DSD+ and One Frequency Trunking

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garys

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I have my local public works department programmed into my 436HP as a OFT. It works fine that way. There are some other town departments that use DMR, probably in OFT mode as well.

I want to confirm those operations and thought to use DSD+ for that. I set up the DPW in the dsd.frequencies file in order to "calibrate" my settings before going on to the unknown systems.

In DSD-CC, I get the correct data, but FMP24 does not generate the frequency, so DSD-VC doesn't work.

Here is how I have the frequencies set up,

DMR, 1, 1, 1, 151.025, 0.0, 0

Has anyone else tried to listen to a OFT in DSD+? Is this the correct set up, or am I missing something?

Thanks.
 

mtindor

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I have my local public works department programmed into my 436HP as a OFT. It works fine that way. There are some other town departments that use DMR, probably in OFT mode as well.

I want to confirm those operations and thought to use DSD+ for that. I set up the DPW in the dsd.frequencies file in order to "calibrate" my settings before going on to the unknown systems.

In DSD-CC, I get the correct data, but FMP24 does not generate the frequency, so DSD-VC doesn't work.

Here is how I have the frequencies set up,

DMR, 1, 1, 1, 151.025, 0.0, 0

Has anyone else tried to listen to a OFT in DSD+? Is this the correct set up, or am I missing something?

Thanks.
Your CC copy of DSDPlus is going to play the audio for a one-freq trunking site, unless you have your CC copy of DSDPlus set to mute all audio on slot1/2 of the CC.

On a one-freq trunk there is only one freq, two slots.

So I seriously doubt you are going to get it to send anything to the VC copy of DSDPlus.

Just make sure your CC copy of DSDPlus is set up to decode the audio on the CC freq. There are switches to mute it, and it may very well be muted in your DSDPlus Cc batch file.

Mike
 

garys

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Thanks. I currently have audio output on DSD-CC set to "0". I'll change that to output to my speakers and see if that works.

It also occurred to me that another approach might be to use SDR# to feed DSD-VC, although I'm not sure how much data I might see.


Your CC copy of DSDPlus is going to play the audio for a one-freq trunking site, unless you have your CC copy of DSDPlus set to mute all audio on slot1/2 of the CC.

On a one-freq trunk there is only one freq, two slots.

So I seriously doubt you are going to get it to send anything to the VC copy of DSDPlus.

Just make sure your CC copy of DSDPlus is set up to decode the audio on the CC freq. There are switches to mute it, and it may very well be muted in your DSDPlus Cc batch file.

Mike
 

mtindor

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Isn't a OFT DMR just a "conventional" DMR? I mean, what you are listening to is just a standard DMR repeater, right? The only things it is going to show are like CC / TG / RID. And of course it's only going to show anything when there is activity on the frequency [which likely isn't 24/7]. It's not going to show any sort of system details since it isn't CAP+ / CON+ or anything like that.

You could just feed SDR# into DSDPlus for an OFT if you wanted.

I am always searching out stuff, so I'm usually using SDR# + AIrspy, no dongles, no FMP. Just SDR# + DSDPlus.

I set my SDR# audio output to my VAC line (which is audio input device 5 in DSDPlus in my case). Then I simply run "dsdplus -i5 -o1 -v4". I like to keep it simple.

mike
 

garys

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This is what I ended up doing. I even ended up using the exact same settings as you did.
I'm doing this just to figure out how the systems work. I don't have all that much interest in listening to school custodians, but it's convenient to listen to them to see how the technology works.

It's running perfectly on the DPW frequency, so I'll input one of the school frequencies and listen.

What's interesting is that no one in any of the departments seems to understand TDMA. I mean they are probably ignorant of the fact that they could use one frequency for two "Channels". Not that I'd expect the Motorola, or whoever, salesman to explain that. After all, that means he can sell more radios, doesn't it? :eek:

Isn't a OFT DMR just a "conventional" DMR? I mean, what you are listening to is just a standard DMR repeater, right? The only things it is going to show are like CC / TG / RID. And of course it's only going to show anything when there is activity on the frequency [which likely isn't 24/7]. It's not going to show any sort of system details since it isn't CAP+ / CON+ or anything like that.

You could just feed SDR# into DSDPlus for an OFT if you wanted.

I am always searching out stuff, so I'm usually using SDR# + AIrspy, no dongles, no FMP. Just SDR# + DSDPlus.

I set my SDR# audio output to my VAC line (which is audio input device 5 in DSDPlus in my case). Then I simply run "dsdplus -i5 -o1 -v4". I like to keep it simple.

mike
 

mtindor

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This is what I ended up doing. I even ended up using the exact same settings as you did.
I'm doing this just to figure out how the systems work. I don't have all that much interest in listening to school custodians, but it's convenient to listen to them to see how the technology works.

It's running perfectly on the DPW frequency, so I'll input one of the school frequencies and listen.

What's interesting is that no one in any of the departments seems to understand TDMA. I mean they are probably ignorant of the fact that they could use one frequency for two "Channels". Not that I'd expect the Motorola, or whoever, salesman to explain that. After all, that means he can sell more radios, doesn't it? :eek:
They might be using one slot for data only or something like that, if that's even a possibility. Schools around here on DMR usually have AVL/GPS stuff going on nearly all the time during day on one slot. Of course, depending on the flavor of AVL, DSD+ may or may not decode the AVL coordinates for use in LRRP.

Mike
 

garys

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There's no indication of that sort of thing. The DPW trucks only have a VHF whip, no sort of GPS puck at all. The town is small enough that it's not an issue. I don't think they do it for the contract plowing companies either, although the state and at least one larger city do that.

No, I think it's just a matter of not knowing what the technology is capable of.

They might be using one slot for data only or something like that, if that's even a possibility. Schools around here on DMR usually have AVL/GPS stuff going on nearly all the time during day on one slot. Of course, depending on the flavor of AVL, DSD+ may or may not decode the AVL coordinates for use in LRRP.

Mike
 

garys

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I figured that out after a while. The SDR+ DSD+ combination gives me the information I seek.

Correct... OFT is just a scanner thing and would be 'conventional DMR' in the radio world. One frequency, 2 time slots.
 

garys

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I have everything working properly now and have observed something interesting. On what turns out to be the towns Water Department, they are using DMR, but there is no slot number in the data stream. I have frequency (of course), CC, TG (there is only one), and RIDs, but no slot number.

I validated that against another town frequency, and that does show slot number.

I've never seen that before.
 

garys

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It is. The DPW is also, at least I think so, simplex, but does show the slot number. Which is always 1.

Interestingly, but departments use TG701 only, and the base station is RID 1000. The Water Department is part of the DPW. Here is a case where it would make sense to use one frequency with two slots. However, I don't think there is anyone savvy enough outside of the FD to understand that. A couple of years ago, the Motorola sales guy convinced the police chief that he had to put a separate antenna up on the FDs tower because "You can only have one radio on an antenna."

Same band for both, of course.

Sounds like simplex.
 

slicerwizard

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If you provided raw audio samples, we could figure this stuff out. Otherwise, I guess one of us would have to take a drive out to the big S and see for ourselves.
 
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DaveNF2G

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DSDPlus does not have the scanner-based limitations, so don't handicap it by treating as you would a DMR scanner.
 
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