20:40 UTC channel 3+4 northbound 32 W, APT also bar-coded
According to the SOCC engineers, the performance of the AVHRR Scan Motor is causing bar-coding in the HRPT/APT imagery once again. This instability has been observed in the family of older AVHRR scan motors (NOAA-15 and NOAA-16). The “jitter” in the Scan Motor usually stabilizes after a period of time (undefined) and the motor current level comes down to a stable level to generate good images. At this time, the HRPT/APT data users are solely dependent on the normal Scan Motor operation. The assumption that there is no fix for this problem is correct. As in the past, due to the lubricant and aging of the motor, the Scan Motor would experience increases in the current and eventually stabilize. As in the past, the engineers have monitored the performance of the Scan Motor and usually it would correct itself. Since this problem is very erratic, it will cycle thorough periods of good data and data with bar-coding. The engineers encourage the users to continue monitoring the quality of the imagery. Thanks for your time and patience.
Steven C. Ross