RunRyder RC
WATCH |
1 page 336 views | POST REPLY |
| RunRyder | Scorpion Power |
|
|
0| TerenceChan
rrNovice Singapore |
HD FPV in 2019 - Letâs talk about HD & FPV tech Since this is also a thread for people looking to start FPV flying as a hobby, I should probably share my findings on the DJI FPV digital system first because it is a very popular choice for High Definition First Person View(HD-FPV) flying . For starters, DJI HD FPV system is available since Sept 2019, it is such a great product, other than (IMO,) the 5.8g radiation of up to 1W fired by the goggles to the userâs head at point blank when the goggles are set to FCC mode. In CE mode, the goggles transmit at a low power 0.25W which makes it less of a concern for most Europeans whom under the law, could only use 25mw for 5.8g anyway. At this point, you would probably be asking, âAre you mistaken? Only the transmitter emits radiation, the receiver in FPV goggles only receives video signal so the goggles have no radiation!â
Well, first of all, indeed all other fpv goggles only receive video signal. However, the receiver in our goggles still produces radiation because most receiver modules have some sort of an LNA (low noise amplifier) in-built. I know there are LNA units by Mini-Circuits for amplifying the received 5.8ghz signal and you put that between your goggles antenna and the gogglesâ SMA. They work just like the usb-powered booster which comes with most HD TV antenna. The inbuilt amplifier is different as it is an essential component in the receiver module itself to ensure rated specs such as > 92% sensitivity or >97% sensitivity for expensive receiver such as the ClearView unit. This radiation is very little as compared to 700mw to 1w of power transmitted by DJI goggles (again in FCC mode).Yes, the goggles use 2 of its 4 antennas to transmit the receiver signal strength info to the DJI digital video transmitter (HD VTx), also known as the DJI air-module so that the air-module knows exactly how much data bitrate it needs to drop for its transmission to minimize latency issues at times of poor video reception. This translates to âmore-blockyâ video in terms of the video degradation instead of displaying freeze frames (as in the Connex HD FPV system). This tech is amazing.Having said this, I personally think that the HD system by Fatshark called âByte Frostâ is pretty neat too. It almost eliminates the latency issue entirely with a different technique, more pixels in the received video are simply turned into snow artifacts as the video reception gets poorer. Hence, you see breakups which are similar to analog FPV video except that the snow bits look kinda squarish rather than grainy. All right, thatâs enough of my rambling, hereâs the video comparing the dji HD system against the old connex HD system. |
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
|
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
 Darren Lee
rrElite Veteran Woodstock, GA |
 |
| SHARE PM EMAIL GALLERY Attn:RR Quote | |
| skew
rrVeteran KY |
TerenceChan Hereâs my findings with the Fatshark HD FPV system! As you can see, the Byte Frost is no slouch! |
| SHARE PM EMAIL GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
Darren Lee I've been flying the DJI FPV system for a couple months now. Love it! I am very impressed with the DJI system too. I like exploring different HD tech so I bought the fatsharkâs system since my buddy already has the DJI. |
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
skew Obviously you have not flown with the DJI's! I am no means a DJI fan boy but after flying them for a few weeks Fat Shark better go back to the drawing board because your still watching a worn out VHS tape compared to the experience with the DJI HD |
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
One more video that looks pretty impressive |
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
Faster recovery for ByteFrostâs HD transmission Demo of faster video recovery from full âstaticâ after firmware update |
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
|
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
|
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
|
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
Working with old Naze32 Flight Controllers Because the HD FPV âbyte frostâ vtx, micro luminier CP antenna and runcam-HD camera weigh about 26g, that is twice the weight of analog 600mw vtx stuff, my quad was having annoying wobbles in flight. I hooked up the old generic naze32 of the quad to Cleanflight and it said âsetup is only available after upgrading firmware versionâ, Chrome must have upgraded my Cleanflight as it was more than a year since I used it. As I did not want to use CLI commands to change PIDs, I clicked on the âFlash Firmwareâ button. Bad mistake! The programming failed and bricked my flight controller! The 2016 board appeared to be too old for even the oldest CF firmware in the drop down selection.I had to desolder the dsm2 rx to access the boot loader pads and short them with a jumper wire. Cleanflight was able to read the board after that but still giving the same flash failure. In the end, I used betaflight and flashed it with a BetaFlightâs naze fw. Thank goodness, it worked!After soldering the dsm2 rx board back to the FC and reconnected it to Betaflight, I realized Betaflight could not recognize the âDefault Serial (Spektrum)â for the dsm2 rx in the Configuration page. It simply would not save that selection and only âPPM Inputâ could be saved. I have a micro Lemon dsm2 rx that uses PPM but the PPM input pin is located at the bottom side of the FC (a pad labeled as âPPMâ). I decided not to go that route as it would be a waste of the original dsm2 rx board and besides, I dreaded the hassle of removing the FC which is now stuck to the quad frame with special 3M foam tape ( rc heliâs gyro type).After evaluating my options, I downloaded an old version of Cleanflight (v1.22) configurator to my PC, thinking that a configurator as old as the FC board, would definitely be able to flash Cleanflight firmware to the board. Sharks, the v1.22 Cleanflight configurator bricked the FC again, even though I was already flashing it with the old v1.9 CF firmware that was originally in the FC. Strange, how did the factory flash it then?GRRRrr.. again I had to desolder the rx and resolder that jumper wire to short the 2 boot loader pins.
