Door Monitoring & Alarms

Radiometrix code-hopping “K” products such as KTX2 and KRX2 can be used to implement an entry monitoring system.

Uses include private home alarm systems, site monitoring and asset management.

Real-life case study

A householder having Bed & Breakfast guests wanted to know if selected private areas of the house were being accessed. Locked doors were not an option since the private areas of concern were child bedrooms. Various burglar alarm systems were considered but none seemed to address the exact needs of the householder. A minimal impact and simple deployment were high priorities in this case.

Requirements

Wireless system
50 – 100m range
Two doors to be monitored (bedrooms)
Opening of a door activates a remote indicator and audible alarm
Closing the door has no effect
Comply with applicable legislation

Solution overview

For convenience in this particular example, two KFX2 (Keyfob) code-hopping transmitters were adapted for use with changeover reed switches (one per door). The KTX2 module is essentially the same as a KFX2 but without plastic case, buttons and batteries. A specific implementation could use KTX2 + battery + reed switch all in one small case.

The remote indicator and alarm device used a KDEC-44, which is KDEC software implemented on a slightly modified CTR44 demo board (This part is available as KDEC-44-000). Again, this was selected for convenience – a KDEC board could have been used or (if relay outputs were not required) a KRX2.

The KDEC software itself was also slightly modified to provide true latched outputs (rather than a toggle on/off). Up to four rooms could be monitored using a KDEC-44 board. To reset the outputs an external reset input was added: this was wired to a push-button. This variation in KDEC software (and others) is available on request when ordering your KDEC, or KRX2.

Radiometrix has been manufacturing radio modules for almost 40 years. In that time new designs have improved older ones, and technologies have changed. Some critical parts have even become obsolete. This has produced a family of legacy designs but Radiometrix does not just discontinue products and does not leave users options. Legacy modules can either still be manufactured (with some limitations and caveats) or technical support assistance can be provided to guide users towards more up to date (and often better, and cheaper) equivalents.
Our legacy product range includes the:
TX1, RX1, NRX1, NTX2, NRX2, BiM1 single channel crystal controlled narrowband modules
TX2, RX2, & BiM2 SAW based 433MHz radios. (Both supplanted by modern PLL based designs)
TX2A, RX2A, TX3A, RX3A, BiM2A, BiM3A, BiM2B, HVR2 (all with obsolescent part issues)
BHX2 (458MHz high power, transceiver superseded by SFX2).

LoRa LONG RANGE REMOTE CONTROL/MODEM

Many Radiometrix modules are conventional single frequency radios, transmitting their RF energy in one distinct channel (even multichannel units only use one channel at a time).
The LRM3 is different. It is a transceiver built around the highly innovative Semtech “LoRa” chip-set, which uses a spread-spectrum technique to distribute it's transmitted power over a much wider spectrum. Up to a MHz or more.
This method (in the past limited to high security military radios) gives a LoRa radio exceptional resistance to jamming and interception, and allows it to advantageously use very low data rates to get much longer range (for given transmit power). As an example, 10mW 869MHz LoRa radios can reach out 10km or more.
The LRM3 is an innovative solution for very long range control and low speed data transmission.

HF RANGE

The most well known low power wireless bands are in the VHF and UHF (400 and 870MHz) regions, but there is an often overlooked world wide allocation at 27MHz.

Radiometrix manufactures 27MHz versions of some of it's better known types of modules. These include the SIL footprint single channel NRX0 receiver and NTX0 transmitter, and the multichannel LMT0 transmitter and LMR0 receiver. With a suitable antenna, these HF units can easily rival the performance of the higher frequency modules.

COMPACT MODULES

The established ranges of Radiometrix products already put a lot of functionality into very small packages, but advances in RF devices in recent years has noticeably raised the game. Using state of the art RF silicon devices, the MTX2 (400MHz band) and MTX3 (869MHz) transmitters take the high performance narrowband multichannel performance of the LMT series and condense it into an uniquely compact 23 x 12.5mm footprint, with no performance trade-offs at all. These modules are ideally suited to integration into hand held “fob” sized products.

458MHz INDUSTRIAL HIGH POWER

In the UK, there is a specific allocation on 458MHz for long range, high reliability wireless links (targeting industrial telemetry, telecommand and machine control tasks). These links are narrowband (only) and are allowed to use up to 500mW TX power (for a practical range of well over 1km)

Radiometrix provides a wide range of 458MHz band capable products, but uniquely matched to this band are the SFX2-458 high power fast switching transmitter and the HMT2-458 500mW transmitter.

SOCIAL ALARMS

Products in this application area such as pendant alarms for the vulnerable, emergency cord alarms for disabled facilities, are allowed to operate on a specific 869.2125-869.2375MHz allocation, and require the highest (EN300-220 category 1 “life critical”) performance.

Radiometrix offers a range of uniquely suited products, including the COR3 and SAR3 receivers and the LMT3B, the SAT3 (SIL footprint) and MTX3 (sub miniature) transmitters.

WIDEBAND BiM SERIES - TRANSCEIVERS

In a uniquely small 33x23mm footprint, Radiometrix offers a range of wideband transceivers, supporting the wideband SIL family for applications where bidirectional communications are desired. Again covering both the 433MHz (BiM2C, BiM2G) and 869 or 914MHz (BiM3C and BiM3G), these modules provide a very small yet high performance radio at an attractively low cost.
Where longer range is needed the 500mW BiM3H is the transceiver-equivalent to the TX3FH transmitter.

Door Monitoring & Alarms

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