Several readers reported on their experiences with the new Best Buy "Insignia" 5- and 7-inch portable ATSC receivers. Thanks to everyone that spent the time and money to check out these receivers. However, as wide variations in DTV performance were reported, I'm wondering if perhaps there are two versions of receivers in distribution.
First, forget analog TV reception with these products--broadcast engineer Henry Ruh reported that his 20-year-old Radio Shack Citizen portable gave better performance.
Second, it would be hard to consider the display quality even "standard definition." When I saw the specified 480x234 resolution for the 7-inch set, I thought it was a typo. Alas, that does not appear to be the case. While these little receivers can display the PSIP program guide and closed captioning, the 480x234 display can make it difficult to read the text. Also, there is no way to swap out batteries and the case limits the angles for antenna positioning, making it difficult to optimize reception.
What about ATSC reception?
Reports from Ruh and others in the Midwest indicated it was very poor. Ruh said his Hauppauge HVR-950 tuner significantly outperformed it using a whip antenna in the same location he used for testing the Insignia antenna. He also reported significant interference from a MediaFLO channel 55 transmitter.
Mike Pruitt at WISH-TV in Indianapolis said that while the on-board antenna is fine for UHF, it is inadequate for VHF. I've found the same problem with the antennas supplied with some of the USB DTV receivers--they need to be longer!
How sensitive is the tuner? Pruitt hooked up the receiver to a good VHF/UHF antenna system and using an inline switchable pad, adjusted the input for a minimum lockable signal. He found a minimum of -78.7 dBm was needed to lock up WISH-DT on Channel 9. At Channel 21, reception was possible down to -83.9 dBm. Sensitivity was slightly less at -83.1 dBm for Channel 46, WTHR-DT.
UHF reception meets the ATSC A/74 recommended sensitivity of -83 dBm, but falls far short of what's needed at VHF. Combined with a less efficient antenna, this doesn't bode well for VHF DTV reception.
According to Pruitt, using the receiver's whip antenna in a parking lot in downtown Indianapolis required some amount of effort to receive the DTV Channel 9 signal. He reported that UHF channels were less picky. "Once the DT signal is locked, any movement of the receiver will require it to re-acquire and lock again," he said. "It took about 2 to 3 seconds to lock up after channel changes."
Another reader in Indianapolis had difficulty with the receiver and said he was returning it.
Bob Davis and Bill Napier of Bahakel Communications tested the receivers in Charlotte, N.C.
"Their performance is dismal at best," Davis said. "I could not keep a solid lock standing on the baseball field less than four miles from our one MW DTV (transmitter)."
After seeing these reports, I was considering issuing a "don't buy these receivers" bulletin. However, on Thursday, I received reports from two markets long considered to be extremely challenging for DTV reception--New York and San Francisco.
TV Engineer Dick Bogner tested the NS-7HTV 7-inch receiver, comparing it to the Samsung DTB-H260F and its fifth-generation chipset.
"The performance of both is essentially identical, which means the Best Buy unit is fifth generation, much better than fourth generation," he said, noting that he was able to decode every New York City and Northern New Jersey station with a bowtie antenna located in his ground floor window, which is some 18 miles to the east of the Empire State Building transmitter site. He remarked that the NTSC performance was not as good, but that the "the ease of use is remarkably improved over the Samsung and other decoders" that he'd tested.
In case you are new to TV broadcasting, Bogner designed some of the first UHF TV slot transmitting antennas and has also built TV stations.
Russell Brown, chief engineer KMTP-TV in San Francisco, tested the 5-inch set. At his home, about 4 miles from the Sutro Tower, he received most Sutro DTV signals. At his office in Palo Alto, 35 miles to the south, he was able to pick up some of the DTV signals in the parking lot and able to receive most at a second floor window location. One of the stations operated on channel 12. He said it came it about as well as the others in the parking lot and came in very well when connected to the rooftop antenna.
Are these wide variations in performance due to differences in the receivers? Did San Francisco and New York City Best Buy stores have a later version of the receiver than the Midwest and North Carolina stores, or is the difference due to the signals and topography in these markets? I'm hoping to have some more reports, including one from Houston, Texas on these receivers.
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