The antennas used at this station are shown below:
Twin Quagi 1.1m Separation
3m Diameter Dish f/D=.28 with 408MHz Quagi Feed
1420MHz Pyramidal Horn
1GHz Helical Antenna
3m Dish with 1420MHz Cylindrical Waveguide Feed
3m Dish with C Band Feed
60cm TVRO 11GHz offset Dish
80cm TVRO 11 GHz offset Dish
The system below has a 30m separation between the Antennas along an E-W Baseline
West arm of 408MHz Interferometer
East arm of 408MHz Interferometer
Receivers and Signal Conditioning
There are a number of receivers and spectrum analysers that are used for making observations. The total frequency coverage available is from a few mHz to 18GHz. The primary receiver used for almost all observations is an Icom-R7000 shown below. An DC – LF output signal is derived from the receivers AGC circuit by linking to the diode that drives the S meter. The output impedance is kept high by a series 10kW resistor no minimise circuit loading.
A coax connection carries the signal to an analogue signal processing unit for amplification and filtering.
Icom - R7000 Communications Receiver
Analogue Signal Processing Unit
From the antennas, signals are either fed directly into the receiving room or passed through an 18dB Gain low noise wide band (10MHz – 2 GHz) line driver . RF signals pass through about 30m of low loss 50W URM 67 coaxial cable into the receiving room. A wideband variable attenuator (shown) is connected between the coax and the receiver.
The SPU has a number of functions including amplification / attenuation, filtering / time constant, level shifting, signal inversion, logarithmic compression and audio signal level measurement with a proportional DC output. The output from the SPU is delivered to conventional meters both inside the room and sent back to the location of the antenna for remote reading. Another output is fed to an 11 channel 12 bit ADC (Pico ADC11/12) for data logging in a PC.
Data processing in the PC relies mainly on Excel with image making / mapping software from Stanford Graphics.
There are a number of Spectrum Analysers covering frequencies from 10 mHz to 18GHz and these are used mainly in developing equipment and antennas etc rather than for long run observations.
PC for Data logging & Analysis
[Temperature control equipment of head amplifiers is also shown]
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