MINDA - The Miniature Duress Alarm system
Designed by Chapman Associates and manufactured in the U.K. by K-Tech Limited.
General
Any user owning a Maxi-MINDA receiver can, with the aid of a standard PC and a MINDA programming kit, read and/or modify all of the programmable options of that receiver, as well as those of any other microprocessor based MINDA receivers or intelligent transmitters.Programming is done using the serial interface built into the Maxi-MINDA receiver in conjunction with the special interface cables and connectors. Users who do not possess a Maxi-MINDA receiver are still, for the present, obliged to return their MINDA equipment to K-Tech for re-programming.
The MINDA programming kit comprises:
* A cable to connect the Maxi-MINDA receiver to a PC's serial port.
* A multi-way cable, used when programming intelligent Re-MINDA transmitters.
* A second multi-way cable used when programming portable MINDA receivers.
* A disk containing the custom-designed PC DOS-based interface program.
The PC-based program has been designed to be user-friendly and intuitive in operation. The PC screen will display details of the Unit's software version and Serial Number together with the current status of each of the user-selectable options.
Each of the options can then be modified by pressing keys on the PC corresponding to the appropriate highlighted characters on screen. Where time settings are involved, pressing a lower case key increments the time, whilst holding 'shift' and pressing the same key will decrement it.
The following options are user-configurable:
Receiver
Put very simply, the family identity determines which transmitters alert which receivers. Normally, for a MINDA receiver to respond to an incoming signal it must be programmed with the same family identity as the transmitter(s) with which it must operate.
All standard MINDA equipment will have been programmed at the time of manufacture with a default family identity code and will inter-operate. It is only necessary for this code to be changed if:
- It is necessary for different groups of transmitters and receivers to operate independently within radio range of each other.
- There is a likelihood of interference from other users of MINDA within radio range.
- A more secure (longer) family identity code is required. This can only be done when exclusively using intelligent transmitters (TX-500) since the basic TX-400 transmitter is only capable of a 2-digit user identity code.
Jamming Alert
The 'jamming alert threshold' period can be set in increments of 53
milliseconds up to a maximum time of around 13 seconds or disabled
altogether. Receiver microprocessors are supplied pre-programmed with this
option enabled, and a default value corresponding to a 'jamming alert'
threshold time of about 5 seconds.
Battery Economiser
The battery economiser operates by switching the receiver on for 4
milliseconds every 400 milliseconds, looking for a signal, and if nothing is
found switching it off again. If a signal is found, the receiver locks on
for long enough to process and display any alarm signal that may have been
received. By using the battery economiser mode, the battery life of a MINDA
receiver is dramatically extended.
All receivers are supplied pre-programmed with this option enabled.
Green Audible Alert (Maxi-MINDA receivers only)
'Yes', 'No' or 'External'
When set to the standard value of 'No', the receiver will beep on receipt of
both red and green signals. By choosing 'Yes' a receiver will remain silent
on receipt of green alerts. The alternative value of 'External' passes
control over whether a green alert produces a beep to a switch mounted on
the front panel of the Maxi-MINDA receiver.
'Loss of signal' Alert Threshold Time
A MINDA receiver can be programmed to expect regular transmissions from one
or more of its associated transmitters. If this is done, and a transmission
is not received from a unit within the pre-programmed time period then the
appropriate LED will begin to flash and an audible alarm will sound to alert
the operator. To cancel this 'loss of signal' alert the operator must press
the RESET button on the receiver. The time period can be independently set
(or the warning inhibited completely) for each of the four possible unit
identities (1, 2, 3 and 4).
'Loss of signal' Alert Repeat Time
If the initial 'loss of signal' alarm has not been acknowledged (by pressing
the RESET button on the receiver) within a second pre-programmable period of
time the receiver repeats the 'loss of signal' alert and continues to do so
at programmed intervals until the operator does acknowledge the alarm by
resetting the receiver. This repeat alarm time period can be independently
set (or the warning inhibited completely) for each of the four possible unit
identities (1, 2, 3 and 4).
NOTE: Because the basic 'dumb' TX-400 transmitter is not able to send automatic confidence signals, all receiver microprocessors are supplied pre-programmed with the 'loss of signal' option disabled. However, as described above, it can easily be re-programmed and alert times set up by using the MINDA programming kit and software program.
'Intelligent' Transmitter
See above.
Red Alert Mode Setup
In normal operation, shown as 'Red Button', the red button on a key-fob
Re-MINDA intelligent transmitter will send a red alert and the blue button
will send a green alert. This can be changed to 'Either Button' in which
case both the red and blue buttons will send a red alert signal.
'Sensor Make' and 'Sensor Break' modes are normally only used with the micro-switch or light-sensitive versions of the Re-MINDA transmitter. In these units, when 'Sensor Make' is selected, the red button (or equivalent switch, detector or control) will send a red alert whilst in 'Sensor Break' mode, it is sent when the red button (or equivalent) is released.
Unit Identity Change Cycle
A user is able to temporarily change the intelligent transmitter's identity
between certain limits without the need to open the case. If power to the
unit is interrupted and then restored (by switching on and off) the unit
will revert to the original identity determined by the settings of the two
internal switches. This facility can also be inhibited altogether, if
required.
Data Message Length
If an economised receiver is NOT being used, the length of the data
transmission can be reduced to conserve transmitter battery power.
Red Transmission Length
If an economised receiver IS being used, it is possible to increase the
number of data word repeats sent when a red alarm signal is being sent,
compared to the number sent with a green signal. The program allows for
'Normal', 'Double' and 'Triple' length red alarm transmissions which, in the
event of difficult conditions will significantly improve the likelihood of
that message being received.
The penalty for lengthening transmission time in this way is that the transmitter battery life will be somewhat reduced.
Confidence Transmission Repeat Interval
A Re-MINDA 'intelligent' transmitter can be configured to automatically send
green alerts at programmable time-intervals. Similarly, the red alert, once
sent, can be automatically repeated from time to time.
The time interval at which these transmissions are repeated can be independently programmed, for each of the unit identities that a transmitter can assume, between around seven seconds and a maximum of about twenty-nine minutes. Alternatively, repeat transmissions can be inhibited altogether.
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