ISPERN reception

[lu81fitter]

Hello all. I have not yet upgraded to a digital scanner yet, and I monitor ISPERN on 155.475. Sometimes I will hear D8/D6 make an announcement and it will be crystal clear, other times, it will be scratchy, and yet other times, it will seem like its over-modulated and you get the "digital" sounding voice that seems like its hitting me like a ton of bricks. I'm assuming ISP uses different towers to broadcast announcements so all of their cars can hear. Which leads me to wonder, do the STARCOM towers also broadcast 155.475 on VHF-HI along with the digital channel, and if there is a car affiliating with tower, it will broadcast? I'm thinking that the closest tower to me doesn't always have a unit affiliating, so it won't broadcast 100% of the time, thus the different signal strengths I am experiencing. Any thoughts?
Thanks.
Tim.

 

[RoninJoliet]

I hear "patched" ISPERN messages here in my location on Starcom TG's 9050,9051 perfect when using 155.475 can be very staticy....

 

[lu81fitter]

I can hear D1, D17, D6, & D8, all with varying degrees of "clearness", if you will. At times, I can get D7, D15, & D5 when conditions are right. All on 155.475. I'm just wondering why it is receiving at different levels?

 

[MikeyC]

When you're hearing them on 155.4750, you're hearing the transmission coming from transmitters located at the respective district offices. The further away (Rock Island, Oak Brook, Jolet, etc) the more scratchy they will be (depending on conditions)

 

[Awesomeman92]

Someone may have more insight on this, but I believe with the consolidation of districts that ISPERN calls can be sent through whichever towers are applicable, but this is not automatic according to affiliated radios or anything. I know for a fact D15 has access to ISPERN through towers from D2 and I'd imagine DChicago, D5, and D1. I've also heard D20 calls come through from the D14 tower. It just depends on which of the towers they use for the call, and really the nature of the call - a DUI probably only requires one district, while a manhunt may require multiple districts and be a wider area effort. I've also heard D14 calls not transmitted on their own tower. I've also once or twice heard D9 ISPERNs for DUIs on I-55 from that same tower when there are virtually no D9 units ever affiliated with the SC21 site in Macomb, leading me to believe there is operator control over where the calls are sent from and they do sometimes pick the wrong site or forget to/don't do it over VHF altogether.

Like I said, someone on the inside may have more inside information than this, this is just my understanding.

 

[lu81fitter]

Thanks for the replies. It was weird one day when a broadcast from D8 totally blew me out of the water. I have never heard any ISPERN announcements that strong, even before when they were still on VHF-HI/VHF-LO. I'm thinking the announcement came from tower 114, which is closest to me, and almost LOS. I don't think ISP used that site before they went to the digital format.

 

[N9JIG]

The last time I was in a few ISP Dispatch centers was just prior to StarCom21's use. As a rule the dispatchers had access to several VHF base stations with ISPERN, HF-4 and HF-1, depending on the district involved. I presume this continues today and the various consolidated districts probably have access to the base stations used by the other districts they now handle.

In addition they usually had satellite receivers for these channels, again depending on the district. They would go thru a comparater and the voted tower indicator would help the dispatcher choose what tower to transmit on. Usually however they had a pretty good idea what tower to use anyway, based on experience.

As far as the links to StarCom21 that remains kind of like voodoo...

 

[W9WSS]

<snip> I know for a fact D15 has access to ISPERN through towers from D2 and I'd imagine DChicago, D5, and D1. <snip> [message truncated for brevity].

Most of time, if/when D15 puts out an ISPERN dispatch, they will use the same towers D2 uses, and will sign "KSB233" which they didn't do several years ago. They've been doing this even before ISP went to Starcom21. Just seems kind of peculiar to me, as D15 used call signs for links, and other transmitters, Examples were KAS213, KD6109 (link), and even KRM754.

 

[eg2138c]

District Chicago on 155.475 seems to be using a south tower or north for TX tower for the area of incident. I feel that the TX tower should just be high power that covers the whole district and not just parts also sounds like they have lowered the RF power on D-Chicago's towers.

 

[JT-112]

And more than a few times, when D15 puts out an ISPERN, nothing goes out on 155.475 at all.

It's happened on three pursuits that I know of, including two felony pursuits, one just recently.

I am wondering if sometimes the D15 dispatcher is somehow selecting a far away tower by mistake/excitement. I've been assuming that the "patch" just didn't work, but it could be mis-programmed/mis-labeled.

It's an officer safety issue.

 

[W9WSS]

I surmise that ISP and probably other entities aren't really that concerned about VHF ISPERN anymore. They're Starcom 21 all the way, and there's probably little regard to 155.475 anymore, sad to say. Whether it's intentional or not, it doesn't appear to be a high priority, at least with ISP.

 

[VASCAR2]

At one time in some of the southern Districts the ISPERN VHF was continually patched into SC21 ISPERN TG which are District specific. When the Troopers had Motorola Syntor High Band you could not lock out ISPERN from the scan menu. This could cause feed back if the operator keyed up on SC 21 ISPERN TG. You could punch out the scan button but in the heat of the moment not everybody thought to do this. You can also turn the volume down on the High Band but that has it's own issues.

Since ISP dispatch consolidation I really don't know the specific set up. In the past most Districts had multiple transmitter sites and voted receivers from multiple sites. The telecommunicator could select multiple towers for transmission but this could cause garbled transmissions depending on the listeners distance from the towers.

