against, can occur to the
Hitchiker
channels or
regular servo channels. This can be avoided by
proper frequency control protocol and turning on
your transmitter first, then your model. Reverse
procedure for powering down. For secure channels
and a truly unique transmitter identification code
ask about our industrial strength
Kommander
Keykoder
systems.
When purchased as a complete system the
KeyKoder comes installed and includes a minor
internal modification to the FP7CAP transmitter
and sometimes the receiver. If your components
require modification VANTEC will do it or supply
instructions to a qualified technician in your area.
We do not recommend customers modify the
equipment.
KH712 system:
The Airplane
KH712
system is
configured differently from the 16 and 32 channel boat
and robot systems. Although the transmitter still uses the
KH16T
Keypad only 12 switches are effective.
Switches 1 through 8 on the
KH16T
KeyPad generate
only Servo Command Pulses and switches 13, 14, 15,
and 16 are the electronic switch outputs on the Receptor.
The KH12R companion Receptor doesn’t use an 18 pin
plug in terminal block. Instead it uses a pin-post
connector 2 X 5 array, sometimes called a .1" header,
labeled as Power/Switch Pairs. Mating connector pairs
with pigtail wires are included. The outputs 14, 16, 15
and 13 are the right 4 pairs. Each pair consists
of an electronic switch output and it's
corresponding ground. Be sure to connect each
output ground wire to the negative of the
battery used to power that channels device.
Usually in aircraft applications the same battery
is used for all devices.
The left-most pair of the Power/Switch Pairs is
the preferred power input connection for the
KH12R
. The ideal power supply for the
KH12R
is +12VDC connected to this pair's +D
pin-post, with the negative connected to the
pairs ground pin. The voltage input here may
range from 4.8-30VDC. When or if power is
not supplied to +D pin post then power and
ground for the Receptor will be derived
automatically from the 4.8VDC power input for
the
Hitchiker
servos "J" style "Bat" connector.
The
Hitchiker
is comes with a limited one year
warranty based upon a fixed repair charge for
units not tampered with, imersed or electrically
or mechanically abused. Call before returning
unit for repair. These products are not safety
devices nor for use in life-critical or life-
support systems. Specifications and prices
subject to change without notice. Patents and
patent pending may apply. Some trade names
and trademarks owned by others.
THE PCM ADVANTAGE
Early R/C transmitted each channels servo position as an analog pulse width that
ranged from 1-2 milliseconds. The pulses were transmitted as a continuous Radio
Frequency energy carrier with their beginning and end marked by Amplitude
Modulating the RF carrier "off" for 0.35 ms. The channels were sent sequentially with
the .35ms end mark of one serving as the beginning mark of the next channel. A
special long pulse delineated the beginning of the channel series, called a Frame. The
receiver used the marks to determine the channels, otherwise the receiver was dumb.
Any noise or interference in the "air" was interpreted as a marker pulse and mis-
commanded the servos because the receiver couldn't tell the difference. FM versions
suffer the same problems.
The Pulse Code Modulation receiver is smart; it contains a microprocessor. By clever
structuring of the servo commands using mathematics and precise timing PCM
facilitates accurate reception even with severe noise or interference.
It begins in the transmitter by conversion of each joystick position into a 10 bit digital
word plus bits to enable the receiver to mathematically verify the word. The next trick
of PCM is to compact this data representing 1024 servo positions/channel into the FCC
specified radio bandwidth while maintaining responsive "real time" control to fly a
helicopter. The PCM data is transmitted synchronously; each bit has a particular
position in time, within the Frame. The Frame continuously repeats. A precision
crystal controlled clock in the receiver locks onto the transmission to maintain
synchronization with the data bit by bit even during major signal drop outs. Thus the
receiver can process data immediately after interference instead of waiting for a
Framing pulse.
Received data is evaluated channel by channel. When the mathematics indicates an
error, previously validated channel data stored in the smart microprocessor is
substituted. If an error persists then failsafe servo operations previously specified by
the operator are initiated until accurate commands are again received. The
microprocessor converts the proper data into pulse widths to command the servos. No
more servo jitters!
Futaba's scheme gives 8 channels of 10 bit resolution. Other competitive systems limit
the resolution of some channels to 8 bits; 1/4 as accurate.
KeyKoder Devices & Technology
The first add-on channel KeyKoder product was sold by
VANTEC
in 1981. We have improved the product several
times since. In this fresh new design we deciphered Futaba's
PCM1024
format to capitalize on it's reliability for secure
robot applications. The on-off added-channel KeyKoder
described in this paper is fundamentally a 32 channel
KeyKoder device. In this new technology up to four
KeyKoder type devices can be piggybacked on one
PCM1024 servo channel. Four of these devices therefore
yields 128 on-off functions through a single servo channel.
Other KeyKoder device functions are available, for example
the transmitter ID and high security function, Key-on/Key-
off operation, or additional 8 bit resolution servo channels.
Some of these functions are available in our
KIK29
and
KIK44
product. A slow speed data channel is also practical;
great for radio controlled advertising blimps or "calling"
special robot functions implemented by an on board
computer.
VANTEC
is interested in your special control application
using KeyKoder technology; give us a call at (541) 471-
7135.
vantec.com
Phone:
(541)471-7135
FAX:
(541)474-3987
460 Honeycutt Dr., Grants Pass, OR 97526
0410
