Go Back  RCU Forums > RC Airplanes > AMA Discussions
 Spread Spectrum >

Spread Spectrum

Notices
AMA Discussions Discuss AMA policies, decisions & any other AMA related topics here.

Spread Spectrum

Old 10-27-2005, 10:08 AM
  #51  
Senior Member
 
Join Date: Mar 2004
Location: SoCal, CA
Posts: 1,195
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum

This:

""2004-2005: Digital spread spectrum
RC system on 2.4 GHz for surface
use is introduced. Next-generation
transmitter using Windows CE and
PCM 2048 is introduced.""

Should be prefeced with:

""While the AMA sat on it's behind ignoring
the dangers of the arcane 72MHz bandwidth it crusaded
to keep;...""
Old 10-27-2005, 10:17 AM
  #52  
J_R
Senior Member
Thread Starter
 
Join Date: Jan 2002
Location: Corona, CA,
Posts: 4,444
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum


ORIGINAL: SoCal GliderGuider

It's not hot air!
Oh yes!!! It is!!!
Old 10-27-2005, 11:05 AM
  #53  
My Feedback: (1)
 
Join Date: Mar 2003
Location: Over da rainbow, KS
Posts: 5,087
Received 5 Likes on 5 Posts
Default RE: Spread Spectrum

SoCal - are you some form of a beast of burden? You should change your tag line to "it's not hot air, I'm just expelling it from my backside"
Old 10-27-2005, 11:15 AM
  #54  
My Feedback: (7)
 
iflyj3's Avatar
 
Join Date: May 2002
Location: Paris, KY
Posts: 1,406
Likes: 0
Received 1 Like on 1 Post
Default RE: Spread Spectrum


ORIGINAL: SoCal GliderGuider

This:

""2004-2005: Digital spread spectrum
RC system on 2.4 GHz for surface
use is introduced. Next-generation
transmitter using Windows CE and
PCM 2048 is introduced.""

Should be prefeced with:

""While the AMA sat on it's behind ignoring
the dangers of the arcane 72MHz bandwidth it crusaded
to keep;...""
Mr SoCal,

Go get this PDF and read the milestones of radio control. I agree with the report as I have been around R/C since the 50's.

http://www.modelaircraft.org/comp/Sp...m/Spectrum.pdf
Old 10-27-2005, 01:36 PM
  #55  
My Feedback: (3)
 
Join Date: Oct 2002
Location: Fair Oaks Ranch, TX
Posts: 2,635
Received 3 Likes on 2 Posts
Default RE: Spread Spectrum


ORIGINAL: J_R

ORIGINAL: drvcrash

This might be a dumb question.. But has the AMA ok'ed the use of these systems at ama fields? I bring this up becuase I mentioned these were out now at a meeting today at the field and the "old gezzers" had a fit that the ama hadnt told them anything about them and wanted to out law them unless I could find something that says the AMA ok'ed them
Excerpt from article by Dan Williams (D II frequency coordinator) referenced by Steve Kaluf in a piece on the AMA site:
*******
Q: Will the AMA Safety Code change, and
when will I be able to fly my models at my
AMA chartered club with SS?
A: AMA’s goal with the system testing is to
make changes to the Safety Code as
necessary to accommodate the new systems.
The Academy wants to encourage the
technology—not hinder it.
The code reads, “I will operate my model
aircraft using only radio-control frequencies
currently allowed by the Federal
Communications Commission … ” These
frequencies are currently authorized, so there
should be no problem as long as the club
doesn’t have additional safety rules regarding
the use only of our current frequencies.
*******
Kaluf's piece is here: http://www.modelaircraft.org/spreadspec.asp
Williams' piece is here (includes more from Kaluf): http://www.modelaircraft.org/comp/Sp...m/Spectrum.pdf
The way I read that is that this is a legal system under the FCC rules as currently written. Unless we (AMA) elects to get all hung up on an FCC definition of what constitutes "radio control" by taking the 'ask permission first' thesis. Take a look at what can exist and use the 2.4 GHz band allowances, which does NOT exclude radio control...
Old 10-27-2005, 02:28 PM
  #56  
Senior Member
 
Join Date: May 2003
Location: St Augustine, FL,
Posts: 2,644
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum


ORIGINAL: Jim Branaum

<snip>
The way I read that is that this is a legal system under the FCC rules as currently written. Unless we (AMA) elects to get all hung up on an FCC definition of what constitutes "radio control" by taking the 'ask permission first' thesis. Take a look at what can exist and use the 2.4 GHz band allowances, which does NOT exclude radio control...
James-

You are ignoring that segment that needs to have rules that give them the control to grant permissions as well as impose prohibitions.

