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Introducing the New DSM System from Spektrum

10/20/2004 by

Copyright:© 2004 Horizon Hobby, Inc.

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In this article...

Page 1: Advancing RC
Page 2: How DSM Works
Page 3: Spektrum FAQs
(continued from previous page)

What is DSM?
DSM or Digital Spectrum Modulation is a form of digital spread spectrum modulation that has been developed and optimized for RC car use.

What channel will I be on?
The DSM system scans the 2.4GHz band and finds a channel that is not being used. Once an open channel is found the transmitter begins transmitting on that unused channel. The DSM System has an available spectrum of 79 channels. In the unlikely event that the spectrum is full, the 80th system will not connect or cause any interference, going into “hold scan” until a channel is free.

Won’t other 2.4GHz devices like phones and wireless computers cause interference?
No, the FCC requires that all 2.4GHz DSS devices be “smart”—incorporating collision avoidance such that when any DSS system is turned on, it scans the 2.4GHz band until a channel that is not being used is found and then begins transmitting on that unused channel.

For convenience the antenna can be routed to either the top or side of the case. Short length fits inside the body.

What is the range?
Typical range is about 3000 feet, depending on conditions.

What kind of response time does Spread Spectrum have?
Spektrum’s DSM system is optimized to give the fastest possible response time of 5.6ms. Typical FM systems offer a response time of 12 to 18ms.

Will the DSM system affect or be affected by other transmitters on 27 or 75MHz or lap counting systems?
No. The DSM system operates in the 2.4GHz ISM band and is well above the range of any equipment, including lap-counting systems presently in use.

So I can just turn on my radio at any time without worry of getting or causing interference?
Exactly!

Sounds like a lot of magic to me. How do I know it will work?
The system has been extensively tested for months by Horizon and Team Losi® drivers, in some of the worst areas in the country. It worked flawlessly in all cases. What’s more, at the recent 1/10 World’s in Kissimmee, Florida, we had 21 units in use by many pro-class drivers. No one had a glitch. In fact, we had some drivers who were being glitched, switched to DSM, and their troubles went away.

What type of telemetry will be available?
The first optional telemetry module will include the ability to monitor real-time engine temperature, engine rpm, speed in mph or kph, battery voltage, signal strength and individual lap times. We hope to have this telemetry module available in early spring.

When the temperature-reading device comes out, where will this data be displayed and will there be an option for an audio alert if the temp gets too high while racing? How much more expensive will the “telemetry modules” be?
That data will be displayed on a hand-held reader. A programmable tone alerting a “max temp” is likely. Pricing of the plug-in telemetry module sensors (that plug into the receiver) and the hand-held reader are in the works. Stay tuned for more info!

Why is it “surface only”?
Surface and air operations are very different in nature. The current system is designed to be used only with surface models. The module will not work with air transmitters. Do not operate on any aicraft— parameters are different for flight. We are looking into these matters, but are currently still not able to know if reliable aircraft operations can be attained.

Are you going to develop this for aircraft?
Applying Spread Spectrum to airplane use involves different challenges from surface. The unit we are presenting today was four years in development. We will try to develop a similar unit for air use, but whether or not aircraft Spread Spectrum can be achieved in production by us is unknown.

I have heard that at Cleveland many of the drivers running it took it out because the response time was too slow. Will this have been corrected in the retail units?
The prototype units that the Losi team used in Cleveland are very different than the production units. The Losi team found an issue that we previously hadn’t discovered in testing outdoors. This issue caused the response time to be inconsistent as some packet information was being lost. The following week through further testing we discovered the specific problem and it was simple to correct. All production units will have corrected programming and hardware changes that prevent this issue.

3PK currently has built in fail-safe feature, and Ex-1 Mars does not have it. Is the DSM module fail-safe function compatible with the fail-safe feature of 3PK? (i.e. can I adjust the fail safe from the 3PK menu?) If equipped with DSM module, does the Ex-1 Mars still need an external fail safe for running nitro cars?
Failsafe is built into every DMS module system. The failsafe servo and throttle positions are stored during the binding process when the system is used for the first time. The 3PK must be operated in FM (not PCM) mode and the preset failsafe position is set during binding by holding the wheel and throttle in the desired positions.

Does the receiver have an antenna? If so, how long is it?
Yes, the stock antenna is 8.5” long, making mounting the antenna easy. What’s more, if you prefer a shorter antenna, you can carefully cut the Spektrum™ receiver antenna to just 3.6” and not lose any performance.

Does the antenna have to be vertical?
The antenna can be either vertical, or can start out vertical and then bend to horizontal. The only condition to be avoided is having a completely horizontal antenna.

Can the DSM system be certified for use worldwide?
Since the Spektrum DSM system operates on the 2.4GHz world-wide ISM band (ISM stands for Industrial, Science and Medical), your Spektrum system is legal to operate in virtually any country throughout the world.

Is it legal for surface RC with the FCC, ROAR, IFMAR, etc.?
The DSM system is currently FCC, ROAR and IFMAR approved.

Can the 75MHz channels that we are currently using be used at the same time with the DSM system when it comes out?
The DSM is on 2.4GHz and has absolutely no effect on 27MHz or 75MHz frequencies.

What type of servo can be used with the receiver? For example, Futaba digital or analog servo? Is there a recommended/approved servo list?
All brands and types of digital and analog servos are compatible. For best results, we recommend digital servos that will utilize DSM’s amazing 4096 resolution to its best advantage. The result? You’ll feel connected with your model like never before.

How many Spektrum-equipped cars can be run at the same time?
Up to 79 cars can be run at one time. As we all know, it’s highly unlikely that this number will ever be exceeded, so from a practical point, you can run as many cars as you like.

Do I have to buy a separate module for each receiver?
No.