Tech, Mech and Blech

Demystifying Technology Empowering Terms and Systems Knowledge
Carrier Variance	We broadcast by using a signal that is emitted off our antenna on top of Magee House. But it’s not like our sound just wafts off the tower in little musical hums. Instead, the signal travels along a carrier wave that spreads over the city. When we first applied for a licence we had to tell industry Canada exactly what carrier wave we would use, and they had to check to see if it was safe. It is very important that the signal we generate doesn’t change from that wave. If it did, it could interfere with other broadcasters, cell phones and even airplanes among other things. Signal does drift a bit from the wave nearly all the time, but it is only considered a problem if the drift goes more than a thousand hertz. If it does, it is likely because the transmitter is wonky and needs repair. We have to monitor our transmitter on a regular basis to make sure it’s working within acceptable limits. The panel in the rack above the transmitter buttons has a red numeric display on it. The numbers that are constantly changing in the display are a measurement of our carrier variance (how much our signal has drifted off the carrier wave). Several hundred either plus or minus is typical. Sometimes - most often in the summer - it can reach up to six or seven hundred. That’s still okay. There’s a spot on the log just before “Lunchbox” that asks for the carrier variance. The programmer who has this as part of the log for their show needs to record this number (the plus or minus is not necessary). If we ever drift a thousand hertz off, we need to repair our transmitter. We may get a call from Industry Canada. They would want an explanation and a fix - immediately. After having drifted once, we wouldn’t want to drift again. They keep a record of such things in our file.
Stay Tuned	More to come.

Demystifying Technology

Empowering Terms and Systems Knowledge

Carrier Variance

We broadcast by using a signal that is emitted off our antenna on top of Magee House. But it’s not like our sound just wafts off the tower in little musical hums. Instead, the signal travels along a carrier wave that spreads over the city.
When we first applied for a licence we had to tell industry Canada exactly what carrier wave we would use, and they had to check to see if it was safe. It is very important that the signal we generate doesn’t change from that wave. If it did, it could interfere with other broadcasters, cell phones and even airplanes among other things.
Signal does drift a bit from the wave nearly all the time, but it is only considered a problem if the drift goes more than a thousand hertz. If it does, it is likely because the transmitter is wonky and needs repair. We have to monitor our transmitter on a regular basis to make sure it’s working within acceptable limits. The panel in the rack above the transmitter buttons has a red numeric display on it. The numbers that are constantly changing in the display are a measurement of our carrier variance (how much our signal has drifted off the carrier wave).
Several hundred either plus or minus is typical. Sometimes - most often in the summer - it can reach up to six or seven hundred. That’s still okay. There’s a spot on the log just before “Lunchbox” that asks for the carrier variance. The programmer who has this as part of the log for their show needs to record this number (the plus or minus is not necessary).
If we ever drift a thousand hertz off, we need to repair our transmitter. We may get a call from Industry Canada. They would want an explanation and a fix - immediately. After having drifted once, we wouldn’t want to drift again. They keep a record of such things in our file.

Stay Tuned

More to come.