Independent tests prove lack of frequency hopping with XPS

[Mithrandir]

My exwife hated it whenever I would cloud the issue with facts!!! lol
Be careful, but what I have read about the FASST Issue sounds a bit H.G. Wells'ish

[sweetpea]

	Quote: Originally Posted by d_wheel
	Hello sweetpea, Just wanted to make sure you understand that the FASST antennas are not 1 inch apart. There are two antennas on FASST receivers. Each are on the end of a length of coax cable and can be located about 6 or 7 inches apart. This gives roughly the same (maybe a tad more) spatial diversity as an AR7000 with one remote receiver. Not pushing either brand, just wanted to make sure you were aware of how they are made. Later; D.W.

Thanks for the clarification. I guess I was a little to vague in the description and was sticking to the the Upper end RX's not the 7ch versions. When you talk 7ch then things get closer (36 in spektrum max, 6-7 inch max FASST and 0 in on XPS)

But with Spektrum you can run a RX 36in from the main in 2 directions. That is a big deal when you think that a 40% airplane is 115in or so. gives you basically the whole plane coverage.

Of course add in dual RX's in either plane and you increase it even more for both systems to cover the entire plane. Right now though Spektrum has slightly better coverage options but I don't think FASST is as bad if you run 2 RX's. I do wish XPS would go dual RX or introduce the Satellites already.

[wrightme]

	Quote: Originally Posted by dick hanson
	my head is made up

As in "pretend?" I am just kidding.

Sorry, back to "serious."

[nordqk]

This thread has been fascinating to read and there has been some very good information and experience learned. I wanted to reconfirm the antenna orientation issue with regards to the comment from Sweetpea (Sam). Spacial resolution with external antennas is important but antenna orientation is also extremely important. If your Tx antenna is oriented vertically, the best signal strength will be obtained with the Rx at that same orientation. Obviously, an aerobatic airplane can undergo many changes in orientation relative to the Tx and the best signal integrity will be obtained when you have three RX antennas in the X, Y and Z position. In my opinion (and we know how people like those), a minimum of three Rx's covering the three axis positions is a MINIMUM. Especially if only one channel is use for the link. JMHO

[sweetpea]

Good point. I hadn't even touched on orientation of antennas

[3ddd]

i for one am going to add the satellite antennas to my xps just because i want to.i have had not one problem all year but i don't want ether

[XJet]

	Quote: Originally Posted by 3ddd
	i for one am going to add the satellite antennas to my xps just because i want to.i have had not one problem all year but i don't want ether

It's good to see commonsense prevailing, despite JD's assurances that satellites aren't necessary -- they most certainly are if you want a truly robust system with optimum performance.

[sweetpea]

Honestly what it comes down to is peace of mind. More antennas throughout your plane shouldn't hurt (as long as they are not on top of each other or touching). And for the small increase in price its no different than adding a 2nd battery to power your system.

[nordqk]

I bought a 35% extra300 and it had an AR9000 Rx with one external Rx at 90 degree orientations. After each flight at our field, the data logger would record fades in the main and external RX of anywhere from the teens to mid twenties and, always, one frame loss. Well, me being the anal kind of guy that I am, I didn't even want that one frame loss. I bought another external and mounted it in the third axis and, now when we check with the logger, there are still the same amounts of fades on the main and both external RX's but the one frame loss is now gone. Is it that the 2nd external "gets more RF" or is it that the orientation of it "filled in" that one orientation that caused enough signal fade on the two original Rx's to rack-up a frame loss? Only very expensive equipment will be able tell but I have my conclusions.

[aviti]

	Quote: Originally Posted by nordqk
	I bought a 35% extra300 and it had an AR9000 Rx with one external Rx at 90 degree orientations. After each flight at our field, the data logger would record fades in the main and external RX of anywhere from the teens to mid twenties and, always, one frame loss. Well, me being the anal kind of guy that I am, I didn't even want that one frame loss. I bought another external and mounted it in the third axis and, now when we check with the logger, there are still the same amounts of fades on the main and both external RX's but the one frame loss is now gone. Is it that the 2nd external "gets more RF" or is it that the orientation of it "filled in" that one orientation that caused enough signal fade on the two original Rx's to rack-up a frame loss? Only very expensive equipment will be able tell but I have my conclusions.

