Machine to Machine (M2M) cellular modems form the bridge between Internet of Things (IoT) device and the internet using the 2G/3G/4G network. The modems typically connect with other systems including remote monitoring, vehicle telematics and other systems via RS232 serial connection (2G/GPRS) or USB (3G/4G modems) and connect to the internet over TCP/IP.
Where will it be deployed?
M2M modems are built around a GSM module which, for 2G/GPRS, will be developed for dual-band (900/1800MHz) or quad-band (850 / 900 / 1800 / 1900MHz) operation. Dual-band modems have limited coverage (e.g. Europe only) whereas quad-band devices will operate worldwide. Note also that some countries are already phasing out 2G in favour of 3G. For 4G, the number of available bands is 44 worldwide which makes manufacture of world-wide supported 4G modules uneconomical. Manufacturers must therefore select the right modem for the intended location.
What will be powering it?
For automotive applications the supply voltage may be nominally 12 or 24V DC but this could drop slightly and will increase with the engine running. Modems deployed for automotive therefore need to be able to operate with a wide input voltage range. The modems should also filter any noise on the DC line such that modem performance is not degraded. Modems can operate in lower power modes whilst in a ‘sleep’ mode of operation, but may consume up to 2A peak during transmission periods requiring careful consideration of power supply to the device.
Asset and vehicle tracking applications require GPS/GLONASS to track the position. Rather than use a separate GPS receiver, cellular modems are available with integrated GPS to minimise interconnections and maximise reliability. These modems have separate antenna connections for the cellular and GPS antenna. Additionally antennas are now available with two or more antennas combined in one package to provide multiple RF connections such as GSM/GPS, GSM/WiFi or GSM/GPS/WiFi.
What data rate does the application require?
Advances in RF technology leads to ever faster download and upload speeds available to product developers and consumers. These faster data rates are opening up new ways of working and enabling the spread of the Internet of Things and ever increasing deployment of M2M devices. For most industrial applications 2.5G/GPRS and 3G/UMTS data rates are acceptable. GPRS (2.5G) networks enable downloads of approximately 40Kbit/s download, whereas 3G enables uploading/downloading images and video with download data rates up to 2Mbit/s speeds. For moving vehicles the data rate on 3G is more likely 384Kbit/s. The new 4G/LTE networks claim data rates of 5 to 12Mbit/s, with upload speeds between 2 to 5Mbit/s.
Lowest power consumption
For remotely installed devices it is often desirable to power the system via a wind or solar. These installations rely on big capacity batteries but are greatly improved with the modems and other equipment operating in a low power Sleep mode when not transmitting/receiving.
The Internet of Things is broadening with new applications constantly in development. These applications take full advantage of increases in cellular data rates available and advanced ‘Smart modems’ to connect to the internet.
For more details about cellular modems for 2G, 3G and 4G please click the link below.
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