High Resolution Picture Transmission (HRPT)

The POES satellite platforms provide high-resolution and lower-resolution image data products. Direct Readout Services include the Automatic Picture Transmission (APT) for low resolution imagery and High Resolution Picture Transmission (HRPT) for higher-resolution imagery.. The HRPT consists of six channels of AVHRR data in the visible, near-infrared and infrared spectrum. The data are digitized to 10-bit precision and transmitted at 360 lines per minute (LPM) at 665 kilobits per second (kbps). The HRPT data stream also includes non-imagery data from other instruments on board the spacecraft.

Several vendors provide HRPT systems as individual components or as an integrated ground station. Features available include automated satellite tracking, geopolitical gridding, longitude/latitude registration, temperature calibration, and scheduled ingest of data.

The AVHRR instrument has a resolution of 1.1 km providing 10 bit data in five separate spectral bands. Table IV-1 summarized the spectral range and primary uses of the five sensors. Contrasted with the 4 km, 8 bit data and 2 spectral bands for the APT transmissions, HRPT, with its 5 data channels and 10 bits of data represents about a 10-fold advantage in the amount of information that may be analyzed when compared to APT data. This is very important to meteorologists and other professionals who need the most accurate information available for analysis.

Parameters for the AVHRR HRPT digital transmissions from the NOAA POES satellites:

1. Transmit Frequencies: 1698,1707,1702.5 MHz
2. Antenna Polarization: Right-hand Circular, Left-hand Circular based ontransmitter in use
3. RF Carrier Modulation: Digital, Split Phase, Phase Modulated
4. Bandwidth: 3 MHz
5. Lines per Frame: 6 per second
6. Digital Words per line: 11090
7. Word Rate: 66,540 per second (665.4 kbps)
8. Number of Bits: 665,400 per second
9. Words per Channel: 2048
10. Spectral:
    1. Channel l 0.58-0.68 uM
    2. Channel 2 0.72-1.1 uM
    3. Channel 3A/3B 3.55-3.93 / 3.55-3.93 uM
    4. Channel 4 10.3-11.3 uM
    5. Channel 5 11.5-12.5 uM