SDS100/SDS200: SDS100 scanning talkgroups

[nlenna]

I have been scanning for a few years with my SDS100 and 436. I understand the basics of Sentinel and programming favorites and updating my database. My question is I feel I am missing something. Do I need to enter the DEC or HEX talkgroup IDs of my local police to monitor those transmissions or was that done in Sentinel when I saved it as a favorite. For example when I go into the RRDB for my local PD sites and frequencies it only lists it as DEC, HEX, Mode and Alpha Tag. I can find no actual frequencies for my local PD. How would I program this? Is it scanning each individual TGID of my local police for a transmission? Or am I missing something? Also, I have never received a transmission that would allow me to operate as a stringer for a news story or to operate a tow truck. I know this sounds silly as I do not wish to do either of these jobs. I am just curious how someone would use these trunking scanners to gain information and locate where the call is physically located. I live in the metro Houston area so I know there is plenty activity to pick up on. Thank you in advance for your help and forgive me if my inquiry seems elementary. But, this stuff is complicated to me. I almost feel I need to take a programming class if I can find one.

 

[Chris0516]

Just the DEC TG #'s

 

[nessnet]

The very first place to start is to understand trunking.
Learn what the terms "control channel", "voice channel" and "channel grant" are....
Hint: The control channels are the actual frequencies that are broadcast from "sites". The radio scans these "sites". Individual departments on a system use "talk groups", not frequencies.

Trunked radio system - Wikipedia

How does trunking work? | Tait Radio Academy

Google Search

 

[hiegtx]

For example when I go into the RRDB for my local PD sites and frequencies it only lists it as DEC, HEX, Mode and Alpha Tag. I can find no actual frequencies for my local PD. How would I program this? Is it scanning each individual TGID of my local police for a transmission? Or am I missing something?

Where you are seeing "Dec, Hex, & Mode is in the listing of talkgroups for a trunked system. The frequencies used to transmit talkgroups to the users in a system are in the Sites, which are shown at the top of the database page for trunked systems. You don't list your location, so we can't give you more specific information on systems of interest in your area.

In addition to the links that nessnet posted, there are articles in the Wiki here at RadioReference that also give you a more complete description of how the systems work, and what needs to be done to monitor them.

Trunking Basics - The RadioReference Wiki

wiki.radioreference.com

Common Trunking Programming Questions - The RadioReference Wiki

wiki.radioreference.com

 

[nlenna]

I am in Harris Co. Seabrook area. Which uses TXWARN, a P25 system. I have all keys needed entered into my scanners. I see no control frequencies for my area only talkgroup ids under sites.

 

[Whiskey3JMC]

I see no control frequencies for my area only talkgroup ids under sites.

The frequencies in red with a "c" suffix are control channels. Harris County has a number of simulcasts and single sites so not sure which one is applicable to your area, I've provided Central Simulcast as an example. Only one control channel can be active at a time

1 (1)	052 (34)	Harris County Central Simulcast	Harris	769.26875	769.70625	769.85625	770.08125	770.25625	770.53125	771.75625
				772.13125	773.48125	773.99375	774.24375c	774.68125c	856.3875	856.7125

 

[pyeman99]

The frequencies in red with a "c" suffix are control channels. Harris County has a number of simulcasts and single sites so not sure which one is applicable to your area, I've provided Central Simulcast as an example. Only one control channel can be active at a time

1 (1)	052 (34)	Harris County Central Simulcast	Harris	769.26875	769.70625	769.85625	770.08125	770.25625	770.53125	771.75625
				772.13125	773.48125	773.99375	774.24375c	774.68125c	856.3875	856.7125

Program them all into the radio.The control channels can change.

 

[dave3825]

I am in Harris Co. Seabrook area. Which uses TXWARN, a P25 system. I have all keys needed entered into my scanners. I see no control frequencies for my area only talkgroup ids under sites.

If your using sentinel, and you append the system, it will download all the sites (freqs) and talkgroups..

