my dongle off of freq a bit ?
3. Why does it show one of the control freq in the DB , as control (pic above) , but it didn't work when place in the playlist editor ?
Sorry new to all of this, and just like to know Why,

 

[dave3825]

1. Have the control freq changed and the DB not updated?

Always possible. Some systems can use all freqs as control and some just use designated freqs. Need to know which site your trying.

2. Is my dongle off of freq a bit ?

It can be off. Click tuners tab in SDRT and look at the ppm






What site were you trying to receive? That freq, 773.03125 is used on 11 sites.

773.03125		1C5		Missouri Statewide Wireless Interoperable Network (MOSWIN)	Warsaw 700	Benton	MO
773.03125		1C4		Missouri Statewide Wireless Interoperable Network (MOSWIN)	St Joseph 700	Buchanan	MO
773.03125		1C1		Missouri Statewide Wireless Interoperable Network (MOSWIN)	Jefferson City 700	Cole	MO
773.03125		1C7		Missouri Statewide Wireless Interoperable Network (MOSWIN)	Washington 700	Franklin	MO
773.03125		1C3		Missouri Statewide Wireless Interoperable Network (MOSWIN)	Springfield 700	Greene	MO
773.03125		1C2		Missouri Statewide Wireless Interoperable Network (MOSWIN)	Trenton 700	Grundy	MO
773.03125		1CE		Missouri Statewide Wireless Interoperable Network (MOSWIN)	Canton 700	Lewis	MO
773.03125				Missouri Statewide Wireless Interoperable Network (MOSWIN)	Hannibal area (*)	Marion	MO
773.03125		1C6		Missouri Statewide Wireless Interoperable Network (MOSWIN)	Portageville 700	New Madrid	MO
773.03125		1C5		Missouri Statewide Wireless Interoperable Network (MOSWIN)	Trailer 1 Site 98	Itinerant	MO
773.03125		1C0		Missouri Statewide Wireless Interoperable Network (MOSWIN)	Trailer 2	Itinerant	MO

 

[maus92]

The SDR software needs to account for SDR hardware error and perhaps some error in the transmitter. This is why there is a ppm adjustment functionality in SDR Trunk. The actual control channel frequency of the site you are monitoring is 773.03125. The software decodes the control channel data stream and displays both the Channel Number and its derived frequency in the Now Playing tab.

 

[dave3825]

Suspect he is trying this site as its one of two that does not have 773.03125 listed as a cc. Just 1 cc with 7 voice freqs. Last updated in 2020.

1 (1)	044 (2C)	Canton 700	Lewis, MO	769.18125	769.44375c	769.90625	770.15625	770.43125	773.03125	773.53125
				773.81875

or this one

1 (1)

998 (3E6)

Trailer 1 Site 98

Itinerant, MO

769.18125c

770.15625

773.03125

773.09375c

773.78125c

774.08125

774.30625c

 

[maus92]

A ppm error of ~1.6 would be the difference between 773.0325 and 773.03125. We need to see the op's tuner panel and waterfall display. The rrdb is probably correct and those control channel frequencies should be configured.