The NTIA Specification is arranged in three categories, describing required, permitted, and disqualifying features.
Absolute requirements The following features were required, but could be provided by the box in various ways. Coupon-eligible converter boxes had to convert all
ATSC (digital) formats to the traditional
NTSC analog system used by analog US television sets. The box needed to output
radio frequency signals (compatible with a television's antenna input),
composite video, and stereo audio. It had to include a remote control, and be compatible with
universal remotes. The units had to support both a
4:3 center
crop of a
16:9 transmitted image, and a
letterboxed rendition of a
16:9 transmitted image. The video outputs had to produce video at an
ITU-R BT.500-11
quality scale of Grade 4 or higher. Various technical performance parameters for the digital tuner were also specified. The boxes were required to decode
Emergency Alert System (EAS) messages,
Closed Captioning data, and
Parental Control (
V-Chip) descriptors and to decode the
Program and System Information Protocol (PSIP) data from the digital transmission, using it to provide the user with tuned channel and program information. CECBs could not consume more than an average of 2 watts of
power when not in use (when there was no video or audio display). They had to provide an automatic power-down option that could put the unit in standby mode when it hadn't received any commands for a period of time.
Optional features Manufacturers could self-certify compliance with these requirements, but had to provide test results and two units to the NTIA for
ad hoc testing. The FCC could also test converter boxes at the NTIA's request. Among the optional features permitted, but not required, were the following: • Support for a
smart antenna, through the use of the
CEA-909 Antenna Control Interface. The manufacturer could optionally provide a promotional package discount for the combination of a smart antenna and a CECB. •
Multichannel television sound (BTSC) stereo at the RF output. •
S-Video output. •
Analog passthrough, as needed for
LPTV,
broadcast translator, and foreign signal reception. •
Electronic program guide •
Software updates. • Support for the
Canadian television ratings system, allowing the manufacturer to sell the same device in Canada. • Support for secondary audio channels, such as foreign languages or
Descriptive Video Service. While an outdoor antenna is required for adequate digital reception in most locations beyond from
TV transmitters, and
smart antenna interfaces were an optionally permitted feature of coupon-eligible converter boxes, there were no subsidies for antennas. Although manufacturers could sell a converter/smart-antenna bundle, they were required to also offer the converter by itself to consumers. DTV converter boxes could earn a
United States Environmental Protection Agency Energy Star label if they consume no more than eight watts of electricity while operating, no more than one watt while in
standby mode, and if they automatically power-down after four hours of inactivity.
Disqualifying features Some features disqualified a converter box from coupon eligibility, such as
high-definition video output and built-in
DVR functionality.
Digital cable and
satellite set-top boxes that incorporate a digital tuner were also disqualified. Certain output features were prohibited from coupon-eligible devices:
component video,
VGA,
RGB,
DVI,
HDMI,
USB video, IEEE-1394/iLink/
FireWire video,
Ethernet video, and IEEE-802.11/
WiFi video outputs. Some converter boxes have a programmable timer, which the user could program to match the recording schedule of their VCR. Then, the converter's tuner will change to the appropriate channel at the time the VCR needs to record. This requires a separate box for the VCR, or the viewer will have to watch what is being recorded. Another, less common option is an "
IR blaster", which a recorder can use to control an external tuner, like a cable set-top box or converter box. However, older devices with IR blasters may not be fully compatible with
digital subchannels; the converter box may require the use of a [-] or [.] button to specify the subchannel, which the pre-digital recorder may not know how to transmit. Some older
TiVo brand digital recorders received software updates specifically to control digital converter boxes via the TiVo's included IR blaster. Small battery-operated portable televisions, while valuable in time of
disaster, are generally poorly suited to digital conversion. While at least one CECB (Winegard's RCDT09A) is operable from an external battery pack, the combination of television, converter, external antenna, and power supply limits portability. , portable digital
LCD TV sets cost at least $100, and could not be used while in motion at significant speeds (restoring this analog functionality would require broadcasters to transmit
mobile TV via the separate
ATSC-M/H standard, which would in itself require new tuners). The inability of some boxes to add new digital channels without a full re-scan—deleting all existing channel settings—renders them unusable to viewers who rely on
directional antennas and
rotors to receive distant stations. Signal strength meters, where available, are awkward, typically only displaying information for channels that have already been found. This is problematic, as digital signals are most often transmitted on higher frequencies or with far less power than their analog counterparts, requiring careful antenna installation, orientation and location to avoid obstructions, fading and
multipath interference problems. Where the converter fails to receive a channel, an often-cumbersome manual process is usually provided; however, this requires knowledge of which frequencies each missing station is actually transmitting on, rather than the
virtual channels each is mapped to by the ATSC protocol. Since the NTIA did not require CECBs to output
MTS stereo signals via their radio-frequency output,
THAT Corporation noted that consumers using RF-only connections with CECBs will lose stereo TV sound. This problem may be avoided by using the converter's
line level audio outputs. == Low-power television concerns ==