Commission proposes technical adjustments to help remote pickup operations enter the digital age.

It looks like broadcasters’ Remote Pickup (RPU) operations may finally be getting pushed into the digital 21st Century. In response to separate petitions filed by the Society of Broadcast Engineers (SBE) and the Engineers for the Integrity of Broadcast Auxiliary Services Spectrum (EIBASS), the Commission has issued a Notice of Proposed Rulemaking and Order (NPRM/O) resolving a couple of RPU-related questions and proposing a number of changes to the RPU rules.

An RPU, of course, is one type of Broadcast Auxiliary Station. RPUs are used to send program-related information – including programming – from remote sites back to the station or network. They operate in one of three bands which are either shared with PrivateLand Mobile Radio Services (PLMRS) or close to PLMRS frequencies. Back in 2002 the Commission took steps to “harmonize” RPU standards and PLMRS standards in the hope that broadcasters would use PLMRS gear, which tends to be more spectrum efficient (largely because PLMRS gear is digital).

But that hope has been frustrated by a couple of practical problems.

For example, PLMRS operations – walkie-talkies, vehicle dispatch, two-way communications, etc. – use narrowband transmission and, therefore, don’t provide the higher audio quality (with no delay) that broadcasters need for audio program feeds.

No problem. The Commission concluded in 2002 that broadcasters could combine, or “stack”, the narrower channel segments to create wider band segments more suitable for their purposes. But that proved to be a less than ideal solution: The RPU rules require that RPU licenses specify the “channel center” on which the station will operate, and when you stack an even number of channel segments the “center” of the resulting stack does not match up with any of the center frequencies specified in the RPU rules. According to both SBE and EIBASS, this anomaly has discouraged broadcasters from using stacked segments; each offered suggestions for clearing up the anomaly.

As far as the Commission is concerned, though, no change is necessary because the rules already address the stacking of even numbers of channel segments: in such situations, the applicant merely specifies a center channel which is half-way between the lowest and highest frequencies in the stack. Problem solved.

SBE also noted that the determination of center channel can result in a frequency specified out to six decimal places, e.g., 455.496875 MHz, a degree of precision not easily achievable with most analog equipment. The Commission addresses that concern by observing that, as long as the broadcaster complies with applicable emission masks and programs its center frequency as closely to the specified center frequency as the equipment will allow, that will be deemed to be in compliance.

Another factor may have discouraged broadcaster use of PLMRS equipment: under the FCC’s rules, RPU operation must be in analog, not digital, mode. But most PLMRS gear is designed for digital use. Both EIBASS and SBE urged that the analog limitation on RPUs be tossed so that RPUs could use any form of digital modulation (as long as the broadcaster complies with the applicable emission mask and bandwidth emission requirements). The Commission is on board with that suggestion, and is now seeking comment on how best to implement it.

SBE also asked for an interim blanket waiver to permit all RPUs operating in the VHF or UHF bands to operate digitally using FCC-certified narrowband RPU equipment right away. The Commission wasn’t willing to go that far, however. Until various questions concerning digital RPU operation are resolved in this proceeding, the FCC is reluctant to jump the gun and permit such operation industry-wide. (One open question: Digital RPU operation would also require changes to the station identification requirements; the Commission is looking for comments on how best to handle that. Another open question: Should digital use be permitted in the HF RPU band?)

And finally, the FCC agrees with SBE’s observation that the need for 100 kHz RPU channels is a thing of the past. Accordingly, it proposes to eliminate such channels in the future. Existing authorizations for 100 kHz channels would be grandfathered indefinitely, and new such authorizations might be issued on a case-by-case waiver basis.

Deadlines for comments and reply comments in response to the NPRM/O have not yet been announced. Check back here for updates.