The remote transmitters were controlled via microwave links or dedicated phone lines which are expensive. You used to get an idea of the transmitter site location by the directional position of the microwave antennas at the district.

With the consolidation there is a greater likelihood the telecommunicator may not be knowledgeable of the geographic area and know which are the most appropriate towers to select on ISPERN. I know D-12 had Eaton and Mason tower and the transmitter at Effingham. District 19 had Carmi, Williams Hill, Fairfield and Beall Woods. District 22 had Ullen and Williams Hill as did DuQuoin.

Back in the late 80's when District 15 was at Oak Brook they had limited range on VHF ISPERN. The SOP was to have the surrounding Districts repeat the Dispatch. Many times a Trooper on I 90 near Rockford was to far away to here D-15 ISPERN broadcast but D-16 almost always repeated the dispatch. In District 15 Troopers were in a pursuit and stayed on the Tollway the pursuit was handled on 800. Depending on the location of the pursuit in relation to Oak Brook would determine which District would handle the pursuit if the pursuit exited the Tollway.

In the Southern Districts you rarely hear pursuits handled on ISPERN. Most Angencies have surrounding agencies programmed into their radios and switch to which ever jurisdiction the pursuit leads them. Most of the local officers in my area rarely monitor ISPERN or other agencies on their mobiles.

Times have definitely changed. I really think there was more interoperability in southern Illinois when the local agencies were on 39.5 and cross talked to Troopers on 42.5. At least back then everyone monitored ISPERN and actually knew how to use it.

 

[TGP]

ISP D 11 routinely uses 155.475 ISPERN and is patched to TG 17037 and most of the time simulcast
On Disp. A TG 17000.

Cencom (St. Clair Co. Disp) always sends a agency with a pursuit or crime particulars to ISP ISPERN.
Tom

 

[N9JIG]

From what I remember back in the day ISP had remote bases at several locations that had ISPERN, HF-2 and occasionally HF4. Later some of these sites had IREACH (HF3) added to them. These sites also had the low-band channels in them. Not all sites had all channels, some were High-band only, some low-band only and some had both.

Most posts had Point (155.370/HF5) and HF4/Channel 7 (155.460) only at the main tower for the District. A couple remote locations had HF4. Some posts had receivers on MERCI340 (155.340) that they could talk back to to EMS units on 155.460. This was identified as "HF-6" but not used that much and usually only downstate. Channel 5 in mobile and portable radios was usually 155.505 with no PL tone used as a unit-unit channel, with no PL it would not activate the mobile extenders.

Channel Layout was:
HF1 ISPERN 155.475
HF2 District Utility channel
HF3 IREACH 155.055
HF4 "Channel 7" 155.460
HF5 Point to Point 155.370 (Mobiles had 155.505 CSQ)
HF6 MERCI Link (155.340 RX, 155.460 TX)

LF1 Dispatch Pair
LF2 Statewide 42.500
LF3 Alternate Dispatch
LF4 Unassigned, often used for neighboring districts channels
LF5 Sheriff Net (39.50 RX, 42.50 TX)
LF6 Point to Point 39.46

Mobile radios often were only 4 channels so they usually only had 1-4.

Remote Sites:
Some of these remote sites were available to multiple districts.

1. Sterling Savanna, Forreston, and Dixon
2. Elgin Plato, Gurnee, and Elmhurst
3. “Chicago” Crestwood, Harlem-Irving, and D-2 sites
4. Crestwood None
   
5. “Joliet” Elwood
6. Pontiac Dawson Lake
7. “Rock Island” Andover
8. “Peoria” None
9. Springfield Mason City, Jacksonville
10. Pesotum Champaign
11. Collinsville Edwardsville
12. Effingham Mason City, Eaton, and Clay City
13. DuQuoin None
14. Macomb Niota, Sand Ridge
15. “Oakbrook” D-2 sites
16. “Rockford” Stockton, Galena
17. LaSalle None
18. Litchfield Beaver Dam
19. Carmi Fairfield, Williams Hill
20. Pittsfield Kingston
21. Ashkum None
22. Ullin Cypress Hill

 

[mws72]

District 7 also had Sheffield in Bureau County, not sure if the site was rebuilt when Bureau County became part of District 17 when that was formed. I know they still had licenses for the District 7 frequencies afterward,

 

[MikeyC]

I surmise that ISP and probably other entities aren't really that concerned about VHF ISPERN anymore. They're Starcom 21 all the way, and there's probably little regard to 155.475 anymore, sad to say. Whether it's intentional or not, it doesn't appear to be a high priority, at least with ISP.

Someone's still listening to VHF ISPERN in the Chicago area at least There was an incident the other day with a US Marshal following a vehicle wanted for aggravated child pornography down I-355. The Marshal contacted ISP on ISPERN. Quite a few ISP units responded and I believe the vehicle finally stopped in Tinley Park.

The dispatcher, however, had a hard time hearing the US Marshal unit on ISPERN. I don't know if that was due to the radio in the car or if they need more remote receivers in Will County

 

[RoninJoliet]

I did monitor that ISPERN call thru Will Co EDACS TG 04-033 ispern rebroadcast and it was all over Starcom TG9099 TWay PD South....Had the guy on the ground in parking lot and needed assistance....

 

[skinnyb82]

Districts 7 and 14 affiliate with the Monmouth tower and District 20 is patched to the Monmouth tower as Monmouth is in D14, D9 and D20 are both dispatched by D9. Monmouth is about 10 miles from the Warren-Knox County line. Can sit and hear stuff going on 100 mi. south of me.

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