[NSRCA-discussion] Speaking of 2.4GHz

Sat Mar 1 11:11:43 AKST 2008

Not every feature of the Zigbee protocol offer an advantage in a real time RC environment; for example, retries.  Retries are useful when you don't want to lose the tip of Grandma's nose when transmitting a jpeg picture, but not all that useful if the receiver tries to initiate a retry, then expects a response that may never come, or may not come in time before the next data frame is ready to be transmitted.  On the other hand, Spektrum has two simultaneous paths going at all times, along with path diversity due to the arrangement of remote receivers, so the chance of missing a packet is reduced to begin with.  Regardless of how many other, diverse applications the Maxstream stuff may be used successfuly in, the reality of some model airplane applications is that some measure of path diversity is important.  Maybe XPS will offer a simple change, like Futaba and Airttronics already have, to extend the antenna out on coax to allow them to be oriented in a more effective way.

Physics don't change from one 2.4 gHz signal to the next, so regardless of where else in the world a Maxstream receiver is working, what matters most of all is that at least one antenna of the one installed in your airplane is exposed to a good signal, regardless of model orientation, or what piece of metal or CF may be installed in the model.

Ed

From: tjs at mail.global-electronics.comTo: nsrca-discussion at lists.nsrca.orgDate: Sat, 1 Mar 2008 12:21:31 -0700Subject: Re: [NSRCA-discussion] Speaking of 2.4GHz

Hello everyone!

If you look closely at the pictures of the XPS product, you see a small daughterboard module.  This is made by a very large company called Maxstream http://www.maxstream.net/.   All of the radio stuff is handled by this module – including the frequency hopping etc.  From a small company point of view, this was an excellent design decision (I use them too in my product – not RC stuff) since all of the governmental approvals have been done by someone else, all of the costly design and development, improvements – all by a larger organization.  

Additionally, since Futaba and JR both went the route of designing their own from scratch, they would have to debug all of their own problems.  Also, since Maxstream’s product is in MANY MANY different and diverse industries and used by thousands of engineers (unlike JR and Futaba to a large extent), the problems would be worked out to a much finer point that just used by modelers in their environment.

My $0.02 …

Tim

From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of John PavlickSent: Friday, February 29, 2008 11:49 PMTo: NSRCA Mailing ListSubject: Re: [NSRCA-discussion] Speaking of 2.4GHz

Yeah, how many people experienced the bug in the early Spektrum stuff? We didn't hear too much about that one. The best part is they addressed it and used their resources to solve the problem quickly. Futaba is going through their teething pains now. NOTHING is perfect. It is in your best interest to use ANY new technology with extra caution until it develops a proven track record. I would be a little "extra" apprehensive about the XPS stuff only because it's not backed by large company like Futaba, JR or Airtronics. Small companies tend to have a harder time solving problems similar to the ones that we've seen with the Spektrum and Futaba systems.

John Pavlickhttp://www.idseng.com

From: Ed Alt 

To: NSRCA Mailing List 

Sent: Saturday, March 01, 2008 12:15 AM

Subject: Re: [NSRCA-discussion] Speaking of 2.4GHz

Spektrum is going to come out with Telemetry for airborne radios.  They've had it for years in their ground radios, so they have a handle on it.  I also like the fact that their lead engineer who started the entire Spektrum line with Horizon came from Cypress Semiconductor, the chip vendor for the Spektrum stuff.  Futaba has a great base of experience with Spread Spectrum.  Their teething pains seem to have more to do with re-packaging their existing technology in a scramble to play catch-up with Spektrum.   Every radio has problems here and there, as we've seen over the years with 72 mHz gear, so when I hear that something just totally died in a few isolated cases, it does not alarm me.  However, "the big 3" have proven that they deliver good products overall and will address problems that do exist.  XPS on the other hand has made some questionable claims and really has no solution to provide path diversity for the receiver.  If you look at Futaba and also Airtronics full range SS receivers, they get path diversity from placing each antenna at the end of thin coax leads that allow them to each have a unique RF environment, much like Spektrum accomplishes with actual receivers at the end of data leads that feed a central unit.   If it was me trying to use XPS, I would spend a couple of years test flying it in stuff I could afford to lose, same as I did with Spektrum when it first came out.  I wounded a foamy with a AR6100 receiver that had an early firmware bug, which Horizon acknowledged and fixed. It had nothing to do with radio reception; it was the one that would slap down elevator and stay there.  Nice!  Since then, all of my foamy kills have been directly traceable to my thumbs. Ed

Date: Fri, 29 Feb 2008 14:17:06 -0800From: edvwhite at sbcglobal.netTo: nsrca-discussion at lists.nsrca.orgSubject: Re: [NSRCA-discussion] Speaking of 2.4GHzEd,I've been digging into (ie, poking around RCU) for XPS issues and as is usually the case find mostly secondhand and anecdotal problems along with a few really unhappy people.  I also find a lot of happy XPS users.  I am attracted to the XPS because it offers the future possibility of telemetry, something I would like to play with.  Lastly on the Spektrum, I've seen only a handful of systems fly at our local field.  I've also seen two crashes on two different Spektrum systems due to total loss of control, at close range.  At least one of those verified good battery voltage under load after the crash (the other one didn't check).  I know there are a huge number of satisfied Spektrum users.  I know of two locally who are not quite so satisfied.  Neither ever did figure out the reason for the loss of control.  And with Futaba's recent problem (which they have fixed), well I think we all have to realize there is no bulletproof system.  Just looking to see if people have had problems with the XPS.EdEd Alt <ed_alt at hotmail.com> wrote: 

With a proven solution from Spektrum / JR and with Futaba introducing what will undoubtedly be a solid solution, why play with XPS?  I can't think of any advantage that it offers and it apparently has some issues to dig into and understand.   Ed

Date: Fri, 29 Feb 2008 08:44:14 -0800From: edvwhite at sbcglobal.netTo: nsrca-discussion at lists.nsrca.orgSubject: [NSRCA-discussion] Speaking of 2.4GHzAnybody have experience with the xtremelink systems?http://www.xtremepowersystems.net/EdKen Thompson <kthompson at stx.rr.com> wrote: 

That's pretty cool, thanks for bringing this to the list.  I saw this in the Flying Giants first thing this morning.

----- Original Message ----- 

From: Kevin Brice 

To: nsrca-discussion at lists.nsrca.org 

Sent: Thursday, February 28, 2008 11:25 AM

Subject: [NSRCA-discussion] The Great 2.4GHz DSM Giveaway

For those on the 2.4 fence, this may encourage you to upgrade to DSM.

I am not sure if the html graphics will show so here is the link to Spektrum’s Receiver Giveaway. 

http://www.spektrumrc.com/giveaway/ 

Kevin Brice

kevinbrice at earthlink.net 

From: Spektrum Signal [mailto:webmaster at spektrumrc.com] Sent: Thursday, February 28, 2008 10:00 AMTo: kevin at wenzlerarchitects.comSubject: The Great 2.4GHz DSM Giveaway

Having trouble viewing this email? Click here.

February 28, 2008

PLEASE VISIT WWW.SPEKTRUMRC.COM/GIVEAWAY FOR MORE INFORMATION

Copyright © 2008 Horizon Hobby. All rights reserved.If you no longer wish to receive this newsletter, you may unsubscribePlease send any questions, comments, or concerns to webmaster at spektrumrc.comMailing Address: Horizon Hobby, Inc., 4105 Fieldstone Rd., Champaign, IL 61822Spektrum is used with permission from Bachmann Industries, Inc.

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