Kiwi's XPS test results are up.

[aristo1963]

Hi kit as to the integrity of the giants I have no doubt,I was referring to the deleted posts from JD's RCGroups forum(his forum for cheerleading only).I apologise if it sounded otherwise.I have no vested interest in XPS,but would have loved for it to have been what it claimed to be,if for no other reason than to provide more diversity and keep the other manufacturers on their toes from a quality cost performance perspective.Face it if your not the only kid on the block with a ball,you will need to make your ball more appealing in order to get the best kids to play with it.
Again my apologies if you felt that I had included the giants in my comment,I just didnt want to call out names of other forums and start any "my fav forum doesnt do that grousing"
john

p.s.while some are going to say it is what it claimed then a reality check.Yes it is a working system,but the claim is it would hop,that was a selling point(a major one)so far it doesnt so no it isnt what it claimed it was.

[cptsnoopy]

The best part of this is that it may help improve this or other products using the higher freqs. All good for us in the long run.

[wingster]

Daemon

An excellent series of posts(376-#78) that review and synthesize the features of the Spectrum and XPS systems.

Just as you stated, "It works for me so you're full of it" argument is the predominate response from spectrum users on various forums. They usually blame the pilot for a poor setup and won't acknowledge that the Spectrum system has issues.

Keep up the good work!

[Pale Rider]

	Quote: Originally Posted by wingster
	"It works for me so you're full of it" argument is the predominate response from spectrum users on various forums.

Funny thing is that I read the same responses from those that use XPS too.

[BZFrank]

	Quote: Originally Posted by Kiwi
	Ian, Frank, Guys I really do appreciate you coming in here and helping explain what I am unable to or dont fully understand yet. I am more than willing to share data, equipment or what ever if you are willing to make this a team effort. If you guys can do some things I cant then I have no trouble getting the Fedex man to move a parcel one way or the other. ... Its just fun to find out what makes them all tick.

Thanks Kiwi!

I already did my share of testing with XPS/IFS, FASST, SpektrumRC and ASSAN (I did the RC system recordings now used by the Wispy folks at metageek.net) and I can fully support your conclusion regarding XPS based on my own test results. I was not able to get it hop regardless of what I shoot at it. When saturated enough it simply did fall into failsafe but it never hopped or recovered as long as the interference was still present.

I also like to stress that I did everything only out of curiosity and without being on the payroll, nor did I receive anything from any RC manufactures. I only like to know what makes the stuff tick.

Cheers

Frank

[Pale Rider]

	Quote: Originally Posted by BZFrank
	Thanks Kiwi! I already did my share of testing with XPS/IFS, FASST, SpektrumRC and ASSAN (I did the RC system recordings now used by the Wispy folks at metageek.net) and I can fully support your conclusion regarding XPS based on my own test results. I was not able to get it hop regardless of what I shoot at it. When saturated enough it simply did fall into failsafe but it never hopped or recovered as long as the interference was still present. Frank

Im interested in your results with the Spektrum stuff---find anything interesting ?

[KrisW]

	Quote: Originally Posted by wingster
	Daemon An excellent series of posts(376-#78) that review and synthesize the features of the Spectrum and XPS systems. Just as you stated, "It works for me so you're full of it" argument is the predominate response from spectrum users on various forums. They usually blame the pilot for a poor setup and won't acknowledge that the Spectrum system has issues. Keep up the good work!

Please list these "issues" concerning the AR7000 and AR9000/9100 series receivers or systems, especially those using the upgraded firmware or software. Please do not include the 6000/6100 series receivers (As Daemon did), since they are listed for park flyers only, and are not really intended to be as robust or hold link as well as the AR7000 or 9000 series units.

I'm really interested in what the "Facts" are. So far I've seen a lot of subjective
"It might . .it could. . " statements and subjective "Anal-ysis" of the Spektrum systems, but nothing that really nails it down. Saying that an AR6100 receiver had issues does not get much credibility, since the unit was probably well outside it's intended operating environment. I cannot recall anything at all being said concerning the updated AR7000/9000 systems.

[BZFrank]

	Quote: Originally Posted by Pale Rider
	Im interested in your results with the Spektrum stuff---find anything interesting ?

Well, I did not want to influence Kiwis measurements but as you ask:

I did test both the DX-6 and the DX-7, also throttled to EU limits. (~ 100mW for the DX-7). The DX-6 plays in a different league as it only uses low power ouput, so the following is about the DX-7. The DX-7 works by first doing an energy scan on the band and then selecting two channels - the two that show the lowest interference level.


Two separate DSSS channels of the DX-7

The system then continues on these two channels forever (until turned off). It does not change them during runtime. You can think of it as a kind of frequency hopping scheme, but only between two channels as it sends alternating on both.

