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Dec 09, 2014, 09:13 AM
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The Beginners' Guide to RC Protocols

POST 1 - Table of Contents (also protocols, frequencies, modulation types)
POST 2 - Link to Various Protocols used in RC
POST 3 - Link to The 2 major channel sequences
POST 4 - Link to Walkera protocol
POST 5 - Link to FrSky protocol
POST 6 - Link to FlySky protocols AFHDS and AFHDS-2 (w/telemetry)
POST 7 - Link to DSM2 & DSMX (Spektrum) protocols
POST 8 - Link to Futaba protocol
POST 9 - Link to KN protocol
POST 10 - Link to HiSky protocol
POST 11 - Link to IIX protocol
POST 12 - LINK to Various MicroChips used for RC in the 2.4MHz band
POST 13 - Link to Cheerson (YD717 protocol)
POST 14 - Link to DT-Link PROTOCOL developed by Detrum
POST 15 - Link to Miscellaneous stuff that may or may not help

POST 18 - LINK to Receiver Protocols
POST 20 - LINK to First Person View (FPV) Video Transmission frequencies

I have tried to write this thread for others like me, i.e. non-geeks or non-hackers. I use that term affectionately. I admire the ability to understand software code and write it. And I admire those that understand electricity and how to wire things with diodes, transitors, etc. so they will do whatever you want. I have very little understanding of writing code or how to do much software installation unless it is written very plainly in English and in great detail. Wiring diagrams help very little unless they are very basic, but I really need actual pictures. I can solder enough to change out a battery terminal, but not much more. As I pick up bits & pieces of info here and there I will add it to my blog here.


1. Transmitter (Tx) Protocols: Protocols have to do with how signals are formatted. Each protocol has its differences in the signal's format. Protocols are independent of frequencies. This post is primarily concerned with Tx protocols which are between a Tx and receiver (Rx) as opposed to Rx protocols which are between a Rx and a flight controller (FC).

2. Receiver (Rx) Protocols: These are address in POST 18, which is linked above.

3. Video Transmission Frequencies: There is 1 major frequency band used for video transmission in RC. It is the 5.8GHz band which covers frequencies from 5650MHz (5.650GHz) to 5925MHz (5.925GHz). Other frequencies are available and can be used, but are not as commonly used for video transmission as the 5.8GHz band is used. These frequencies are fixed and not frequency hopping as the Tx protocols are. A link to POST 20 is above.

4. Tx Frequency Bands: There are 2 major frequency bands used for Tx protocols in RC.

a.) The Citizens Band (CB) 27 - 75MHz band: The CB band includes some of the fixed frequencies from 27MHz to 75MHz. There are 4 Frequency Bands and each is divided into Channels. In the USA the Frequency Band for Model Aircraft is 72MHz, 50 Channels numbered 11 to 60. Each channel has 20KHz of separation. For surface models such as Cars, Boats, Robots, etc. the band is 75MHz, 30 Channels numbered 61 to 90. In most European countries the Frequency Band for Model Aircraft is 35MHz, 36 Channels numbered 55 to 90. For surface models the band is 40MHz, from 40.665 to 40.995MHz.

b.) The 2.4GHz ISM (Independent, Scientific, Medical) band. The ISM 2.4GHz band is a new frequency band for the RC hobby and is used with frequency hopping protocols. It starts with 2.4000GHz and goes up to 2.4835GHz. Each manufacturer of Txs design and use their own unique protocols for frequency hopping within the band.
Link to Frequencies that are allowed here:

5. Modulation Types: Modulation types are Pulse Code Modulation (PCM) & Pulse Position Modulation (PPM). This pertains to how the signal is digitally modulated versus the radio frequency type of modulation, i.e. FM, frequency modulation or AM, amplitude modulation.

