Monitoring MOTOTRBO Connect Plus DMR

[Rabid716]

Hi Everyone,

I would like to monitor a MOTOTRBO Connect Plus DMR system - specifically site 1 (Seneca One Tower) located here: SaiaNet Trunking System, Various, New York

It appears to have 4 control channels and 5 voice channels. I am interested in listening to a handful of local agency talkgroups on this system.

I am brand-new to SDR and I am trying to figure out what I need software+hardware-wise to accomplish this, and what guides/tutorials to use.

I would like to know:

1. I would like to use a Windows machine and use TCP communication for a cleaner setup without VBAudio. What software do I need - would DSD+FL by itself do the trick?
2. How many USB RTL-SDRs do I need... 1, 2, or more?
3. All the tutorials I've seen show users monitoring one control channel. What do you do in this scenario where the Seneca One Tower has 4 published control channels in the RRDB?
4. Any recommendations for a start-to-finish tutorial (or multiple tutorials) on what I am trying to accomplish?

Thank you!

 

[dave3825]

I would like to use a Windows machine and use TCP communication for a cleaner setup without VBAudio. What software do I need - would DSD+FL by itself do the trick?

DSDPlus Fastlane does not require any cables and works good.

How many USB RTL-SDRs do I need... 1, 2, or more?

DSDplus uses Fmp24 as the tuner. With that, you park dongle on control channel. Dongle will leave control channel and will tune to active voice channel. Then returns to the control channel when done. I will double check latter but that's how it is with P25.

Sdrtrunk should also work on that system with one dongle also.

 

[Rabid716]

DSDPlus Fastlane does not require any cables and works good.

DSDplus uses Fmp24 as the tuner. With that, you park dongle on control channel. Dongle will leave control channel and will tune to active voice channel. Then returns to the control channel when done. I will double check latter but that's how it is with P25.

Sdrtrunk should also work on that system with one dongle also.

Thank you Dave, this helps a lot. In this case of having 4 different control channels, do I just pick 1 of the 4?

 

[dave3825]

If you go with DSDPlus fastlane, you would need all these freqs defined in the DSDPlus freqs file in the correct format for it to track properly.

Seneca One Tower

LSN	Frequency	Color Code
1	424.875c	1
3	424.425c	1
5	424.625c	1
7	424.7125c	1
9	424.9	1
11	424.6625	1
13	424.575	1
17	424.5625	1
19	424.675	1

All said and done, you need a networks entry, a sites entry and freqs entry. You said you only wish to monitor a handful of tg's yso thats a lot less copy pasting you would have to do in the end.

 

[Rabid716]

If you go with DSDPlus fastlane, you would need all these freqs defined in the DSDPlus freqs file in the correct format for it to track properly.

Seneca One Tower

LSN	Frequency	Color Code
1	424.875c	1
3	424.425c	1
5	424.625c	1
7	424.7125c	1
9	424.9	1
11	424.6625	1
13	424.575	1
17	424.5625	1
19	424.675	1

All said and done, you need a networks entry, a sites entry and freqs entry. You said you only wish to monitor a handful of tg's yso thats a lot less copy pasting you would have to do in the end.

I really appreciate this. Thanks so much for the help. I'll give this a go!

 

[enosjones]

U canjust use one dongle and pick one of the 4 or use 4 dongles or 2 dongles, using 4 required some kind of hub or a tripod with 4 usbs

 

[enosjones]

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[dave3825]

using 4 required some kind of hub or a tripod with 4 usbs

If a pc lacks sufficient usb's, then a hub is needed. Mine has 6 so I do not need a hub. As far as that tripod, I would not use that as that's putting a decent amount of force on the usb sockets. And if I did want my hub to float in the air, I would just epoxy a 1/4 20 tree nut to the bottom of the hub. Those dongles look like the ones that drift off frequency.

 

[enosjones]

It has a warp or a correction, I agree about the pressure on the usb sockets . I'm using a 3.0 hub, for a 2.0 hub isn't fast enough for the dongles

 

[dave3825]

It has a warp or a correction

The dongle does not have warp or correction, the software being used does. I run nooelec dongles that are 0.5ppm TCXO and never really require any adjustments for local stuff. For distant / weaker signals, a little fine tuning may be needed. I have a few of those cheap blue China dongles and they can be off as much as 90 ppm plus or minus, are not stable and do drift off freq quite a bit.

a 2.0 hub isn't fast enough for the dongles

What are you running the dongles at? I have a 2.0 hub and ran some Nooelecs @2.56 in Sdrtrunk and did not have any issues. Also ran an airspy mini @6.00 with 10 traffic channels and had no issues.

 

[enosjones]

I'm using unitrunker and dsdplus, the hub 2.0 wouldn't keep the dongles connected kept disconnecting, the 3.0 hasn't done that. I don't run them any different. Mine don't drift but I only had 1 that I didn't need to adjust the rest of them I do