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WHAT FC LOOPTIME SHOULD YOU USE?

This article explains what FC looptime is and whether faster looptime is really better for your quadcopter. We’ll also talk about gyro update frequency and ESC refresh rate which is equally important.

With all the new technologies coming out every day in the FPV multirotor world, it can be hard to keep up. “Looptime”, “Gyro update frequenc Continue reading

RC RADIO PROTOCOLS: PWM, PPM, SBUS, DSM2, DSMX, SUMD

When it comes to radio transmitter and receiver, acronyms are often used: PWM, PPM, SBUS, DSMX etc. In this post we will explore the differences of these radio signal types.

These radio protocols are confusing to beginners, but often times we don’t need to be bothered to know what they are. Although it’s good to know the basic differences between these radio communication protocols and technologies, so you don’t buy the wrong one. We will also have a look at some of the technology, and see how it makes flying more reliable and safer.

PWM – Pulse Width Modulation

This is the most common and basic radio control protocol. In the old days when there were only RC fixed wings planes, the receivers were used to control the servos or ESC directly with standard PWM signal, one channel for each servo. Until today the same technology is still being used in many models.

Multirotors require at least 4 to 5 channels (sometimes even more) and you will see the same numbers of servo leads connected between the receiver and flight controller.

PWM stands for pulse width modulation. It’s an analog signal where the length of the pulse specifies the servo output or throttle position. The length of the signal pulse normally varies between 1000µs and 2000µs (micro seconds), with 1000µs being the minimum & 2000µs the maximum.

PWM radio receiver is the most common and usually the cheapest option. However due to the messy wiring, hobbyists now prefer PPM or SBUS over PWM.

PPM – Pulse Position Modulation

PPM is also known as CPPM or PPMSUM. The advantage of PPM is that only one signal wire is needed for several channels (typically 8 channels max), instead of a number of individual wires. So you should only connect the ground, power and signal cable.

A PPM signal where basically a series of PWM signals sent one after another on the same wire, but the signal is modulated differently.

PPM is what they call “analog signal in time domain” (although it can be a bit controversial  at times), channels are sent one after another and not at the same time. Therefore it’s not as accurate or jitter free as serial communications, but it’s more widely available and supported by many Flight controllers.

PCM – Pulse Code Modulation

PCM stands for pulse code modulation, it’s a data types similar to PPM. However PCM signal is digital signal (using ones and zeros) while PPM signal is analogue, which is the length of time the signal is on. PCM has the potential of signal error detection even error correction, but this still depends on the product you buy.

PCM is more reliable and less susceptible to interference, but additional conversion is required so the equipment tends to be more expensive.

Serial Protocols

Serial Receiver is a digital loss-less protocol that uses only 3 wires (signal, power, ground) for multiple channels. As the name suggests this type of receiver requires serial port on the flight controller. This includes SBUS, XBUS, MSP, IBUS, and SUMD.

SBUS (S.BUS, Serial BUS) – By Frsky, Futaba

SBUS is a type of serial communication protocols, used by Futaba and FrSky. It supports up to 18 channels using only one signal cable.

SBUS is an inverted UART communication signal. Many flight controllers can read UART input, but cannot accept inverted one (such as the Naze32 Rev5) and an inverted is required. However F3 FC’s and some FC such as Pixhawks has built-in dedicated signal inverter for this purpose.

IBUS – By Flysky

IBUS is the new flysky serial protocol. It’s a two way communication which means it can send and receive data: one port for servo data output and one port for sensors.

XBUS – By JR

XBUS is used by JR, which supports up to 14 channels in one signal wire. One of the advantages is the tiny time delay between each channel.

MSP (multiwii serial protocol)

Protocol that was created as part of the multiwii software. Basically it allows you to use MSP commands as the RC input and it supports 8 channels in one signal cable.

Graupner Hott SUMD

The Graupner SUMD is a serial protocol like Speksat and SBUS. The channels are encoded into one digital signal and have no noticeable latency. Advantages of SUMD are:

  • Compared to SBUS, SUMD doesn’t require signal inverter
  • Compared to PPM, SUMD has better resolution and no jitter while PPM has only 250 steps and always 4ms jitter

Graupner SumH

SUMH is a legacy Graupner protocol. Graupner have issued a firmware updates for many recivers that lets them use SUMD instead.

Spektrum DSM2 and DSMX

DSM2 signal is more resistant to noise, interference and other transmitters transmitting on the same frequency. It also finds a backup frequency at start-up in case the primary frequency fails. This lower the chance of losing signal greatly, however if both channels becomes unusable you may still lose the connection.