Early RC Txs use frequency modulation (FM) to provide signals from the Tx to the Rx. That puts them in the upper part (27MHz) of the High Frequency (HF) to the lower part (72 & 75 MHz) , of the Very High Frequency (VHF) spectrum. The upper part of the VHF band is used for air to ground and air to air voice communications and navigation. The newer ISM band 2.4GHz Txs use FM modulation as well but on a different frequency band from earlier models. They also use Pulse Code Modulation (PCM) to code the signal in order to take advantage of PCM over PPM.

(HF = 3MHz-29.9MHz)
(VHF = 30MHz-299.9MHz)

a.) PCM Signal Modulation
PCM or Pulse Code Modulation
digitizes (1s & 0s) a FM signal. Your Rx decodes the signal. If noise is present, the Rx ignores it until it gets a good signal. It is looking for precise digital signals and ignores anything else. To use PCM you must have a computerized Tx.

b.) PPM Signal Modulation
PPM or pulse position modulation
is an analogue signal with the signal length (transmission time equals length), or pulse width representing the data being sent. PPM was popular with the early CB radios but fell out of favor with the advent of PCM due to the ability to code, do error correction and create a failsafe setting. If one of your devices needs an analogue signal, and it is receiving a digital one (PCM), it will have to be decoded to an analogue signal (PPM) before it can be used.

A detailed explanation of PPM & PCM can be found here:

Just as AM gave way to FM, PPM has given way to PCM for signal modulation. But now instead of being on the CB (VHF) band, we have switched more and more to the 2.4GHz (UHF) band. Each manufacturer has a unique way to use error correction and coding the PCM signal. Since it is proprietary, you must use each manufacturer's proprietary Tx in combination with their proprietary Rxs. Some new manufacturers have decoded or broken the code and make Tx modules and Rxs that can use mimic or use a proprietary signal with their own equipment.

That is why you cannot use just any Tx with just any Rx or model you decide to buy.The Tx & Rx protocols must match.

This thread assumes you already know the differences between RTF, BNF, Tx-R, Rx-R, RR, ARF, KIT, PNP, PNF, etc and the implications for your Tx and Rx combinations. If not you may find my blog entry Some Basic beginner terms, Small & Medium battery connector types, links helpful.
Last edited by hifinsword; May 31, 2018 at 09:19 AM.
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Dec 09, 2014, 10:59 AM
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Various Protocols used in RC

Here is a link to a very detailed explanation (at my level) of the 2.4GHz band and how it is used in the RC hobby. "RC Spread Spectrum Demystified" by David E. Buxton April 27, 2014 It is posted on by John Salt. It is pretty much over my head but maybe some one here may get much more out of it. It also debunks the claims by many of the different manufacturers of different Txs that their Txs use a better protocol than the competition.
Link to David Buxton's article:

John Salt himself also has written an explanation about the 2.4GHz band some here may find helpful.
Link to John's article:

The following is my short synopsis of the protocols I am somewhat familiar with. More seem to pop up every other week so I'm sure it is not comprehensive.

POST 12 HERE is a listing of the most frequently used chips in Txs on the market.

DSM (Digital Spectrum Modulation) is synonymous with Spektrum, E-flite, Blade &
DSSS (Direct Sequence Spread Spectrum): one type of 2.4 GHz modulation (used by Spektrum), where one or more fixed frequencies are chosen at power-on and carry the control signals. As opposed to FHSS (used by Futaba).
DSM2 protocol = It uses 2 frequencies for data transmission. It is the older of the 2 DSM protocols.
DSMX protocol = This is the newer generation of DSM that uses up to 60 frequencies for data transmission.

DMSS protocol (Dual Modulation Spectrum System) is synonymous with JR's new protocol. They originally licensed Spektrum's DSM protocol but have created their own DMSS protocol that is not compatible with DSM2 or DSMX.

