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Spektrum SPMAR9100 User Manual

Page 12

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Spektrum AR9100

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Spektrum AR9100

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Your DSM2 equipped 2.4GHz system is intuitive to operate, functioning

nearly identically to FM systems. Following are a few common questions

from customers:

Q: Which do I turn on first, the transmitter or the receiver?

A: It doesn’t matter, although it is suggested to turn the transmitter on

first. If the receiver is turned on first, the throttle channel doesn’t put

out a pulse position at this time, preventing the arming of electronic

speed controllers, or in the case of an engine powered aircraft, the

throttle servo remains in its current position. When the transmitter is

then turned on the transmitter scans the 2.4GHz band and acquires

two open channels. 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 two open channels. When the

receiver is turned on, the receiver scans the 2.4GHz band looking for

the previously stored GUID. 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.

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 continuous (one after

the other) uninterrupted perfect packets from the transmitter. This

process is purposely critical of the environment ensuring that it’s safe

to fly when the system does connect. If the transmitter is too close

to the receiver (less that 4 feet) or if the transmitter is located near

metal objects (metal transmitter case, the bed of a truck, the top of

a metal work bench, etc.) connection will take longer. 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 up again will cause a

connection to occur. This only happens during the initial connection.

Once connected the system is locked, and should a loss of signal

occur (failsafe), the system connects immediately (4ms) when signal

is regained.

Tips on Using 2.4GHz Systems

Q: I’ve heard that the DSM system is less tolerant of low voltage. Is this

correct?

A: All DSM receivers have an operational voltage range of 3.5 to 9 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 a single or inadequate battery/power source, heavy

momentary loads can cause the voltage to dip below this 3.5-volt

threshold causing the entire system (servos and receiver) to brown

out. When the voltage drops below the low voltage threshold (3.5

volts), the DSM receiver must reboot (go through the start up process

of scanning the band and finding the transmitter) and this can take

several seconds.

Q: Sometimes my receiver loses its bind and won’t connect, requiring

rebinding. What happens if the bind is lost in flight?

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 transmitter is put into bind mode, the transmitter looks for the

binding protocol signal from a receiver. If no signal is present, the

transmitter no longer has the correct information to connect to a

specific receiver and in essence the transmitter has been “unbound”

from the receiver. We’ve had several DX7 customers that use

transmitter stands or trays that unknowingly depress the bind button

and the system is then turned on losing the necessary information to

allow the connection to take place. We’ve also had DX7 customers

that didn’t fully understand the range test process and pushed the

bind button before turning on the transmitter also causing the system

to “lose its bind.”

If the system fails to connect, one of the following has occurred:

• The transmitter is near conductive material (transmitter case, truck

bed, etc.) and the reflected 2.4GHz energy is preventing the system

from connecting. (See #2 above)

• The transmitter was put into bind mode knowingly (or

unknowlingly) causing the transmitter to no longer recognize

the receiver.

Tips on Using 2.4GHz Systems (continued)