A frame loss is a simultaneous fade on all receivers so with the third receiver it becomes less likely that all receivers would have a fade at the same time.

[Kiwi]

Righty ho folks.

Just to let you know what where and how things are progressing with the 2.4 Ghz testing we are trying to get done.

Two of our members have kindly loaned me an XPS system so we have the whole ball of string in place for that brand. Writeme and 1bwana1 I owe you guys a cool refreshment when we catch up some time. Many thanks for the support and trust you have in us.

ASSAN have sent us their complete product line (albeit for Futaba as that is what I have) for testing and comparison.

I have access to SPEKTRUM with a brand new in the box 7 channel unit available.

FUTABA FASST knocked me off the back order list so we are beating the door down at Hobbico to try and jump the list to get a 14 channel setup on the way.

However our biggest thanks goes to Metageek and Ryan Woodings who have sent a scanner so we can record all we do and post the files here on FG. All you will need to do is download the veiwer from their site and you have exactly what I get. I cant thank these guys enough for jumping in to help us here.

Likely I will kick the results off in a new thread and Xjet your more than welcome to use the same one. As the old proverb says. Many hands make light work. Not sure if they referring to physical effort or power failures but it is a true statement.

As for the testing I have a ton of ideas noted and the important thing is to keep them repeatable and exact. One of the great benefits of my location is the desert. I can drive 10 miles out of town and there is not even an ant. No bugs, nothing. I can drive for a year and never squish a bug on my windscreen. Its clinically clean, open spaces so the tests can be as real as possible in a real environment. No stray RF from local airports, military, nothing. This is my own area 51 for the top secret stuff.

I will keep you posted once I get closer but in the time being hang in and lets see what we can get out of all these systems.

Thanks again for the support guys.

Seeing as I live south of the equator please give me a little time to get everything here in place and set up. Then its gonna be feet to the fire and get it done.

[Pale Rider]

	Quote: Originally Posted by sweetpea
	But with Spektrum you can run a RX 36in from the main in 2 directions. That is a big deal when you think that a 40% airplane is 115in or so. gives you basically the whole plane coverage.

THAT is exactly why I went with Spektrum.

[nordqk]

Kiwi says:

However our biggest thanks goes to Metageek and Ryan Woodings who have sent a scanner so we can record all we do and post the files here on FG. All you will need to do is download the veiwer from their site and you have exactly what I get. I cant thank these guys enough for jumping in to help us here.

I just received my WiSpy from the folks at Metageek and the unit is awesome. I'm checking out a 10x with DSS module and DX7 to see how they play with each other. Interesting, the 10X w/module has a 10 dBm lower signal strength than the DX7 for the same distance. It's going to be a real help in monitoring the airspace when there is a lot of 2.4 gigs flying around. I also will be able to check out Tx problems without having to send it in and wait.

It's amazing how much 2.4 gig cr@p is floating around out there.

[Kiwi]

Nordqk,

That last statement is one that I dont think too many realise is an understatement. Its a very crowded sky out there, you just cant see how much without something like this tool.

[XJet]

	Quote: Originally Posted by Kiwi
	Nordqk, That last statement is one that I dont think too many realise is an understatement. Its a very crowded sky out there, you just cant see how much without something like this tool.

You think there's a lot of crap at ground level -- just take a look from 100-feet or higher and your jaw will really drop!

What's worse, the noise-profile at altitude is often *very* different (ie: worse) to the noise profile at ground level (due to the shielding effects of ground-clutter).

When you see just how many extra 2.4GHz sources become visible with a bit of elevation/altitude, you realize just how important frequency redundancy/diversity is to a robust 2.4GHz RC system.

And now (with XPS and its bi-directional protocol) we even have relatively powerful 2.4GHz transmitters flying over our heads.

We live in interesting times