  The Planck Low Frequency Instrument (LFI) will observe the Cosmic Microwave
Background (CMB) by covering the frequency range 30-70 GHz in three bands. The
primary instrument data source are the temperature samples acquired by the 22
radiometers mounted on the Planck focal plane. Such samples represent the
scientific data of LFI. In addition, the LFI instrument generates the so called
housekeeping data by sampling regularly the on-board sensors and registers. The
housekeeping data provides information on the overall health status of the
instrument and on the scientific data quality. The scientific and housekeeping
data are collected on-board into telemetry packets compliant with the ESA
Packet Telemetry standards. They represent the primary input to the first
processing level of the LFI Data Processing Centre. In this work we show the
software systems which build the LFI Level 1. A real-time assessment system,
based on the ESA SCOS 2000 generic mission control system, has the main purpose
of monitoring the housekeeping parameters of LFI and detect possible anomalies.
A telemetry handler system processes the housekeeping and scientific telemetry
of LFI, generating timelines for each acquisition chain and each housekeeping
parameter. Such timelines represent the main input to the subsequent processing
levels of the LFI DPC. A telemetry quick-look system allows the real-time
visualization of the LFI scientific and housekeeping data, by also calculating
quick statistical functions and fast Fourier transforms. The LFI Level 1 has
been designed to support all the mission phases, from the instrument ground
tests and calibration to the flight operations, and developed according to the
ESA engineering standards.
