GB2119141A - Transmitter token - Google Patents

Abstract

A portable or pocket token for a security system is capable of transmitting at a first frequency (F1) or the first frequency (F1) and a second frequency (F2) alternately or simultaneously, or the first frequency in coded bursts, so that by presetting and/or programming the token, it is suitable for use with a number of different kinds of security system in which access to a secured area depends upon a pocket token transmitting appropriate signals. <IMAGE>

Description

SPECIFICATION Transmitter token British Patent Specification No. 1414119 discloses a security system in which access to a secured area can be given automatically to individuals carrying a pocket token transmitting at a predetermined frequency. The specification also describes a system in which access can only be given if the token is transmitting at two different predetermined frequencies. British Patent Specification No. 1528901 discloses another type of security system in which access is given to the holder of the token transmitting at a predetermined carrier frequency which is coded into pulses consisting of a pre-set number of carrier frequency cycles separated by intervals consisting of another predetermined number of carrier frequency cycles.

The different systems have different applications and have different degrees of security and in general the higher the security level the more expensive will be the equipment necessary for installing the system.

According to the present invention, a portable or "pocket" token comprises means for generating a signal at a first frequency, and programme means for setting that frequency, means for generating a second frequency and programme means for setting the second frequency, or for setting a code to be applied to the first frequency, and logic means for selecting whether the output transmitted from the token is continuously at the first frequency or is in coded pulses of the first frequency, or consists of a first frequency and a second frequency.

It has been appreciated that it is economical to manufacture tokens by mass production methods, each of which tokens can be easily preset, and/or programmed to be suitable for operating on any of the systems described above, or on variations of those systems.

A particular token may be set during manufacture in accordance with the particular system with which it is to be used, or there may be accessible programming terminals on the manufactured token enabling the method of operation to be changed after manufacture, or indeed both facilities may be available.

In general it is likely that the mode of operation will be preset during manufacture, whereas the particular frequencies and the particular type of coding will be capable of being changed after manufacture so that operation can be on the same system, but with different frequencies or coding which are changed from time to time to keep the system secure.

Thus, there may be select logic means in the token which is preset during manufacture. Also the token may include a fixed frequency crystal oscillator, or the equivalent, and programmable dividers for setting the first and second frequencies which can be programmed during use as it is required to change those frequencies.

There may be a time-out system driven from the reference oscillator and arranged to switch the token off after a preset time corresponding to the longest time that an individual will be required to be near a secured area.

There may also be "spitting" logic for causing the transmission to be in short burst separated by longer intervals between bursts, so as to save power consumption in the token, and to render it unlikely that, where two tokens are used adjacent a single pick-up at a location to be protected, there will be complete overlap between them. In a coded system, a spitting burst would be long enough to embrace a number of complete pulses of the coded carrier frequency and would be synchronised to begin at the beginning of a code, and end at the end of a code.

There may also be "toggle" means arranged to cause the transmission to alternate between one frequency and the other, or perhaps between one frequency continuously and that same frequency coded.

According to another aspect of the invention a security or identification system includes a number of portable tokens all capable of transmitting radio signals at the same predetermined frequency, and each coded to transmit in spaced pulses with a pulse consisting of a set number of carrier frequency cycles which number is characteristic of that token.

The tokens also being arranged to transmit in bursts of spaced coded pulses separated by intervals between bursts which are long compared with the length of the bursts. Such a system makes it unlikely that if two tokens are near a single pick-up their bursts of coded pulses will overlap to "jam" the system.

According to a further aspect of the invention an access control and identification system includes a number of portable tokens each capable of transmitting at the same time, two signals, one of which is an access control signal common to a number, but not all, of the tokens, and the other of which is an identification signal which is unique to that token.

The tokens may each have two aerials, one for each signal.

It will be appreciated that if say, the said one signal is a continuous transmission at a predetermined frequency, and the other is a coded signal, perhaps consisting of pulses of transmission, each consisting of a certain number of carrier frequency cycles at another frequency, then a single token can be used for access control, and also for providing an identification of each token.