The two channels helps the DX to cope with interference. As long as one still gets through control is maintained. If both are hit at the same time, it goes into failsafe.

There is also another trick the DX uses to get the message through. For all SS systems on the market it is the 'loudest' - it sends with the most output power on the least speading width. Where FASST is 90 mW and XPS is 60 mW the DX-7 is 100 mW (EU version) and even more ( ~ +3 db ) for the US version. You can see that also when comparing the signal in the analyser.

So metaphorical speaking: While FASST is elegantly hopping from door to door to tell its story, the DX-7 sits on the middle of the street and uses two megaphones to be heard. Both methods seems to work in the real world.

Frank

[KrisW]

	Quote: Originally Posted by BZFrank
	Well, I did not want to influence Kiwis measurements but as you ask: I did test both the DX-6 and the DX-7, also throttled to EU limits. (~ 100mW for the DX-7). The DX-6 plays in a different league as it only uses low power ouput, so the following is about the DX-7. The DX-7 works by first doing an energy scan on the band and then selecting two channels - the two that show the lowest interference level. Two separate DSSS channels of the DX-7 The system then continues on these two channels forever (until turned off). It does not change them during runtime. You can think of it as a kind of frequency hopping scheme, but only between two channels as it sends alternating on both. The two channels helps the DX to cope with interference. As long as one still gets through control is maintained. If both are hit at the same time, it goes into failsafe. There is also another trick the DX uses to get the message through. For all SS systems on the market it is the 'loudest' - it sends with the most output power on the least speading width. Where FASST is 90 mW and XPS is 60 mW the DX-7 is 100 mW (EU version) and even more ( ~ +3 db ) for the US version. You can see that also when comparing the signal in the analyser. So metaphorical speaking: While FASST is elegantly hopping from door to door to tell its story, the DX-7 sits on the middle of the street and uses two megaphones to be heard. Both methods seems to work in the real world. Frank

Great information Frank, thanks.

I just went over to RCU and went back to the beginning of the year, looking at all the posts concerning Spektrum. Not ONE that was not a problem with the users setup, from bad batteries to a system that glitched on 72mhz, so gee, it was glitching on 2.4 as well, to a few brownout cases to adding separation distance betweenthe satellite RX's. That's it, no "Major" issues to talk about.

I'm sure I could go back a lot farther and find instances of problems from before the firware upgrades, but current systems seems to be pretty much locked in and very reliable.

[Pale Rider]

Great info Frank..appreciate it--

[gareth.ky]

	Quote: Originally Posted by BZFrank
	Well, I did not want to influence Kiwis measurements but as you ask: I did test both the DX-6 and the DX-7, also throttled to EU limits. (~ 100mW for the DX-7). The DX-6 plays in a different league as it only uses low power ouput, so the following is about the DX-7. The DX-7 works by first doing an energy scan on the band and then selecting two channels - the two that show the lowest interference level. Two separate DSSS channels of the DX-7 The system then continues on these two channels forever (until turned off). It does not change them during runtime. You can think of it as a kind of frequency hopping scheme, but only between two channels as it sends alternating on both. The two channels helps the DX to cope with interference. As long as one still gets through control is maintained. If both are hit at the same time, it goes into failsafe. There is also another trick the DX uses to get the message through. For all SS systems on the market it is the 'loudest' - it sends with the most output power on the least speading width. Where FASST is 90 mW and XPS is 60 mW the DX-7 is 100 mW (EU version) and even more ( ~ +3 db ) for the US version. You can see that also when comparing the signal in the analyser. So metaphorical speaking: While FASST is elegantly hopping from door to door to tell its story, the DX-7 sits on the middle of the street and uses two megaphones to be heard. Both methods seems to work in the real world. Frank

Good stuff there. That answers one of my questions. Your comments on power output are exactly in line with what I thought was really going on and what I read the band rules in the US are.

A US DX7 should be able to transmit at up to 1 watt. A FASST system is capped at 100mw. Basically systems that lock on a channel must avoid transmitting on the channel if it is in use BUT as a trade off they get to use more power. Continuously hopping systems like FASST don't have that restriction, they can transmit anywhere BUT they must do so at lower power to avoid knocking out systems locked to a single channel.

Its a trade off, more volume or better interference avoidance. Since the band rules dictate that other devices shall not interfere with one another its a pretty safe bet to just use two high power channels. You shouldn't actually need more than one.

Rules in the rest of the world would seem to favor FASST. The power output cap is much lower so there is not as big an advantage in being the loudest.

[Four Stroker]

Am I completely missing something here ? You guys are getting excited about the loudest system at 100 mW vs. the wimpy system at 90 mW.