FrSky is synonymous with Taranis & FrSky (pronounced FreeSky) is both a protocol & a manufacturer.
ACCST = Advanced Continuous Channel Shifting Technology); some FrSky systems use the same chip as Futaba but may or may not be compatible with Futaba.
FrSky is known for its low-cost Rxs that have telemetry.

FASST protocol is synonymous with Futaba
FASST protocol (Futaba Advanced Spread Spectrum Technology) = Futaba. It is older system than Futaba's FHSS protocol.
FHSS & S-FHSS protocols = Futaba. Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly switching a carrier wave among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver.

A-FHSS protocol = HiTec or HiTec Minima?

HiSky protocol = synonymous with WL Toys 6 Channel 3D helo collective pitch models In trying to sort out protocols, I posted a question to a HiSky official. HiSky's reply to my inquiry is here:

FlySky protocol = synonymous with many manufacturers such as Hubsan, WL Toys, Syma, DoubleHorse, GreatWall, NineEagle, etc for their 4 Channel models. Their protocols now use the designations AFHDS and AFHDS-2 (w/telemetry).

V2x2 (LanGuang) protocol = WL Toys models of V2x2 quads. The V2x2 models use a PCB manufactured by LanGuang. See the HiSky link above.

YD717 protocol = Cheerson CX-10 quadcopter

KN protocol = WL Toys models of the V977 6 axis helo uses the KN protocol. KN uses the NRF24L01 Module and is used by Feilun with their line of FX series helicopters also.

KNFX protocol = Deviation has a KNFX protocol setup in their Deviation software that differentiates it from WL Toys models KN protocol.

DEVO protocol = Walkera

DEVO protocol = Walkera S.

J6PRO protocol = Nine Eagles
Don't know anything about the signal or format to write down here. It is a separate protocol I think closely related to Futaba's and Walkera.

WK2401, 2601, 2801 protocol = Old Walkera protocol before the DEVO class of Txs were developed.

Other acronyms:
RSSI (Received Signal Strength Indication is a dB ratio) = voltage at the battery A1 port (dedicated battery) or A2 (BEC circuit) port. (MAX of 3.3Volts) maybe unique to FrSky systems? At 100M a 70 RSSI value is ideal.

A1 = always measures the voltage supplied via 1 of the 6 servo connections, usually the voltage supplied by the BEC.
A2 measures external battery voltage, i.e the flight pack. It looks like a servo connection but no servo can be connected.

RSSI = PWM signal.
CPPM signals allow a 1 wire connection to the Flt Controller.
FrSky's S.Port is used for sensors; the S.Bus is used for servos.
Last edited by hifinsword; May 31, 2018 at 09:20 AM.
Dec 09, 2014, 10:59 AM
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THE 2 major channel sequences

The 2 major Tx/Rx Channel sequences:
This pertains mainly to how receivers (Rxs) are set up. Channel sequences may be assignable for different transmitters (Txs), especially the newer computerized models. Older Txs like the Spektrum DX6i follow the same sequence as their Rxs.

T - Ch1 Throttle (THR) - Spektrum (the 3-wire servo type connector from the BL ESC goes here)
A - Ch2 Ailerons (AIL) - Spektrum
E - Ch3 Elevator (ELE) - Spektrum
R - Ch4 Rudder (RUD) - Spektrum

A - Ch1 Ailerons (AIL) - Futaba
E - Ch2 Elevator (ELE) - Futaba
T - Ch3 Throttle (THR) - Futaba (the 3-wire servo type connector from the BL ESC goes here)
R - Ch4 Rudder (RUD) - Futaba

(Separate Battery Eliminator Circuit [SBEC] if used, goes to a spare unoccupied channel)

The DSM2/DSMX (Spektrum) protocol uses TAER versus AETR by Futaba on the first 4 channel (primary control ) assignments. This was my first rude realization when I learned about the different choices.
I have no idea what other protocols use but all the channel sequences I have been exposed to follow one of these 2 major sequences.

