THP Someone explain

[madmedic]

I fall in District 3, Nashville, Sumner county as well.
OK, can someone explain me the system THP uses. To this day it is still alittle confusing.
You can hear them on Low Band (very badly most of the time), sometimes on VHF, and other times on UHF wich I believe are the on board repeaters right?
How can they possibly take to each other or hear each other with that kind of system. It seems pretty confusing to me, verses other agencies that havea couple of repeaters and everyone talks on the same channel.
I never hear anything on the channels I programmed of the database, just of an on, and most of the time i only hear one side of the conversation, mostly the dispatcher.
I ended up programming my PRO 2096 with all avl ferquencies and on my FT7800R I hear THP on the on board repeaters farely well in the downtown Nashville area but thats it.
Someone help me hearing BOTH sides?
Clarification would be welcome if you ahve the patience to enlight me LOL

Thank you for reading me!

 

[n4yek]

Don't know if this would help you or not, but here in District 5 (East TN) the dispatcher
talks to the troopers on 42.42mhz. When the troopers talk back, the cars transmit on
42.26 mhz back to a tower link that transmits back to the dispatcher on 72.02mhz.
I program 42.42mhz and 72.02mhz into the scanner and get both sides of the conversation.

District 1 (Knoxville) Dispatcher 42.56mhz
Tower to Base is on 72.58mhz

Try listening to the 70 mhz freqs for replies from the troopers.

 

[jimg]

I fall in District 3, Nashville, Sumner county as well.
OK, can someone explain me the system THP uses. To this day it is still alittle confusing.
You can hear them on Low Band (very badly most of the time), sometimes on VHF, and other times on UHF wich I believe are the on board repeaters right?
How can they possibly take to each other or hear each other with that kind of system. It seems pretty confusing to me, verses other agencies that havea couple of repeaters and everyone talks on the same channel.
I never hear anything on the channels I programmed of the database, just of an on, and most of the time i only hear one side of the conversation, mostly the dispatcher.
I ended up programming my PRO 2096 with all avl ferquencies and on my FT7800R I hear THP on the on board repeaters farely well in the downtown Nashville area but thats it.
Someone help me hearing BOTH sides?
Clarification would be welcome if you ahve the patience to enlight me LOL

Thank you for reading me!

In the Nashville district, #3, both the post and the cars are on 42.360 mhz. The cars go through a repeater back to the post on 452.275 mhz, both in Gallatin and Murfreesboro. Also, they use 45.58 and 45.66 mhz as base and car repeaters. The cars have to be within a few miles of each other to hear each other on 42.36, but when they use the 45.58 (F5) and the 45.66 (F7) relays they can hear each other and the post (if they are talking on that channel) because they are all going through the repeater. Does this help?

 

[madmedic]

thanks for the reply, it enlights a little. though, i guess all frequencies have to be programmed and u just can not monitor one channel and hear both side.
Got it, a year ago I programmed the UHF tower frequency and recive it well at all time. then i programmed the UHF CAR frequency for Rutherford county and i received pretty good most of the time. Now i cant hear THP in Smuner county at all. Anyone has those UHF Gllatin Post UHF and CAR UHF frequencies by any chances?

 

[jimg]

You program in 42.36 to listen to the Nashville post (base). You will also hear the cars on 42.36, if they are close by, depending on what kind of antenna you are using. The tower relay frequency for BOTH Murfreesboro and Gallatin is 452.275. (FCC Call sign for both is KNIT 587) So, if you live in the Gallatin area, you are hearing the tower around Gallatin, and not Murfreesboro, and vice-versa if you live in the Murfreesboro area. You have to program in both frequencies and then put the scanner on scan to hear both sides of the conversation, or you could put one on priority, the post or relay, and the other one on manual. The post transmits back to the relay tower on 457.275 to transmit to the cars on 42.36, but it is a more directional "beam" and you probably won't hear it as well, (if at all), as the tower relay for the cars on 452.275. Also, THP in Lawrenceburg, District 7, uses this frequency, 452.275, as a tower to post relay, (FCC call sign WZY 278), near Hornertown which is in Hickman County.