For those needing permission to use the 2.4 GHz band for R/C, I hereby grant it. You may cite me on that in response to anyone that challenges your privilege to do so. Simply defer to someone with higher authority than his. I am not only a member of the prestigious National Geographic Society, but further possess Vaccination and Completion of Primary Education Certificates, and an International Driver's License.

Abel
Old 10-27-2005, 04:43 PM
  #57  
My Feedback: (2)
 
Join Date: Jan 2002
Location: Ivyland, PA
Posts: 2,299
Received 1 Like on 1 Post
Default RE: Spread Spectrum

It seems to me that while spread spectrum as a modulation technique could be a very positive improvement for RC flying, the use of 2.4 GHz is just a bad idea. I realize this is a tall order, but I would like to see the AMA approach the FCC for another frequency allocation. Something in the hundreds of MHz should greatly improve the performance of spread spectrum. With TV going from analog to digital and reassignment of the analog TV channels expected to occur in the next 5 to 10 years, this may be the opportunity we need.



Old 10-27-2005, 04:52 PM
  #58  
Senior Member
 
Join Date: May 2003
Location: St Augustine, FL,
Posts: 2,644
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum

Changed my mind
Old 10-27-2005, 04:56 PM
  #59  
My Feedback: (35)
 
Join Date: Jul 2003
Location: Bowling Green, KY
Posts: 2,497
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum

these radio's will be ready to ship soon to the LHS. The price is $ 199.99. Dennis
Old 10-27-2005, 07:54 PM
  #60  
My Feedback: (15)
 
mongo's Avatar
 
Join Date: Dec 2001
Location: Midland, TX
Posts: 3,540
Received 85 Likes on 75 Posts
Default RE: Spread Spectrum

JP is starting to get us headed towards the real right answer.
SS is to antana placement sensitive even at 900 mhz, but at 100????? just maby
Old 10-27-2005, 11:13 PM
  #61  
My Feedback: (1)
 
Join Date: Mar 2003
Location: Over da rainbow, KS
Posts: 5,087
Received 5 Likes on 5 Posts
Default RE: Spread Spectrum

With TV going from analog to digital and reassignment of the analog TV channels expected to occur in the next 5 to 10 years, this may be the opportunity we need.
On Oct. 20, the Senate Commerce, Science and Transportation Committee approved legislation with April 7, 2009, as the deadline (for phasing out analog TV broadcasts).

The House Energy and Commerce Committee late Wednesday approved legislation setting Dec. 31, 2008, as the date that broadcasters must switch to DTV (digital television) broadcasts, in order transfer the upper 700MHz radio frequency spectrum to emergency response agencies and commercial wireless vendors.

Somewhere inbetween, the frequencies will be available. But most likely not to fly models, since the government expect to sell them for a great deal of money. Auctions of the spectrum vacated by broadcasters is projected to raise at least US$10 billion.

As it is, we have exclusive use of the frequencies on 72 Mhz, wedged between other users that are only 10 kHz from each of our frequencies. A slightly more difficult receiver design than the old 80 kHz systems, but the results have been good the past 15 years.

What has not been discussed yet on this thread is the need of more bandwidth to improve the data rate and resolution that an RC system can provide. Current FCC regs require our transmitters to only use 8 kHz of bandwidth. For pulse width coded systems this limits the rise and fall times of the signal. So the receiver is burden with resolving when a pulse is turned on and off with less than crisp waveforms. For PCM systems it limits either the resolution and/or the data refresh rate.

So with a wideband system, we can send a lot more data to provide more resolution and higher updates rates. I noticed that Spektrum car radios are 4096 PCM which is twice the resolution of the 14 MZ Futaba and 4 times what a typical high end radio uses.
Old 10-28-2005, 05:23 AM
  #62  
My Feedback: (7)
 
iflyj3's Avatar
 
Join Date: May 2002
Location: Paris, KY
Posts: 1,406
Likes: 0
Received 1 Like on 1 Post
Default RE: Spread Spectrum


ORIGINAL: HighPlains

As it is, we have exclusive use of the frequencies on 72 Mhz, wedged between other users that are only 10 kHz from each of our frequencies.
It is actually worse than you have indicated. This quote is from FCC rule 95.207(g)

"These frequencies are not afforded any protection from interference due to the operation of fixed and mobile stations in other services assigned to the same or adjacent frequencies."

