Abstract: An inexpensive portable RF (radio frequency) microcontroller-based digital spectrum analyzer is automatically calibrated for passband amplitude tilt/variations. Resulting software-obtained calibration parameters are used during operation to reduce or eliminate passband amplitude errors. The spectrum analyzer also includes a PLL frequency synthesizer arrangement, but the PLL controls a VCO only during calibration to derive calibration values for controlling a digital-to-analog converter. During normal operation, the VCO is driven in an open loop configuration under software control using such calibration values--achieving nearly the accuracy of closed loop operation while avoiding the penalty of long PLL lock time. These amplitude and frequency calibration techniques and arrangements permit the spectrum analyzer to have relatively inexpensive components and circuit arrangements and nevertheless achieve high accuracy over a wide band.

Abstract: A television distribution system includes a frequency agile satellite transponder down converter operating in the satellite block converted frequency range, typically 950-1450 MHz, along with an IF stage incorporating bandpass filtering and a frquency agile up converter. This arrangement allows a head-end configuration with optimum selection of transponders from one or more satellites and with both vertical and horizontal polarities. The transponders are converted to an available slot allowing twelve slots to accommodate transponders of preference. The block may then be distributed to multiple subscribers in apartment complexes, condominiums and subdivisions.