In a previous article, we have seen the FrSky R9M module and its feature list. This time we will take a look at the R9M Lite module and put it up against its bigger brother, the R9M module. So without further adieu let us look at this short FrSky R9M Lite Review.
What is the long range receiver R9M Lite for?
The FrSky R9M Lite has been created mainly to address the crowd that has bought or been using the FrSky X-Series of radios. This is largely because of the different style of the JR module bay in the X-Series of radios. The X-Series of radios uses a smaller version of the bay with a totally different form factor and so to create a long range receiver module for that market, FrSky came up with the R9M Lite version.
The R9M Lite, like its bigger brother, is a 900MHz Long-Range RC link system. The R9M Lite is compatible with all the receivers the R9M supports as well. This is because the R9M Lite is the same as the R9M except for the limited output power of just up to 100mW. This is much lower than the R9M’s max output power of 1W, which is 10 times more than the R9M Lite.
But 10 times power output does not translate to 10 times range. Since the range is the logarithmic value of the output power, you will only get 3 times the range. In case you are looking for more power than the R9M Lite, you can 3D print a JR-module adapter and do a few mods to get the full-size R9M module to be used on the X-Lite radios.
Update: FrSky launched an upgraded version of the R9M Lite, called the R9M Lite Pro which has up to 1W of output power as well as the support for the new ACCESS protocol from FrSky for OTA updates and spectrum analyser among other features. We will take a deeper dive at this later on.
Why use a long range receiver 900MHz system?
Let us assume that you are flying your drone in an open area without any obstacles, your stock 2.4GHz radio is going to have a pretty solid range and link quality throughout the flight without much hiccups. Now, imagine a scenario where you have a few buildings and other objects obstructing your Line of Sight with your drone. Things are going to get a bit hazy, isn’t it? Chances are that your Taranis radio will blurt out “RSSI Critical” sound a lot more than you are comfortable with and you realize you just lost your telemetry signal and possibly got a failsafe quad somewhere in the field.
To overcome this issue, we use a 900MHz system for more penetration between buildings and other obstructions as we have discussed previously in another article.