IRC Ghost Atto Duo Manual de usuario
Rev 1.4 - Oct 2020
Introduction, and History
Back in early 2013, when FPV was still in its infancy, and mini-quads hadn’t been invented yet,
ImmersionRC introduced the EzUHF 433MHz remote control system.
In the early days, this system was used for some of the most iconic fixed-wing FPV flights, pushing
limits out past 10s of km.
Since then, FPV has evolved massively, and now, 7 years later (4 years after development started), it
is time to bring a new innovative R/C link to the market.
Ghost doesn’t run on 433MHz, nor does it run on 868/900MHz. Ghost uses an innovative new
chipset on the 2.4GHz band for some very good reasons.
Why 2.4GHz, Are We Nuts?
At first glance this seems to be a questionable design decision, after all, shouldn’t ‘UHF’ systems run
on 433MHz, or 868/915MHz?
In Europe, the 868MHz band, commonly used for controlling hobby-class drones, has a couple of
serious limitations. Firstly, the entire (legal) band is only 2MHz wide (vs. 76MHz for 2.4GHz). This is
just not enough bandwidth to run more than a small number of systems simultaneously, and is just
not suitable for racing.
Secondly, duty-cycle limitations which allow other potentially life-saving equipment (fire alarms,
home automation, medical systems) to co-exist on this band, make it a poor choice for low-latency,
high duty-cycle model control.
The chirp-spread-spectrum technology used by the Internet of Things (LoRa WAN, etc.) when run on
the 2.4GHz band has some serious advantages, including:
- Tiny antennas, 2.4GHz antennas are only 36% of the size of the equivalent on 868MHz
- Much wider band, 76MHz vs. 2MHz on 868MHz (or 26MHz on 915MHz)
- Much better sensitivity (= much longer range) than traditional 2.4GHz systems
- Much better selectivity (adjacent channel rejection) than traditional 2.4GHz systems
- Much smaller directional antennas for the really crazy long range missions
- More range than 99% of pilots need, and with a higher gain (but still small) Tx antenna,
comparable range with 868/915MHz systems.
- Enough bandwidth to run 150Hz+ modes using the advantages of LoRa modulation
- Lower power consumption than Sub-GHz systems for longer radio battery life
ImmersionRC Limited, Kwai Chung, NT, Hong Kong, www.immersionrc.com
Specifications
Ghost General
Frequency Range, Ghost 2G4
2406 - 2479MHz 3
Ghost Protocol
Modulation
Chirp Spread Spectrum + Adaptive FHSS 3
(With LBT for EU versions)
Binding
Bidirectional, with confirmation and protocol negotiation
RF Profiles
Initially 4, Race, Pure Race, ‘Normal’, and Long Range, more to come
Ghost JR Module Transmitter
Uplink Tx Power
16uW - 350mW (100mW EU) (+/- 0.5dB) 3
Frame Rate
222.22Hz (purerace), 160Hz (race), 55Hz (normal), 15Hz (long range)
Format
Standard JR Module, tested with most common OpenTx compatible radios.
Antennas
Twin antenna, with Tx-side diversity. Antennas are 2.1dBi Dipoles
Compatibility
Any R/C Tx which accepts JR modules (Taranis, etc. )
Serial Formats
SBus, GHST 1 - Auto-Sense
Firmware
USB Upgradable (with OTA updates for receivers)
Power Supply
6V-20V, 1.75W @ 350mW, ~250mA at 7.4V
Ghost Atto/Zepto Receiver
Downlink Tx Power
+13dBm
Sensitivity
-117dBm in Long Range mode, less in Race modes
Serial Formats
SBus, SBus-Fast (200k) , SRXL-2 (400k), GHST 1, SBus Inverted 2
Firmware
Over-the-air (OTA) upgradable
Power Supply
5V recommended, 3.6-6.0V (no more than 6.0V!)
