Here's my current configuration:

Radio Shack TV-FM antenna #15-1718A (over 20 years old):

• 12' 6" boom
• 8 elements VHF low (V-shape)
• 4 elements FM (includes VHF channel 6, I guess)
• 9 elements VHF high
• 16 elements UHF (channels 14-83)
• 75 ohm coupler at antenna
• 100' RG 59/U coaxial cable (no manufacturer info on jacket)
• located in attic (~25' above ground)
• attic has vinyl siding on exterior and fiberglass shingles on roof; only aluminum is on the fascia
• rotor

Local stations (Pennsylvania):

• Reading - 12 miles
• Philadelphia - 23 miles
• Allentown/Bethlehem - 31 miles

As far as analog signals are concerned, I have no trouble receiving any of the Philadelphia, Reading and Allentown/Bethlehem stations, although some may have some ghosting. I can also receive some stations in Lancaster and Scranton PA; NJ; Baltimore, MD; Washington, DC; and New York, NY; albeit with varying amounts of "snow". Basically, I have been a "very happy camper" with analog TV signals.

My GPS coordinates (according to Google maps) are 40.148709 N, 75.656426 W. I am located within a few feet elevation (at ground level) of the top of a hill, surrounded by trees up to 60' tall. If you want to see my location on the satellite view of Google maps it is here.

antennaweb.org says I need to have the antenna at 40' to receive Allentown stations with a medium directional antenna (in some cases with a preamplifier); for most Philadelphia and the Reading stations only a small to medium multidirectional antenna.

However, with my current setup, I can receive the WBPH and WFMZ Allentown DTV stations with a signal strength of 90-100 if I aim the antenna as they specify at 22 degrees (34 degrees magnetic); a signal strength in the 80s if aimed at 90 degrees (almost 70 degrees off target!).

The Philadelphia stations have signal strengths that peak at best in the low 80s when I aim the antenna at 90 degrees, 108 degrees (the recommended direction - 120 degrees magnetic), or 135 degrees. The lone exception is KYW, whose signal strength is consistently above 90. On virtually all the other stations, their signal strengths also bounce around quite a bit, leading to severe pixelation at times. I can't receive any of WHYY's digital signals.

The following table shows sample signal strengths I've recently received on a Panasonic Model TC-32LX70 LCD TV manufactured in May of 2007, using the above antenna aimed at 90 degrees true for all channels (a compromise which should favor the Philadelphia stations):

Station	Analog RF Channel		Digital RF Channel		RF Channel Post-transition	Maximum Digital Signal Strength		Digital Signal Strength Range
	Number	Maximum ERP (Date)	Number	Maximum ERP (Date)		Dec 13, 2008 10:00 PM	Dec 14, 2008 5:00 PM	Jan 5, 2009 9:30 AM	Apr 26, 2009 8:30 PM	Jun 15, 2009 8:30 PM
KYW	3	100 kW	26	770 kW	26	92	92	92-92	92-92	0-91
WBPH	60	1239 kWd	9		9	84	86	86-87	86-87	83-87
WCAU	10	137 kW	67	560 kW	34	69	37	0-74	38-53	57-83
WFMZ	69	4344 kWde (12/19/08)	46c	269 kWcde (12/19/08)	46c	92	83	83-92	83-86	71-77
WGTW	48	2340 kW	27	30 kWd	27	0	0a	0-74	69-73	0-38
WHYY	12	130 kWd	50	34.8 kWd	12	0	0	cna	cna	78-84
WLVT	39f	460 kWe (12/01/08)	62cf	21.5 kWde (12/01/08)	39	0	7	0-47	60-66	0-64
WMCN	53b		44	191 kWcd	44	0	0	cna	cna	cna
WMGM	40b		36		???	0	0	cna	cna	cna
WNJS	23bc	1530 kW	22	197 kWc	22	0	0	cna	cna	0-0
WNJT	52bc	1950 kW	43c	46 kW	43c	0	0	cna	cna	cna
WPHL	17	2340 kW	54	112 kWd	17	71	56	28-60	43-52	28-79
WPPX	61f	3020 kW	31f	60 kWd	31	45	44	40-69	70-77	0-2
WPSG	57	26 kW	32	22.1 kWd	32	0	0	cna	0-38	0-53
WPVI	6	74.1 kW	64	500 kW	6	53	46	0-59	77-83	99-100
WTVE	51f	4853 kWd	25f	48.9 kWd	25	73	13	0-72	47-58	0-53
WXTF	29	5000 kW	42	107 kWd	42	77	67	48-67	67-71	70-77
WUVP	65	706 kWd	66	86.7 kWd	29	65	37	0-47	cna	cna
WWSI	62bc		49		49c	0	0	cna	cna	cna
WYBE	35	1000 kW	34	500 kW	35	65	73	30-76	cna	65-79

