HIAPER Cloud Radar Transceiver

ExciterReceiver

OscillatorsHigh-Powered Amplifier

Calibration

ExciterReceiver

OscillatorsHigh-Powered Amplifier

Calibration

Overview

• Exciter• Receiver• Oscillators• High-Powered Amplifier• Calibration

• Exciter• Receiver• Oscillators• High-Powered Amplifier• Calibration

Exciter: Requirements

• 200 ns to 2 µs transmitted pulse (Phase A)– Requires 5 MHz linear-phase bandwidth

• Accommodate extension to a pulse compression waveform (Phase B system) such as an amplitude tapered linear FM or non-linear FM

– Require arbitrary phase and amplitude control within generated pulse– Design for 20 MHz of linear-phase bandwidth in order to shape the

spectrum of the transmitted pulse

• 200 ns to 2 µs transmitted pulse (Phase A)– Requires 5 MHz linear-phase bandwidth

• Accommodate extension to a pulse compression waveform (Phase B system) such as an amplitude tapered linear FM or non-linear FM

– Require arbitrary phase and amplitude control within generated pulse– Design for 20 MHz of linear-phase bandwidth in order to shape the

spectrum of the transmitted pulse

Exciter: Waveform Generator

• Baseband I and Q samples used to generate a Hilbert transform pair of signals centered at 125 MHz

• Images at 375 MHz (using 500 MS/s DAC) will be suppressed by 70 dB

• Allows for amplitude and phase control to shape the transmitted spectrum

• Baseband I and Q samples used to generate a Hilbert transform pair of signals centered at 125 MHz

• Images at 375 MHz (using 500 MS/s DAC) will be suppressed by 70 dB

• Allows for amplitude and phase control to shape the transmitted spectrum

Exciter: 1.3 GHz Up-Conversion

• Up-conversion to 1.3 GHz using a quadrature modulator

• Lower sideband is suppressed by > 20 dB

• Up-conversion to 1.3 GHz using a quadrature modulator

• Lower sideband is suppressed by > 20 dB

Exciter: Single Sideband Generation

• m(t) and mh(t) form a Hilbert transform pair centered in frequency at 125 MHz

• Output of the quadrature modulator is a single sideband signal (the lower sideband at 1050 MHz is suppressed)

• m(t) and mh(t) form a Hilbert transform pair centered in frequency at 125 MHz

• Output of the quadrature modulator is a single sideband signal (the lower sideband at 1050 MHz is suppressed)

m(t)

mh(t)

Exciter: 1.3 GHz Filtering

• Filter signal at 1.3 GHz to further suppress lower sideband by 40 dB (min.)

• Filter has a 20 MHz, linear phase passband

• Filter signal at 1.3 GHz to further suppress lower sideband by 40 dB (min.)

• Filter has a 20 MHz, linear phase passband

Exciter: 94 GHz Up-Conversion

• Up-convert 1.3 GHz signal to 94 GHz using a single sideband modulator

• Lower sideband signal at 91.4 GHz is suppressed by 20 dB

• Up-convert 1.3 GHz signal to 94 GHz using a single sideband modulator

• Lower sideband signal at 91.4 GHz is suppressed by 20 dB

Exciter: 94 GHz Filtering

• Filter 94 GHz signal to further suppress lower sideband at 91.4 GHz by 26 dB

• Transmitter will further suppress image due to limited bandwidth (~100 MHz)

• Filter 94 GHz signal to further suppress lower sideband at 91.4 GHz by 26 dB

• Transmitter will further suppress image due to limited bandwidth (~100 MHz)

Overview

• Exciter

• Receiver• Oscillators• High-Powered Amplifier• Calibration

• Exciter

• Receiver• Oscillators• High-Powered Amplifier• Calibration

Receiver: Requirements

• Receiver Requirements– 5 MHz linear phase bandwidth (Phase A)

• Accommodate extension to a pulse compression waveform (Phase B system)