vTx Control
Tramp control from ‘T’ pin on Rx, regardless of selected serial format
Atto Dimensions
14.8mm x 11.5mm, 0.6g (w/o antenna)
Zepto Dimensions
10.0mm x 10.0mm, 0.38g (w/o antenna)
General Features
Tx-side Spectrum Analyzer
Supported, full frequency range
Rx-side Noise Floor Analysis
Auto on power-up, or on demand from the tx
1
GHST protocol available in a custom OpenTX build at product first shipment (IRC Website)
2
Sbus is inverted by definition, SBus Inverted flips it over so that it doesn’t require inverters on F4 FCs
3
Some specifications vary depending upon the regionally-specific product SKU
ImmersionRC Limited, Kwai Chung, NT, Hong Kong, www.immersionrc.com
Getting Started
OpenTx Configuration
The Ghost transmitters, and high frame rate + low latency that they can supply, are optimized for a
new OpenTx protocol, GHST.
For transmitters which do not yet support this protocol, either download one of the ‘Nightly OpenTx
Binaries’ from the Ghost page on the ImmersionRC website, or use the commonly-available SBus
protocol.
The Ghost transmitter auto-senses the R/C control protocol, no need to set anything.
For more details on the OpenTx build, along with the telemetry sensors that it supplies, refer to
section ‘OpenTx Custom Builds for GHST’ later in this document.
Make sure to disable the Internal RF when using the Ghost. Newer OpenTx builds will
enforce this, but will mean that if Internal RF is enabled, GHST doesn’t appear in the protocol list.
ImmersionRC Limited, Kwai Chung, NT, Hong Kong, www.immersionrc.com
Binding
Binding SUCKS, it really does. How many times have you had to tear apart a model to get access to
some buried bind button. How many times have you received a new ‘BNF’ model only to have to
scour the internet for an out of date manual that tells you which of the identical-looking three
buttons on the model are the bind button, and whether you need to press it while deftly plugging the
battery (three hands would be useful for this), or just after power up. How many times have you had
to find some ‘secret’ betaflight ‘CLI’ command to figure out how to bind an SPI receiver?
Then once you do find the button does the Tx need to be in E8, E16, E32, or JJAJ mode to bind
successfully?
Ghost attempts to be a little different.
New Receivers
New Receivers are shipped with bind mode enabled. For new receivers, just power them on, power up
the Tx, enter the Binding menu, and start the bind sequence.
The Rx LED will be blue when in bind mode.
The Tx will show the binding confirmation, if successful, with the ID of the receiver, and the firmware
version installed on it.
Note: To prevent surprises if the bind button is pressed during flight, the bind button is deactivated
30 seconds after the Rx is powered up. Simply cycle Rx power to re-enable if bind was intentional.
Deja Vu Binding
Deja Vu Binding records all receivers used by a Ghost transmitter and can bind to them in the future
without the need to touch the bind button on the receiver.
Receivers, after powered on, and before they have a valid connection to a Ghost transmitter,
periodically scan for transmitters attempting to bind.
This feature also enables the Ghost Updater to transfer firmware updates only for receivers that you
own.
ImmersionRC Limited, Kwai Chung, NT, Hong Kong, www.immersionrc.com
Receiver Pinouts
2G4 Atto
The smallest of the Ghost receivers, the Atto is optimized for use in race/freestyle quadcopters.
it has the following pinout:
Receiver Protocols
Ghost receivers support a number of common protocols, selected during binding.
Each has its own merits, and performance characteristics.
PWM should be used for fixed-wing flight, with 4 PWM outputs capable of driving servos, and motor
ESC.
SBus is offered (with it’s ‘Fast’ variant) as a compatibility mode, since it is supported by most flight
controllers, whether running Betaflight, iNav, PX4, etc.
SRXL-2 is the preferred protocol for Betaflight 4.2 and later, since it supports passing Link Quality
(LQ) to the OSD for a little more confidence while flying.
The GHST protocol is not supported by flight controllers at Ghost release, but will be added shortly
after.
Protocol
Frame Time
Baud Rate
Packet Duration
Channels
Telemetry
PWM
20ms
N/A
N/A
4
None
SBus
Same as RF
100k
3ms
12
None
SBus Fast
Same as RF
200k
1.5ms
12
None
SRXL-2
Same as RF
400k
800us
12
LQ passed as RSSI
GHST
Same as RF
TBD
TBD
TBD
Yes
ImmersionRC Limited, Kwai Chung, NT, Hong Kong, www.immersionrc.com
Receiver Wiring
SRXL-2 Wiring to Betaflight Flight Controllers
SRXL-2 is a bidirectional protocol which requires connecting via a single wire to a UART TX pin, NOT a
RX pin. This is the preferred protocol for Ghost receiver hookup until the GHST protocol is ported to
betaflight.
