Specktrum Frequency Analyzer for RC!!!!

[Kiwi]

Gents.

Do you know if there is an analyzer available for RC some what like the old 72Mhz thing you keep in your flight box.

I know you can spend zillions on a pro unit but I´m talking about a field handheld that you pop out of your box and hold up to see what the 2.4 Ghz traffic is like in your area.

Any information you can share on here with us would be greatfully appreciated.

[tkilwein]

There is for ~2-3k on the low end. do a search for spectrum analyzers.
I have seen a few on ebay for 1500-2K used.

[RH1N0]

Something like this perhaps: http://www.metageek.net/products/wi-spy24x

The original model is a little cheaper: http://store.metageek.net/product-p/2400i1v.htm

[Kiwi]

Holy snapping what evers RHINO, thats the ducks darned nuts mate. Does that cover the band width we will be using for RC because if it does you have answered all my prayers mate.

I mean living in Brisbane and all means I can get Dakers to shout you a beer or ten for this.

Who can tell me if the band width is what I need and then this is a done deal.

[RH1N0]

Yep, it covers the full 2.4 range and will show the signals from RC 2.4 radio equipment and other sources of potential interference such as microwave ovens, video transmitters etc.

I will track down some cool data...

[RH1N0]

I found some good info on this German RC forum. The pictures link to a directory on the original posters web site and show Wi-Spy screen captures of various 2.4 radio systems. Here are the basic system comparisons:

Spektrum DX7 showing the use of two channels: http://www.wizards.de/~frank/RC/WS_Img/DX7.png

Futaba FAAST showing constant frequency hopping: http://www.wizards.de/~frank/RC/WS_Img/FAAST.png

XPS showing a single channel:
http://www.wizards.de/~frank/RC/WS_Img/XPS_1.png

ASSAN system on a single channel:
http://www.wizards.de/~frank/RC/WS_Img/Assan_1.png

It's not my data so I can't comment on the test conditions etc but it certainly is interesting and confirms that the Wi-Spy would be a useful tool for testing and trouble shooting 2.4 RC systems.

[DesertHucker]

Thats cool RH1N0,
Looking at the images, spectrum is on 2 channels, and the faast is hopping quickly through them all
Assan and XPS is on singel channels.
Is that rite what I am seeing?

Loza

[RH1N0]

	Quote: Originally Posted by DesertHucker
	Thats cool RH1N0, Looking at the images, spectrum is on 2 channels, and the faast is hopping quickly through them all Assan and XPS is on singel channels. Is that rite what I am seeing? Loza

Exactly!

Note that these tests were done in a basement to limit the amout of other signals in the picture so this is about as clean as the 2.4 spectrum should look with only one system operating. Throw in a wireless network signal, the neighbours cordless phone, a microwave oven operating nearby etc and it gets a lot more crowded.

[Stainless Skills]

Why do microwave ovens emit on the 2.4 GHz range?

I was wondering, for example:

If I wanted to put a 2.4 GHz transmitter into my rc airplane that transmitted a 50mw feed into a 2.4 GHz amplifier that amplified the signal into a 5 Watt signal that got sent into an antenna in the plane... would that cause any kind of interference to my JR 2.4 GHz system?


If you have something transmitting on 2.450 GHz at around 5Watts and then a receiver next to it which is receiving from the JR transmitter at 2.420GHz and 2.480GHz would there be interference?



I mean, they are on separate channels. Conceptually, to me, it would seem that there should be NO interference. Does something have to be really close or exactly on your frequency to be causing interference or does the RF have to be emitting at exactly the same frequency as our radios or can it be relatively high powered 2.4 GHz RF at a slightly different frequency that causes interference? Would this new high powered frequency as in the video example just 'bleed' of into the radio's frequency because it is of such high wattage?

Hope that is not to bothersome, Google was not too much of a help in that area.

[Kiwi]

RHINO,

That has to be one of the best simple setups I have seen and now all I need to do is sneak this pass the boss without here seeing the CC statement. You can see who the boss is in my house eh!!! Yes its me because I said so.

