Co-ordination and line-up procedures
Each time an uplink is to undertake a transmission, there is always co-ordination via a co-ordination telephone line – which can be a land-line, cellular or satellite phone. Co-ordination is the process by which the line-up, start of transmission and end of transmission are discussed and agreed by telephone between the two points – uplink and downlink.
This will occur either between the uplink and the final destination of the transmission (such as the destination downlink control centre as usually occurs with long-term leases and some short-term leases) or between the uplink and the satellite operator’s control centre (for occasional transmissions).
The satellite operator’s control centre is usually in its home country, and booking information is checked and confirmed, as well as the technical parameters. If there are any problems at either point during the transmission, this is dealt with via the co-ordination line.
The number of the co-ordination line must be known to the control centre, and must be kept clear of other calls during the transmission in case of a problem that the control centre needs to alert the uplink operator about.
‘Line-up’ is the term used for the initial establishment of the signal from the uplink, and it is the period during which the signal is checked for technical compliance by the reception point. Normally no longer than 5 min, line-up is terminated by the commencement of the transmission. When the transmission is terminated, the end time (known as the ‘goodnight’) is agreed by the uplink and the satellite operator’s control centre. This is particularly important for occasional transmissions where the chargeable period has to be accurately agreed and recorded for billing purposes.
Once the uplink is rigged and aligned to the correct satellite (commonly referred to as being ‘panned-up’), a typical sequence for an occasional booking is as follows (the time of the start of transmission is often referred to as Z):
• Z–10 min: Uplink calls control centre. Identifying its uplink registration, the booking details are confirmed, including uplink frequency and polarization.
• Z–5: Line-up usually begins. With clearance from control centre, the uplink starts to transmit (brings up) an unmodulated (clean) carrier of 5 to 10% of full nominal power. The control centre checks the carrier is at the correct frequency, polarization, and nominal power with no ‘out-of-band’ rogue transmission – which would indicate a problem with the RF part of the uplink transmission equipment.
• Z–3: With the carrier still at less than 10% full power, the control centre instructs modulation to be switched on – which will simply be typical modulation as the control centre may not be able to decode the digital modulation (if there is a CA on the signal). Once control centre agrees the modulated signal looks correct, power is raised to full nominal power. Control centre finally checks the signal, and agrees transmission can commence.
• Z: Chargeable period commences. Test signal is removed, and programme signal now switched to transmission.
• Z + n: End of transmission. Uplink brings down signal, and agrees the transmission end time (the goodnight) with control centre.
Lining up with the control centre (Photo courtesy of Simon Atkinson)
Over-runs
During the transmission, the uplink operator may need to extend the booking; for instance, if the ‘live’ slot has been moved in the news programme running order, or the tape has arrived at the last minute and there is more material to be fed than had been anticipated. A last-minute booking extension is termed an ‘over-run’. Although it will be in the satellite operator’s interest to grant an over-run (as it is increased income), it may not be possible if there is another booking on the same channel immediately after the booked time. Obtaining an over-run may not be possible if the uplink is unable to contact the satellite operator’s control centre before the end of the booked time – the control centres can be quite busy and not always able to answer all phone calls. However, it is strictly forbidden by all satellite operators for any uplink to continue to transmit beyond the end of the booked time unless prior authorization has been obtained.