I did not realize that there could be other devices exactly on our frequencies until I read this section.
Old 11-28-2005, 08:19 PM
  #63  
Junior Member
 
Join Date: Jul 2004
Location: Bristol, TN
Posts: 27
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum

I just came across an article in this months "Model Aviation" (December 2005 - page 9) about the DX6 written by the AMA Frequency Committee. The final paragraph reads:

You are urged to keep an open mind as this new type of RC system is introduced into our hobby. When that first SS system shows up at your flying field, don't look for that frequency flag; it won't be necessary! But please welcome this technology; it can offer many advantages for our future RC flying!
It seems to me that the AMA is pro SS despite the hostility people have expressed toward their stand on the technology. If any "old geezers" give you any flack when trying to operate an SS radio on their field, I would bring this article along.
Old 11-28-2005, 08:22 PM
  #64  
My Feedback: (162)
 
jonkoppisch's Avatar
 
Join Date: Dec 2001
Location: Mobile, AL
Posts: 2,942
Likes: 0
Received 2 Likes on 2 Posts
Default RE: Spread Spectrum

I can't wait to show up with one!!!!!
Old 11-28-2005, 09:21 PM
  #65  
My Feedback: (22)
 
TexasAirBoss's Avatar
 
Join Date: Oct 2002
Location: Houston, TX
Posts: 2,972
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum

Hey Stryker, I lived in JC til 1984.

I've been shopping for a live TV camera rig for my plane. They are only 94 bucks. Amazing ! Color, 380 lines and audio !

These airborne camera sets are on 2.4 Ghz also. The range of these cameras is about 1000 ft .

My question is this. Do the SS xmitters have a range greater than 1000 ft ?
Old 11-29-2005, 02:49 AM
  #66  
Senior Member
 
typicalaimster's Avatar
 
Join Date: Jul 2004
Location: Fairfax, VA
Posts: 255
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum

Someone did a review and test of the SS radio. They tested the unit up to 0.7 miles on the ground.
Old 11-29-2005, 08:58 AM
  #67  
My Feedback: (3)
 
Join Date: Oct 2002
Location: Fair Oaks Ranch, TX
Posts: 2,635
Received 3 Likes on 2 Posts
Default RE: Spread Spectrum


ORIGINAL: typicalaimster

Someone did a review and test of the SS radio. They tested the unit up to 0.7 miles on the ground.
I would very much like much more detail than someone. Who, when, where, and what were the test parameters. After all, we are potentially putting people at risk if it is as limited in range as I have been lead to believe. Care to share some of that information?
Old 11-29-2005, 11:49 AM
  #68  
Senior Member
 
Join Date: Mar 2004
Location: SoCal, CA
Posts: 1,195
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum

Geawd some of you old farts are a lead anchor around the necks of any advancement to rc. Spread spectrum is here, right now and it works for 90% of the flying (jets and distant sailplane flying excluded). It also takes away the AMA's mantra of "We Saved The Frequencies".

I like what Abel stated; "You are ignoring that segment that needs to have rules that give them the control to grant permissions as well as impose prohibitions." Think frequency board -- for one.

Attached Thumbnails Click image for larger version

Name:	Zx71976.jpg
Views:	16
Size:	42.2 KB
ID:	362057  
Old 11-29-2005, 03:45 PM
  #69  
Senior Member
 
Join Date: Oct 2002
Location: Leesburg, IN
Posts: 1,047
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum

Jim Branaum - The link to the review is in post #47 on page 2 of this thread. Since you obviously have not been following this thread until now, here's another link to the review http://www.flyingcirkus.com/forum/Fl...m_96209/tm.htm

After all, we are potentially putting people at risk if it is as limited in range as I have been lead to believe.
I strongly believe that people are more at risk from those who simply charge their batteries and don't check to see if the charger actually was working by using a good voltmeter before every flight, or those that connect their ailerons backwards, or those that don't do a simple pre-flight of their aircraft that's been in storage for a couple months, etc. Further, I'll bet that less than half the flyers at any field have done a correct range check of their current radio and plane combination, or if they did it was so long ago as to be meaningless.

