RF Remote Control Systems - The MisconceptionsFollow article
When it comes to RF Remote Control Systems there are many misconceptions within the industry, here at RF Solutions, we have been doing some digging around; see below five common misconceptions that are highlighted on a regular basis.
1. Two products on the same frequency can’t work side by side
When it comes to RF Solutions Remote control systems, two products on the same frequency can work side by side. One transmitter will not be able to control another system’s receiver without being paired with it.
The firmware or hardware can differ, meaning that a transmitter and receiver will only communicate with each other if they are designed for and paired with each other.
2. The lower the frequency, the longer the range
Low frequencies possess valuable qualities which make them a unique asset compared to higher frequencies. Low-frequency radio waves can diffract around obstacles like mountain ranges and travel beyond the horizon following the contour of the earth.
Lower frequency radio waves can also reflect off the ionosphere, and the earth’s surface, multiple times and so can travel for very long distances; therefore, a line of sight is not required.
However, whilst the above statement defines the characteristics of the physics of the wave in practice this is not always the case. This is because the legislation allows a higher transmit power in the 868MHz band compared with the 433MHz band, which means that many of the 868MHz products will provide a longer range.
When considering 2.4GHz (Wifi) whilst a high power can be transmitted, the characteristic of the RF signal is poor, which is one of the main reasons for that poor Wi-Fi performance at the far end of your house!
3. 915MHz can’t be used in the UK
915MHz can be used in the UK on short-range devices (SRDs) on a license-exempt basis. This means that the regulatory authorities allow suitably approved and tested radios to be used without the need for an individual user operating license. A wide variety of frequencies and bands are available, although some are only available in particular countries as shown below:
|Band||Region & Comments|
These are some examples of license-free bands that can be used by SRDs
The regulations for SRDs vary according to the country in question. Applications for short range devices include the below listed; Products applicable with these applications are available at RS Components; www.uk.rs-online.com/web/ or RF Solutions; www.rfsolutions.co.uk:
Garage door and Gate controls: Recommendation – Hornet Pro
Alarms: Recommendation – Fobloq
Movement detectors: Recommendation – Mainslink
Industrial controls: Recommendation – Pro Sabre
Industrial monitoring: Recommendation – 725 Series
Low rate data transmission: Recommendation- Lambda Modules
4. GSM products will interfere with 868 and 915MHz remote control systems
868MHZ and 915MHZ frequency bands are known to be relatively interference-free; although GSM shares some very similar frequencies. The spot frequencies are far enough apart that they have no noticeable effect.
5. You can’t transmit radio waves through water
It is possible to transmit radio waves through water at a very low frequency however it is limited to a fraction of a wavelength due to the density of the water. This gets worse with higher frequencies. The signal strength is lost and therefore is unable to reach its destination. You can use remote control systems underwater but at very short range due to the density of the water.