In an access control system, all individuals at one security level would have tokens transmitting at one predetermined access frequency, while those at another level would have tokens transmitting at another access frequency, and the areas of different security level would be controlled so that perhaps one area would only allow entry to people at the highest level of security, while access could be allowed to another area to people with tokens transmitting at either of the access frequencies.

The invention may be carried into practice in various ways, and one embodiment will now be described by way of example with reference to the accompanying drawing which is a rather diagrammatic block diagram of an integrated circuit and gating logic included in an integrated token.

A security control system may be arranged to operate in different ways depending upon the degree of security required. In one system a token is required to be capable of generating oscillations at two different predetermined frequencies before ac cuss to a given area can be given, orto prevent an alarm being sounded. In another, less secure system, it is sufficient if the token can generate a single frequency. In another system a signal at a predetermined frequency is coded so that it emits oscillations in pulses of a pre-set time duration, or for a pre-set number of carrier frequency cycles, which pulses are spaced by intervals which may be measured intervals of no generation. Combinations of those systems are also possible. Any system can be used for access control or identification.

For simplicity of manufacture, it has been found to be desirable if a pocket token can contain an integrated circuit, which is capable of being pre-set to operate according to a particular system and can be programmed during use to set a predetermined frequency. Then whatever security system is being supplied by the manufacturers, the same standard tokens can be set to be suitable for use with that system.

The token is a hands-free token, that is to say it is in a case which is small enough to be fitted in the pocket or the handbag of the user, and is capable of transmitting oscillations while in the pocket of the user, which can be picked up by a pick-up loop at a location where control is required.

The circuit to be described will be in the form of an integrated circuit, possibly on a single chip.

A small wristwatch type crystal oscillator 11 produces a reference frequency at 32.768Hz, and the output is divided down by a fixed divider 12 to produce a reference frequency at 13 or 8 Hz, and also to produce another reference frequency at 14 of 16 Hz. The 8 Hz reference frequency is supplied to a combination of a phase comparator filter or phaselocked loop 16 with a voltage controlled oscillator which produces an output frequency F1 at A. The output frequency F1 is fed as input to a programmable dividing chain 15 whose output is fed back to the phase comparator 16. The divider 15 can be programmed at 17 to divide the frequency F1 in a selected one of a number of steps each of 8 Hz up to 240 KHz.Any difference between the reference frequency at 13, and the output from the divider 15 produces a voltage for changing the frequency of the oscillator at 16, so that the frequency F1 can be controlled to any desired frequency as programmed at 17, with a stability as accurate as that of the oscillator 11. The frequency F1 can be controlled to have any value between about 30 KHz and 250 KHz in 8 Hz steps with an accuracy within 4 Hz.

The reference frequency at 13 is fed to a second PLLNCO 21 which can be connected to a second divider chain 22, programmable at 23 to set a second frequency F2 in a similar way to the setting of the frequency F1 provided that select logic 24 is set to connect the PLLNCO 21 to the divider 21 in the same manner as the units 16 and 15. Then the second predetermined frequency F2 will appear at B. The divider 22 will be programmed at 23 to divide by the necessaryfactorto produce the predetermined frequency F2.

Now if the token is to be used on a system which requires only a continuous single frequency F1, then the select logic 24 will leave the phase locked-loop circuit open, and no frequency F2 will appear at B.

However a single frequency F1 can in some systems referred to herein as "K9" systems, be generated in pulses of a predetermined number of carrier frequency cycles, separated by intervals of a different number of carrier frequency cycles. For that purpose the predetermined frequency F1 can be supplied through the select logic 24to the counter 22 which can be set by the coding selector 25, as controlled at the pins 26 not to divide by the above mentioned factor, but to count the carrier frequency cycles F1 alternately for the number of cycles required in a pulse, and for the number of cycles required in an interval between pulses. The coded F1 frequency will in that mode of operation appear at B instead of the frequency F2.

In orderto reduce power consumption in the token and to render it unlikely that if more than one K9 transmitter is operating within range of a particular pick-up, there will be complete overlapping, the token can be arranged to "split" that is to say to transmit in bursts lasting for example, for one sixteenth of a second, separated by off periods of seven sixteenths of a second. There will thus be two spits or bursts per second. That effect can be achieved by supplying the K9 coded F1 frequency from the select logic 24 through spitting logic 31 which has reference frequency inputs at 16 Hz from 14, and at 2 Hz from a divider 32 of the 8 Hz reference frequency. The select and spitting logic would be set for spitting operation during manufacture of the particular token.A one sixteenth of a second spit period would start at the beginning of a code and end after the end of a code so that only whole codes are transmitted. There would be many coded pulses in a spit.