This time I used Betaflight configurator to flash the same v1.9 CF firmware and to my surprise, it completed without error!I then closed the Betaflight configurator and opened the Cleanflight configurator v1.22, which connected easily to the FC .. so far so good! After soldering the dsm2 rx board back onto the FC, it was the moment of truth to see if the receiver could be detected. I connected it to Cleanflight configurator again and went to the receiver page. Voila, the channel bars were responding to stick movements on the radio and all the mapping were correct!Oh, i forgot to mention that the jumper wire had to be removed after flashing firmware , else the FC would not work after a reboot (which occurs after saving new settings).Phew! That was a tiring way to spend the evening! Nevertheless, I finally got to increase the P, I and D (more increment for âIâ) to compensate for the increased weight. Most of the wobbles are gone now.  If anyone needs the BF naze fw / CF naze fw/ old CF configurator to flash or unbrick your old naze FC:
http://www.tiny url.com/naze32old      |
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
(unfortunately my uploaded video below doesnât because YouTube degraded the actual quality).
|
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
DJI has done it again! Well DJI Digital HD transmitter had just gotten smaller with the latest release of their Caddx Vista.It comes in at 31g with the camera and antenna, a few grams heavier than the byte frost (28g). It has no onboard SD card recorder and a single antenna unlike its first standard-size unit which has 2 antennasWhatâs interesting is, with only one antenna, the transmission module has to drop the CDD or Cyclic Delay Diversity. CDD requires the 2nd antenna for the delayed data channel. And looking at the plots below which showed the SNR (Signal to Noise Ratio) over cyclic delay for indoor and outdoor, we could expect to see it perform noticeably poorer in indoor and perhaps slightly poorer in outdoor, as compared to the standard size unit. |
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
A well balanced high performance omni If you are willing to cough 30usd for the VAS 5.8ghz skyhammer antenna, you are getting a 5.25db-gain array of 2 circularly-polarized omni antennas (each one is a VAS âionâ antenna), which is the highest-gain circularly-polarized omni antenna in the world (an array is used as a single antenna so we could ignore the fact that it is made up of 2 antennas). The radiation gain pattern of the skyhammer looks like a burger with an over-stretched patty in the middle. The gain is measured from that âpattyâ. And that patty is the actual radiation pattern that is used for the video signal coverage. At 5.25db, the âpattyâ is already pretty thin which means that the skyhammer is suited for low-altitude fpv flying only. If one were to increase the separation distance between the two VAS ion antennas of the skyhammer, it is possible to get a maximum gain of 5.4db but the âpattyâ would be so thin that it is really easy to get out of the skyhammer antennaâs coverage if the drone flies higher (say above the treesâ line). After trying out various separation distances in the antenna array simulation, I get 5.1db of gain with 43mm separation, and I get a thicker âpattyâ than the skyhammer, with losing only a bit of radius of the âpattyâ. I then cut off the SMA connectors of two pagoda antennas that I have, and soldered them to a home-built microstrip PCB (matching network or Wilkinson splitter) so that they merge to produce a perfect 50ohm. Alright, I will leave you to watch my build video and the test results of it on the Fatshark HD FPV system.  |
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
2.3â prop iFlight DC2 running DJI HD After the release of the smaller Caddx Vista (smaller form-factor equilvalence of the DJI Digital FPV Air-unit), not only are companies producing smaller frame-drones such as Beta95x DJI HD Whoop, they are also more selections in the 2â to 2.5â props class. Here is a stylish 2.3â prop drone designed for the DJI HD air-unit, the iFlight Titan DC2 |
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
Super-amped ByteFrost FPV with 2.5W booster Amplifying the Fatshark HD FPV video transmission from 450mw to 2500mw. |
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
Does LNA work for digital FPV? Short answer is âYesâ. Find out more from the test video below.
|
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
PCB Biquads & Dipoles for digital FPV PCB Biquads and micro Dipoles made a good linear polarized setup for digital FPV. Hereâs why:
|
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
| TerenceChan
rrNovice Singapore |
|
| SHARE PM EMAIL HOMEPAGE GALLERY Attn:RR Quote | |
WATCH |
1 page 336 views | POST REPLY |
| RunRyder | Scorpion Power |
|
|
| Print TOPIC | Make Suggestion |
Tuesday, May 26 - 1:43 pm - Copyright © 2000-2020 RunRyder EMAIL • Enable Cookies