Common to both major protocols. Each Rx may be programmed uniquely on these auxillary channels.
Ch5 - GEAR/Flight Modes (Helos)/Stabilizer ON/OFF
Ch6 - FLAPS/Gyro (Helos)/AUX1 (Left Aileron [LAL])/Stabilizer ON/OFF

Found on Lemon-Rx receivers (and some others). Each Rx may be programmed uniquely on these channels.
Ch7 - AUX2 On Lemon-Rx receivers, 2nd BIND port used to change servo frame rates.
Ch8 - AUX3 On Lemon-Rx stabilizers/receivers used to control Master Gain inflight.
Last edited by hifinsword; Oct 08, 2017 at 04:33 AM.
Dec 09, 2014, 11:00 AM
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Walkera protocol

Walkera's DEVO line of Txs opened the door to open source firmware for Txs. I don't own a Walkera or DEVO Tx or product. But their influence on many new lines of hacking the DEVO 7e and others has led to actual multiple protocol Txs for those clever enough to hack the hardware and/or develop the software.

The main source for new developement is

Other links:

Link to POST 14 on the Walkera S Tx module in the "Mini-HowTo DIY Multiprotocol TX Module Reply to Thread":

Walkera 1 x A7105 Wireless RF 2.4GHz Transceiver Module link here:

DEVO = Walkera. This is an open-source protocol Walkera came out with. It had no code protection and was hacked. That hacked product is the firmware still being developed by I believe a variation of the original code is used by many of the FlySky products. I'm not sure that it is actually different from FlySky but possibly only uses opposite channel directions. This seems to be the case for many of the products using FlySky. The same Tx can be used with channel reversing being the only problem. When the DEVO line of Txs was released, they became objects of development by and their guiding force.

DEVO = Walkera S.
I believe this is an update to the Walkera protocol. I'll reference post 14 from the "Thread: Mini-HowTo DIY Multiprotocol TX Module Reply to Thread" on using a new module to get telemetry on the Walkera protocol. The "Walkera S" upgrade module givies access to all CYRF based protocols. Since this is not a hackers or engineering thread, I'll leave the reference to CYRF-based protocols alone for now. Maybe someone who knows which protocols they are can comment.
Last edited by hifinsword; Jun 08, 2017 at 05:02 AM.
Dec 09, 2014, 11:00 AM
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FrSky protocol

FrSky synonymous with Taranis & FrSky is both a protocol & a manufacturer.
ACCST = Advanced Continuous Channel Shifting Technology); some FrSky systems use the same chip as Futaba but may or may not be compatible with Futaba.
FrSky is known for its low-cost Rxs that have telemetry.

FrSky Rxs
FrSky V mode = nontelemetry
FrSky D mode = telemetry (aka D8)
FrSky D8 mode = 8 Channels (D=duplex?) telemetry
FrSky D16 mode = 16 Channels (D=duplex?) telemetry (aka X mode) mode
FrSky L mode = long range mode (nontelemetry)

FrSky Tx modules
Old V8FT, V8JT, V8HT TX modules could only transmit in V mode.
Current DJT, DFT, DHT can operate in V and D mode.
New XJT can operate in D (aka D8), D16 and L modes.
Last edited by hifinsword; Jan 16, 2015 at 11:46 AM.
Dec 09, 2014, 11:00 AM
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FlySky protocols AFHDS and AFHDS-2 (w/telemetry)

FlySky = synonymous with many manufacturers such as Hubsan, WL Toys, Syma, DoubleHorse, GreatWall, NineEagle, etc for their 4 Channel models. FlySky (FS) is both a protocol & a manufacturer. The early FlySky protocol used with the 4Ch helicopters and quads was notorious for not having a failsafe or range testing feature. Like IIX by RadioLink, the signals between Txs can interfere with other FS Rxs if more than one is operating at the same time.