 

[nessnet]

1 (1)	005 (5)	Humble	Harris	851.225	851.450	851.600	851.725	852.5875	852.7375c	852.925
				853.125	853.150c	853.400	853.625	854.0875
1 (1)	006 (6)	Bush Intercontinental Airport	Harris	856.2875	856.3125	857.2875	857.3125	858.2875	858.3125	859.2875c
				860.2875c
1 (1)	007 (7)	Hobby Airport	Harris	856.2625	856.9375	858.7375	859.7375c	860.7375c
1 (1)	012 (C)	Harris County East Simulcast	Harris	769.21875	769.40625	769.68125	769.96875	770.46875	770.68125	770.90625
				773.03125	773.55625	773.80625	774.33125c	774.59375c
1 (1)	013 (D)	Harris County Northwest Simulcast	Harris	771.71875	772.49375	772.64375	772.86875	773.69375c	774.45625c	851.975
				852.250	852.575	853.100	853.7625	854.9625
1 (1)	014 (E)	Harris County Northeast Simulcast	Harris	770.23125	771.23125	771.98125	773.21875	774.15625c	774.43125c	851.450
				851.600	852.5875	852.925	853.125	854.0875
1 (1)	029 (1D)	Pasadena	Harris	851.1125	851.3625	851.6125	851.8625	852.1125	852.3625	852.6125
				852.8625	853.1125	853.3625	853.6125c	853.8625c
1 (1)	030 (1E)	Reed Road	Harris	769.19375	770.65625	773.30625	773.53125	773.78125c	774.05625c
1 (1)	033 (21)	Houston Transtar	Harris	851.300	851.700	852.150	853.1375	853.675c	857.7125c
1 (1)	035 (23)	Wade Road	Harris	851.100c	851.550	851.925	851.950	852.350	852.375	852.600
				852.875	852.950	853.050c	853.225	853.250	853.650	853.775
				853.9375
1 (1)	038 (26)	Huffman	Harris	851.375	851.9375	852.4625	853.0375c	853.975c
1 (1)	039 (27)	Tomball	Harris	851.575	852.650c	852.9875c	853.950c	858.4875	860.4625
1 (1)	052 (34)	Harris County Central Simulcast	Harris	769.26875	769.70625	769.85625	770.08125	770.25625	770.53125	771.75625
				772.13125	773.48125	773.99375	774.24375c	774.68125c	856.3875	856.7125
				856.9125	857.3875	857.9125	858.2375	858.3875	858.6875	858.9125
				859.3875	859.9125	860.3875
1 (1)	094 (5E)	Barbours Cut Terminal	Harris	769.45625	770.43125	770.69375	773.05625	773.31875c	774.53125c
1 (1)	095 (5F)	Bayport Terminal	Harris	769.43125	769.91875	770.16875	770.41875	770.70625c	770.95625c
3 (3)	001 (1)	Houston Public Safety Northeast Simulcast	Harris	769.08125	769.29375	769.50625	770.50625	770.80625	771.38125	771.55625c
				772.78125c	773.13125c	773.43125c
3 (3)	002 (2)	Houston Public Safety Northwest Simulcast	Harris	771.10625	771.33125	771.91875	772.08125	772.26875	772.43125	772.80625c
				773.24375c	773.65625c	773.96875c
3 (3)	003 (3)	Houston Public Safety Southeast Simulcast	Harris	769.80625	770.05625	770.33125	770.58125	770.83125	771.05625	771.40625c
				771.63125c	772.93125c	773.38125c
3 (3)	004 (4)	Houston Public Safety Southwest Simulcast	Harris	769.55625	770.60625	770.75625	771.08125	771.28125	771.43125	771.84375c
				772.21875c	772.59375c	773.74375c
3 (3)	005 (5)	Houston General Government Services Simulcast	Harris	853.725	854.0125	854.3875	854.4625	856.4375	856.7375	856.7625
				857.2625	857.4375	857.7375	857.7625	857.9375	858.2625	858.4375
				858.6125	858.7625	858.9375c	859.2625c	859.4375c	859.7625	859.9375c
3 (3)	017 (11)	Houston Public Safety Downtown Tunnel System	Harris	769.54375c	769.75625c	770.00625c	770.30625c