- RCA DMT 335R-
Last spring I convinced myself that, indeed, the M/H application in a notebook stick configuration is viable from a user standpoint. (see previous Ed’s View)
Now, I wanted to verify M/H viability in a “hand-held” configuration with a marketed receiver. So, I acquired an RCA DMT 335R 3.5” Mobile DTV/ATSC Digital TV from the RCA web-store for a field test. This receiver tunes, demodulates and decodes ATSC as well as ATSC M/H but does not demodulate NTSC (analog) services. I was unable to obtain a block diagram of the circuitry layout but assume it employs a typical three chip tuning solution: RF/IF amplifier, ATSC demodulator/decoder and ATSC M/H demodulator/decoder. Power is supplied by four replaceable 1.5V AA cells.
The user interface is straightforward except that toggling between ATSC and ATSC M/H reception is not automatic. The tuning protocol assembles and stores two separate scan lists for each format that must be selected manually. The antenna is an approximate ten inch swiveling telescoping monopole, but provisions are made for an external antenna via an accessory cable (not included).
ATSC performance using the monopole, as expected, is intermittent with no reliable reception outside the stations’ “community of license” coverage area (about 15 miles from the transmitters). However, M/H performance exceeds expectations. I tested the receiver’s M/H performance in suburban Columbus, Ohio, on the edges of the coverage areas of channels 21, 14, and 48. These stations were simulcasting M/H data from virtual channels 10-1, 4-1 and 6-2 respectively. Reliable M/H reception was obtained on all three channels, indoors and out, moving and stationary, and in most cases with the monopole antenna not deployed! If the RCA receiver is an example of M/H band-held performance, clearly the system works as advertised. Indeed, the extra M/H transport stream coding and M/H pilot robustness allow viable portable DTV reception. The major technical problem with M/H remains VHF performance that is limited by low receiver antenna gain in portable units.
However, the overriding issues with M/H in general are not technical but commercial. At this time several ad hoc organizations with seeming overlapping objectives are attempting to develop commercial models for broadcasters to monetize the technology. No doubt these models will involve some type of conditional access and therefore program encryption schemes that will render presently available receivers incompatible with such protected programming.
With the rapid build-out of wireless 4G smart phone capability, it is not clear how or why 4G and M/H technologies commercially co-exist. By the end of this year it is estimated that M/H will service 48 US markets with 126 stations but with virtually zero receiver penetration – and the programming is free! In my view, unless M/H is technically incorporated within smart phone and tablet capabilities and, most importantly, the appropriate commercial agreements between traditional broadcasters and wireless providers are consummated, M/H will be little more than another historical footnote, and the neat little RCA DMT 335 will find itself gathering dust in my hardware museum.
Posted by Ed Milbourn, October 10, 2011 7:48 AM
About Ed MilbournAfter graduating from Purdue University with degrees in Electrical Engineering and Industrial Education in 1961 and 1963 respectively, Ed Milbourn joined the RCA Home Entertainment Division in 1963. During his thirty-eight year career with RCA (later GE and Thomson multimedia), Mr. Milbourn held the positions of Field Service Engineer, Manager of Technical Training and Manager of Sales Training. In 1987, he joined Thomson's Product Management group as Manager of Advanced Television Systems Planning, with responsibilities including Digital Television and High Definition Television Product Management. Mr. Milbourn retired from Thomson multimedia in December 2001, and is now a Consumer Electronics Industry consultant.