N+1: Cost Effective Automated Transmitter Backup
To help ensure that broadcasters stay “On Air ” Nautel designs extreme reliability and redundancy into all Nautel transmitters. However, for facilities that broadcast multiple programs from a single site, N+1 capability can provide even higher levels of redundancy that is both automated and cost effective. Nautel N+1 configurations can support up to six identical main transmitters plus a backup transmitter serving outputs of 300 watts to 40 kilowatts of solid-state power.
N+1 Solution Features and Advantages
- Reduce the need for multiple back-up transmitters while maintaining high reliability.
- Cost savings.
- Automatic switchover back up.
- Facilitates easy maintenance while keeping station on air at full power.
- Station back up prioritization: Key station(s) take priority over lower priority stations.
- Full power backup transmitter.
- Automated stereo input routing and backup.
- Complete isolation of the +1 transmitter from lightning strikes.
- Remote or local control.
4+1 Implementation Example
In this example four Nautel NV series FM broadcast transmitters (A through D) plus one backup transmitter are configured with a series of coaxial switches that are part of a 4+1 switch matrix, RDS and audio program switchers, and a Nautel SC1 system controller.
Each transmitter (A through D) operates individually at one frequency between 87.5 MHz and 108.0 MHz. The system is designed to allow the backup transmitter to be used in place of any one of the main transmitters in the event of a main transmitter failure. The +1 transmitter can back up only one transmitter at a time. A 50 kW dummy load acts as the dummy load for the backup transmitter or the transmitter that the backup is replacing.
The Nautel SC1 System Controller provides system control and monitoring functions for up to six NV-series FM broadcast transmitters connected in an N+1 configuration. When the SCI recognizes a fault condition that has inhibited output power of any of the 4 NV transmitters, the SCI inhibits the faulty transmitter and transfers it to a dummy load. The audio, SCA (if applicable) and RF are all switched to the +1 transmitter which begins broadcasting the faulty transmitter’s channel.
The user can prioritize which transmitter is being backed up in the event of failure of more than one transmitter. For example: If transmitter 1 failed and had a higher priority over the other transmitters and the + 1 transmitter was currently backing up transmitter 2, the SCI would switch to broadcasting transmitter 1 channel. Transmitter 2 would be sent to it’s antenna port and disabled. Transmitter 1 would be inhibited and sent to the dummy load (there is only 1 dummy load).
Additional Implementation Details
- Each transmitter is single channel, has its own audio and frequency.
- The +1 transmitter must be able to broadcast each of the other transmitters.
- The user can prioritize which transmitter is backed up by the +1 transmitter in the event of multiple transmitter failures.
- The transmitter system is controlled by the Nautel SC1 system controller. The SC1 provides all the control, monitoring and metering circuitry for the 4+1 NV series transmitter system.
- The SC1 system controller provides the necessary ‘program select’ control signal to the audio program switcher and RDS program switcher to select the appropriate program inputs to apply to the backup transmitter.
- All user-provided audio and RDS program inputs are applied to the XLR interface PWB, located in the equipment cabinet.
- The 4+1 switch matrix contains four motorized coaxial switches (S1 through S4), one for each of the four main transmitters. Each switch controls the routing of its associated transmitter’s RF output, either directing it to an antenna output or to the dummy load. The position of these switches is controlled by the SC1 system controller.
- All RF outputs go to one common antenna or are configured to go to separate antennas.
- If a common antenna is used the RF outputs go through a channel combiner after the switch matrix.
Remote Control Circuits
- The system can be controlled from a remote location using external switching circuits.
- A complete, independent set of remote controls can be used for each transmitter.
- You can also control and monitor the system via the LAN.