– Desire 20 MHz of linear phase bandwidth– Non-polarimetric receiver (Phase A) that should be upgradeable to a

fully-polarimetric receiver in Phase B

• Receiver Requirements– 5 MHz linear phase bandwidth (Phase A)

• Accommodate extension to a pulse compression waveform (Phase B system)

– Desire 20 MHz of linear phase bandwidth– Non-polarimetric receiver (Phase A) that should be upgradeable to a

fully-polarimetric receiver in Phase B

Receiver: T/R Isolation

• Receiver must be protected from the reflected transmit signal from the antenna

• For an antenna with a 14 dB return loss (1.5:1 VSWR), an a peak incident power of 60.7 dBm at the antenna terminals, the signal at the input to the latching circulators is 45.4 dBm

• For a LNA max. input power of +20 dBm, T/R isolation required is 42 dB (2 latching circulators @ 25 dB each)

• Receiver must be protected from the reflected transmit signal from the antenna

• For an antenna with a 14 dB return loss (1.5:1 VSWR), an a peak incident power of 60.7 dBm at the antenna terminals, the signal at the input to the latching circulators is 45.4 dBm

• For a LNA max. input power of +20 dBm, T/R isolation required is 42 dB (2 latching circulators @ 25 dB each)

Receiver: 94 GHz Filtering

• Image rejection filter suppresses received signals at the image frequency by > 46 dB

• Image rejection filter suppresses received signals at the image frequency by > 46 dB

Receiver: 94 GHz Down-Conversion

• Received signal is down-converted to 1.3 GHz

• If suppression of image at 91.4 GHz is not sufficient, then an image reject mixer will be used

• Received signal is down-converted to 1.3 GHz

• If suppression of image at 91.4 GHz is not sufficient, then an image reject mixer will be used

Receiver: 1.3 GHz Filtering

• Received signal is filtered which suppresses signals in lower sideband by > 40 dB (> 100 dB rejection)

• Received signal is filtered which suppresses signals in lower sideband by > 40 dB (> 100 dB rejection)

Receiver: 1.3 GHz Down-Conversion

• Received signal is down-converted to 125 MHz

• The 5 MHz anti-aliasing filter will be changed for Phase B

• Received signal is down-converted to 125 MHz

• The 5 MHz anti-aliasing filter will be changed for Phase B

Receiver: Performance

• Receiver performance was calculated using commercially available components

– Noise figure• Receiver noise figure 9.35 dB (noise power in 5 MHz BW is −97.9

dBm)– Dynamic range

• Maximum input signal to the receiver is −22.4 dBm• Dynamic range is −22.4 − (−97.9) = 75.5 dB• 14 bit ADC required to capture receiver dynamic range

– Intermodulation products will be analyzed during component selection

• Receiver performance was calculated using commercially available components

– Noise figure• Receiver noise figure 9.35 dB (noise power in 5 MHz BW is −97.9

dBm)– Dynamic range

• Maximum input signal to the receiver is −22.4 dBm• Dynamic range is −22.4 − (−97.9) = 75.5 dB• 14 bit ADC required to capture receiver dynamic range

– Intermodulation products will be analyzed during component selection

Overview

• Exciter• Receiver

• Oscillators• High-Powered Amplifier• Calibration

• Exciter• Receiver

• Oscillators• High-Powered Amplifier• Calibration

Oscillators: Phase Noise

Offset Frequency

Phase Noise [dBc]

10 Hz −40

100 Hz −65

1 kHz −75

10 kHz −85

100 kHz −95

1 MHz −105

10 MHz −110

• Phase noise analysis performed on W-band local oscillator using data in the table below to determine phase noise requirements

• Velocity variance due to phase noise for an echo at 10 km is 0.07 m/s

• Phase noise analysis performed on W-band local oscillator using data in the table below to determine phase noise requirements

• Velocity variance due to phase noise for an echo at 10 km is 0.07 m/s