DSMX was based on and improved from DSM2, which also uses the same econding scheme. The difference is the DSMX signal is able to switch to a new frequency channel in case of cut out within a couple of milliseconds, so in theory you wouldn’t even notice the glitch.

DSM2 is still a popular technology, if you are away from sources of radio interference (such as WiFi, microwaves, and wireless security cameras), it should work just as well as DSMX. But DSMX is just more reliable.

Spektrum Satellite

A Spektrum Satellite is an additional antenna and receiver circuit that usually gets connected to the “main” receiver to improve link reliability by providing diversity reception.

What Radio Protocol and Reciever Should I use?

First of all, it depends on your radio transmitter. Personally I would prefer PPM or SBUS for multicopter in general because of the simple wiring. However for drone racing and freestyle I would choose SBUS due to it’s minimal lag.

 

 

WHAT IS DSHOT ESC PROTOCOL

This artical is credit to Mr. Oscar Liang from Oscarliang.com

DShot is a new communication protocol between flight controller (FC) and ESC, substitute to Oneshot and Multishot. DShot stands for Digital Shot.

The project is developed by Flyduino in collaboration with Betaflight. Many might be surprised by how fast things are moving forward: Multishot has only just been implemented and adopted by the mini quad FPV community, and now there is already a newer, better technology a few months later.

Learn about other existing ESC Protocols:

Advantage of DShot

Compared to Oneshot and Multishot, we are informed that DShot is better because:

  • No More ESC Calibration Required (no oscillator drift)
  • More Accurate ESC Signal, and more robust against electrical noise
  • Higher Resolution of 2048 Steps, compared to others of 1000 steps
  • Faster Than Oneshot
  • Safer, every signal has cyclic redundancy check

So What is DShot, Really?

DShot is a digital protocol!

Standard PWM, Oneshot125, Oneshot42, and Multishot these are all analogue signals. They all rely on the length of the electrical pulse to determine the value being sent. Analog signals have potential issues with value accuracy because:

  1. Due to the possibly different speed of the oscillators in ESC’s and FC, the length of the pulse might not be measured accurately. This is also the reason why ESC calibration is required to sync the oscillators
  2. Electrical noise (voltage spikes) can corrupt analog data

With digital protocol, there won’t be any of these problems. It’s exciting to know that ESC calibration will no longer be necessary. Because of the nature of digital signal, which is one’s and zero’s, it will also be much more resistant to electrical noise.

How Fast is DShot?

Options: DShot600, DShot300, DShot150

There are 3 speed options with DShot, the numbers are indication how much data is sent per second.

  • DShot600 – 600,000 bits/Sec
  • DShot300 – 300,000 bits/Sec
  • DShot150 – 150,000 bits/Sec

Calculate Latency

Firstly we need to know how many bits are in a data packet, then divide the speed of the protocol. A DShot data packet consists of a total of 16 bits: 11 bits for throttle value (211 = 2048 steps), 1 bit for telemetry request and 4 bit for CRC checksum (cyclic redundancy check).

For example DShot600 would have a frequency of 600,000/16 = 37500Hz = 37.5KHz, which means it will take about 26.7uS to send a single throttle value from FC to ESC.

Speed Comparison

In comparison to the speed of Oneshot125, Oneshot42 and Multishot, we have the following table (assuming signal is at 100% throttle)

  • Oneshot125 – 250 uS
  • DShot150 – 106.7 uS
  • Oneshot42 – 84 uS
  • DShot300 – 53.3 uS
  • DShot600 – 26.7 uS
  • Multishot – 25 uS

The fast transmission speed of DShot will theoretically allow up to 33KHz FC Looptime. (Not as high as 37.5KHz because there needs to be some space between values). Although DShot600 is not quite as fast as Multishot, as long as it’s faster than FC looptime then it’s plenty enough 🙂 With all other advantages we’ve discovered so far, it still out-weights that small speed difference.

What ESC Supports DShot?

BLHeli_S ESC

Currently certain ESC’s that run BLHeli_S firmware  will support DShot. Such as Cicada, Racerstar V2, Aikon SEFM, TBS 25A, Lumenier 30A, DYS XS30A, etc. However these ESC’s have speed restriction and only support up to DShot300, some can only run DShot150. According to Steffen Skaug (BLHeli Developer), future ESC’s that use EFM8BB21x chipset will be able to run DShot600.

DShot for BLHeli_S is being developed by BLHeli and Betaflight team, if you would like to know more such as known issues, full list of supported hardware etc, please check here.

