Simulcast Question

blues222

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I have questions, I have been in scanning for over 25 years. But this has got me stumped, My county has 2 sheriff dispatch channels, DMR system one of the tower is over 25+ miles and one of my scanners receives the transmissions from that tower and my other scanner receives the other tower transmissions from the other tower I can see from my front porch. Shouldn't both scanners receive the closest tower too me? Radio Reference has the channels down as SImulcast.
 

pb_lonny

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How do you know which tower it is if it is simulcast and both transmit on the same frequency?
 

blues222

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How do you know which tower it is if it is simulcast and both transmit on the same frequency
How do you know which tower it is if it is simulcast and both transmit on the same frequency?
Radio Reference has both channels down as Simulcast and they don't transmit on the same frequencies, but both channels have the same transmissions. Because the tower that is closet to me was the only channel they had. Then when RR came out with there other channel its tower is in another city 25 miles away
 

n5ims

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It sounds like a bit of confusion (totally understandable). There is a difference between a simulcast system (multiple towers broadcasting the same traffic on the same talkgroups over the same frequencies) and a talkgroup or channel that simulcasts the same traffic over a different frequency or talkgroup. With a simulcast system you typically will receive the signal from only the closest tower (and you really won't know which tower it comes from since they're on the same frequency).

The simulcast issues are on simulcast systems since your radio may pick up signals from multiple towers at the same time and can have trouble with the signals mixing together making the transmission unreadable. Simulcast traffic (that is the same traffic broadcast over multiple different channels) shouldn't be an issue since your radio should not have mixing issues because the frequencies are different. That said, it's possible that a channel from one system (or a stand-alone frequency) may be patched (temporarily or permanently) on a trunking system that may be a simulcast system and you could have issues picking up that system due to the issues mentioned above related to simulcast systems.
 

pb_lonny

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My understanding is that Simulcast means that both towers transmit on the same frequencies. If one site (closer to you) carries the traffic, can you only program / hold on that site?
 

blues222

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It sounds like a bit of confusion (totally understandable). There is a difference between a simulcast system (multiple towers broadcasting the same traffic on the same talkgroups over the same frequencies) and a talkgroup or channel that simulcasts the same traffic over a different frequency or talkgroup. With a simulcast system you typically will receive the signal from only the closest tower (and you really won't know which tower it comes from since they're on the same frequency).

The simulcast issues are on simulcast systems since your radio may pick up signals from multiple towers at the same time and can have trouble with the signals mixing together making the transmission unreadable. Simulcast traffic (that is the same traffic broadcast over multiple different channels) shouldn't be an issue since your radio should not have mixing issues because the frequencies are different. That said, it's possible that a channel from one system (or a stand-alone frequency) may be patched (temporarily or permanently) on a trunking system that may be a simulcast system and you could have issues picking up that system due to the issues mentioned above related to simulcast systems.
Thank you, I was think there where patched.
 

blues222

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My understanding is that Simulcast means that both towers transmit on the same frequencies. If one site (closer to you) carries the traffic, can you only program / hold on that site?
No I can recieve both sites, but a can recieve the farthest site on one scanner and the closet site on the other scanner. Shouldn't i just receive the closet site because I can see that site from my front porch?
 

hiegtx

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If programmed correctly, and presuming that you are not using a directional antenna aimed at the farthest tower on one scanner but not the other, you should be able to hear the closest site on both scanners,

What system, and which sites? And, which two scanners & the type of antenna each is using.
 

blues222

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If programmed correctly, and presuming that you are not using a directional antenna aimed at the farthest tower on one scanner but not the other, you should be able to hear the closest site on both scanners,

What system, and which sites? And, which two scanners & the type of antenna each is using.
Dmr system, 436hp and Whistler ws1080, one tram 1411 and one hustler bcl-b .
 

jonwienke

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Broadcasting the same traffic on multiple frequencies is multicast, not simulcast.

Simulcast is broadcasting the same traffic on the same frequency from multiple transmitters simultaneously.
 
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Simulcast > Transmitting the same information at multiple sites on the same frequency at the same time.
Multicast > Transmitting the same information at multiple sites on different frequencies at the same time.
Sloppycast > First rule of sloppycast is we don't talk about sloppycast.

For trunking, you have simulcast and wide area. This is because with wide area, you need a radio affiliated on the talk group of interest at the site of interest to hear anything. So if you have three sites, each operating on a different set of frequencies. Users for Group A are affiliated to Site 1 and Site 3 and Group B is affiliated to Site 2. Group A's traffic will only be multicasted to Site 1 and Site 2 and Group B's traffic won't be multicasted at all. Now if someone from Group A roamed to Site 2 or someone from Group B roamed to Site 1 or Site 3, that would dynamically change.

Now, there is an exception to the above when it comes to pseudo trunking (Linked Capacity Plus, XPT, and LTR Passport). Wide area traffic is actually multicasted as there is not a affiliation mechanism in those formats and it can be a select number of sites or all sites (configurable by the system owner).

Also, keep in mind, DMR does not have true simulcast capability. Only multicast and wide area trunking.
 
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DMR tier 3 (oops, III) can have the same freqs at different sites (channel pooling), the controller keeps track so it does not use both xmtrs at the same time.
 

hiegtx

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Dmr system, 436hp and Whistler ws1080, one tram 1411 and one hustler bcl-b .
While that identifies the two scanners, it still does not indicate the actual system in question other than it's DMR.

If the system is in the database, please provide a link to it's page. If not in the database, what is the call sign for the license for the site(s).

If it is in the database, and you appended the system to a Favorites list via Sentinel. then you should be able to hear it on your 436HP (unless the details in the database are incorrect).

If you created the system manually, either using Sentinel or other software, or by direct entry through the keyboard, did you enter all of the required information?

If this is a system that you created manually (i.e. it's not in the database), and you hear the system (the nearby site) on your WS1080 but not on the 436HP, then probably either the LCNs and/or color code , are incorrect. Your WS1080 does not use the LCNs, as it does not actually track the system. For the 436HP, you do need the LCNs to be correct, or else you will not be able to monitor it as a trunked system.

Is the "nearby" site in a separate system? Or is it paired with the "farthest site" in a DMR system with more than one site. If it is a separate system, are you using ID Search, or ID Scan? Do you have a Department created for that (nearby) system, with at least one talkgroup? For the WS1080, and the other Whistler database scanners, when you create a system, EZ-Scan automatically adds a wildcard. For the Uniden scanners to work (after you have addressed any LCN or color code issues), you need to have at least one talkgroup in the 'Department' for that system.

Even with the system set as ID Search, unless you have a Department created, with at least one TGID, the 436HP will not scan the system. And neither System Status nor the LCN Finder will work. You cannot run a Discovery session either, unless you have a Department, that is not empty, associated with the system. For a potential "new" system, that I create based on license data, I include a Department, and enter a 'default' TGID set as either a zero, or simply 1. Once the system is programmed, and I see the actual talkgroups begin to show up when using ID Search, then I can delete the 'default' and replace it with one or more of the talkgroups that appear to be active.
 
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