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Welcome to Tech Talk, Pico Macom's series of technical notes, featuring useful information and equipment tips.This installment of Tech Talk discusses Pico Macom’s off-air channel processing equipment and accessories.
Analog-to-Digital Broadcast Conversion
The conversion from black and white to color was a smooth transition. By simply adding a color subcarrier into the existing television channel signal, the broadcast was transformed to color. This took place within the existing channel signal so additional bandwidth was not required. The television receiver that was not designed to display color in the signal simply ignored the additional subcarrier and worked as it was designed. The new color TVs were designed to decode and display the color subcarrier when it was present. Much of the program content available was still black and white. So the new TV sets were backward compatible: If there wasn’t a color subcarrier available in the broadcast signal, the picture displayed was black and white.
The conversion from analog to digital isn’t as easily accomplished. The signal types are so completely different that they are not compatible at all. The existing analog televisions will require a set-top digital-to-analog converter to change the format into something it recognizes. Many of the new televisions provide both an analog and digital tuner and will be compatible through the conversion process.
Adding Off-Air signals to your channel line-up
Whether adding off-air analog or digital signals into the channel line-up, Pico Macom has the perfect solution for your application.
Simple addition of off-air analog channels can be done in one of two ways:
- The signal from the antenna is connected into the input of a PFAP550M agile channel processor. The output signal of the PFAP550M is summed with the other channels (modulator and processor outputs) using a PHC-24G signal combiner. The PFAP500M provides front panel control adjustments for audio and video carrier level
- The signal from the antenna is connected into the input of a PFAD900CS demodulator. The audio and video output of the PFAD900CS is connected to the audio and video inputs of a PCM55SAW modulator. The output signal of the PCM55SAW is summed with the other channels (modulator and processor outputs) using a PHC-24G signal combiner. The PFAD900CS-PCM55SAW combination provides front panel control adjustments for audio and video carrier level and audio and video deviation control.
Simple addition of off-air digital channels can be done easily:
- To keep the signal in its broadcast form, the signal from the antenna is connected into the input of a DSP806 agile digital channel processor. The output signal of the DSP806 is summed with the other channels (modulator and processor outputs) using a PHC-24G signal combiner. The DSP806 has the unique feature of operation in digital or analog mode. Front panel adjustments provide selection of signal type and control of channel carrier level.
- To convert the signal from digital into analog format, the signal from the antenna is connected into the input of an ATSC (digital) set-top decoder. The audio and video output of the ATSC decoder is connected to the audio and video inputs of a PCM55SAW modulator. The output signal of the PCM55SAW is summed with the other channels (modulator and processor outputs) using a PHC-24G signal combiner. The ATSC decoder-PCM55SAW combination provides front panel control adjustments for audio and video carrier level and audio and video deviation control.
Following the steps in the stated procedure and the use of Pico Macom equipment will ensure that you are up and running, watching free off-air programming the same afternoon. Our sales engineers are available to advise you with useful planning support and equipment selection. Please give us a call at 1-800-421-6511 and let Pico Macom help you.
Click here to download instructions for the DSP-806