DSM

[Doug Cronkhite]

There are some issues to work out before you could use it in airplanes.. the
major one being the antennae are very directional. That doesn't mean it's
not possible.. just that there are hurdles to overcome.
 
-Doug
 
 


  _____  

From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On
Behalf Of Ed Miller
Sent: Wednesday, February 16, 2005 11:18 AM
To: discussion at nsrca.org
Subject: Re: DSM


Sent this to the list several weeks ago, apparently it is in use in RC cars
now but no mention of RC airplane application yet. 
Ed M.

----- Original Message ----- 
From: Grow  <mailto:pattern4u at comcast.net> Pattern 
To: discussion at nsrca.org 
Sent: Wednesday, February 16, 2005 1:54 PM
Subject: DSM



Just read this. "VERRRYY interesting, gutten nacht liebschen..."
 
Advancing RC Technology To The Next Generation
  <http://www.horizonhobby.com/Images/px-clear.gif> 	
Written by: John Adams, Horizon Hobby Engineering Manager
<http://www.horizonhobby.com/Images/px-clear.gif> 	

	 	


	
	

AM, FM, PCM and now DSM. Spektrum's newly released DSM (Digital Spectrum
Modulation) system advances RC radio technology to the next generation.
Based on an optimized version of Direct Sequencing Spread Spectrum, DSM
offers pure digital control providing an impenetrable radio link that's
immune to all types of interference. And with 4096 bit resolution and 5.6ms
response time, the DSM system offers seemingly infinite accuracy and
instantaneous response for a totally connected driving experience. 

WORLD'S MOST SECURE RADIO LINKS

For the highest security levels of radio communications, NASA, the U.S.
military and government agencies like the CIA and FBI rely on Spread
Spectrum technology. Whether guiding unmanned reconnaissance aircraft over
enemy territory, controlling satellites in space or communicating critical
mission orders to the battlefield, the impenetrable secure link that Spread
Spectrum coding provides makes it ideal for these decisive security
applications. 

And now Spektrum offers this technology for your RC car's radio system.



SPEKTRUM'S DSM TECHNOLOGY

In development for over four years, Paul Beard, a leading engineer in the
Spread Spectrum industry, designed Spektrum's DSM system. The DSM system
utilizes Direct Sequencing Spread Spectrum technology that has been
optimized for RC car use. Unlike current narrow band 27 and 75MHz systems,
Direct Sequencing Spread Spectrum or DSSS generates a wide signal on a
single frequency, and information is encoded with its own Globally Unique
Identification number (called GUID) such that the receiver only recognizes
the information from its specific transmitter. And with over 4.2 billion
available GUID codes, it is virtually impossible for a receiver to be
controlled by anything other than its mating transmitter. Spektrum calls
this optimized form of modulation DSM-Digital Spectrum Modulation.


DSM SYSTEM SPECIFICATIONS

*	Frequency Band 2.400-2.4835GHz 

*	Channels 79 

*	Channel Spacing 1MHz 

*	Range 3000 ft 

*	Latency 5.6 ms 

*	Resolution/Channel 4096 steps 

DSM RECEIVER VB SPECIFICATIONS

*	Weight .40 oz/ 11.3 g 

*	Dimensions (LxWxH) 1.62x 1.06x.57"/ 41.2x 27.0x 15.3mm 

*	Input Voltage 3.2-9.6V 

*	RC Channels 3 

*	Current 40 mA @ 4.8V 

*	Antenna Length 8.5 in



ULTRA HIGH FREQUENCY ADVANTAGE

	
	

The Spectrum DSM system operates in the ultra high 2.4GHz ISM (Industry,
Science and Medical) band. This ultra high frequency offers several
advantages over conventional 27 and 75MHz systems. First, all
model-generated radio interference from noisy motors, speed controllers, bad
bearings, metal-to-metal noise, etc. exists below 300MHz. At 2.4GHz (that's
2400MHz) the operational frequency range of the Spectrum system is 8 times
higher than the range of this model-generated RF noise, making the system
immune to these types of interference. Secondly, 2.4GHz is an
internationally accepted band, so it's not necessary to change radio
equipment when traveling to overseas events.And because the 2.4GHz
wavelength is very short, the required lengths of the antennas are much
shorter. The receiver antenna is 8.5" and can be cut down to 3.6" if
desired, making antenna mounting within the body easy. The transmitter
antenna is a mere 3.5" long, eliminating the "fishing rod" that normally
extends into view. 

FCC learned valuable lessons from other bands and applied those lessons to
the 2.4GHz band. And unlike the 27 and 75MHz band, the FCC limits the power
output in this 2.4GHz to a maximum of 1watt, thus preventing other 2.4GHz
systems from overpowering each other. In other words, there are no "high
power" commercial users interspersed in the 2.4 GHz band. 



THE BENEFITS OF DSM

Spektrum's DSM system eliminates all types of radio interference, including
model-generated noise from motors, ESCs, bad bearings, etc. and from outside
sources like pagers, cell phones, wireless computer systems and other RC
radio systems, and offers these benefits:

*	No more waiting for an open frequency-just turn it on 

*	Ultra fast 5.6ms response time 

*	No tuning or maintenance to perform (ever) 

*	Built-in fail-safe drives servos to preprogrammed position if signal
is lost 

*	Ultra precise 4096 bit resolution 

*	Operates on international 2.4GHz ISM band so no need to change bands
when traveling to international races 

*	Short 8.5" or 3.6" receiver antenna length and 3.5" transmitter
antenna length 

*	40% less current draw with the transmitter means 40% more battery
life 

*	Telemetry ready for rpm/speed, temperature, battery voltage, lap
times and signal strength 

*	Legal for most racing organizations including ROAR, NORRCA and IFMAR


*	Available for most popular 3-channel module radio systems for easy,
inexpensive conversion to DSM technology 


FHSS VS. DSSS

There are two primary types of Spread Spectrum technology- Frequency Hopping
(FHSS) and Direct Sequencing (DSSS). FHSS systems transmit a narrow band
signal and rapidly jump from one frequency to the next spending a few
milliseconds on each frequency. DSSS systems transmit on a single selected
frequency but on a very wide band. Only a small portion of that band is used
for specially encoded information. Originally, Spektrum engineers started
their development with FHSS-based systems because they were relatively easy
and inexpensive to develop. However, it was soon discovered that FHSS had
several limitations that would prevent it from being the optimal solution
for RC. 

While more difficult and costly to develop, our engineers began
experimenting with Direct Sequencing Spread Spectrum and optimized the
modulation scheme to overcome critical response and re-link issues. In
addition, DSSS offered 18dB increase of processing gain for significant
improvements in range. With years of development and testing the DSSS
modulation scheme was optimized for RC car use and Spektrum's DSM system was
born.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.f3a.us/pipermail/nsrca-discussion/attachments/20050216/431aa2b9/attachment-0001.html