? About LoJack and 173.075 mHz

[jeffmulter]

Most of the scanning-related material and lists refer to 173.075 mHz as the frequency used for the LoJack systems.

Is that frequency used by the base stations that are used to trigger the vehicle transmitters, or by the vehicle tracking units to reply to the base station inquiry ?

Or, is it used for both base and the mobile transmitters ? And, if so, is there an audible difference between the data burst from a base transmitter, as opposed to the responder in the vehicle ?

Also, am I correct that the LoJack location units in the law enforcement vehicles only receive ... they do not transmit to / interrogate the LoJack unit in an activated vehicle.

Just curious, as I have something in my area transmitting data bursts on 173.075 at irregular intervals (8 to about 20 seconds apart, with some signals very strong, and the rest being at threshold).

Although my county law enforcement does not have LoJack equipment, two of the neighboring counties do.

Thanks in advance for any comments.

 

[N1GTL]

http://en.wikipedia.org/wiki/LoJack

Lojack units in the cruisers are RX only. When a car is entered into the computer as stolen, somewhere a computer cross references the VIN to whether there is a lojack unit in the vehicle. If there is, it will trigger a signal to have the unit in the car start transmitting. Those signals come from towers, not cruisers. I do not remember the amount of time the unit will TX but it will TX once a second for an hour or something like that. After that it will revert back to once a minute. If an officer picks up a signal after that, he can call it in and a dispatcher with the code on his lojack display and dispatch can enter it and it will send a signal to that util to get it beaconing to once a second again.

 

[jeffmulter]

Thank you for the information, James.

If I understand correctly, the LoJack unit is normally silent. When triggered by a LoJack base station, the unit in the car transmits closely-spaced data bursts for an hour. It then reverts to bursts spaced a minute apart ... unless triggered by a base transmitter again.

 

[Northe]

Jeff,

I receive occasional bursts on the LoJack frequency. I'm assuming that I'm hearing the tower transmissions.

Northe
N6KO
Green Valley, AZ

 

[MtnBiker2005]

LoJack and Law Enforcement


LoJack and Law Enforcement
A Cooperative Relationship for Stolen Vehicle Recovery
* 9 pages
* For Law Enforcement Use Only
* March 10, 2003

http://publicintelligence.net/lojack-and-law-enforcement/

http://info.publicintelligence.net/LoJackLawEnforcement.pdf - (PDF FILE)

 

[RKG]

In most metropolitan areas in which LoJack service is offered, the trigger signal is broadcast on a sideband of a broadcast FM station.

 

[ScannerSK]

Here in Colorado there are constant signals on 173.075. I once spoke with a LoJack representative about four years ago and advised that there was a signal in the area. He checked out the area and advised what I was hearing were signals from the towers. When a car is stolen, I have read that the tower can also change the rate at which the stolen item (usually a vehicle) transmits its signal. During a pursuit, I believe the LoJack transmitter can broadcast every five minutes, every minute or possibly several times per minute.

I enter 346.15 MHz (the first image of 173.075) into my scanners to monitor for any LoJack signals in my immediate area.

Shawn

 

[ecps92]

???

Lo/Jack for Vehicles/Boats and Construction Equipment [USA] operates entirely on 173.0750 Mhz - Nothing on the FM Broadcast stations.

And the Signal is initially activated on that frequency.
After a period of time to save the battery the signal slows down.
Once an Officer inquires on the signal thru NCIC [by Code] the Towers send out a speed-up [Track] signal which again speeds up for a period of time until it's inquired upon again.

Lo/Jack has bought out a few other companies, one of them in the 200 Mhz band, used for tracking persons [Alzheimers etc]

In most metropolitan areas in which LoJack service is offered, the trigger signal is broadcast on a sideband of a broadcast FM station.