More recently FS seems to have taken up the Automatic Frequency Hopping Digital System or AFHDS acronym as a protocol name. It may be due to their newest protocol, the AFHDS-2. That newest protocol has telemetry capability. The older AFHDS protocol does not have telemetry. The FS-i6S Tx is NOT backwards compatible with AFHDS. It is strictly a AFHDS-2A (2nd generation) protocol Tx.

The newer FS Txs do have failsafe and are now available in 6 & 10Ch Txs here at BG among others. The FS-i6 & FS-i6B can be hacked and have the FW updated to be 10Ch Txs. The FS-iA6S & X models may also be updateable to 10Chs but I have not investigated that further. If you want to get a 10Ch Tx for less than $50, read this thread on hacking the FS-i6 family (includes the iRangeX) of Txs. Link -!

They have Txs ranging in price from about $16 on up to $190. I have a $25 Tx that came with my V913 4Ch helicopter that flies it quite well. It seems comparable to my $170 Spektrum DX6i as far as feel and capability to fly the a/c it was designed to fly. My DX6i has many more features like a timer, and ability to program that the basic FS Tx I have does not have. But I have had to open each for minor problems and repairs.
Last edited by hifinsword; May 31, 2018 at 09:33 AM.
Dec 09, 2014, 11:00 AM
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DSM2 & DSMX compatible protocols

In 2014 Spektrum released new models for the DX6, DX7, DX8, DX9 & DX18 with new voice alert technology using the AirWare software.
Link to Spektrum aircraft radio systems:
Spektrum uses TAER vs AETR by Futaba on the first 4 channel assignments. This bears repeating for a newbie when trying to setup a new system. The newer Spektrum DX series Txs with AirWare software allow the user to reassign channel assignments. There may be others that allow reassignment as well.

T - Ch1 Throttle - Spektrum
A - Ch2 Ailerons - Spektrum
E - Ch3 Elevator - Spektrum
R - Ch4 Rudder - Spektrum

1. Rock solid reputation on performance of their Txs & full-range Rxs.
2. The higher end starting with the DX6i have a nice feel and quality components.
3. The newer AirWare models have a SD card that can store almost unlimited models. The AirWare Txs can hold up to 250 models internally.

1. Expensive. This is a relative term. I use it for Txs over $150 for a Tx without a Rx.
2. Spektrum reuses old names for Txs such as the DX6. The original DX6 came out prior to the DSMX protocol as far as I can tell. In 2014 Spektrum released a new DX6! It is a totally different new Tx bearing no resemblence to the old DX6. There is no designation such as Gen.2, Ver.2, etc. To know exactly which Tx you are using, you must know the SKU or MODEL code.

At one time in the early phases of developing DSM, JR was in collaboration with Spektrum. From what I've been able to determine, it no longer is but their older products are compatible with Spektrum. Around 2011 or 2012, JR came out with their own unique protocol, Dual Modulation Spectrum System (DMSS), that is not compatible with DSMX. JR products have a very good reputation.

Lemon-Rx makes DSM2 & DSMX compatible Rxs, telemetry modules and a stabilzer. These have been called knockoffs, fakes, etc. But they are their own unique technology. They are no more fake or knockoff than a Pepsi is a knockoff of Coke. They are DSM2 & DSMX compatible. They do not advertise themselves as DSM2 or DSMX products.

(started May 2014): Rxs thread oldest Lemon-Rx thread
(started Nov 2012): Lemon-Rx Rx/Stab thread
(started Oct 2014): Lemon-Rx System Telemetry thread

PROs: has produced a range of 6 to 10 Channel Rxs compatible with the DSM2/X line of Txs. They also have a new line of telemetry modules. Their 7Ch/Stab has an excellent reputation for range, ease of use, size and performance.
Lemon-Rx receivers are 1/3rd to 1/4th the cost of similar Spektrum Rxs.

None unless you are looking for a bigger selection of products. They currently produce a Rx/stabilizer, Rxs & sensor modules.