A time out feature can also be programmed on during token manufacture, so that if the token is inadvertently taken home by the holder, it will be automatically switched off after say 18 hours. The 2 Hz frequency at the output of 32 can be passed through a fixed divider 33 to produce a signal at D after 18 hours. When the transmitter is brought back to the premises and replaced in its charging slot for recharging the batteries, the timer will be reset automatically.

In another possible method of operation, known as "toggle" operation, the transmission may be continuously switched between the predetermined frequencies F1 and F2 at a rate of say 2 Hz. In a similar manner toggling could operate between continuous carrier frequency F1 and K9 coded carrier frequency F1.

The 2 Hz toggle frequency from 32 could be supplied at 35 to the gating logic shown in the lower part of the Figure.

It will be seen that there are inputs, A, B, C and D for F1, F2, or K9 coded F1 spitting control, and the 18 hour time-out control. There is also an input for selecting single frequency F1 only.

The various signals are supplied to the various inputs of a number of AND gates the operation of which will probably be readily understood from examination ofthe Figure.

Thus, a bistable 36 controlled by the toggle control 35 can either turn the AND gates 37 and 38 on alternately with each being off while the other is on, or if toggle is not required, can turn both AND gates 37 and 38 on continuously. The AND gates 41 and 42 will be on for 18 hours, and then switched off at D.

The AND gate 43 will be turned on and off alterantely from the spitting control C and the AND gate 44 can be turned off if the select logic 24 produces a signal requiring a single frequency F1 only.

Both gates 44 and 45 would be turned off during battery charging.

Each ofthesetwo gates has its own aerial; both aerials which would be used in the two frequency mode, but only one would be in use during single frequency or K9 mode.

However, a token could be used to fulfill two functions simultaneously. Thus one aerial could transmit continuously at F1 for access control, while the other aerial could transmit a K9 or otherwise coded signal at F2 at the same time for identifying the token.

It will be appreciated that for a wide range of different security systems, the same standard integrated circuit tokens can be used with certain presetting during manufacture in dependence on the use, and the possibility of reprogramming during use in accordance with the particular frequencies F1 and/or F2 required, or the particular K9 coding required.

Claims (9)

1. A portable or pocket token comprising means for generating a signal at a first frequency, and programme means for setting that frequency, means for generating a second frequency and programme means for setting the second frequency, or for setting a code to be applied to the first frequency, and logic means for selecting whether the output transmitted from the token is continuously at the first frequency, or is in coded pulses of the first frequency, or consists of a first frequency and a second frequency.

2. Atoken as claimed in Claim 1 including select logic means for enabling the method of operation of the token to be changed.

3. A token as claimed in either of the preceding claims including a fixed frequency oscillator, and programmable dividers for setting the first and second frequencies.

4. A token as claimed in any of the preceding claims including a time-out system driven from a reference oscillator and arranged to switch the token off after a preset time.

5. Atoken as claimed in any of the preceding claims including logic means for causing the transmission to be in short bursts separated by longer intervals between bursts.

6. A token as claimed in any of the preceding claims including toggle means arranged to cause the transmission to alternate between two different kinds of transmission.

7. A security or identification system including a number of portable tokens, all capable of transmitting radio signals at the same predetermined frequency, and each coded to transmit in spaced pulses with a pulse consisting of a set number of carrier frequency cycles which number is characteristic of that token, a token also being arranged to transmit in bursts of spaced coded pulses separated by intervals between bursts which are long compared with the length of the bursts.

8. An access control and identification system including a number of portable tokens each capable of transmitting at the same time two signals, one of which is an access control signal, common to a number, but not all, of the tokens, and the other of which is an identification signal which is unique to that token.

9. A system as claimed in Claim 8 in which the one signal is a continuous signal at one frequency and the other signal is a series of coded pulses at another carrier frequency.