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  #3561 (permalink)  
Old 03-28-2018, 10:41 AM
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Anyone contemplating buying a Unication G4 / G5 to monitor FiRST or the local Baltimore systems might want to hold off for a bit. Uniden announced a new SDS100 scanner the will (allegedly) handle simulcast / LSM system much better than their 436 for about the same price as the Unication pagers, and is a "true" scanner vs. a pager. It is due Q22018, which is between now and July. I'm a sucker, and will buy one.
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Old 03-28-2018, 10:58 AM
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I was going to get a G5 with the Phase II upgrade until that announcement was made. I think timing was intentional since the offer for free Phase II ends 3/31

The question I would have though - not factoring in simulcast and general reception issues - how does a G4/5 handle going across multiple sites in comparison to a 325P2 or 436HP?
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Old 04-16-2018, 7:15 AM
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New site licensed in Jefferson (Frederick County)? Phase 1?

ULS License - Trunked Public Safety 700 MHz License - WRBK639 - STATE OF MARYLAND - DOIT
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  #3564 (permalink)  
Old 04-16-2018, 7:30 AM
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Quote:
Originally Posted by troymail View Post
New site licensed in Jefferson (Frederick County)? Phase 1?

ULS License - Trunked Public Safety 700 MHz License - WRBK639 - STATE OF MARYLAND - DOIT
Thanks for this. The Marlu Ridge site has been mentioned in program and other documentation before. I have mapped two potential tower site locations, and this will help to clarify the ambiguity. Last month I drove through Frederick County, and did not hear the site on the air (this prompted me to buy a dedicated laptop to use for this purpose, instead of the HP2.) There is also another Frederick County site - Tower Road - mentioned in CAPRAD that doesn't appear to be on the air yet.
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Old 04-16-2018, 7:33 AM
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Quote:
Originally Posted by maus92 View Post
Thanks for this. The Marlu Ridge site has been mentioned in program and other documentation before. I have mapped two potential tower site locations, and this will help to clarify the ambiguity. Last month I drove through Frederick County, and did not hear the site on the air (this prompted me to buy a dedicated laptop to use for this purpose, instead of the HP2.) There is also another Frederick County site - Tower Road - mentioned in CAPRAD that doesn't appear to be on the air yet.
Unless it is some type of priority project, I wouldn't expect it to be active too quickly ... but you never know. The real question is - what is it? (standard 6 channel single site but Phase 1 per the license).
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  #3566 (permalink)  
Old 04-16-2018, 7:33 AM
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Did anyone make it to the Control Board meeting last week? I was in Florida last week.
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Old 04-16-2018, 5:07 PM
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Anybody know when Dorchester Fire/EMS is going to come online with FiRST?
I was speaking to a member of Rescue Fire Co and they thought it'd be a month or so, but I haven't heard anything through my contacts yet.
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Old 04-16-2018, 5:10 PM
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Quote:
Originally Posted by boatbod View Post
Anybody know when Dorchester Fire/EMS is going to come online with FiRST?

I was speaking to a member of Rescue Fire Co and they thought it'd be a month or so, but I haven't heard anything through my contacts yet.

The radios are in County. They will be switching to those at anytime. As far as coming online with the new system I have heard by June 30. Also per a reliable source all law enforcement will be encrypted.


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Old 04-16-2018, 5:15 PM
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Quote:
Originally Posted by boatbod View Post
Anybody know when Dorchester Fire/EMS is going to come online with FiRST?
I was speaking to a member of Rescue Fire Co and they thought it'd be a month or so, but I haven't heard anything through my contacts yet.
I was under the impression that it was a matter of converting their EOC consoles. They already own the subscriber units. The state also wants to add some channel capacity / possibly a new site, but that might be a longer term desire.
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  #3570 (permalink)  
Old 04-16-2018, 7:28 PM
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Quote:
Originally Posted by troymail View Post
Unless it is some type of priority project, I wouldn't expect it to be active too quickly ... but you never know. The real question is - what is it? (standard 6 channel single site but Phase 1 per the license).
Hmmm... I looked at the licences for other ASR / single sites on FiRST, and they also use the 8K10F1E emission designator. The simulcast sites seem to use multiple emission type designators - 8K10G1W, 9K80D7W, 8K10F1D.
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Old 04-16-2018, 7:50 PM
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Quote:
Originally Posted by troymail View Post
New site licensed in Jefferson (Frederick County)? Phase 1?

