S155 Smart Charger

Spektrum™ DSMR™ technology is exclusive 2.4GHz radio control technology that can be used with any land-based RC vehicle or boat. The DSM in DSMR stands for Digital Spectrum Modulation and is what creates pure digital control providing an impenetrable radio link immune to all types of interference. The R in DSMR is the Spektrum Surface "Racing" protocol. Spektrum’s DSM system eliminates radio interference, including model-generated noise from motors, ESCs, bad bearings, etc., and outside sources like cell phones, wireless computer systems, and other RC radio systems.

With DSMR, the range and response, particularly in noisy 2.4GHz environments, is superb. It's also backward compatible with DSM2 and marine-specific Spektrum receivers.


DSMR technology is built on the same wideband DSSS (Direct Sequence Spread Spectrum) foundation used in DSM2 technology. Compared to the narrowband technology used in other 2.4GHz transmitters, Spektrum DSMR and DSM2 signals are far less likely to suffer crucial data loss in the event of on-channel interference. Think of a wideband 2.4GHz signal as a river and a narrowband 2.4GHz signal as a stream. It takes much more interference to stop a river than a stream. 

The big reason wideband is so robust is coding gain. Essentially what this means is that the unique coding in a DSM2 or DSMX wideband signal allows it to be heard well above the noise of surrounding 2.4GHz signals without requiring any more power. In fact, a Spektrum wideband signal can achieve as much as 3X the range of its narrow-band competition using the same amount of power.


With its wideband DSSS foundation, DSMR technology gives you extra interference protection and faster reconnection times of frequency-agility. DSMR frequency shifts are coordinated using the most advanced FHSS (Frequency Hopping Spread Spectrum) algorithm in an RC application. Unlike other FHSS transmitters that hop from frequency to frequency using the same fixed patterns, every DSMR transmitter has its own unique frequency shift pattern calculated using its GUID (Globally Unique Identifier). Additionally, each pattern uses just 23 channels in the 2.4GHz spectrum.

By adding the agility of unique frequency shifts to the superior interference resistance of a wideband signal and limiting those shifts to a smaller portion of the 2.4GHz band, DSMR transmitters provide on-channel interference protection that is simply second to none. The result is quicker reconnection times and superb response in the noisiest 2.4GHz environments.


What is DSM?

DSM or Digital Spectrum Modulation is a form of digital spread spectrum modulation developed and optimized for the radio control hobby. The latest DSM protocol for surface transmitters and receivers is DSMR.

What is the difference between DSM, DSM2 and DSMR?

DSM is the original 2.4gHz Radio Control Modulation developed by Spektrum and was released back in 2005 and it pioneered the way for better communication and faster response rates for RC models and made the frequency flag and transmitter impounds obsolete. DSM2 was developed soon after DSM to include the advantages of dual channels for increased interference resistance. The latest iteration, DSMR, uses a more robust connection with randomized frequency hopping, making it nearly impossible for any interference on your system from other 2.4gHz signals and transmitters. DSM and DSM2 systems are no longer available but DSMR transmitters are backward compatible with DSM2 receivers in the US and Canada. The EU version only supports DSMR receivers.

Can I use DSMR in a Boat or Watercraft?

Yes, but it is important to have the tip of the antenna up and away from the water, preferably in an antenna tube. Water is a reflective surface when it comes to 2.4gHz signals, essentially causing the signal to bounce around more when used on land. For this reason, it is a good practice to get the antenna as far away from the water as possible, and if able, to use a receiver with a longer antenna for even better reception.

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 the best interference-free experience, we recommend using the latest DSMR receivers and transmitters.

What is the range?

The typical range is about 3000 feet (or about 915 meters), depending on conditions and the RF environment. For maximum range, antenna placement is key. Inserting the antenna into a tube that positions the antenna up and away from the chassis and other electronics will help protect the antenna from damage as well as maximize reception.

What kind of response time does DSMR have?

Spektrum’s DSMR Protocol is optimized to provide a blazing fast response time of 5.5ms. This frame rate is most consistent when utilizing a DSMR Transmitter and Receiver. Please note that 5.5ms mode is only available on some models and limits channel output to 2 channels.

Why is it “surface only”?

Surface and air operations are very different in nature. Each modulation is designed to work most effectively in their specific applications. For these reasons, Air transmitters cannot bind to surface receivers and vice versa.