Here's one man's experience with receiving digital OTA in the Monterey area. I hope it will encourage others to give OTA reception a try.
My house is located just off of Hwy 68, between Laguna Seca Golf Course and Laguna Seca Raceway. The house is slightly above the level
of Hwy 68, but is in a bowl surrounded by mountains on all sides. I am mainly concerned with reception of:
KSBW8 NBC Digital ch 10, 20 mi to the NE
KCBA35 Fox Digital ch 13, 20 mi to the NE
KION46 CBS Digital ch 32, 9 mi to the SE
KCAH26 PBS Digital ch 58, 20 mi to the NE
I am able to receive a good picture with no dropouts on all but KCAH. KCAH seems to be a lost cause where I am located.
I started with the idea that it was unlikely I would receive anything. This was based on the topography around my home, and the comments of my D* installer and the folks at Radio Shack in Del Monte ctr, who both said that I would only be able to receive digital channels OTA if I was located on a hillside near the ocean. The guy at Radio Shack even refused to sell me an antenna - "Just go with cable if you want HD locals". He threw down the gauntlet, and I accepted the challenge.
Based on posts here on AVS forum, I selected the Channelmaster 4228. My logic was that it was a UHF antenna with excellent gain for the high VHF channels I was trying to receive (10 and 13). I started with the idea that I would mount it outdoors. To test reception I bought a couple of sections of antenna mast from Radio Shack, and used my Ultimate bicycle tripod stand to hold the mast and antenna. I also purchased a Sencore signal meter on ebay to make it easier to peak the antenna signal.
To my surprise, I received a strong signal (anywhere from -14 to -3 db) for KION right off the bat. Anything in the general direction of the tower yielded a strong signal. KSBW and KCBA were another matter. I was able to get an acceptable signal on either one of channel 10 and 13, but no one location worked for both. This was very curious to me since both channels 10 and 13 are broadcast from the same tower, and are on the same band. After much experimentation outdoors, I decided to try mounting the antenna in the attic. To my surprise it did not have a large negative effect on signal strength. My house has a tile roof. But I still was unable to find a location which would work for both channels 10 and 13. For a few weeks I left it mounted in the attic, set up to receive channels 10 and 32 only.
After researching the gain numbers for the CM4228 antenna at http://www.hdtvprimer.com/ANTENNAS/comparing.html
, I noticed that the gain for this antenna dropped off between channels 10 and 13. The lost gain was apparently just enough to make the OTA tuner on my D* HR10-250 unable to sync reliably to the digital signal on ch 13. First I purchased the CM7777 preamp to see if that would boost the gain enough that the HR10-250 would sync to the signal for ch 13. Signal strength was higher with the preamp but still not good enough.
So I decided to try a high gain VHF/UHF antenna, reasoning that I had gain to spare on the UHF band but obviously needed more gain on the VHF side. I selected the Antennasdirect v-21 antenna.
I mounted the new antenna in the same attic location as the 4228, tweaking the position until I was able to reliably get the following readings (db readings are without the CM7777 preamp, HR10-250 readings are with the preamp connected):
-16 to -17 db for channels 10 and 13 = 60 on the HR10-250 signal meter
-13 db for channel 32 = 89 on the HR10-250 signal meter
-38 to -40 db for KCAH(58) = 0 on the HR10-250 signal meter
So I would call my quest for digital TV a success. I'm getting a good picture with no dropouts on all channels except KCAH. Luckily I get KCAH in SD via D*, and it doesn't appear that KCAH has much HD content anyway. I get ABC in HD (HD Lite) via D* DNS.
Here's my tips to those who would like to try to receive digital OTA:
1) Don't listen to anyone who tells you that the topography, etc. will prevent you from receiving a signal. Without hooking up an antenna and signal meter, no one can know for sure if you can receive a signal at your location. Even if surrounded by hills and trees, you may be able to receive a reasonable signal. Be prepared to give it a shot, and if you can't receive a signal then at least you know it for sure. Obviously you want to purchase antennas and stuff which you can return in case you can't get a signal.
2) Use antennaweb only as a rough guide. I would recommend stepping up to the next higher gain antenna than the one that antennaweb recommends. In my case antennaweb recommended a medium directional with preamp, I ended up with a long distance directional with preamp.
3) In our area, you probably want to lean toward an antenna which has better VHF gain than UHF gain. Although those of you who are farther away from the KION tower than I am may still need high UHF gain. Both the CM4228 and antennasdirect v-21 will do a good job for both VHF and UHF, the CM4228 doing a little better on UHF, and the antennasdirect v-21 doing a little better on VHF. If your'e closer to the KSBW/KCBA tower you may want to opt for the CM4228 antenna. Those closer to the KION tower may want to opt for the antennasdirect v21 antenna. Make sure you purchase the antenna from a dealer which accepts returns as it is very possible you may need to try several antennas to find the right one.
4) To test your signal I would recommend taking your ATSC tuner to the antenna location and connecting the tuner to the antenna and a small portable TV. Once you have determined you can receive any signal at all, a signal meter or spectrum analyzer will greatly simplify antenna aiming. I would not have been successful in aiming my antenna without one. I have a Sencore SLM1453 meter I purchased on ebay for ~$300. Signal meters such as the Sencore and the Sadelco Displaymax CLI, usually sell on ebay for $300-$700. If you don't want to spend money for a meter the ATSC tuner/portable TV combination should work ok. I would not recommend trying to point the antenna with someone standing downstairs giving you feedback. If your signal is marginal you'll be shocked how a small movement of the antenna will affect your signal strength readings.
5) Attic mounting is not out of the question even in a marginal location. Try the antenna outdoors on a portable tripod, and if you get a good signal, then proceed to the attic (but only if you don't have a metal roof :-)
As a postscript, check out PGDave's earlier post in this thread http://www.avsforum.com/avs-vb/showt...&&#post6018790
about receiving SF Digital channels OTA in the Monterey area. I tried to receive the SF digitals in my location using the antennasdirect xg-91, but was unable to receive any measurable signal. Luckily antennasdirect accepts returns :-) I have to assume that PGDave's home is located on a hillside near the ocean in order for him to receive any signal from SF.