Digital ATV opens the door to clean, noise-free pictures on the amateur bands. This construction article walks through the planning and the key concepts behind a DVB-S station like the one ATCO has operated 24/7 since January 2004 — the first DVB-S ATV repeater in the USA.
Why DVB-S?
We believe DVB-S is the best DATV choice for 23 cm and above, and it is well justified in practice. (DVB-T has become the standard for 70 cm operation.) DVB-S is robust, bandwidth-efficient, and well supported by inexpensive commercial satellite receivers, which makes it an excellent match for amateur repeater work.
Planning Your DATV Station
Planning a Digital ATV station means making a series of decisions, and — especially in the US — Digital-ATV can feel like a maze. Start from the band you intend to operate, then work outward: choose your mode (DVB-S for 23 cm and up), your symbol rate and FEC, your transmit chain, and finally the antenna. Decide each step deliberately rather than buying hardware first and reverse-engineering a plan around it.
Symbol Rates, FEC and RF Bandwidth
A few Digital-ATV concepts are typically not understood by hams — or even by analog ATVers — yet they are central to transmitting a digital ATV signal with the DVB-S standard. The symbol rate sets how many symbols per second are sent and is the main driver of occupied RF bandwidth. Forward Error Correction (FEC) trades throughput for robustness: a lower FEC ratio adds more protection so the picture holds together at lower signal levels. Together, symbol rate and FEC determine both the bandwidth your signal occupies and how gracefully it degrades.
As a concrete reference, the ATCO repeater transmits DVB-S on 1268 MHz at a 3125 symbol rate, and accepts DVB-S input on 1288 MHz at a 4167 symbol rate. Those values are good starting points when you plan a station to work the repeater.
Analog vs. Digital Signal Levels
If you are coming from analog ATV, remember that the familiar P0–P5 signal-level scale does not map onto digital. Analog pictures degrade smoothly through noise as the signal weakens; a digital DVB-S picture stays perfect until it suddenly drops out at the threshold. Plan your link budget for that "cliff edge" rather than for gradual fade.
For deeper references on each topic, see the DVB-S Details, Planning a DATV Station and Symbol Rates, FEC & Bandwidth pages.
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