This is one in a series in which Ibiquity Digital Corp. answers questions about how to implement in-band, on-channel digital audio broadcasting. Broadcast Technology Manager Jeff Detweiler answers here.
Q: What factors determine where my station falls into the $30,000 to $200,000 IBOC conversion range that has been publicized?
A: IBOC conversion costs depend on a station’s transmitter power output and the current state of the transmitter and other equipment.
In the case of FM, the method of conversion is also a factor. A station on the low end of the cost range would be an AM station with a newer, solid-state transmitter. This station could convert for little more than the cost of an IBOC exciter.
A station on the high end of the cost range would be a high-power FM station without any overhead in the existing transmitter. This station would need to purchase a new transmitter and related equipment. Ibiquity Digital predicts the average station cost to be about $75,000.
Overall, a station that has kept pace with technology will find its transition cost on the lower end of the range compared to a station of similar power that is operating with dated equipment.
Almost all stations converting to IBOC will be able to use existing studio equipment. A few will need to reduce or eliminate audio compression in the studios to avoid incompatibility with PAC-encoded audio. Some will need to upgrade STL systems to deliver digital quality audio. Most stations will need to purchase digital audio processors with AES audio input and output for the IBOC audio chain.
AM facilities that have transitioned to a recent generation of solid-state transmitters will probably only have to make minor modifications for IBOC compatibility. Tube AM transmitters will likely be replacement candidates. For many AM facilities, the purchase of a stereo STL, an IBOC compatible audio processor and an IBOC exciter will comprise the majority of the upgrade costs.
The FM equation is a little more complex. If the station’s FM transmitter operates with an output of less than 8 kW it will generally be more cost effective to look at the low-level or common amplification conversion method. Common amplification uses one linearized transmitter to amplify both the analog and IBOC signals. This implementation is most efficient in regard to energy consumption and space utilization. The bulk of the cost of such conversion will be the new transmitter.
For FM stations operating with transmitter power levels above 8 kW, low-level implementation will typically cost more than high-level or separate amplification. In separate amplification, the existing analog transmitter is combined with the digital transmitter using a 7 dB or 10 dB combiner.
The decision between high-level and low-level combining usually rests in the amount of headroom in the existing transmitter. If the transmitter has at least the 10-percent headroom required to overcome the insertion loss of the injector/combiner then high-level combining may be less expensive.
If however, your transmitter does not have the required headroom it may be more costly to replace the existing analog transmitter and buy the necessary high-level components than it would be to buy a single low-level common IBOC/FM amplifier.
The estimated cost range is quite broad, but can be narrowed greatly once the existing equipment is evaluated. The good news is that those broadcasters who have invested in updating their equipment will benefit by a reduced cost in converting to IBOC.
Send your IBOC questions to [email protected].
Radio World welcomes other points of view.