Link budget so far… EBNO is a symbol and does not equal E b divided by N 0 (in dB) EIRP = P t + G...

Link budget so far…

EBNO is a symbol and does not equal Eb divided by N0 (in dB)

EIRP = Pt + Gt

Path Loss

Signal to Noise ratio

dBf

constssBoltzmannT

GEIRP

N

Eb

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0N

Eb

Mhz1log20

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f

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P

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E rr

b

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Signal to Equivalent isotropically Reciever Boltsmans, distance Frequency speed B (bits

noise ratio = Radiated Power + Perfomance + pi etc - attenuation - - per second)

Eb/N0 in dB = (Pt + Gt) Gain = 0 + Gr / noise + 4 k π / c - 20.log(d/1 km) - 20.log(f/1 Mhz) - 10.log(B/1Hz)

Temperature

Ebno = EIRP + G/T + const - path loss - frequency - B

42.23189872 = -10 + 5.531728273 - -376.15131 - 125.929314 - 163.5218252 - 40

const = -376.15131

Pt = 0.1 w

Gr = 20 dB

Noise figure = 0.4 dB

Tn = 27.97867688

G/T = 5.531728273

height = 300000 m

Path dist. = 1979090.7 m

Downlink (freq) = 150000000 hz

Speed B (of bits) = 10 kbits s-1

radius of the earth = 6378000 m

k = 1.38065E-23

c = 299790000

Pr (W) = Pr (dB) = EIRP + Gr - 20 x log (4π/c) - Path loss - Frequency Loss

6.45804E-14 = -131.8989936 = -10 + 20 - -147.5521456 - 125.929314 - 163.5218252

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Other factors that will effect Power Received

• Atmosphere; this is transparent at our chosen frequency.

• Ionosphere; which is something that needs looking into.• The Effect of tumbling which will pulsate the power and is disused briefly later.

Chosen frequency Information

• Using two frequencies we can uplink and downlink at the same time.

• 436MHz (down link) and 146MHz (Up link)

• They are both transparent to the atmosphere.

• They will gives us our needed bit rate.

• They are in the amateur bands so the licences are easily available

Original Transceiver (DJ-C7T/E) Specs

• Frequency Coverage; – Uplink: 144-145.995MHz– Down Link: 430-439.995MHz

• Modulation;– Uplink: 16k0F3E (FM)– Downlink: FM

• Output: 300mW with EBP58N / 500mW with 6Vdc power-source • Power Supply Requirements: 3.7Vdc EBP58N / 3.7 - 6.0Vdc

external power source • Current Drain (approx) ;

– Transmitting: 320mA – Receiving (squelched): 70mA – Receiving (BS-on): 19mA

• Operating Temperature: -10 ~ +60 degrees oC

Considerations for aerial

• Need to match aerial impedance to the impedance of the transceiver.

• Find the aerial length that gives the heights power output.

• If two frequency's are used then a trade off will be needed between them both.

• Decide on whether a monopole or dipole aerial would be more effective

Experiments That Could Be Done

1. Map transmitted power of the aerial to find any points of low power, this can show the feasibility of using a monopole.

2. Find length of aerial that transmit's the most power. Add an inductor and capacitor so the aerial impedance matches the impedance of the transceiver.

3. Calibrate Radials (if used).

Consider Beacon

• Only needs 80mW Transmitted Power therefore ~ 240mW Total Power.

• Can beam down house keeping data constantly.

• Is a good failsafe for satellite

Other Considerations

• Need to look at Signal Modulations (which is limited by choice of transceiver)

• If a packet System is used to transfer data or continuous stream.

• Data Link Protocols (which will effect the amount of data that can be transferred)

• Will be an analogue signal transmitting digital data