EMERGENCY GENERATOR SIGNALING
EMERGENCY GENERATOR SIGNALING
By: Don McClatchie
One of the Cardinal rules in Broadcasting is that the programming material must be delivered to the customer, well at least the advertising must get there. Interruptions in transmission should be avoided so that the advertising revenue is not affected, and so most Broadcast and Cable systems use some form of backup power source to keep it all running in the event of a power outage. This is especially important for emergency broadcasts of local weather conditions or other emergencies for public safety.
Almost all these backup power systems will automatically turn on and pick up the power requirements for the station or Cable hub. At remote sites like mountain top transmission sites or un-maned Cable hubs these power sources are powered by fuel or natural gas held in tanks that if not monitored can run out of fuel, so it is important for remote sites or un-maned sites to signal when the backup power source has started and when they stop so that maintenance staff can keep them supplied with fuel to guaranty continued operation of the broadcast signal.
In the case of the un-maned remote transmitter site or cable hub site, the signal being transmitted from that site is usually monitored at some other location, so the programming signal can be used to return the generator ON signal if you can find a way to incorporate the signaling into the program transmission without annoying the customers watching the programming.
Another way is to use any other signal path that is being used for other purposes like a network connection. For the most part the signal you want to convey is a switch or relay, On or Off signal format so to get these types of contact switch signals onto the return path transmission you will need some type of terminal equipment at each end of the pathway.
Let’s look at ways you can incorporate the remote backup generator signaling into an existing broadcast signal. If you have a digital transmission signal with extra channels being encoded at the remote site, you could use one of those to send the binary switch signals.
If you don’t have an input of this type, then you could use a product called SCT-8 to add the signaling to an existing audio channel if the baseband audio signal is encoded at the remote location. This device takes the contact switch information and inserts an audio signal at 19KHz above the audible range at such a low level that it cannot be detected by the human ear. At the receive location an SCR-8 unit would be used to recover the contact switch signal for relay outputs and then removes the subliminal 19KHz signal from the audio path. Up to 8 switch and relay contacts can be transmitted over an existing audio signal.
If a network connection to the remote site is available, then you can use the IPG-8T transmitter using TCP/IP protocol to send the contact relay information over your network. At the receive end an IPG-8R receiver with relay outputs are used to mirror the switch inputs from the transmitter. These devices are programmed using a web interface or by direct Ethernet cable connection and they are addressed to communicate only with the matching peer and can be password protected. The receiver unit has an extra relay output that monitors the communications path for high signal security.
If you have a backup generator at a remote site or have any need for transmitting switch contact information over an existing audio signal or over a network, have a look at these products and other that we have for piggybacking on existing signals. Click on the links or go to our website: fmsystems-inc.com.
