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Conditional Access Tests Underway

Field tests of conditional access of an IBOC system are expected to continue through May at WUSF(FM).

(click thumbnail)From left: Hal Kneller, Tom Rucktenwald, Tim Anderson, Pat Malley, Mike O’Shea, Bob Hadden, Tom Dollenmayer, Dustin Hapli and Girish Warrier.
Photo courtesy of Hal Kneller
TAMPA, Fla. Field tests of conditional access of an IBOC system are expected to continue through May at WUSF(FM).

As RW reported in the March 28 issue, this testing is a next step towards refining software and hardware necessary to encrypt the HD Radio signal for stations that choose to do so.

Conditional access requires encrypting and un-encrypting a broadcast signal, then “permissioning” a receiver so that it can decode the signal. Conditional access company NDS has developed the technology for HD Radio and its system is being tested at the station in Tampa.

Stations would need two pieces of NDS hardware to support the software, mating units called the Initiator and Protector. The Initiator is an administrative control unit; the Protector encrypts the signal. Both are installed ahead of the Importer in the air chain of a station using a second-generation or later HD Radio Importer. The Importer requires a software upgrade to accommodate conditional access.

WUSF is a longtime-Ibiquity test bed and was also the first public station to go HD Radio. Also involved in the tests are NDS, Ibiquity Digital and Harris; NPR Labs is observing.

The International Association of Audio Information Services is involved; WUSF is transmitting its radio reading service on its analog SCA as well as its HD3 channel. Program-associated data is being transmitted on the HD3 signal; for example, “WSJ” is displayed if an announcer is reading from the Wall Street Journal.

The process of permissioning a receiver to access the protected channel is being tested. There’s no detrimental effect on the audio quality of either the HD3 or main digital signals by the encryption process, said Hal Kneller, senior manager of public radio initiatives for Harris.

The station is operating with a throughput of 48 kilobits per second on its main and HD2 channels and operating on the extended hybrid carriers at 24 kbps on the HD3, he said.

Test participants are turning on and off the equipment that encrypts the signal to see how the digital sounds and if it affects the analog SCA at all. Kneller said it does not.

The audio quality at 24 kbps is noticably different than what it would be on an SCA, he said. “It sounds almost as good as analog FM. It’s in mono. There’s no static or hiss and all distortion is gone.”

In order to receive a protected channel, a consumer would have to provide a serial number from his or her radio to the station or an entity in charge of a national database. Once the number was verified, that receiver would be unlocked, allowing the consumer to hear that channel, either for a one-time event or for as long as the individual pays for access.

The stations would decide how to use the channels and if they should be encrypted full-time or occasionally.

The serial number system and the actual encryption are two levels of security against system hackers, Kneller said.

Results of these tests were to be shared at the NAB show. By then, proponents hoped to refine the user interface, a Web browser that stations would use to operate the conditional access technology.

Kneller stressed that the software and hardware used in the tests is considered beta gear still under development. It may look different this summer, when NDS plans to ship equipment to stations. Receivers that can de-code the encrypted signals could be on the market by year-end.

When engineers were installing the HD3 test equipment, WUSF’s HD2 channel was off the air for 10 minutes while participants upgraded the Importer. That could happen to a station when it completes initial setup of a conditionally accessed multicast channel, Kneller said.

WUSF is not using a second-generation Importer and required a loaner from Harris for the test; that could account for some of the downtime, he said.

WUSF personnel involved in the testing include Station Manager Tom Dollenmayer, Chief Engineer Mike O’Shea and Operations Manager Dustin Hapli. Representing NDS are Tom Rucktenwald, director of data applications delivery, and Bob Hadden, project manager. Ibiquity’s Pat Malley and Girish Warrier, Business Analyst, Advanced Application Services, also are working on the project. Contract engineer Tim Anderson, President, TBA Communications, is helping Ibiquity on the project.