OrangeRx sold by HobbyKing:
Just as Lemon-Rx products are inexpensive, so are HK's line of Orange-Rx products. HK carries a full range of OrangeRx Txs, Tx modules, Rxs, Stabs.

There is some question as to whether or not different Txs can shoot down an Orange Rx. OrangeRx has duplicated only a limited number of Unique IDs for transmission compared to the large number Spektrum has produced. Although the odds may be quite small, there is some debate on how likely it is.
Last edited by hifinsword; Jun 08, 2017 at 05:16 AM.
Dec 09, 2014, 11:01 AM
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Futaba protocol

Futaba uses AETR vs TAER by Spektrum on the first 4 channel assignments. This bears repeating for a newbie when trying to setup a new system.

A - Ch1 Ailerons - Futaba
E - Ch2 Elevator - Futaba
T - Ch3 Throttle - Futaba
R - Ch4 Rudder - Futaba

Futaba uses 4 protocols. Ref. September 2017 issue Model Aviation magazine, page 14, Product Spotlight segment.
1) FASSTest

The FASST (Futaba Advanced Spread Spectrum Technology) has telemetry. The S-FHSS (frequency-hopping spread spectrum) protocol and the FASSTest protocol are not compatible with each other. It seems the S-FHSS systems are lower cost and have fewer features. I am not sure about the S & T-FHSS protocols and whether they are compatible with any other Futaba protocols. Futaba has come out with the T16SZ Txs that is compatible with ALL of their protocols.

FHSS & S-FHSS are a method of transmitting radio signals by rapidly switching a carrier wave among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver.

AirTronics and HiTec are also FHSS but use a A-FHSS designation.

Quote from PIPPIN at
"Due to lower output power Futaba FHSS has less range than FASST.

The Futaba FHSS antenna is not inside the Tx handle. Just open one Tx and check yourself.

Airtronics uses two different FHSS protocols along their line of air radios. The cheaper one called FHSS-1 is similar to Futaba or Hitec's FHSS. The second more advanced protocol called FHSS-3 uses the whole band, is faster and has some extra features like strong interference resistances, temperature resistance, low voltage (down to 1,2V) etc."
Last edited by hifinsword; Aug 28, 2017 at 06:24 PM.
Jan 16, 2015, 09:55 AM
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KN protocol

The KN protocol is used mainly by the Feilun Company and used in their FX series of helicopters. It is also used by WL Toys in their helicopters, the V966, V977, V988 & V931.

Note: The lower numbered WL Toys helicopter models in the V9xx series such as the V922, V933, etc. use the HiSky protocol.
Last edited by hifinsword; Jan 03, 2016 at 11:09 AM.
Jan 16, 2015, 07:21 PM
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HiSky protocol

HiSky protocol
This is both a manufacturer and a protocol. They make the highly popular series of quads and helos. One of the most popular is the fully brushless (BL) HCP100S.
There is a Tx module you can add to a Tx that accepts a JR form module such as the TH9X Tx. The HT8 module transmits the HiSky protocol (FHSS ).
You can find them here:

You can find out more on it here:

Some of the HiSky & Align helicopter Rxs come with a port for a satellite Rx. With a specific Rx and satellite using specific HiSky setups, you may be able to use DSM2/DSMX protocol Txs with HiSky products. See the linked thread above for more details.
Last edited by hifinsword; Jan 03, 2016 at 11:11 AM.
Mar 15, 2015, 08:56 AM
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IIX protocol by RadioLink

RadioLink is a fairly new company that sells the RadioLink Txs and Rxs. It appears not to have the same robust signal form as other better known brands have. Like FlySky (FS), the signals between Txs can interfere with other FS Rxs if more than one is operating at the same time.

The protocol is IIX. The channel sequence is Futaba's AETR.

They have 2 RCGs threads. Their thread covering the older model AT10 Tx is here:

The AT10 seems to be a Futaba 10C clone.

