Spektrum SPM20320 DX3.0 - Manual (Page 5)

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• DSM 2.4GHz Spread Spectrum Modulation
• Now compatible with DSM2 and Marine surface receivers, in addition to
DSM surface receivers
• Three channels
• Easy-to-read LCD graphics display
• Four-model memory
• Three-character model name entry
• Electronic digital trim levers for throttle and steering
• Two assignable electronic grip switches (Lever A and Button C)
• Third channel accessible through Grip Lever A or Grip Button C
• Direct display trim function
• Sub-trim
• Steering rate adjustment
• Independent steering endpoint adjustments
• Brake/throttle endpoint adjustment
• Low battery alarm
• Charge jack receptacle (rechargeable batteries not included; order JRPB958)
While your DSM equipped 2.4GHz system is intuitive to operate, functioning nearly
identically to 27 and 75MHz systems, following are a few common questions from
customers.
1. Q: Which do I turn on first, the transmitter or the receiver?
A: If the receiver is turned on first—all servos will be driven to their preset failsafe
positions set during binding. When the transmitter is then turned on the transmitter scans the
2.4GHz band and acquires an open channel. Then the receiver that was previously bound to
the transmitter scans the band and finds the GUID (Globally Unique Identifier code) stored
during binding. The system then connects and operates normally.
If the transmitter is turned on first—the transmitter scans the 2.4GHz band and acquires an
open channel. When the receiver is then turned on all servos are driven to their preset failsafe
positions for a short period of time (the time it takes to connect). The receiver scans the
2.4GHz band looking for the previously stored GUID and when it locates the specific GUID
code and confirms uncorrupted repeatable packet information, the system connects and
normal operation takes place. Typically this takes 2 to 6 seconds.
2. Q: Sometimes the system takes longer to connect and sometimes it doesn’t connect at all.
A: In order for the system to connect (after the receiver is bound) the receiver must
receive a large number of consecutive uninterrupted perfect packets from the transmitter.
This process is purposely critical of the environment ensuring that it’s safe to operate when
the system does connect. If the transmitter is too close to the receiver (less than 4 ft.) or if
the transmitter is located near metal objects (metal TX case, the bed of a truck, the top of a
metal work bench, etc.) connection will take longer and in some cases connection will not
occur as the system is receiving reflected 2.4GHz energy from itself and is interpreting this
as unfriendly noise. Moving the system away from metal objects or moving the transmitter
away from the receiver and powering the system again will cause a connection to occur. This
only happens during the initial connection. Once connected the system is locked in and
should a loss of signal occur (failsafe) the system connects immediately (4ms) when signal
is regained.
System
Features
Typical Range
Power
System Test
Guidelines
Receiver
Power System
Requirements
Tips on Using
Spektrum
2.4GHz
Inadequate or intermittent power to the receiver that is unable to provide the necessary
minimum voltage during operation is the number one cause of control failures with Spektrum
systems. Some of the power system components that affect the ability to properly deliver
adequate power include:
• Receiver battery pack (number of cells, battery construction quality, connector and state
of charge)
• The ESC’s capability to deliver current to the receiver and servos in electric vehicles
• The switch harness, battery leads, servo leads, regulators etc.
All Spektrum receivers have a minimum operational voltage of 3.5 volts. If the voltage drops
below 3.5 volts, the system will cease control until power is regained.
If a questionable power system is being used (e.g. small or old battery, ESC that may
not have a BEC that will support the servo’s current draw, etc.), it is recommended that a
voltmeter be used to perform the following test.
Plug the voltmeter into an open channel port in the receiver and with the system on, load
the servos (apply pressure with your hand) while monitoring the voltage at the receiver. The
voltage should remain above 4.8 volts even when all servos are loaded. For gas vehicles,
tap and twist the receiver battery pack while watching the voltmeter. Some battery packs
have poorly welded tabs that give only intermittent power. Such a defect will show up during
shock and vibration, so this test will verify that the battery construction is good.
Your system’s range can vary greatly due to your installation and the environment. In most
cases you should be able to have full control of your vehicle to the limits of sight (about 300
ft with a 1/10-scale car). If range issues exist your installation can be optimized by extending
the receiver’s antenna as vertically as possible locating it as high in the vehicle as practical
and also by routing the antenna away from any onboard electronics.