Category Archives: KÅ«ryba

Latency comparison on FPV HMD screens/goggles, part 2

First part is here: http://lag.lt/latency-comparison-on-screens-for-hmd-fpv-use/

Got new firmware for my HMD, purchased some equipment for testing, borrowed goggles and did another measurement. Entire chain:

Sony Xperia Z1 compact => HS1177 => BF OSD => VTX03 => HMD/Goggles – so, keep in mind that visible latency is from entire chain included. Results in short:

  1. LTD056EV7F (my HMD with 5.6″ screen and RTD2662, firmware from smth like 2016.06): min: 29, max: 55, avg: 44ms. Main issue – blur on screen itself (old type LCD screen)
  2. Headplays with low latency firmware: min: 30, max: 69, avg: 39ms. Slightly less blurry than old Toshiba 5.6″, but more blur compared to any goggles.
  3. Quanum Fatshark Genesis: min: 45, max: 89, avg: 64ms. Again, less blurry compared to my HMD, but still more than goggles.
  4. Fatshark Dominator v2: min: 31, max: 51, avg 38ms.
  5. Fatshark Attitude v3 (should be the same optics dom v2?): min: 27, max: 69, avg: 50ms. Maybe optics is identical to doms, but something is different in processing chain, because averages are clearly higher.

Photo samples if someone is interested (taken with SONY A6300 + Samyang 8mm F2.8, ISO 25600 EV -2.7, but allways at 1/4000 shutter speed, so you know what quality to expect =)

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Small airplane – looking for best motor/propeller combo – some benchmarks

Compared to situation few years ago – now you do not need to use 50g+ motor and 15g+ ESC  to get 1kg thrust. Mini quadcopter racing mania made small motors/ESC much better, cheaper and better in terms of thrust/weight. They are high-kV (usually) but for small planes this isn’t bad – you still need speed and not only static thrust.

So, my requirements for motor/esc combo:

  • Still have enough thrust for unlimited vertical (so at least 800g of thrust)
  • Have enough pitch speed for penetrating headwind and flying around (so at least 100km/h at WoT)
  • Efficient setup at low throttle – need ~40km range endurance (total trip, not one-side).

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LT-FPV organizuojamos lenktynÄ—s

Aš aišku smarkiai stabdau su šiuo postu, nu bet geriau vėliau nei niekad.
Taip jau gavosi, kad suorganizavome mini-kopterių lenktynes:
DSC00382_visi
Ir ties tuom reikalai nesibaigÄ—, bus dar vienos lenktynÄ—s (ir gal dar vienos… Bus matyt)
Na, bet projektas turi savo puslapį, kam įdomu: http://fpv.team/
Tam kartui – trumpas (dar nepadÄ—tas archyve) filmukas iÅ¡ buvusių lenktynių:

Prisijunkit, dar liko laiko užsisakyti įrangą, užsiregistruoti ir sudalyvauti =)

Surveilzone (Foxeer)/Aomway VTX comparison

Got ~10x Surveilzone (Foxeer) VTX’es around, from 25mW to 600mW, also 25/200mW Aomway and decided to check what’s inside.

Testing setup – RFE + attenuator chain. 60dB attenuation + 3dB offset in RFE, so in total you need to add ~63dB to visible averaged result on graph. All tests done on C1 channel (5705MHz).

Absolute power ouput is not precise, relative – much better (0.5dBm or better).

Cold testing – ~10s after powering on (already full averaged cycle), hot – after 5 minutes on my desk.

This looks like:

sz_tsetup

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Latency comparison on screens (for HMD-FPV use)

I noticed slightly increased latency when flying with my HMD’s, compared to my old cinemizers (plus, not OLED). Not critical, flyable – but noticeable on corners and flying over obstacles at high speed.

Had few screens around, measured latency (just to remind – @25FPS one frame takes 40ms; at 50km/h you fly ~1.4m over 100ms), only few screens provided, i did > 100 photos and averaged:

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5.8G analog receiver comparison (RX5808, RX5880 modules suitable for FPV and FR632 RX)

While 1.2G video is working very well for flying around obstacles, it also has own limitations. 2.4G video is somewhere in middle – small VTX, smaller antennas and good enough penetration, but unsuitable for flying in city (WiFi everywhere) and in meetings (2.4G RC adds a lot of noise even on 2370/2510 channels).

So, i moved back to 5.8G with some of my copters. Did simple RSSI-based diversity, added RX5808 modules to my HMD… Works good enough for everyday flying, but i noticed, that my friend can fly further using FR632 RX. LOS Range is acceptable for both, but he was flying further over obstacles  and in buildings.

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Antennas for mini-copter – what we can do?

Long story short – started with 5.8GHz on mini FPV copter (pocket rocket quad), soon got another, tried 1.2GHz (see earlier videos here) and finally picked 2.4GHz for my video.

Things change with time, Lithuania now has #1 Wi-Fi coverage/speed in the world and now i found that 2.4GHz for video usually has lower range than old 5.8GHz setup. It still works fine in forests or far far away from populated places, but flying in city is next to impossible (for example, Vilnius Old Town, near Užupio KÅ«drų parkas – loosing video in 20m away from me, using 2370MHz or 2510MHz which should be away from common Wi-Fi range).

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2014 vasaros foto – debesys, rÅ«kas

Kelios foto iÅ¡ pernai metų….

NEX 5N/Samyang 8mm.

Sidabriniai debesys…