The rep's handle is RadioLink and his most comprehensive post on that thread is # 10 on Page 1. According to RL, their protocol is "not compatible with any other brands receivers and any other brand transmitters".

Their thread covering the newer AT9 Tx can be found here:

Another rep's handle is RadioLink520. His name is Michael Huang.

HobbyKing (HK) sells a RadioLink version using the Turnigy brand. They are not completely compatible it seems.
Last edited by hifinsword; Dec 29, 2015 at 07:30 AM.
Dec 29, 2015, 06:36 AM
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Various MicroChips used forRC in the 2.4MHz band

Transceiver Chips or Integrated Circuits (ICs) used by the 2.4GHz RC radios:

•'s article -
• AtomicSkull's POST# 36 Thread: Discussion protocol: why so many? -
• David E. Buxton's article dated 27 April 2014 -
• Google spreadsheet -

RF Chips:
Micro Linear ML2724 RF Chip used by Futaba FASST.
Cyprus CRYF6936 RF Chip used by JR/Spektrum’s DSM, DSM2, DSMX, JR Pro, Walkera Devo.
Texas Instruments CC2500 RF Chip used by JR DMSS, HiTec, Corona, FrSky, Tactic, Futaba S-FHSS, Skyartec, Wi-Spy’s USB spectrum analyzer.
Amiccom A7105 RF Chip used by FlySky AFHDS/AFHDS-2A, Turnigy, Hubsan, HK6S brands.
Nordic Semiconductor NRF 24L01 RF Chip used for lots of protocols. Some I'm aware of are Hisky, Syma, Assan, WL Toys V2x2 quads, WL Toys V977 helicopter, Feilun's line of FXxxx series of helicopter, Cheerson CX-xx quads (YD717 protocol), and all new SYMAX products.
STM32 RF Chip used by GAVIN brand for the protocol. It is part of the Dynam/Detrum brands. Ref: HERE
Last edited by hifinsword; May 04, 2018 at 02:55 AM.
Jan 03, 2016, 10:42 AM
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Cheerson (YD717 protocol)

Cheerson (YD717 protocol) Cheerson uses the NRF24L01 chip.
Cheerson is a new protocol for me. I see they have a line of quads, the CX-10 and the improved CX-10A, CX-11, CX-20 & the CX-30W .
Link here to POST 770 about the Cheerson protocol on the "DIY Multiprotocol TX Module" thread
Last edited by hifinsword; Jan 03, 2016 at 11:29 AM.
Jan 03, 2016, 11:29 AM
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DT-Link PROTOCOL developed by Detrum

Detrum/GAVIN have developed a new protocol that uses the AETR channel sequence. You can find out more about it here on the "Detrum GAVIN-8C Transmitter with Two Innovations" discussion thread.

If you do a search at MotionRC, search for "Gavin" and their family of Rxs and Txs will come up.
Last edited by hifinsword; Mar 12, 2018 at 05:07 PM.
Jan 03, 2016, 11:32 AM
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Miscellaneous stuff that may or may not help

When you talk channels, AUX (auxillary) channels, switches, they often get confused due to where they are located, i.e. on the Tx, Rx, or may refer to an assignment somewhere in the Tx software. When you read Ch3 is for the ELE, it may mean on the Rx and on the Tx, depending on the Tx you are using. Non computerized Txs and the older computerized Txs like the DX6i use whatever Ch the stick or switch controls to control that Ch on the Rx. The stick or switch that controls Ch. 3 will control Ch. 3 on the Rx that is plugged into that channel. Depending on the brand (protocol) Ch3 may refer to the Throttle or the Elevator if you are talking about the Tx assignment. The stick on the Tx may be labeled "Elevator". Newer programmable Txs like the DX6, DX7, DX9, DX18, can have Ch3 assigned to any stick, button, knob or switch on the Tx, and to any function, not just the Throttle or the Elevator. So nowadays each brand and each specific Tx or Rx can be Channel assignment unique.