KISS ESC

KISS 24A ESC supports DShot with all 3 speed levels, available to choose from in their Chrome GUI configurator (even the highest speed – DShot600).

KISS 24A ESC’s use STM32 processors, our mini quad FC’s also use  STM32 MCU’s. Between these STM32 chips they have something called DMA controller (Direct Memory Access) that communicate directly between them. This allows faster DShot signal as it doesn’t use much additional processing resource that might cause delay.

Requirement For Flight Controller

Looks like only F3, F4 flight controllers can run DShot at the moment.

For example, X-Racer F303 flight controller runs on the open source Cleanflight software and its compatible with the Bores B. Betaflight firmware.

 

2016-multigp-drone-racing-championship-group-photo

2016 MultiGP Drone Racing Championship

Pictures & Contents from MultiGP.com

 

The 2016 MultiGP Nats set a new standard in drone racing. A standard governed by this one simple rule, “By Pilots. For Pilots.”

We believe an open invitation combined with structured competition defines a sport. Our 2016 MultiGP Drone Racing Championship was designed to seek out the nation’s top pilots and it delivered.

Participants competed against well-known pilots and undiscovered talent, giving our sport the foundation and platform it needed to develop and showcase it properly. MultiGP is delighted to share with you our ranked pilot lists, stunning snapshots and heart pounding videos of our annual championship. Enjoy pilots…you deserve it.

 

2016-multigp-drone-racing-championship-1st-place-shaun-taylor

The 1st Place: Shaun “Nytfury” Taylor

2016-multigp-drone-racing-championship-2nd-place-jordan-temkin

The 2nd Place: Jordan “Jet” Temkin

2016-multigp-drone-racing-championship-3rd-place-siddha-kilaru

The 3rd Place: Siddha “SIDFPV” Killaru

  2016-multigp-drone-racing-championship-full-52-ranking-results

The Fastest 52 Pilots in the Nation

rs2205s

EMAX Released New RS2205S Red Bottom Motors

EMAX newly released a upgraded version of the Red Bottom RS220S racing motors, the RS2205S. Available in 2300kv and 2600kv as the same to previous version. Purchase the EMAX RS2205S motors from FPV Model.

The completely redesigned RS2205-S is upgraded with features racing multirotors absolutely need. The motor is lighter, yields faster bell rotational response, higher thrust, uses premium materials and backed with EMAXs legendary production quality.

Lighter and Lower Profile
2 grams lighter than the first version of the RS2205, the RS2205-S is a 2205 motor which has been overhauled for the weight conscious racer. The bell has been redesigned to have a lower profile without sacrificing the structural integrity of the motor. This eliminates unnecessary mass and allows quicker rotational response of the bell. The shorter motor height allows a lower center of gravity closer to the mounting point.

Cooling
RS2205-S cooling fins have been reworked to keep the motor height and weight low while maintaining functionality.

N52SH Curved Magnets:
By utilizing N52SH curved magnets, the pulling force between the stator and magnet is greatly increased. The design of the motor extracts every bit of force from these magnets and keeps it constant throughout the phases.

Bearings
Japanese NMB bearings ensure smooth, long-lasting performance.

Thrust
Compared to the RS2205, the new RS225-S cranks out another +100g of thrust. Paired with a KingKong 6×4 propeller, expect over 1,400 grams of thrust (Check out the full motor results:http://www.miniquadtestbench.com/emax-rs2205s-2300kv.html).

Hollowed Steel Prop shaft and main shaft
The upgraded shafts maximize durability. No worry of damaging threads during crashes.

Bell Retaining Screw
No more E-Clips. With a retaining screw, RS2205-S has no chance of having bells pop out during a race. It is also easy to service the motor without needing a special tool.

EMAX Legendary Production Quality
Engineered and produced In-House with state-of-the-art production techniques and machines, every motor that comes out of our factory is guaranteed to have the tightest build tolerances. It is with this ability, that we can achieve 0.10mm magnet to stator air-gap and crash-durability racers come to love.

4th Hong Kong Drone Race Will be Held on 12/11/2016

The 4th Hong Kong Drone Race 2016 will be held at MX Club, Sheung Shui, Hong Kong. The race is organized by Hong Kong FPV Racers

Race Date: 11 DEC, 2016
Entry Deadline: 5 DEC, 2016

Race requirements:
Drone size 130-250mm, Power 4s Battery, Max Voltage 16.8V, Prop size 5 inch or below, VTX POWER 25,200mw (recommend adjustable VTX, e.g. TBS Unify Pro, 40ch include Race Band, Any Flight Controller, Quadcopter only.
All age is welcomed, age under 18 need parents consent to participate.
A confirmation email will be sent to you if you are accepted as participant.