ULS License - Trunked Public Safety 700 MHz License - WRBK639 - STATE OF MARYLAND - DOIT

DSDPlus shows this on site 1-17 -
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Old 04-17-2018, 5:51 AM
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Quote:
Originally Posted by amickey1979 View Post
The radios are in County. They will be switching to those at anytime. As far as coming online with the new system I have heard by June 30. Also per a reliable source all law enforcement will be encrypted.


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Originally Posted by maus92 View Post
I was under the impression that it was a matter of converting their EOC consoles. They already own the subscriber units. The state also wants to add some channel capacity / possibly a new site, but that might be a longer term desire.
Thanks.

Guess we'll have to wait and see about LEO encryption. Talbot, Caroline, Queen Anne and MSP only encrypt some law TAC channels. I wonder why Dorchester wants to be different?
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Old 04-17-2018, 9:21 AM
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Quote:
Originally Posted by boatbod View Post
Thanks.

Guess we'll have to wait and see about LEO encryption. Talbot, Caroline, Queen Anne and MSP only encrypt some law TAC channels. I wonder why Dorchester wants to be different?
It's only a rumor (apparently) at this point. Not sure if Dorchester County is a hotbed of organized crime, but encryption seems to be more widespread in smaller jurisdictions where it is easier to implement and manage. If I lived in Dorchester and encryption was enabled, I would make sure to attend council sessions and ask why it is necessary.
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Old 04-17-2018, 10:03 AM
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Default Simulcast site data

Taking a look at the data recovered by ProCom and Unitrunker when monitoring a simulcast site on FiRST. I'll try to find a stand alone site and compare the data, but Unitrunker reports the modulation as C4FM with P2 voice, which I assume means Phase 2, or TDMA - or maybe ABME2? IDK, trying to learn.
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Old 04-17-2018, 3:56 PM
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Quote:
Originally Posted by maus92 View Post
Taking a look at the data recovered by ProCom and Unitrunker when monitoring a simulcast site on FiRST. I'll try to find a stand alone site and compare the data, but Unitrunker reports the modulation as C4FM with P2 voice, which I assume means Phase 2, or TDMA - or maybe ABME2? IDK, trying to learn.
FiRST has CQPSK modulation.
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Old 04-17-2018, 4:53 PM
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Originally Posted by boatbod View Post
FiRST has CQPSK modulation.
I monitored the Westminster ASR this afternoon, and Unitrunker reports the site using CQPSK. I'm not sure why UT reports C4FM on the AA simulcast site, but it also reported C4FM on Wicomico's new simulcast P25P2 site. I'm going to post on ther UT site to see if there is an explanation for this behavior. Note that I wrote "Westminster ASR," and not "Carroll Simulcast" as the RRDB reflects. Carroll County does not have a simulcast site. In fact, it appears there are plans to add additional ASRs in Carroll County: Sykesville in the south, Taylorsville in the west, and Cherrytown in the north. Currently the Howard simulcast site covers southern Carroll, and the Westminster ASR covers mid Carroll, Lineboro ASR covers the northeast. FiRST is fairly weak in the western portions of the county. Here are the UT system properties for Westminster ASR and the under construction Wicomico P25P2 site.
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  #3577 (permalink)  
Old 04-17-2018, 8:32 PM
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Originally Posted by maus92 View Post
I monitored the Westminster ASR this afternoon, and Unitrunker reports the site using CQPSK. I'm not sure why UT reports C4FM on the AA simulcast site, but it also reported C4FM on Wicomico's new simulcast P25P2 site. I'm going to post on ther UT site to see if there is an explanation for this behavior. Note that I wrote "Westminster ASR," and not "Carroll Simulcast" as the RRDB reflects. Carroll County does not have a simulcast site. In fact, it appears there are plans to add additional ASRs in Carroll County: Sykesville in the south, Taylorsville in the west, and Cherrytown in the north. Currently the Howard simulcast site covers southern Carroll, and the Westminster ASR covers mid Carroll, Lineboro ASR covers the northeast. FiRST is fairly weak in the western portions of the county. Here are the UT system properties for Westminster ASR and the under construction Wicomico P25P2 site.
I was under the impression (based on what's written in the TIA-102 spec) that phase 1 fdma FNE downlink is either C4FM or QPSK (depending on simulcast) but phase 2 tdma is always H-DQPSK. Subscriber uplink is of course always C4FM regardless of fdma/tdma.
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Old 04-17-2018, 9:06 PM
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Quote:
Originally Posted by boatbod View Post
I was under the impression (based on what's written in the TIA-102 spec) that phase 1 fdma FNE downlink is either C4FM or QPSK (depending on simulcast) but phase 2 tdma is always H-DQPSK. Subscriber uplink is of course always C4FM regardless of fdma/tdma.
I don't have access to the TIA documentation, but I wish I did or any other tech document that defines control channel data.)