So why learn the channel sequences if they can be changed arbitrarily? Because just as with computers, most of the RC world still uses old style Txs, the way most of us still use the MS or Apple operating system, not LINUX or binary code. The newer totally software controlled Txs are fairly new, and there are still plenty of the old style hard-wired Txs out there (like the DX6i). Since the market isn't all geeks or hackers the manufacturers will continue to provide what the market demands, easy to program and use Txs.


I am not an expert in protocols but I know enough to be dangerous. And knowing something about them will help you navigate and choose the products that will serve you best and hopefully cost you less in the long run.

This is not an engineer's, programmer's or geek's thread. The use of the term protocol may not necessarily be accurate how I have used it in this thread. What I believe are protocols in some cases turn out to be message formats or some other property of a protocol that is far beyond my knowledge level. This thread is to help me, and hopefully you, to understand which protocols are out there and the differences and commonalities between them. I add to it as I pick up bits and pieces here and there.

There is a lot of debate over range, resolution, reliability, etc of these different products, protocols and manufacturers. As far as most of us concerned, especially the newbies, expensive full featured transmitters (Txs) as well as cheap Txs with only basic features will fly your helo, plane, quad, etc, out to beyond where you can see the orientation.

I regularly fly my V913 to the limits of my eyesight using the basic Txs it came with. It can be bought for $25. I also fly my 1M foamies with a DX6i Tx that cost me $170 new, coupled with a Lemon Rx from that only cost me $18.90. Top brands and high prices don't give you better range necessarily. With brand names and higher prices, you are paying up for better quality workmanship in soldering, and features such as timers, better gimbals, LED displays, color screens, etc. My DX18 G1 gives me more options to use the full capabilities of the Rxs, and features of my aircraft not available with basic 4 or 6 channel Txs. Features such as inflight gain on a stabilizer may require a Tx with at least 8 channels if you have an aircraft with flaps & retractable gear. One Ch is to turn the Stab ON & OFF. Another to adjust its gain inflight. Eight channels is the new 6.

Unless you're doing FPV (first person video) or performing with a top of the line aircraft, where crashing is not an option, you will be fine with most Txs out there. Finding a retailer that stands behind the product, and a Tx that doesn't require some soldering to fix poor solder joints within the first 6 months will be your biggest challenge.


When I helped "aspoon" set up the initial Excel spreadsheet for the "Transmitter Compatibility and Protocol" at
I thought that would help me sort out all the confusion. It has certainly helped but I need a small cheat sheet I can look at for quick reference so I created this BLOG entry to help me get info quickly.

Another helpful data sheet is the "RC Model database" developed by and is found here:

The European Telecommunications Standards Institute (ETSI):
The ETSI standards EN 300 328 Version 1.9.1 defines the spectrum sharing mechanisms and requires transmitters outputting more than +10 dBm EIRP to use Adaptive Frequency Hopping. This requirement does not apply for equipment with a maximum declared RF output power level of less than 10 dBm EIRP or for equipment operating in a mode where the RF output power is less than 10 dBm EIRP. This would in effect outlaw the DSM2 protocol were it broadcast at a level above 10 dBm EIRP. Currently DSM2 is not setup to do so by Spektrum. Txs using the DSM2 protocol are no longer sold in Europe. Ref:

LBT = Listen Before Talk is an EU (ETSI) standard EN 300 328 Version 1.9.1 standards requirement of any manufacturer of Txs with a MU (medium utilization factor) of greater than 10% to not sell any Tx that is not capable of listening on a frequency before transmitting on it. The frequency must be open before transmission. The standard seems to be a draft as of 1/22/2015.
Ref: 300 328 v1.8.1&matchall=true&matchany=false&matchexact=tru e&title=true&keywords=true&ed=true&versions=fals e

If you can add clarity to any of this, please post.

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