Rape Prevention Personal-Security System


This Rape Prevention system is based on a very low cost hand-held device for young ladies to rent/buy to assist in their personal security. Several Receiver antennas are installed around the community, that are connected to a computer processing system which calculates the location of the young lady's transmitter very quickly and very precisely.

The PSST rape prevention system is based on each young lady having a small (bicycle-handgrip-sized), inexpensive ($5 per month rental), low power, hand-held transmitter. When in potentially dangerous surroundings, she would keep it in her hand. If attacked or if under imminent attack, she would depress two momentary pushbuttons that would turn on the transmitter. A brief pulse train is radiated out. PSST receivers around the community always listen for such signals.

Extremely Quick and Precise Readout

Since the signals radiated from the transmitter travel at the speed of light to each receiver, they arrive at those receivers at slightly different times. Each Receiver antenna installation accurately measures a time interval that allows extremely precise location of the transmitter and girl.

A computer at the central office will take the time intervals and quickly does some processing to calculate exactly where she is, generally, it will be accurate within 1 foot!

Concurrently, the computer also identifies the exact transmitter that sent the signal, and looks up and presents the personal data on the registered holder of that unit. It immediately displays the name and physical description of person on the PSST (or Police) monitor.

Rapid Police Response

Therefore, within 1/4 second of the young lady squeezing the device, the PSST computer screen will show her EXACT location including address and even where (in the yard, on the sidewalk, in the building, in a car at the curb, etc), and her name and description. This information would be relayed to the Police Department to have a squad car dispatched. Depending on how far the police car had to travel, it should be able generally to reach the scene within 1-3 minutes. The officers would know where to look and even whom to look for, even including the girl's name to call out.

The officers would have an excellent chance of apprehending the attacker, by getting to the scene so quickly. The attack would not have had a chance to progress very far in three minutes, so the young lady would be spared the horror of experiencing a rape and the paranoid life many victims spend afterward. But there is an even larger and better benefit from this device and system. Within a month of it being instituted on a broad scale in a community, and a few rapists being caught, the resulting publicity would likely affect the thoughts and activities of a potential rapist. He would hopefully think "I won't have enough time to accomplish what I want, and even then I am likely to get caught. I won't try it in this town." The number of ATTEMPTED rapes would drop off to near zero.


The PSST system includes a number of features to control false alarms, to make sure batteries stay charged, and to reduce the number of functional transmitters that fall into the hands of pranksters, etc. Some of these features are basically as follows:
A Demonstration System was intended to be in Gainesville, Florida, for protection of the campus of the University of Florida and the city as a whole. PSST intended to operate five receiving antennas on the perimeter of the Gainesville area. Signals from these antennas would be relayed to a central Office near the Gainesville Police station. Unfortunate events delayed this proposed demonstration project. It is hoped that some community or some interested companies might have interest in again arranging such a Demonstration System.

Later Enhancements

Assuming the two-year test program works as envisioned, then other allied uses for the system would be instituted.

With the rape prevention system, once the computer has determined the correct street address of the attack, a tie-in with telephone company records could allow the computer to call that household. If PSST believes that the attack is in the front yard, for example, we could ask the homeowner to turn on their porch light until the police arrived to further distract/discourage the attacker. If PSST believes it is happening inside the house, a discreet call FOR THE YOUNG LADY might delay things enough until the squad car shows up outside.

A clear channel frequency is crucial to the effectiveness of this system. Any interference could cause a signal not to be picked up, and a young lady could wind up with a problem. We believe that this clear channel can be on any frequency from about 150 Mhz up to about 2 Ghz. The fact that PSST will keep getting updated pulses once each second should minimize signal loss problems. If PSST receives even a single signal (which is only around one-millionth of a second long), PSST will know where she is.

In some ways this system is a VERY sophisticated version of the CB Channel 9, where the channel is supposed to stay clear except for emergencies. In that critical microsecond, PSST must be able to receive all the data PSST needs to dispatch a police car. In the event of some momentary interference source (such as lightning) or even the actuation of another of the PSST transmitters, THAT location determination cannot occur. However, the whole system will again determine her location about one second later, and EVERY second during which she has it actuated. If she is running or in a car, PSST will be able to monitor the movements including calculating speed and direction of motion, almost in real time.

This system was first invented during 1980 in response to a surprisingly honest presentation of the scale of the rape problem by the University of Florida in Gainesville. The University deserves great praise for being so open on the subject. Nearly all other Colleges and Universities had the same problem but worked hard to hide it from publicity. The University of Florida should be applauded for having that attitude of openness.

We intended to show a working demonstration for the Gainesville Police, the U of Florida Police, the FCC and other interested parties in middle 1980. Shortly thereafter, it was expected to initiate full scale operation to start giving some peace of mind to these young Americans.

Unfortunately, various problems conspired to delay the implementation of this system. Its value is still just as great, and its urgency still as strong.

Several years later, a serial killer stalked Gainesville for a number of months until he was eventually stopped. During that period, a HUGE number of companies descended upon the Gainesville community, trying to make a profit on the fear hanging over it then. I once passed a young girl on campus who looked like she had a full military pack on her back that included very sophisticated electronics and transmitters, which was unbelievably expensive. Such a contraption is well beyond the finances of most college students, and few students would be willing to wear such a huge device even if it represented their personal safety. It is hard to imagine that it did her social life much good.

Amazingly Economical

There have been some devices being sold/rented that achieve the general functions indicated but they are rather expensive (often $80 to $150 cost per month) and beyond the means of most college students. This PSST device is based on a hand-held transmitter device that will cost the student no more than $5 per month. This is well within the budget of the student for the peace-of-mind it will offer. In the event of needy students, we (and the University of Florida) have thought of some possible alternatives.

This whole system is intended primarily as a public service, even though we believe it makes sense to operate it as a for-profit company.

Please Click Here for an explanation of the theory on which the PSST System is based and for instructions on creating and installing a PSST installation. For more information yet, please e-mail to the address below.

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E-mail to: cj@mb-soft.com

C Johnson, Theoretical Physicist, Physics Degree from Univ of Chicago