Digital Alert Systems enters ATSC 3.0 dispute, declines to take sides on DRM

Digital Alert Systems told the FCC on July 3 that Weigel Broadcasting’s test of two NextGen TV boxes, which found no emergency alerts on encrypted channels when the devices were offline, is a useful data point but not proof that ATSC 3.0 or its content protection is at fault. On the technology at the center of the fight, the company was explicit: it takes no position at all.

Weigel’s ATSC 3.0 tests show emergency alerts fail without internet on DRM channels

“Digital Alert Systems does not take any position on Digital Rights Management (DRM) overall,” wrote Edward Czarnecki, the company’s vice president of government and international.

The letter, filed in GN Docket No. 16-142, responded to a June 4 Weigel submission that had already drawn replies from the National Association of Broadcasters and A3SA, the group that licenses ATSC 3.0 content protection. NAB and A3SA defended the standard and Weigel used the test to challenge it; Digital Alert Systems confined itself to the emergency-alerting question and to what the test did and did not establish.

Weigel’s June 4 filing described testing in four markets — Chicago, Charlotte, Green Bay and South Bend — using two devices, the BitRouter ZapperBox and the Silicondust HDHomeRun.

When the boxes were disconnected from the Internet, Emergency Alert System messages were not delivered on channels protected by DRM, the broadcaster reported. Weigel described the products as “low cost” converter devices, a characterization the content protection group later disputed.

Evan Fieldman, president of Weigel, used the results to argue against a mandated “flash cut” to ATSC 3.0 sought by NAB, and to press two remedies: keeping current simulcast rules in place until consumer adoption thresholds are met, and requiring every ATSC 3.0 transmission to carry a “Broadcast PLP” of at least 19.3 Mbps for free over-the-air video with no Internet requirement. A PLP, or physical layer pipe, is a slice of a station’s data stream that can be configured with its own error protection and capacity; 19.3 Mbps is roughly the payload of a legacy ATSC 1.0 channel.

Weigel’s underlying concern, stated in the filing, is that the transition could make a free service expensive and a simple service complicated, with rural viewers who lack reliable broadband among the most affected.

The clarification from Digital Alert Systems

Czarnecki’s letter agreed with the principle that viewers must receive emergency information over the air even when broadband is down, then argued that the test does not show why the alerts failed. The presentation, he wrote, did not identify firmware versions, device configuration, DRM authorization state, broadcaster service configuration, signaling paths or receiver logs.

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The result “should be treated as a useful data point, but not as a complete technical diagnosis or proof of a standards-level defect,” the company wrote.

Much of the letter turned on distinctions the filing said the record had blurred.

Czarnecki separated three modes of DRM operation, online authorization, key caching that stores credentials for continued offline use, and an offline or “group-license” mode meant to work on devices that have never connected to the Internet, and argued that a test result depends on which mode a device was in at the time. He also drew a line between a receiver’s inability to decrypt a video channel and the availability of the alert itself.

“A failure to authorize or decrypt a protected video service should not automatically be presumed to mean that emergency alert signaling is unavailable over the broadcast path,” Czarnecki wrote.

On Weigel’s proposed 19.3 Mbps pipe, the company was more direct, calling it a separate issue from the device behavior at hand. A fixed capacity allocation, the filing argued, does not by itself determine whether emergency signaling is encrypted, whether a receiver has cached keys or whether alerts override a content-license error. Reserving that much capacity, the company added, could constrain bandwidth for other ATSC 3.0 services, including Advanced Emergency Information, an optional broadcast feature that can carry maps, evacuation routes, multilingual text and other data alongside a standard alert.

Digital Alert Systems noted that one of its executives sits on the board of the Advanced Television Systems Committee, which develops the standard, and chairs its IT-1 team on Advanced Emergency Information. The company said it did not file on behalf of the committee.

The content protection group’s account

The organization that licenses ATSC 3.0 encryption, ATSC 3.0 Security Authority LLC, known as A3SA, filed on June 26 and placed the blame on the two device makers. Its counsel argued that the failures “stem directly from implementation choices made by specific manufacturers” and had nothing to do with DRM or the standard.

A3SA described the HDHomeRun as a network-oriented DVR that relies on cloud-based processing to decode the ATSC 3.0 audio format, AC-4, and that was never built to decrypt protected content in the first place.

“Silicondust … has nonetheless chosen to not implement a solution for the HDHomeRun device that supports A3SA’s content protection framework,” the filing said.

The ZapperBox, A3SA said, needs an Internet connection only the first time an encrypted channel is tuned, after which the license persists; the manufacturer expects to add “never-connected” operation through a software update by the end of the year. The group said more than 18 million devices in the field can already receive all NextGen TV content, encrypted or not, without an Internet connection or subscription, and attached a device-by-device table, “ATSC 3.0 EAS Support,” listing televisions and set-top boxes from ADTH, Hisense, LGE, Panasonic, Samsung, Shift2Stream, Sony, TCL, Zinwell and others as displaying alerts on encrypted channels while never connected. The same table lists the HDHomeRun as failing that test and the ZapperBox’s never-connected support as in development.

NAB’s position

NAB, in a June 23 filing from Alison Martin, vice president of innovation and strategy, made a similar implementation-versus-standard argument and pointed to WJLA-TV’s Advanced Emergency Information project as an example of what the standard enables.

“It is important to distinguish between implementation-specific issues associated with particular devices and the capabilities of the ATSC 3.0 standard itself,” Martin wrote.

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The association urged the commission to set a date-certain path to complete the transition.

The four filings agree on the baseline: emergency information must reach viewers over the air when broadband is unavailable.

They part on what Weigel’s test demonstrates. GN Docket No. 16-142 remains open for comment.