2023-04-05 - RCA for 1.3 GHz Video Issues

Incident overview

 Executive summary

Essentially when on the ground 1.3 vtx range is crap.

When in the air we had excellent video (150m altitude 4km range). We need to be able to receive video when landing on far away landing pads (otherwise how do we land on them?).

There was also large interference when a manned aircraft came overhead leading to concerns about us requiring more filtering or something.

From Anni we were videoing at 1280 MHz.

Research

• A look at frequencies that are near our “1.3 Ghz Video”

  • Our VRX: RMRC 900MHz-1.3Ghz High Performance Receiver with Custom Tuner

    • CH0:910MHZ

    • CH1:980MHZ

    • CH2:1010MHZ

    • CH3:1040MHZ

    • CH4:1080MHZ

    • CH5:1120MHZ

    • CH6:1160MHZ

    • CH7:1200MHZ

    • CH8:1240MHZ

    • CH9:1280MHZ

      • This is what we were flying at.

    • CHH:1320MHZ

    • CHC:1360MHZ

    • CHd:1258MHZ

    • CHE:1100MHZ

    • CHF:1140MHZ

  • ADS-B: Automatic Dependent Surveillance–Broadcast

    • 978 MHz OR 1090 MHz

    • Mostly 1090 Mhz I guess

    • 1090 extended squitter

      • 1080 – 1100 MHz

  • Distance Measuring Equipment (DME): Distance measuring equipment

    • 960 to 1215 MHz

  • TACAN: https://en.wikipedia.org/wiki/Tactical_air_navigation_system

    • 960 MHz - 1213 MHz

  • LDACS

    • 960 MHz - 1213 MHz

  • Universal Access Transceiver (UAT)

    • 978 MHz

  • SSR: Secondary surveillance radar

  • ACAS: Traffic collision avoidance system

    • 1090 Mhz

  • PSR: Primary radar

    • 1215 – 1400 MHz

  • GNSS

    • https://novatel.com/support/known-solutions/gnss-frequencies-and-signals

      • GPS

        • 1575.42

        • 1227.6

        • 1176.45

      • GLONASS

        • 1598.0625-1609.3125

        • 1242.9375-1251.6875

        • 1202.025

      • Galileo

        • 1575.42

        • 1176.45

        • 1207.14 

        • 1191.795 

        • 1278.75 

      • BeiDou 

        • 1561.098 

        • 1207.14

        • 1268.52

        • 1575.42

        • 1776.45

        • 1207.14

      • NAVIC

        • 1176.45 

      • SBAS

        • 1575.42 

        • 1176.45 

      • QZSS

        • 1575.42 

        • 1227.6

        • 1176.45

        • 1278.75

• Looking at band plan:Band Plan

  • 1280Mhz allows for 1276 to 1282 so it is 6 Mhz wide

    • “The need to avoid harmful interference to FAA radars may limit amateur use of certain frequencies in the vicinity of the radars.”

    • 1280Mhz sits in ATV Channel #3 so amateur television (at least for the US band plan)

• A note about changing to a diff channel

  • We chose 1280Mhz because defaulters

  • our current tx antenna from arch doc is rated for 1280-1258mhz so we’d need to switch antennas for a diff channel

• Legality

  • In the US 1256MHz and 1280MHz are the only legal channels in the 1.3 GHz range so yea

• Harmonics

  • 2.4 GHz is Wifi and some RC links, 1.3 GHz stuff is pre close to a harmonic especially the way we running it

 Recommendations for future