 

[EZlistener]

THP-Someone please explain

The "dispatch" frequencies for THP are "Simplex." Knoxville and Nashville are "1-frequency simplex" (42.56 and 42.36, respectively), and Fall Branch, Cookeville, and Chattanooga are "two-frequency" simplex (42.42 base, 42.26 mobile). You will only hear the mobile side of a conversation if you are very close to the mobile unit, or you are monitoring one of the UHF or mid-band "links" that form the "backbone" of the system.
Channels 5-8 are repeated channels, primarily for car-car traffic, although dispatchers have the ability to use them if a dispatch channel is occupied with a pursuit, or is disabled.
Each district also has a simplex car-car channel, e.g., channel 4 (42.36) as used in Districts 1,2, 5, and 6, or channel 3 (42.56) in the Nashville District.
The mid-band, high band, and UHF links use directional antennae, and one must be in a "line of sight" to hear them.
PL tones are used to select the site for both the dispatch and the repeated car-car channels.
Hope this is helpful.

 

[madmedic78]

Thank you, this was very helpful. Wish they had the directional antennas pointing this way lol

I really appreciate your time for the info. Was very informative

 

[jerk]

Thank you, this was very helpful. Wish they had the directional antennas pointing this way lol

I really appreciate your time for the info. Was very informative

No but you could always point a directional (Beam) antenna their way.
Bob Grove and Larry Van Horn use that method for their intercepts.
One day I may change my set up to that, especially if Louisville Metro changes everything to trunk and I can't receive it at home.

AL

 

[xmguy]

Will any of these work in the McMinnville, TN area?

 

[Airdorn]

I'm in Memphis, and I only ever hear the dispatcher talking to.......??

The other day, I had a hand-held with me and I heard both sides of the conversation. I think that was because the trooper was somewhere close.

They seem to have a very rudimentary system. Their patrol cars are encrusted with no less than 8 antennas.

 

[xmguy]

I'm in Memphis, and I only ever hear the dispatcher talking to.......??

The other day, I had a hand-held with me and I heard both sides of the conversation. I think that was because the trooper was somewhere close.

They seem to have a very rudimentary system. Their patrol cars are encrusted with no less than 8 antennas.

Digital or analog? Trunked or conventional?

 

[Airdorn]

Digital or analog? Trunked or conventional?

I think they use radios from 1932.

Conventional and analog.

 

[EZlistener]

"I'm in Memphis, and I only ever hear the dispatcher talking to.......??

The other day, I had a hand-held with me and I heard both sides of the conversation. I think that was because the trooper was somewhere close.

They seem to have a very rudimentary system. Their patrol cars are encrusted with no less than 8 antennas."

There will be one large 1/4 wave whip antenna for low band, then a trunk mount for the VHF vehicular repeater, another UHF, VHF, or 800 for local inter-agency comms, perhaps an 800 for cell phone, and maybe a CB for CVE units. I don't know if any of these cars have a Lojack antenna for vehicle tracking.

Not all cars will be equipped with these (pool cars, e.g., may have low band only). Low band may seem rudimentary, but it is a good choice for covering large areas, especially when augmented with the receiver links as in the THP system.

 

[kf4lhp]

I think they use radios from 1932.

Actually (surprise!) it's all fairly new, with the base infrastructure having been rebuilt over the last few years. Low band equipment is all from Daniels Electronics, high band is from Motorola.

The cars have Kenwood mobiles, 90-series units, with both a high band and low band deck. I've seen reports that they have a single control head for both decks, which is a Kenwood option.

 

[W4EMS]

If you hear both sides of the conversation on low band the trooper is indeed pretty close.
I use this as one means of situational awareness when driving.

 

[jimg]

Will any of these work in the McMinnville, TN area?

McMinnville is in the Cookeville District, #6. The post transmits on 42.42 mhz and the cars transmit on 42.26 mhz back to the post, through a repeater. Sometimes the repeaters are on microwave, and you cannot pick them up on a scanner. If they are on mid-band (70 mhz) or UHF (450 mhz) you may be able to pick them up. I think there is a repeater around Carthage on 452.450 and one around Pikeville on 75.80 mhz, but you need to verify this in the data base.

 

[CAPTLPOL1]

That is not a repeater. It is a fixed relay link.