Question: Cannot pick up stations broadcast from four miles away

usaar33

DTVUSA Jr. Member
#1
I live in San Francisco in a 4th floor apartment next to the SF Bay and have been trying to set up DTV. I have a Mohu indoor leaf antenna.

Here's my TV Fool report:
TV Fool

With the exception of channel 7, I can't pick up any of the stations at azimuth 200 to 250, which knocks the vast majority of visible channels (I can't get any major network but ABC!). The ones at 125 degrees come in fine (they are coming from 40+ miles across the San Francisco Bay). My TV shows extremely weak SNR for the ones at 242 (around 5 db) and really weak SNR for the ones at 201 (around 9 db). KGO (7) gives much stronger SNR at around 22 db.

Roting/Moving the antenna around the room really doesn't help much.

Any ideas?
 

dkreichen1968

Moderator
Staff member
#3
You may be so close to the towers that the Mohu is overloading the tuner on your TV. That would explain why channel 7 (VHF which the Mohu really isn't designed for) would come in while the others (UHF) wouldn't. Try using a paper clip plugged into the coax connection on the TV for an antenna. I know that Trip has even used a thumb tack as an antenna in strong RF areas.
 

usaar33

DTVUSA Jr. Member
#5
I'm using a non-amplified Mohu antenna: Amazon.com: Paper Thin Leaf Indoor HDTV Antenna - Made in the USA!: Electronics

I tried using a clip. SNR for the non-working stations is about the same, for 7 (ABC) it has dropped to about 18 db. Others are a bit lower.

Questions:
Given that even under a terrible antenna I can't pick up these stations, would the attenuator help?

Could I be having line of sight issues? I pick up every UHF station coming across the Bay (it may be 40 miles away, but the signal is just passing through my apartment building). On the other hand, the signals 4 miles away has to pass through at least 1 skyscraper (possibly 2) to reach me. The one from 7 miles may have a baseball stadium in its line of sight. Can buildings block signals? If so, does TV Fool factor them in? And if so, what do I do about it?
 

dkreichen1968

Moderator
Staff member
#6
Questions: Could I be having line of sight issues? I pick up every UHF station coming across the Bay (it may be 40 miles away, but the signal is just passing through my apartment building). On the other hand, the signals 4 miles away has to pass through at least 1 skyscraper (possibly 2) to reach me. The one from 7 miles may have a baseball stadium in its line of sight. Can buildings block signals? If so, does TV Fool factor them in? And if so, what do I do about it?
Yes, buildings can block and distort signals. No, tvfool doesn't account for that. Without being able to look at the signals using a scope it's hard to say what is really going on. Overload is a possiblility. Multipath interference (what was ghosting in analog) is a real possiblity (multiple signals bouncing off buildings). Or, you may be just "under the beam" due to the buildings between you and the towers. Multipath can be fixed with a directional (or even shielded) antenna, but a directional antenna would only add to the overload problem. Being "under the beam" would pretty much be a show stopper.
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#7
Usaar33,

At 85 feet above ground level you have a wonderful TVFOOL report, Line-of-site and plenty of signal strength. Have you changed your tuner's settings away from Cable to Antenna or Terrestrial?

Jim
 

usaar33

DTVUSA Jr. Member
#8
Fringe: Yes, I'm on Antenna setting.
dk: What is the best way to determine if I'm "under the beam" or suffering from multipath interference?
(In terms of the building details, if I trace a direct line from my antenna to the broadcast tower, it passes through 220 feet (linearly) of a 140+ foot tall building. -- how 'penetrable' is that?)
 

dkreichen1968

Moderator
Staff member
#9
Fringe: Yes, I'm on Antenna setting.
dk: What is the best way to determine if I'm "under the beam" or suffering from multipath interference?
(In terms of the building details, if I trace a direct line from my antenna to the broadcast tower, it passes through 220 feet (linearly) of a 140+ foot tall building. -- how 'penetrable' is that?)
Not penetrable enough. I haven't had to deal with it myself, but "downtown" city areas can be the worse reception areas due to the "concrete jungle" effect. That's why Barry Diller and company put together Aereo in NYC. If you had a portable TV I'd say walk the neighborhood and see where the hot and weak spots were.
 

usaar33

DTVUSA Jr. Member
#10
So I guess a different antenna won't help? I'm very likely just out of luck?
(dk: This weekend, I will try bringing my TV to a friend's place a mile away that has a line of sight to the broadcast tower and seeing how reception there is)

If I am out of luck:
1. Aereo looks great and cheap; would be exactly what I'd want. Anyone know of a San Francisco equivalent?
2. The only TV line-based service that is doable in the complex in my budget is old-school cable TV. Unfortunately, their line-up is a subset of broadcast TV; they not only won't provide some stations I currently do pick up, but also won't give me 720p TV (I get one 720p station right now over broadcast (KGO -- abc -- ch7)). If I have to go this route, I'd want to somehow 'merge' the signals. A manual switch between antenna and cable lines is the obvious approach, but that can be a pain to use (I'd have to switch it AND (I believe?) the TV antenna/cable settings receiving settings). Is there some sort of 'more intelligent' device that can merge the two lines together and just assign them to different channels?

Thanks a lot for all your help!
 

Tim58hsv

DTVUSA Member
#11
So I guess a different antenna won't help? I'm very likely just out of luck?
I wouldn't say that.

I've always heard that a two bay bow tie antenna is the best indoor antenna there is. A four bay would work better yet but that's getting kind of large for an indoor antenna application. While I've never seen a Mohu in action the other flat panel antennas I have seen are pretty much worthless. I guess if you place one (flat antenna) where no obstructions are in the way it may work pretty well, otherwise you'll need to try something better and without a doubt there are better antenna's.
 

usaar33

DTVUSA Jr. Member
#12
Update: Tested my TV at this location: TV Fool
Antenna/TV combo worked great. Given that location is even closer, I doubt I am suffering from over-amplification. Guess I'll try the two bay (no one rents these things out right? I hate buying products and then returning them). If that fails.. hopeless?
 

nbound-au

The Graveyard Shift
#13
You cant call it hopeless until youve had a qualified installer with a signal meter check it out. We'll try and help you do it DIY but the former is always an option.
 
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