Precision Systems For Critical Applications COMSTRON FEATURES * Removable Front-End with Lightning Suppressor * Absence of Coherent Interference * Sensitivity Time Controlled Front-End * Modular Construction * Approved for NOAA Wind Profiler System CS-4012 WIND PROFILER RECEIVER DESCRIPTION The National Oceanic and Atmospheric Administration (NOAA) Wind Profiler System uses an unattended UHF clear-air Doppler radar to profile the upper winds with a maximum height of 16.25 Km in 250 meter increments. This system pioneered the capability of continuously and automatically measuring upper-air wind fields. These measurements are critically important to weather forecasting, ranging from short-term regional severestorms, to national major winter storms. The Wind Profiler System has made a major improvement in the timeliness and specificity of operational forecasts. Wind Profiler System is different from S Band weather radars such as the Next Generation Weather Radar (NEXRAD) or Terminal Doppler Weather Radar (TDWS); S Band radars rely on the turbulence signature of water molecules in the atmosphere to detect wind turbulence, whereas the wind profiler is a clear air system. In order to detect clear air turbulence to a height of 16.25 Km, the CS-4012 radar receiver must be able to detect signals that are considered to be at the theoretical noise floor. A digital signal processor can then process the receiver's I/Q demodulated output and integrate for a period of six (6 ) minutes to extract signals that are within 1 dB from the KTB noise floor, or 174 dBm, this high receiver sensitivity, often cause a secondary problem; coherent interference. Coherent interference is defined as any random signal with amplitude above -174 dBm. Any power supply ripple, T/ R transients, harmonics of the A/D clock and any other signal that are repetitive in nature, with power levels greater than -174 dBm, will show up as coherent interference. Two of the most critical signals in terms of coherent interference are the harmonics of the A/D clock and the harmonics of the T/R clock. The wind profiler's A/D converters are clocked at 550 KHz to 600 KHz, and one of these clocks' harmonics could show up in the 30 MHz IF passband. The only solution to this dilemma is to maximize signal isolation with proper mechanical packaging and filtering between RF, IF and the A/D sections. Any extraneous signals at the input of the 30 MHz IF must be lower than -134 dBm, and any signal within the 404/449 MHz RF inputs must be to less than -173 dBm. The packaging of the CS-4012 wind Profiler Receiver achieved this kind of isolation through the use of optical isolators for all command logics, ground plane isolation amongst different functional areas, and extensive shielding among all related compartments. The result is an easily serviceable receiver with a removable frontend and easy access to components resulting in low MTTR (Mean Time To Repair). CS-4012 CS-4012 Table 1: Technical Specifications STANDARD OPTION Frequency Range: Standard: 404.37 MHz 449/915 MHz Receive Mode: High, Low Low-Low Noise Figure: 0.6 dB Transmitter Leakage: 10 dBm max LO Leakage: - 40 dBm max LO Input: 374.22 MHz, +18 dBm, COHO Frequency & Level: 30MHz , +13 dBm 2ND IF: 30 MHz 3RD Intercept Point: -44 dBm Converter Clock: 500 - 670 KHz Limiting: 19 dB from noise floor to full limiting Video Gain: 3.5 dB Max Safe RF Input: +20 dBm, CW & Pulse Image Rejection: 50 dB min Recover Time: 200 nsec Video bandwidth: 1.2 MHz Internally Gen. Spur: None above -173 dBm equivalent RF input STC Range: 30 dB, 80 nsec to 16 usec I/Q Phase Matching: 3 Max. I/Q Amplitude Matching: 1% of amplitude Output format: Digitized I & Q Output, Standard: 8 Bits T/R Isolation: 90 dB Min. Power Supply: +15V @ 600 mA, -15V @ 150 mA 20 dBm 418.85 MHz, 18 dBm 10/12 Bits +5V @ 450 mA -5V @ 200 mA Environmental: Operating Temp: 10 C to 30 C Storage -40 C to 60 C Humidity Operating: 100% Rel. @ 35 C Non-Operating: 100% Rel. @ 60 C Altitude Operating: 3,000 meters above sea level Non-Operating: 15,000 meters above sea level Dimensions: Height 1.5 inches Width 9.25 inches Depth 13 inches Weight 8.25 Lb. Precision Systems For Critical Applications 35 South Service Road Plainview, NY 11803 TEL: 516-694-6700 FAX: 516-694-6771 COMSTRON