I have a theory that UT will show P25P2 simulcast sites as C4FM, and standalone sites as CQPSK, and I don't know why. I need to test out a few more standalone sites to verify the theory. I don't know if UT analyzes the stream to figure out its modulation, or if it reads the data stream and extracts a value from a packet that corresponds to a modulation type. I'm going to post up to the UT group and ask the question after I post this.
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  #3579 (permalink)  
Old 04-17-2018, 10:49 PM
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And for those who are interested, I submitted the following question to the UT2 support group:

"I have a couple of questions regarding the UT Properties page, and what certain values represent, and how the values are obtained. Ideally, I'd like to know how each of the values are derived, but I'm sure nobody has the time for that. Anyway, how is the Modulation value derived? Is it sensed / measured from the stream, or is it read from a data field? The system I am monitoring is a Motorola P25 Phase 2 wide area system, built with a combination of simulcast sites and single standalone sites. The simulcast sites indicate C4FM modulation, while the standalone sites show CQPSK modulation. I was expecting to see H-DQPSK ."

And the answer from the dev was:

"HDQPSK is a property of a voice channel.

The C4FM vs. CQPSK derives from the respective demodulators. The better of the two wins. Sometimes they tie for decode rate hence the "not reliable" warning."
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Old 04-18-2018, 6:55 AM
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Quote:
Originally Posted by maus92 View Post
And for those who are interested, I submitted the following question to the UT2 support group:

"I have a couple of questions regarding the UT Properties page, and what certain values represent, and how the values are obtained. Ideally, I'd like to know how each of the values are derived, but I'm sure nobody has the time for that. Anyway, how is the Modulation value derived? Is it sensed / measured from the stream, or is it read from a data field? The system I am monitoring is a Motorola P25 Phase 2 wide area system, built with a combination of simulcast sites and single standalone sites. The simulcast sites indicate C4FM modulation, while the standalone sites show CQPSK modulation. I was expecting to see H-DQPSK ."

And the answer from the dev was:

"HDQPSK is a property of a voice channel.

The C4FM vs. CQPSK derives from the respective demodulators. The better of the two wins. Sometimes they tie for decode rate hence the "not reliable" warning."
Interesting.

The only way I know to passively determine modulation is to look at the eye pattern. C4FM is wider than CQPSK. It's certainly not set in any parameter that can be decoded from the voice channel.

While working with op25 I can categorically say you can often lock and decode a control channel in either C4FM or QPSK but pretty much never successfully decode phase 2 voice in C4FM. Perhaps for backward compatibility different modulation schemes are used between the control channels and voice channels?
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