Illinois State Police Control Frequencies

Status
Not open for further replies.

shifty277

Member
Premium Subscriber
Joined
Jan 31, 2010
Messages
57
Does anyone know all the Illinois State Police Control frequencies? I found a PDF document with them all but my scanner still says Finding Control Channel..
 

n9mxq

Member
Premium Subscriber
Joined
Dec 15, 2005
Messages
1,617
Location
Belvidere IL
If you mean for the Starcom system. You should find what you need in the database. Pick the nearest tower site and use that.
 

shifty277

Member
Premium Subscriber
Joined
Jan 31, 2010
Messages
57
So if I wanted the state frequencies to work in the entire state I would have to add every counties simulcast control frequencies essentially?
 

rk911

Member
Premium Subscriber
Joined
Dec 11, 2004
Messages
255
Location
Wheaton, IL
So if I wanted the state frequencies to work in the entire state I would have to add every counties simulcast control frequencies essentially?
essentially, yes. but many CC are re-used throughout the state. there are primary and secondary CC's. for example, 852.96250 is used as a primary or alternate at 5 different sites....in Henry, Brown, Coles, Perry and Pope counties.

if you can convert your PDF to an Excel spreadsheet (this app will do it...https://www.pdftoexcelonline.com/ there are others) you could sort the frequencies and determine how many unique freqs there are.

unless you truly travel throughout the entirety of Illinois on a regular basis you might find it easier to set up regional scan lists...northeast, central, southwest, etc. besides entering the CC's you'd need to either use a wildcard TGID character resulting in hearing everything coming thru that control channel or individual TGIDs.

good luck to you.
 

jeatock

Member
Premium Subscriber
Joined
Jul 9, 2003
Messages
589
Location
090-45-50 W, 39-43-22 N
Don't get bogged down in details.

Unlike conventional scanners, trunking scanners don't scan frequencies. They listen to one tower's control channel for each different system you monitor and follow talkgroups (a virtual channel). Your scanner automatically shifts to whatever frequency the control channel says the active talkgroup traffic is on, then back to the control channel. You only need to program and scan additional control channel frequencies if you want to monitor totally different trunking systems (i.e. Illinois' Starcom and Missouri's MoSWIN).

For Starcom go to http://www.radioreference.com/apps/db/?sid=2324 and program the red control channel frequency for the tower you want to use.

Unless it is in your car you only need to program your scanner with one control channel frequency (or one for each different system), ideally the tower with the most desired talkgroup traffic and decent signal for your area. My base scanner has only one Starcom system control channel frequency programmed and that control channel is not the closest or strongest one; I use the control channel of a tower with more desired talkgroup traffic.

If you are mobile, you only need to have your radio scan for another control channel when you have moved into a different area of the system and your 'home' tower is out of range. Depending on where you are that can be thirty miles.

P25 trunking is really pretty simple. Each tower has a single control data channel that is always in transmit and tells all radios registered on that tower what to do when a desired talkgroup goes active. You don't need to program the voice channels in P25 trunking systems - that is automatic.

When a mobile Starcom radio is turned on it finds and registers on a tower and tells the tower what talkgroup it is using. When that talkgroup goes active, the control channel tells registered radios to shift up or down "X" MHz to follow the talkgroup. Although your scanner doesn't register on the tower, it will still follow the control channel's instructions.

Once a good control channel is found your scanner will obey the control channel data and automatically shift frequencies to follow enabled talkgroups (or any talkgroup in ID SCAN mode).

Remember that all talkgroups are not active on all towers. There must be at least one real Starcom radio registered on a given talkgroup for that talkgroup to go active on a monitored tower. For example, if you are in Chicago a Chicago tower will only have ISP District 11A talkgroup traffic IF there is a Starcom radio registered on D11A on that tower.

One last thing. Don't confuse simulcast with trunking. Simulcast is where two different systems are bridged to transmit the same signal to different user groups (i.e. ISPERN is both 155.4750 VHF analog for us old-fashioned hicks out in the boonies and a Starcom talkgroup, or a non-Starcom county/city system bridged to be interoperable with Starcom). Trunking allows a single user to follow a given talkgroup no matter what tower the radio is registered on. Multiple Starcom towers may transmit the same talkgroup traffic at the same time, but only because multiple radios on that talkgroup are registered on multiple towers - not technically simulcast.

Edit: To clarify, simulcast can also be used where a single frequency (most often analog) needs to be transmitted from multiple locations at the same time. Normally this is used to improve downlink coverage for a given area, such as a rough and hilly county. Simulcast in this context is a royal PITA to configure as the signal from every tower must be precisely timed to be in sync over a wide area. The speed of light and reflected signals can make this a daunting task. These systems are being discontinued in favor or trunking.
 
Last edited:

n9mxq

Member
Premium Subscriber
Joined
Dec 15, 2005
Messages
1,617
Location
Belvidere IL
Also keep this in mind. If I want to listen to my local PD's (Belvidere/Boone County) I need to be near a tower that one of their squads is using. Which would be my county and the ones closest to it. I can't listen to them down in Springfield, unless one of their units is down there, registered on a tower.

I had to explain this to an ex boss that wanted his scanner to pick up the locals wherever he went..
 
Status
Not open for further replies.
Top