I needed to do a proper range test on my FrSky Tx/Rx components with my Turnigy9XR. This is how I did it.
I have the 7db 2.4ghz patch antenna from Hobby King hooked up to my Turnigy9XR. Make sure you test this antenna as the ‘wireless sticker’ on my patch was on the wrong side.
I had to make a little coax extension with the proper SMA connector and plug. I bought a few meters of RG316 as I read this was the best to use for FPV and some connectors. I needed the extension because the right angle bend that the antenna has doesn’t bend the way it needs to.
Test Equipment
Receiver Kit
I wanted to walk so I took a basic servo/receiver combo with an ESC and battery.
I used a 20amp ESC, my very first 1300mAh battery which I think is only 15C, a generic 9g servo and the FrSky D8R-II Plus receiver with stock 15cm antennas.
I setup the 9XR in front of my steering wheel on the dash for the first test and on the parcel tray in the boot for the second test.
Transmitter Configuration
Note: this will work for any Tx module as the configuration is on the 9XR – the Tx module is irrelevant.
I setup the 9XR to constantly cycle the servo. The 9XR would move the servo the whole time so when I dropped out of range, the servo would stop moving. When I would come back in range the servo would jump to where it should be. This is a perfect way to measure a Tx/Rx link. Using the lights on the Tx isn’t as exact.
To configure the 9XR I setup a dummy plane and added the Servo Test Template.
This adds some custom switches for us.
All that you need to do is add a mix using the channel your servo is plugged in to. Add that to CH15. I had my servo plugged in to CH2 on my receiver which was is the Ailerons in Mode 2.
As you can see I set it to the Gear switch so it would only cycle when I flicked the switch.
The Tests
Test #1
The first test is below. I actually ran out of line-of-sight road so I had to stop. I had signal right up to the end point.
It was good to get 750m in the middle of suburbia. I didn’t expect to get more than 500m due to noise/interference from everyone’s 2.4ghz wifi routers. I got signal the whole way – except when a bus would pass between me and the car. I wanted a better test so I needed a longer straight road.
Test #2
I went slightly north and parked at the top of a hilly section of Mt Eden Road. As you can see from the map below, this section of the road is nice and straight.
As you can see I got to 1.4kms before the signal dropped out completely. This was due to a small rise of the road blocking line of sight between me and the car/transmitter. I’m sure on a level piece of land I would get further.
Below is how I setup the transmitter in the boot. You can see the little blue light.
The patch antenna is pointing straight down Mt Eden Road. I parked just after the corner so I could point the antenna down the middle of the road.
This is the middle of suburbia and I would say 90% of the houses have a wifi broadband router. There was always 2 or more access points showing on my phone during my walk. FrSky runs on 2.4ghz but didn’t seem to mind all the other traffic.
Conclusion
The FrSky system is awesome. I didn’t expect it to be this solid on the ground and in a populated area. I expect to get 2KMs in the air easily.
This article is on my website here: http://tomflite.com/2013/06/12/ground-range-test-for-frsky-and-turnigy9xr/
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