Spektrum SPMSR301 - Manual (Page 4)

EN
Failsafe
Failsafe positions are also set during binding. In the unlikely event that the radio link is lost
during use, the receiver will drive the servos to their preprogrammed failsafe positions (nor-
mally full brakes and straight steering). If the receiver is turned on prior to turning on the
transmitter, the receiver will enter failsafe mode, driving the servos to their preset failsafe
positions. When the transmitter is turned on, normal control is resumed.
Tips on Using Spektrum 2.4GHz
Your DSM equipped 2.4GHz system is intuitive to operate, functioning nearly identically
to FM systems. Following are a few common questions from customers.
1. Q: Which do I turn on fi rst, the transmitter or the receiver?
A: It doesn’t matter, if the receiver is turned on fi rst, all channels will be driven to
the failsafe position 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 fi nds
the GUID (Globally Unique Identifi er code) stored during binding. The system then
connects and operates normally. If the transmitter is turned on fi rst, the transmitter
scans the 2.4GHz band and acquires an open channel. When the receiver is
turned on, the receiver scans the 2.4GHz band looking for the previously stored
GUID. When it locates the specifi c GUID code and confi rms 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. Why?
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 use 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
refl ected 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.
3. Q: I’ve heard that the DSM system is less tolerant of low voltage. Is this
correct?
A: The SR301 has an operational voltage range of 3.5 to 9.6 volts. With most
systems this is not a problem as in fact most servos cease to operate at around
3.8 volts. When using multiple high-current draw servos with an inadequate
battery/power source, heavy momentary loads can cause the voltage to dip below
this 3.5-volt threshold thus causing the entire system (servos and receiver) to
brown out. When the voltage drops below the low voltage threshold (3.5 volts), the
receiver must reboot.
4. Q: Sometimes my receiver loses its bind and won’t connect, requiring
rebinding.
What happens if the bind is lost during use?
A: The receiver will never lose its bind unless it’s instructed to. It’s important to
understand that during the binding process the receiver not only learns the GUID
(code) of the transmitter but the transmitter learns and stores the type of receiver
that it’s bound to.
If the system fails to connect, more than likely the transmitter is near conductive
material (transmitter case, truck bed, etc.) and the refl ected 2.4GHz energy is
preventing the system from connecting. (See #2 above)