2.4 GHz RC Radio Spectrum Analysis with a PC Laptop

[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 !

[Blueray450]

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

[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.

[jbx907]

@tsisapik sir it looks like frsky is using most of the entire band than other modules!

[tsisapik]

@jbx907 Looks that way - but that's only the transmission side you see. The data packet handling on the rx is another angle equally important but not observed here ... each "brand" has their unique protocol/s. Personally, for the range I use them, they all perform as expected.

[jbx907]

@tsisapik do you think the true diversity works well on frsky thats why its so good?

[tsisapik]

@jbx907 Diversity refers to the capability of using the optimal antenna and this is usually a feature of the Rx. I can't say FrSky is the "best" but for the units I use, I can't complain.

[jbx907]

@tsisapik yes, i hope so, i am a HAMster, diversity is a technic of using two recievers and tracking which has stronger reception between the two! diversity was intended to fight deadspots ensureing continues link even if one looses link! it is also used in fpv video link nowdays!

[tsisapik]

@jbx907 True ... the best way to fight dead spots for VHF landmobile service is to have chained and uplinked repeaters with linear amps attached to the RF output coupled to high gain low SWR multi-stack collinear antennas ... a hand held in Laguna could trigger repeaters all the way to Nueva Ecija. Cell phones work that way too with the cell towers and the cell network - except we have to pay for the service.

[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!

[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 can you share the spectrum analizer software and hardware? where can i get one for my laptop? how accurate is it?

Thanks

[tsisapik]

@jbx907 Software is a open source and is a free download from the Ubiquity website ubnt.com. The USB AirView2 dongle you need to buy to use the software - also at the Ubiquity site. I only show two panels - there are actually three panels and you can calibrate the software to scale to what you want. These analyzers are used by technicians on the field to troubleshoot commercial Wifi installations - as well as those like me who want to know what's going on around me in the 2.4Ghz bands.

[jbx907]

@tsisapik thanks again!

[wallaguest1]

@tsisapik hi, i am into rc world, just bought a flysky 9x at leaderhobby, and was looking exactly to see how it looks the stock module compared to frsky in the spektrum analyzer.

i just read stock one got some drift problems with servos so i will end up switching to frsky,

[tsisapik]

@wallaguest1 Great news ... a fellow pilot! I have several FlySky setups and I have not observed any drift issues. Maybe the drift happens after an extended period of time? In realty, how long would you be in the air anyway? The MPX Gemini or PKZ P-51D Frankie would be about 10-12 min. EDF J-power F-16 or F35 about 5 min - okay the MPX EasyGlider and ST-330 EasyFly maybe 30 min. I do like the FrSky specs but not too happy with the "push to bind" button on the 4 ch Rx.

[wallaguest1]

@tsisapik  take a look in the HK forums, maybe its a bad batch of transmitter modules, they talk about this "bug" search in google for this line:

Turnigy 9X 9Ch Transmitter "BUG"

and in the first link they talk about

[tsisapik]

@wallaguest1 Thanks for the info - I did the search and from what I read, the observations do not conclusively arrive at the root cause. Could be the drift is a designed compromise between quality and price. For some 2.4 radios, the price of the module is the price of a complete TGY 9x Tx/Rx. To be honest, I could have the "bug" but I would not "feel" it. Also use the ER9x firmware so the sticks can be centered/calibrated manually as often as needed.

[wallaguest1]

hey wonderfull video :)

[tsisapik]

@wallaguest1 Thank you .. if you use 2.4 Ghz radio gear, this setup is a good trouble shooting tool. Are you by chance a RC pilot? If so, fly safe!

[aussie507]

you have the same laptop and transmitter as me

[tsisapik]

Nice to hear ... if you're into 2.4 Ghz RC, this set up makes it a lot more "fun". Your water jet video with the on board camera is interesting - can you do the same on a larger area of water?

[tsisapik]

@aussie507 Good ... these radios are probably the best deals out there. Also use the Thinkpad for setting up the Flymentor on a HK500, flashing the firmware of the TGY 9x to ER9x not to mention the FMS simulator which works with the TGY 9x for those rainy/windy days. How's the RC NQD video coming along?

[aussie507]

@tsisapik some parts are no backorder so a month or two but i will put up a vid on whats happening

[tsisapik]

@aussie507 Yep backorders do get in the way of our high priority RC projects .... anyway, please do post status - thanks!

[snehal50samarpit]

what do we learn from it?? cant understand what is the inference??Please tell

[tsisapik]

Thanks for dropping by. Manufacturers (FrSky, FlySky, Hitec, EFlite for example) have different implementations of the technology. The video reveals some of these differences. The areas of difference is enumerated in the video description. The video presents the observable and repeatable behavior for those who want to know first hand what the differences are. You need to make your own conclusion/s. Regards !

[tsisapik]

The purpose of the video is to show how 2.4Ghz radios can be "analyzed" with a PC and inexpensive hardware/software. This set up presents a powerful but cheap tool to troubleshoot possible radio related problem/s. How about experimenting with antennas, place the radio 30-50-60 ft away ... will a higher dB antenna affect the signals received? How much? How about changing the driver voltage ... does it change the output signal ? Now you can know for sure ....

[kamashi85]

what spectrum analyzer system are you using?

[tsisapik]

@kamashi85 I used the USB type AirView 2 made by Ubiquiti Networks. The program can be downloaded from their site. It was around ~$30 on sale from one of Ubiquiti's dealers.