Ankle bracelet monitors

This regards another thread I’ll update later.

A teenager I know may be required to wear an ankle bracelet due to his failure to obey court orders. This may cause a big problem because he does not live someplace with a landline. It seems to me a GPS tracker would be a better idea than something that reports by phone. I see recharging issues to deal with, but is this being done at all?

I remember reading about the colony of registered sex offenders living under a bridge in Florida (because of all the laws saying they had to be so many feet from all sorts of stuff) having a generator on site to charge ankle bracelet monitors.

I don’t even know if they need recharging. I figured they emit a signal periodically or are passive devices that don’t need power. I wondered initially if a cell phone could be used, but then you could be anywhere and the idea is to identify your location. But cell phones can be tracked very closely, so if that can’t be done it’s just a matter of the monitoring systems taking advantage of the technology. It ought to be easy to make a cellular bracelet that returns location information periodically, and just needs charging.

And if you don’t have a display on it, the battery life can be pretty good. You’d need a way to house a decent battery, but you could easily get weeks of time on a charge.


It depends entirely on which model he is required to wear.

More advanced models are essentially a cell phone and GPS receiver packaged together in a case which is strapped to the person’s leg. There are mechanisms to detect efforts to cut or tamper with the strap. The monitoring unit makes a phone call every few minutes to relay data (GPS coordinates and any tampering detected). The unit must be recharged daily and it can take a couple hours to fully charge (leave it plugged in overnight as he sleeps). My office acts as a monitoring center for these units in our area.

More primitive units use a base station plugged into an electrical outlet and landline along with a monitoring unit attached to the person’s leg. The distance between the monitoring unit and the base station is determined by a radio signal (somewhat like a cordless landline phone). A violation results if he goes out of range. These monitoring units still require recharge, though I don’t know with what frequency. I have not worked with these units but got to test one out.
There are a few basic types of violations. How those will be dealt with depends on local protocols. Some types of violations are:

  • low battery
  • No GPS signal (monitoring unit cannot pick up a GPS signal)
  • Unable to connect (the built in cell phone cannot connect to the cell network)
  • Home violation (person outside of assigned zone during curfew hours)
  • Restricted zone violation (person inside an excluded zone)
  • Strap violation (person has cut or tampered with the strap that secures the unit to leg)

Finally, a topic that Lindsey Lohan could actually contribute to.

The devices used here(western Massachusetts) require a landline phone. The base station makes periodic check in calls to a system run by the Sheriff’s office. If the ankle bracelet leaves range of the base station, the station immediately alerts the authorities. If the base station fails to check in, police come.

I’d bet cellular/GPS devices have too many failure modes to be used for large numbers of offenders. Every time there is a connection problem with either system, police have to check it out. If a cell tower needs maintenance, the police need to visit every offender in that tower’s range.