Note that F4 flight controllers may require a ‘cli’ command to enable the high speed SRXL-2 mode:
set srxl2_baud_fast = ON
Specification
Value
Gnd
Ground
5V Power
Clean 5V Power, from FC pin
Serial Out
Wire to TX pin on an unused UART. No inversion required (incompatible with most S.Bus inputs)
Serial In
Optionally wire to Tramp Telemetry pin, for Ghost control of Tramp vTx channel
NOTE: When using SRXL-2 with Betaflight, an internal setting in Betaflight does not allow
Ghost’s Long Range mode to be used. For Long Range mode (for the moment), use SBus, or
SBusFast instead of SRXL-2.
This will be resolved when the native GHST protocol is ported to betaflight.
SBus Wiring to Betaflight Flight Controllers
SBus, unlike SRXL-2, requires an inverted UART signal. Flight controllers that support S-Bus generally
have a dedicated S-Bus input, with any required inverters.
Ghost does allow SBus to be wired to a non-inverted UART input on the FC by selecting the ‘SBus Inv’
mode while binding. This causes Ghost Rx to emit a pre-inverted SBus signal.
Specification
Value
Gnd
Ground
5V Power
Clean 5V Power, from FC pin
Serial Out
Wire to SBUS pin on an unused UART. FC pin generally labelled SBus
Serial In
Optionally wire to Tramp Telemetry pin, for Ghost control of Tramp vTx channel
NOTE: If your Flight Controller does not detect a valid serial connection from the Ghost Rx,
ensure that the
Ports
tab in the Betaflight Configurator only has one
single port
enabled for
Serial Rx. If more than one is selected, the serial Rx will not work.
ImmersionRC Limited, Kwai Chung, NT, Hong Kong, www.immersionrc.com
PWM Operation for micro-Fixed wing
The Atto receiver may be used for fixed-wing applications with up to 4 servos without any additional
hardware.
Pinout for PWM mode is as follows:
Specification
Value
CH1
SBus Output ‘S’
CH2
Telemetry Input Pin ‘T’
CH3
‘3’ Pad on bottom side of PCB
CH4
‘4’ Pad on bottom side of PCB
Note: Production PCBs have ‘3’ and ‘4’ marked on the bottom of the board, pre-production doesn’t have the
markings, but pad location and function is the same.
Specification
Value
Power
20mW downlink
Sensitivity (approx)
Variable, -112dBm Normal Mode, -106dBm Race/PureRace
-117dBm Long Range
PWM Channels
4
UARTs
One, Serial_TX/Telemetry
Protocols
SBus, SBus Fast (200k)
USB
None
Firmware Upgrades
Over the air (OTA)
ImmersionRC Limited, Kwai Chung, NT, Hong Kong, www.immersionrc.com
Link Quality (passed as RSSI)
If using the SRXL-2 protocol, link quality is automatically communicated to BetaFlight.
If using other protocols, the link quality may be passed down an unused R/C channel, and betaflight
configured to that channel’s value as RSSI.
And enable the value in the OSD setup (if present):
ImmersionRC Limited, Kwai Chung, NT, Hong Kong, www.immersionrc.com
Direct Tramp Control
To control the frequency and power of a Tramp HV/Tramp Nano vTx, simply run a single wire from
the ‘T’ pin of the Ghost to the ‘TEL’ pin of the Tramp.
Note that this replaces any connection between the Tramp and the Flight Controller, which is not
required with direct control.
To set the channel/power, joystick click left from the main Ghost screen.
Move up/down to change settings, then click Send.
Note that Receivers will remember the requested vTx parameters, and will reload them into the vTx
upon next powerup.
ImmersionRC Limited, Kwai Chung, NT, Hong Kong, www.immersionrc.com
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