Thin-Air ATSC (And NTSC): Reception Absolution And Condemnation

The latest in an ongoing series…

Near the beginning of the report I filed after KTVN chief broadcast engineer Jack Antonio’s first visit to my home office several weeks ago, and in spite of the abundance of reception data we did collect at that time, I said:

I’ll apologize upfront that, due to limited schedule availability on their part, we were unable to measure the signal strength coming from my Antennas Direct ClearStream 2 antenna.

Antonio revisited my place last Friday morning, accompanied this time by KTVN engineer Steve Sonnenburg, to finish the work we’d earlier started. Antonio and Sonnenburg first took front porch (i.e. thereby not including any incremental attenuation caused by my home’s coax wiring) signal strength measurements from a Winegard YA-6713 high-band VHF antenna mounted on a ~20′ pole and pointed directly at the cluster of towers at Slide Mountain, using both the earlier-mentioned Sencore AT1506 and, for NTSC signals, a Wavetek SAM 1000. Here’s what we got:

Recall that I’m able to receive KRNV (at least when I don’t have a Motorola signal booster in-line) and KTVN (after re-orienting my antenna), along with a highly distorted version of KOLO’s NTSC signal, but I can’t receive KOLO’s digital broadcast. Since the Winegard YA-6713 is a VHF antenna, we didn’t try receiving Fox affiliate KRXI on ATSC channel 44. Note, too, that KTVN explicitly uses the Winegard YA-6713 for reception measurements as a sort of ‘worst-case’ testbed, due to the antenna’s low cost and small size.

The above data definitely implies a degraded KOLO ATSC broadcast at my location versus the NTSC alternative. But remember that I don’t have a Winegard YA-6713 antenna; I have an AntennasDirect ClearStream 2, which the manufacturer promotes as offering ‘consistent gain through the entire DTV channel spectrum’ but (after much pressing on my part) admitted was primarily a UHF unit, with some degree of high-band VHF coverage. That limitation should still be ok, though, since the Reno-area ATSC transmissions I have any reasonable chance of receiving are all high-band VHF and UHF. So how’d the ClearStream 2 do in the same location and orientation as its Winegard YA-6713 predecessor, according to KTVN’s measurement gear?

Note that KRXI’s tower is ~60° off-axis from the ClearStream 2 (in its current orientation). Fortunately, according to TVFool, my location has line-of-site proximity to the tower, thereby explaining (along with the fact that the ClearStream 2 is predominantly a UHF antenna) why I’m still able to get a solid KRXI signal.

Other thoughts:

• Given that KRNV and KTVN’s signal strengths are below –20 dBmV, it’s pretty amazing that I’m able to solidly receive their transmissions. Kudos to the tuner manufacturers whose hardware resides inside my Syntax-Brillian LCD TV and HP ExpressCard TV adapter!
• At –32 dBmV, KOLO’s ATSC signal is too weak to tease out of the noise. The TVFool report suggests part of the reason why; there’s a substantial (~150 kW) signal strength differential between this ABC affiliate’s NTSC and ATSC broadcasts. However, KOLO’s digital stream, which I can’t receive, is of comparable broadcast strength to the signals coming from its Slide Mountain neighbors at KRNV and KTVN, which I can receive. I suspect, therefore, that KOLO’s transmissions are asymmetrical around the compass, whereas they’re supposed to be omni-directional. Whether that’s a reflection (pun intended) of an antenna problem, a geographic anomaly, or both, I have no idea.
• Judging from my measurements, Antennas Direct needs to stop promoting its ClearStream line as ‘designed and optimized for 2009 frequencies associated with the DTV transition’. In a practical sense, these are predominantly UHF antennas, not applicable for low-band VHF reception and only applicable in high-band VHF environments with already-very-solid signal strength.
• I think I need to buy a Winegard YA-6713 and negotiate a multi-antenna merger as Maury did a few years ago.

Followup: The Winegard YA-6713 unfortunately appears to be out of production, per my Google research (though I’ve directly contacted the manufacturer and am hopeful I can obtain one that way), and its YA-1713 replacement is much larger. Alternatively, the AntennaCraft Y5-7-13 also looks interesting…