Seriously despite all the hoo haa about 2.4Ghz I think bigger clubs are going to want to keep a handle on who soes what and with what.

Example:

We have a young engineering student working on a powered glider that he flies with those video glasses. Cool setup and its like bing in the cockpit. He cant see the plane but he can see out of it. Well his video setup is 2.4Ghz and very powerful compared to a radio transmitter. I have no idea how much band width it hogs.

So if he decides to go to a neighbouring club one day where ten guys are flying 2.4Ghz will he swamp them. Also the ability to be able to see how clean your environment is (from a club point of veiw) I think is important.

There is a huge tendency these days for internet providers to setup these huge wireless zones in cities and large towns. Those things are going to be a handful if your Tx system is not capable or robust enough to work in that cluttered environment. The scanner will at least let you see whats going on.

[XJet]

	Quote: Originally Posted by Kiwi
	RHINO, We have a young engineering student working on a powered glider that he flies with those video glasses. Cool setup and its like bing in the cockpit. He cant see the plane but he can see out of it. Well his video setup is 2.4Ghz and very powerful compared to a radio transmitter. I have no idea how much band width it hogs. So if he decides to go to a neighbouring club one day where ten guys are flying 2.4Ghz will he swamp them. Also the ability to be able to see how clean your environment is (from a club point of veiw) I think is important.

We've flown UAVs with a bi-directional 2.4GHz data link *and* a 2.4GHz video sender onboard and although the range is slightly reduced, the interference between the two is fairly small and therefore not a real problem (for our application).

As to whether the video transmitter will interfere with 2.4GHz RC systems, I think this is one of the great unknowns right now.

Certainly (as per my observations in another thread) *some* video transmitters can adversely affect at least one 2.4GHz system under the right conditions but whether others video-transmitters and RC systems will interact as badly is yet to be established.

All the current systems *should* be able to handle being turned on and flown while a low-powered 2.4GHz video transmitter is operating in relatively close proximity. There is a possibility that Spektrum and XPS (possibly Assan and others) may be affected if a powerful (600mW+) video transmitter is turned on while they're in the air.

If I had the money and time I'd buy one of each new 2.4GHz system as they came on the market and do the testing -- but work and rent just keep getting in the way of this master-plan :-)

[Kiwi]

Well I guess it time to have a whip around and see if I can line you up with one of each. They likely wont be keepers sorry but I´m sure we can get you one of each and put this to the test as best we can.

Let me start searching.

[prizzy]

That is what I call data!! Thanks

[wrightme]

How is the horizontal scale annotated? I see that vertical shows power, but how are the "11, 12, 13, etc" correlated to frequency?

	Quote: Originally Posted by RH1N0
	I found some good info on this German RC forum. The pictures link to a directory on the original posters web site and show Wi-Spy screen captures of various 2.4 radio systems. Here are the basic system comparisons: Spektrum DX7 showing the use of two channels: http://www.wizards.de/~frank/RC/WS_Img/DX7.png Futaba FAAST showing constant frequency hopping: http://www.wizards.de/~frank/RC/WS_Img/FAAST.png XPS showing a single channel: http://www.wizards.de/~frank/RC/WS_Img/XPS_1.png ASSAN system on a single channel: http://www.wizards.de/~frank/RC/WS_Img/Assan_1.png It's not my data so I can't comment on the test conditions etc but it certainly is interesting and confirms that the Wi-Spy would be a useful tool for testing and trouble shooting 2.4 RC systems.

[RH1N0]

	Quote: Originally Posted by wrightme
	How is the horizontal scale annotated? I see that vertical shows power, but how are the "11, 12, 13, etc" correlated to frequency?

The horizontal scale is showing ZigBee channels:

In the 2.4 GHz band there are 16 ZigBee channels, with each channel requiring 5 MHz of bandwidth. The center frequency for each channel can be calculated as, FC = (2405 + 5*(k-11)) MHz, where k = 11, 12, ..., 26.

See http://en.wikipedia.org/wiki/ZigBee