INTERFERENCE 



Large scale, sporadic, short term fluctuations in the chart record appear to have 

 occurred during all of our survey flights. They appear to be more frequent in the vicinity 

 of military installations or operations such as Pt. Mugu, Pt. Conception, Arguello and San 

 Clemente Island. These points are key installations in the Pacific Missile Range and have 

 considerable radar tracking and radio operations. 



It has been confirmed that aircraft transmissions in the UHF band affect the chart 

 readout, and fluctuations in the recorder have been noticed when in the proximity of naval 

 warships. Whether these fluctuations are the result of high-frequency radar or UHF trans- 

 mission is not known. Operation of the radar mounted in the Grumman UF appears not to 

 result in interference, and on one survey flight aboard a P5M the 14-312 console and Varian 

 G-14 were positioned within three feet of the bow radar reflector without interference. 



VIBRATION 



The effects of vibration on the temperature readout has been noted during engine run- 

 up and takeoff. However, the recorder stabilizes after takeoff and at cruising altitude. 



Changes in propeller pitch and a resulting change in engine speed have caused chart 

 fluctuations when using the IT-2. The source of error (detector or electronic console) is not 

 known, but damping vibration of the console has stabilized the readout, and fluctuations did 

 not occur again even though the propeller pitch and speed remained the same. 



We have found that after attachment of the detector head directly to the air frame, 

 vibration of the detector head was responsible for high amplitude fluctuations in the chart 

 record. This was corrected by shock mounting the detector head. 



POWER SUPPLY 



The 28 Vdc power source aboard heavy aircraft and the 12 Vdc source in light air- 

 craft have been used to power the ATR inverters. Changes in the power system of the 

 Grumman UF appeared not to affect the IRT readout temperature. A test was conducted by 

 having the IRT view inside the aircraft water of known temperature and operating tests on: 

 1. 28 Vdc aircraft battery bank, engines stopped, 2. Ei^ines started and at idle, 3. Engines 

 accelerated to drive generator cut-out into charging position. No observable change in read- 

 out temperature was noted. Accessory electronic equipment aboard the aircraft as a source 

 of noise has not been checked. 



CONCLUSIONS 



Comparisons of carefully controlled and correctly calibrated airborne IRT observa- 

 tions at 500' with surface casts indicate a difference in temperature that falls to near the 

 sensitivity limits of the instrument. Unless in-flight calibrations are made to reduce the 

 many variables present in the determination of sea surface temperatures, both by the surface 



-89- 



