If you've ever experienced a complete or deteriorating range problem with your remote control, the chances are it's 433Mhz. 433Mhz ia the typical frequency band used by the vast majority of remote controls for the past few years.
The problem is that it has become overloaded or 'saturated' because it shares the air space with many other more powerful devices running on the same or adjacent frequencies. The result is a remote control that can become unreliable even though it worked perfectly fine to start with.
This deterioration pattern is also apparent with frequencies that
preceded 433Mhz. The 868.35MHz frequency band was introduced exclusively for security remotes and devices on a strict set of guidelines
to ensure reliability. On 433MHz your signal is competing in a total
free-for-all of alarms, garages, gates, barriers, baby monitors, door
bells, telephony and other devices, including TETRA Emergency Services Radio.
What distinguishes 868.35MHz is called "limited duty cycle". This means
that no device using the 868.35MHz frequency band is allowed to transmit
for more than a few milliseconds (0.001 - 0.005 sec) per second - so at any one time,
there are far fewer devices transmitting at any one time. According to
Manufacturers of 868.35Mhz transmitter chips, the frequency has at least
100 times more "interference immunity".
Other Devices Using the saturated 433.92Mhz Frequency Band...
* Used by Emergency Services, TETRA is the name
given to a network (Trans European Trunked Radio Apparatus) of base
stations and mobile handsets. The signal strength has caused serious
interference problems with wire free products such as bell chimes,
electric gate remote controls, car and burglar alarms. TETRA operates on
frequencies between 410 and 430MHz, adjacent to 433MHz.
* Amateur radio transmitters also operate on the 433Mhz frequency with
power levels of up to 400 watts. This is 40,000 times more power than
433MHz radio remote devices and can cause extreme 'show stopper' interference when nearby.