Thin-Air ATSC (And NTSC): Current Conditions, and Comments On Comments
Continued from ‘Thin-Air ATSC (And NTSC): An Engineer Visit And An Antenna Reposit‘…
KTVN’s Jack Antonio concurred with reader Ellis Feinstein that ionosphere affects predominantly affect AM radio broadcasts, not FM or TV-band signals. He also assuaged Ron Wilson’s concerns about ham radio (and perhaps not surprisingly, is a ham radio operator himself); the vast majority of equipment he encounters operates within FCC specifications, and anyway his quick eyeballs’ scan of my neighborhood revealed no visible ham radio antennas. However, in echoing reader jed martin’s suggestions, I’ll share what I experienced late last Wednesday night. KRNV’s channel 7 ATSC transmissions, normally crystal clear, were rife with interrupted-bitstream artifacts. Conversely, for once I was able to pick up a rock-solid KNPB (PBS ATSC channel 15) signal, in spite of the fact that its transmitter is on Red Peak, north of Reno, nearly 30 miles away and on the other side of the tall Mt. Rose Range. The next morning, KNPB was silent again, and it’s remained so ever since.
Antonio would likely (and I definitely) disagree with Feinstein’s critique:
The antenna orientation should be optimized for each station in such tests [editor note: by means of a rotor, as reader Randell Jesup also recommended) rather than "splitting the difference"
Antonio candidly admitted, in fact, that tower location diversity was a big downside of the Reno reception situation; with transmitters located north, northwest, south and southwest of the city, it was virtually impossible to receive all possible broadcast channels without means of a rotor. Facing that expensive and hassle-to-use reality, many consumers will instead, as reader DW offered, "just go with DirecTV or Dish Network" (or, for that matter, cable or IPTV service) instead. At least in my case, all of the towers are ‘east-ish’ of me, although not all of their signals reach me due to granite-induced attenuation.
Speaking of large lumps of granite, thanks go to readers Mike M and bigRoN who recommended TVFool instead of AntennaWeb; the former site seems to incorporate terrain-related factors that the latter ignores. Below, you’ll respectively find the analog-plus-digital station, analog-only and digital-only results of TVFool’s analysis of my location (and here’s the FAQ):
I’m delighted to report that, as of last Thursday evening, I’m now able to reliably receive KTVN’s ATSC transmission in addition to KRNV and KRXI. I accomplished this by moving the antenna from its ’splitting the difference’ 60° compass orientation to 90°, thereby pointing it straight at Slide Mountain. Happily, even though I’m now ~60° off-axis from KRXI’s signal, I’m still able to solidly receive it, a fact which is particularly impressive considering that as bigRoN points out, the station is currently broadcasting at much lower than its eventual peak power. The TVFool report suggests the reason for my continued success; it’s the only tower to which I have line-of-sight visibility.
Conversely, echoing Larry M’s multipath observations, KTVN and KRNV’s towers are both a 2-edge path away; the signal must ‘bend’ around two distinct mountain ridges in order to get to me. Why, then, can I receive them but still not get KOLO’s close-proximity but single-edge transmission? Reader Mac may have figured out the answer:
Depending upon your location, you may very well be able to see the KTVN and KRNV antennas, but not the KOLO antenna (which is on the South face towards Carson City, compared to the North face for 2 and 4 digital). KREN and KAZR are just down the hill from KOLO. Is it possible that you cannot see that side of Slide Mountain?
In (unsuccessfully) striving to snag KOLO, I’ve also temporarily added an Antennas Direct CPA-19 signal amplifier to my setup. It’s not yet on the company website, but here’s how Richard Schneider explains the differences between it and the PA-18:
…The CPA-19 will not pass low VHF; it is designed to only amplify and pass high VHF and core UHF. This improves its noise characteristics and overload resistance…
The old amps and the new Clearstream amps can both be used for the same purpose, but the Clearstream may be better suited a little better for fringe locations or in areas that have lots of interference.
The CPA 19 has only slightly higher gain than our existing pre amps, (between 17 - 19 dB) but that was incidental. (Anything over 10 or 12 dB in a residential application is almost overkill).
The goal of the Clearstream preamp was 4 fold:
- Lower noise. (About 1.5 - 2.1 dB)
- Higher resistance to overload (the signal ratio at the antenna between a high-power nearby station and a distant station can be 500,000 to 1)
- Better filtering and rejection of signals outside high VHF and core UHF (174- 216 Mhz and 470-700 MHz) such as cellular, wireless broadband and public safety frequencies, and
- Improved RF shielding
Often times, amplifiers can do more harm than good when they either introduce noise onto the line overload in the presence of a nearby transmitter. The Clearstream amp should have noise levels and overload resistance comparable to commercial grade amps, but as with all amplifiers, it’s not a magic bullet. They cannot create a signal that doesn’t exist at the antenna to begin with. (But worst case, they shouldn’t do any harm).
Since the CPA-19 was a loaner, I’ve gone ahead and purchased Motorola’s model 484095-001-00 signal booster, whose operation extends down to low-band VHF. Maybe it’ll be enough to tease a solid KOLO bitstream out of the ether. I also tried using my Samsung SIR-T151 STB instead of the ATSC tuner built into my Olevia LCD TV, but surprisingly found that the standalone Samsung unit had worse reception prformance. Additionally, I’m using a HP-branded version of Hauppauge’s WinTV-HVR-1500 analog/digital tuner module (ExpressCard form factor), which appears to have similar reception sensitivity to the Olevia LCD TV, in my Windows Vista-based laptop.
KOLO continued shortcomings aside (for which your added suggestions are welcomed), I seem to be set with CBS, NBC and Fox. On Wednesday night I watched (through an Xbox 360 acting as a Media Center Extender) a hiccup-free high-def ATSC recording of House from the night before, and I’ve already got the laptop queued up to capture NBC’s daily Olympics coverage beginning later today. I’m glad I got a large HDD on this system…
Happy weekend, all!