Seat is limited. The entry fee is $200HKD. Please sign your name HERE to enter the race.

For information please email to bernardyiu@gmail.com
Hong Kong FPV racers: https://www.hkfpvracers.com

poster-4th-hkdr

p4

DJI Announced the New Phantom 4 Pro

Further to the Inspire 2 Announcement DJI have announce the New Phantom 4 Pro.

This new upgraded version of the P4 has had an very big overhaul since the original Phantom 4 launch earlier in the year.

The Body

The adoption of titanium alloy and magnesium alloy construction increases the rigidity of the airframe and reduces weight, making the Phantom 4 Pro similar in weight to the Phantom 4, It’s flight control system is the same as the P4 but it now uses an upgraded Lightbridge HD video transmission system that adds 5.8 GHz transmission support with the ability to choose between 2.4Ghz and 5.8Ghz, this allows pilots to cut through interference and eliminates image lag caused when flying in an area with extensive interference.

The Lightbridge HD video transmission system used in the Phantom 4 Pro uses TDM (Time Division Multiplexing) to transmit signals, allowing it to send controller signals and receive video transmission signals at the same frequency. As the 2.4GHz frequency band is often affected by Wi-Fi, 4G cell towers, and other types of interference in urban areas, a 5.8Ghz band will increase transmission reliability. When switched on, the Phantom 4 Pro evaluates local signal levels, automatically choosing the transmission frequency with the lowest level of interference. This ensures the optimum range of a maximum video transmission of 4.3mi (7km)*

The first big change to the P4 Pro is its now fitted with a all new 1-inch 20-megapixel sensor capable of shooting a maximum of 4K/60fps video and Burst Mode stills at 14 fps, its also capable of recording 4K 30Fps in H265 as well.
DJI say its their first camera to use a mechanical aperture, this eliminates rolling shutter distortion that can occur when taking images of fast moving subjects or when flying at high speed, Its also fitted with a mechanical focus as well, In effect DJI believe it is as powerful as many traditional ground cameras out there.

With more powerful video processing it now supports 4K 60fps video on H.264 and 4K 30fps in H.265, both with a new 100Mbps bitrate, this means the sensors and processors can captured with more image detail than anything else in this class out there.

Sensor size is more important to image quality than the number of pixels because a larger sensor captures more information in every pixel, improving dynamic range, signal-to-noise ratio, and low light performance. The 1-inch 20-megapixel CMOS sensor in the Phantom 4 Pro is almost four times the size of the Phantom 4’s 1/2.3in sensor and it uses larger pixels. Maximum ISO is 12800 as well as increased contrast.

An enhanced video processing system allows video to be captured in cinema and production optimized DCI 4K/60 (4096 x 2160/60fps) at a bitrate of 100Mbps, enabling you to get high-resolution slow motion shots.
The Phantom 4 Pro also supports the H.265 video codec (Maximum resolution 4096X2160/30fps). For a given bitrate H.265 doubles the amount of image processing as H.264, resulting in significantly enhanced image quality. Record in the high dynamic range D-log mode to make the most of this image data for color grading.

This is a huge step forward compared to where we have been with the previous generation Phantom 4.









The Phantom 4 Pro has a new larger 5870mah battery, its the physical size as the original Phantom 4 pack and is believed to be backwards compatible with the Phantom 4, this new larger capacity battery allows a maximum flight time of 30 minutes providing more time in the air to capture the perfect shot. The DJI GO app shows battery lifetime and calculates remaining flight times according to distance traveled and more. It will give alerts when it reaches a minimum safe amount required for a safe journey back to the takeoff point. An advanced battery management system is also in place to prevent overcharging and over draining. When placed in longer term storage, batteries will discharge power to maintain good health.


 

betaflightf3

FPVModel Released New BetaflightF3 Flight Controller

FPV Model released a new Betaflight flight controller on November 15th, 2016.

FPV Model has been working with Betaflight on the flight controller for over several months. A lot of time and effort has been put into this.  With the technical support from Hector Basil Hind and Boris B., finally stuck with what will be the finished product.

The BetaflightF3 is an all in one design, designed to fit those critical builds but give the users the options they most commonly use, all the while keeping the same standard footprint of most flight controllers used. PDB, OSD(betaflight configurator), SD Card writer, 3A power draw, DShot compatibilty…the list goes on.

The BetaflightF3 flight controller will be around the end of November. Let’s keep an eye on it.

BetaflightF3

BetaflightF3