2.4 GHz RC Radio Spectrum Analysis with a PC Laptop

I was always curious to know what the RF signatures of the different 2.4 GHz RC radio implementation look like. I've done some research and read discussions on how they work/perform but never really "saw" them in action - until now.

Using my trustworthy IBM Thinkpad I set up a 2.4 GHz spectrum analyzer system designed to monitor the 2.4 GHz bandwidth for WIFI applications. Turns out the system works very well for RC radio systems as well !

I am not an electrical engineer but I do understand RF theory and have experience working with radio transmitters and antennas (ahh the DXing days...). Having said that, these are what I observed about the differences in the modules.

a) channel coverage
b) tendencies of the peaks to be more concentrated on section/s of the band
c) number of well defined peaks
d) shape of the peaks - base vs height
e) power output and relative presence of ambient noise

I am no expert and cannot determine which is the good, better or best module based on what I observed. What I can say is that all the radio/modules I used performed very well in the field.

Thanks for dropping by and fly safe!

Category:

Howto & Style

Tags:

• Spectrum
• analyzer
• turnigy
• frysky
• corona
• e-flite
• hitec
• optic

[mike1305]

Whats up! Thanks for the video. I am currently researching if this same ambient analysis is possible using the wireless NIC that already exists in my laptop (aka don't need the dongle). Any thoughts? Perhaps you researched the same subject before finding the USB attachment.

Thanks!

[tsisapik]

@mike1305 Hi! What you are thinking is very possible. There is an open source software that allows you to "see" available access points that are transmitting within the receiver's (WiFi card) range and with the help of a GPS can even tell you where the access point is located. With a little software hacking, I am sure you can get it to display ambient 2.4Ghz signals (not only Wifi). You are definitely headed in the right direction !!

[jcer93705]

What is the name of the software and hardware? How much is the combo?

[tsisapik]

@jcer93705 Thank you for dropping by! The hardware is the USB "AirView2" made by Ubiquity Networks. The software is the "Airview Software" which is open source and can be downloaded free from ubnt.com / airview. The USB dongle can be purchased for about $39 (at least when I bought it) depending on the authorized dealer/s you can pick from the Ubiquity site/url. There are other choices but I am biased to open source programs if available (like you do). Good luck and stop by often ...

[KingGoddard]

you didn't really say how you did it .. are you connecting to the controller?

[tsisapik]

@KingGoddard The objective is to measure the RF being generated by the radio controller. The laptop has a USB / antenna dongle that is covered by the metal socket wrench to attenuate the high level of the signals coming in due to the close proximity of the signal source. The optimal set up would be to have a predetermined distance to mimic the conditions of field use but doing so would make the video production more complicated. In short, no direct physical/electrical connections dude. Regards !

[tsisapik]

@Blueray450 The analyzer will pick up ambient 2.4Ghz signals. Since the antenna is omnidirectional, you will not be able to tell you the direction from where the signal is coming from.

[Blueray450]

Do you think the analyzer would pick up interference signals at a flying field from cell or wifi towers?

[tsisapik]

@jbx907 True but we fly unobstructed "line of sight" (well theoretically). Multipath issue have been identified more for the FPV camera transmitters that use fixed frequencies - like routers! Frequency hopping TX/RX systems avoid conflicts but to your point does not address congestion. I've had more "glitches" with 72 mhz (single channel though) than with a 2.4 Tx/Rx - not a good feeling to loose control for even a split second !!!

[jbx907]

@tsisapik yeah i used to trigger the amature repeater in makiling! one thing i dont like on 2.4 is the mutipath problem, thats why 72mhz are more supreme than 2.4ghz, before we can say 2.4 is good but now day with all that wifi and gadget working in the 2.4 band make it really noisy, wifi router are also into 5.8ghz band, gosh.. those dual band wifi systems being out late last year! it really noisy now!