I believe that the tone of your post reflects what many on this thread have said about folks that are resistant to change. Some of their comments - such as "If any "old geezers" give you any flack when trying to operate an SS radio on their field, I would bring this article along.", “I mentioned these were out now at a meeting today at the field and the "old gezzers" had a fit that the ama hadnt told them anything about them and wanted to out law them unless I could find something that says the AMA ok'ed them” and “I've got a "geezer" in my club trying to stir up a fuss about these systems too. WHY WHY WHY WHY WHY WHY WHY WHY WHY???? What possible motivation could these people possibly have to object to the biggest advancement in R/C radio systems in nearly thirty years?” – while not too politically correct, accurately reflect the feelings toward those who take shots at something new just because they aren’t familiar with it and much of this is that they haven’t taken the initiative to learn about the new idea or product.
Old 11-29-2005, 03:56 PM
  #70  
Senior Member
 
Join Date: May 2003
Location: St Augustine, FL,
Posts: 2,644
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum


ORIGINAL: Jim Branaum


<snip>

I would very much like much more detail than someone. Who, when, where, and what were the test parameters. After all, we are potentially putting people at risk if it is as limited in range as I have been lead to believe. Care to share some of that information?
Hey Jim-

The vendor isn't claiming range comparable to existing (i.e., 72 MHz) radios. For one thing Tx power output is 10 dB down from what FCC allows in the service and it is being marketed for park flyers only; they have been very clear about this. No people are going to be put at risk, unless it is used in a manner for which it is not intended. Then, I suppose using the rationalization of The Emperor Brown in killing autonomous model aircraft again, AMA should ban the Spektrum radio because it allows the operator to use it irresponsibly.

The report of getting 0.7 mi range was posted in another RCU forum, so I'm sure you can find it readily. You'll see that it was on the ground, under static conditions. Be aware that range will be affected by vehicle dynamics and the resulting rapid changes in antenna orientation. The effect on the received signal is manifest as phase jitter, essentially an added noise component, so (S+N)/N is reduced and consequently so is useful range.

Abel
Old 11-29-2005, 05:35 PM
  #71  
My Feedback: (3)
 
Join Date: Oct 2002
Location: Fair Oaks Ranch, TX
Posts: 2,635
Received 3 Likes on 2 Posts
Default RE: Spread Spectrum

Abel,
Thank you for providing the answer I already knew about. Your second paragraph explicitly highlights the issue I was pointing to very precisely. Thanks for making it clear enough for the peanut gallery of change for the sake of change to see (I hope). I want the grown up version of this rado as soon as it is available, and that means the unit with the multipath issues under control at longer ranges in the air at all attitudes.

I am going to ignore the other two posters as being unresponsive and offensive since I have been following this thread since the 20th of October, and will let them discover the proof of that activity which is over a month old, unless they really are below average village idiots.

SoCalGliderGuider, do you want your habitat shared with those looking for you on the newsgroup or are you hiding?
Old 11-29-2005, 06:15 PM
  #72  
Senior Member
 
Join Date: Oct 2002
Location: Leesburg, IN
Posts: 1,047
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum

I have been following this thread since the 20th of October
Since this is the case, why didn't you know where the review was?
Old 11-29-2005, 07:00 PM
  #73  
Senior Member
 
Join Date: Mar 2004
Location: SoCal, CA
Posts: 1,195
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum

ORIGINAL: JLNewc

I have been following this thread since the 20th of October
Since this is the case, why didn't you know where the review was?
Old fart brain burp or just shear obstinance.
Old 11-29-2005, 07:01 PM
  #74  
Senior Member
 
Join Date: Mar 2004
Location: SoCal, CA
Posts: 1,195
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Spread Spectrum

ORIGINAL: Jim Branaum
SoCalGliderGuider, do you want your habitat shared with those looking for you on the newsgroup or are you hiding?
Don't threaten me Jimmy. You will NOT like the results.
Old 11-29-2005, 07:45 PM
  #75  
My Feedback: (2)
 
aeajr's Avatar
 
Join Date: Jan 2003
Location: Long Island, NY
Posts: 8,573
Likes: 0
Received 11 Likes on 11 Posts
Default RE: Spread Spectrum

Isn't the market for this radio more defined by wing span than power source? I think it would be great for most planes 60" and under.

Certainly slope gliders under 60" would be a good fit. That is a huge part of the slope market! They are typically flown within 2000 feet of the pilot. Hard to get out further than that with a 60" sloper.

And I don't see any reason why small glow planes would not be a good fit as well. Unless the glow engines emit some kind of RF that would cause a problem, the issue of range seems to be related to the size of the plane, not the power plant.

How about 1.5 and smaller DLG, HLG and thermal gliders? That is the bulk of this market. The components are small and light. Why not for small gliders? Again, at 2000 feet, these planes are dots, no different from a "parkflyer".

Why define the target market by the type of power plant. Doesn't make sense to me. Anyone disagree?

By defining the market as electrics, you could easily have 2M electric planes using this and something that large can get out to 2500+ feet pretty easily which is on the edge of rated range.

Thread Tools
Search this Thread

Contact Us - Manage Preferences Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.