ATV

摘要

CONTROLLERS. Comtech transmit and receive modules are the dominant force in analogue (FM) ATV. Following reader requests, this month's column concentrates on controlling these modules with a programmable integrated circuit (PIC). Control functions include selecting and displaying the operating frequency, indicating received signal strength, scanning, additional VFOs and transmit-receive switching with sequential PA control. Generally, ATV module controllers fall into the following categories - individual Rx or Tx module control, combined Rx and Tx and multiband control, all with an LCD frequency and function display. There are two further general categories, push button and tuning knob tuning.