業餘衛星 AO 51 通聯......繼續追擊

VR2GY

用9單元八木 下鏈 AO51

VR2VBU

至於上鏈 AO51 就用這簡單 2 單元144 MHz 頻段 HB9CV

VR2VBU

22# VR2VBU

VR2VBU

記得留意衛星的方位及仰角

VR2VBU

由於 AO-51 當時是以 J mode 通訊模式, 即是 144MHz 上鏈, 430 MHz 下鏈, 所以我們用了兩組不同的天線互相配合通聯

VR2VBU

對正衛星軌跡經過的時間, 方位, 仰角, 頻率, 等待及追蹤衛 AO-51 出現

VR2VBU

發射及接收都是同一方向, 所以天線都是向著同一角度, 方位

VR2VBU

在戶外操作時, 器材一定要輕便, 安裝容易, 效率卻要高, 一定要可以單兵也能操作, 這樣才可以享受通聯的樂趣

VR2GY

再研究一下 5月30日 AO-51的資料

VR2GY

AO51技術可行性
;心Instructions

Let's start with the FM transponder mode Down Link. Echo will produce a minimum power of 1 Watt (+30dBm) on 70CM. The transmit antenna is 2dBic. The path loss at maximum range (3000 km) is 155 dB. We should allow an extra 3dB loss for polarisation mismatch and another 1dB from travelling through the ionosphere.

A typical 70CM hand held transceiver is rated at -120 dBm for 12dB SINAD, considered the minimum useable signal. So we have:

    Satellite Tx (minimum)         +30 dBm
    Antenna Gain         +2 dB
    Path Loss         -155 dB
    Polarisation         -3 dB
    Ionosphere         -1 dB
    Hand held yagi gain         +10 dB
            -117 dBm

This is just above the minimum for a useable signal.

At minimum range (800 km) the path loss reduces to 143 dB so we have:

    Satellite Tx (minimum)         +30 dBm
    Antenna Gain         +2 dB
    Path Loss         -143 dB
    Polarisation         -3 dB
    Ionosphere         -1 dB
    Hand held yagi gain         +10 dB
            -105 dBm

So Echo in FM mode will be able to be received on a dual band handheld with a handheld yagi antenna.

For the 2M Up Link we have a path loss of 145 dB at maximum range and a receiver on Echo that is specified at -125 dBm for 12dB SINAD. So with a hand held yagi antenna we have:

    Ground Station Tx (5 Watts)         +37 dBm
    Path Loss (maximum)         -145 dB
    Polarisation         -3 dB
    Ionosphere         -1 dB
    Hand held yagi gain         +6 dB
                            -106 dBm

And at minimum range we have:

    Ground Station Tx (5 Watts)         +37 dBm
    Path Loss (maximum)         -134 dB
    Polarisation         -3 dB
    Ionosphere         -1 dB
    Hand held yagi gain         +6 dB
                            -95 dBm

So Echo in FM mode will be easily workable on a dual band handheld with a handheld yagi antenna. If the transmitters can be run at increased power levels then the Echo could be worked with "rubber duck" antennas.