cna - Channel Not Available
^aChannel 48.48 displays "Video Lock Error WGTW 48" and a color pattern (signal strength 55).
^bCan't recieve these analog channels with antenna pointed in this direction.
^cPossible adjacent/co- channel interference.
^dAdjusted according to my location.
^eActual Effective ERP.
^fTransmissions discontinued on February 18, 2009.

• I talked to someone at WPVI (Philadelphia) and was told that they are only broadcasting their digital signal at about 80% of the power they'll be using after the transition. He gave me the email address of one of their engineers and I received the following response (11/18/2008):

  You have a nice set up for analog reception. The digital signal always seems to need a little extra help. May I suggest the following:

  • Possibly replace the antenna. After 20 years there could be some corrosion etc. A newer antenna would probably have a 75 ohm output and you would not need the balun. I assume your antenna is mounted on your roof. Getting it as high as possible would obviously help the signal.
    (The antenna is in my attic and shows no signs of corrosion so I suspect this isn't part of the problem. Also, the balun came with the antenna.)
  • Use a better coax such as RG 6 or 1694A.
  • A pre amp mounted at the antenna would provide some extra gain.
    (Might this not cause an overload on signals that are already showing a signal strength of 100?)
  • Any splitter in the line would drop the signal 3db.
    I'm not using any splitters.
  • Hopefully some of the suggestions will improve reception for you.

• I sent an email to WHYY (Philadelphia) and received the following response from their Technology Coordinator (12/1/2008):

  We are transmitting a digital signal on UHF Channel 50, however, the reception problem that you are experiencing with WHYY's new digital TV channel is a temporary situation. We are completing a technical transition from analog TV12 to the new digital service. The current digital signal is transmitting from the same location as the other channels (our transmitting towers are in Roxborough) and is weaker than most other digital stations at this point, which is why you cannot get our digital signal. Beginning at midnight on February 17, 2009 (subsequently changed to June 12), a very powerful digital signal will replace the weaker signal. We will also be on our permanent channel assignment of Channel 12. You should have no problem receiving WHYY-DT when this occurs.

• I sent an email to channel 39 (WLVT - Allentown) and received the following response from their Acting Chief Engineer (12/2/2008):

  Our analog transmitter is putting out about 460KW, and 69 (WFMZ) is putting out more than 1MW. I'm not sure what power they are putting out of their digital transmitter. WFMZ is broadcasting their DT signal on RF channel 46, and WBPH (channel 60) is broadcasting on RF channel 9. We are currently broadcasting our digital signal on RF channel 62, with a power of about 45KW, out of an antenna 'cut' for channel 62. After the transition, our digital signal will be broadcast on RF channel 39 at a final power of about 50KW. So, if your antenna is pointed in our general direction, and you've performed an autoscan on your receiver and still cannot get us, all I can say right now is that hopefully the increase in our final output power, along with the change in transmit frequency (from channel 62 to 39) will fix your reception. And believe it or not, our service contour moving to the lower power digital is basically the same as what we have now on the analog. If you're curious you can look them up at the FCC website. I did look at your google map location and you certainly are buried in the trees, which may be part of the issue now. I'm sorry I can't give you a more definitive fix at this time. This transition is turning out to be very 'interesting' for all of us.

I had a hard time believing that a station could drop its ERP by about 90% when it switches from analog to digital and still have essentially the same basic service contour as stated by the engineer at WLVT (and shown in the FCC database for their channel). However ...

• I sent an email to WFMZ (Allentown) and received the following response from their President and GM (12/19/2008):

  We are 5MW in your direction analog, 400KW digital. The digital signal has proven to be a significant improvement over our old Channel 69 analog signal as you are seeing. Channel 46 is just a better channel overall, and our current power level has proven to be a winner so far.

  As for the digital power levels being a lot less, one must remember, the high power levels of analog were due to having to send a huge sync pulse out to early tube type televisions, so they could discriminate between sync and the picture. So while the sync pulse could be at 5MW, the average picture level was always significantly less. Now with modern digital technology, we don't need that massive difference, we simply decode the data and know what to do with it.

• I sent an email to WTXF (Philadelphia) and received the following response from their Engineering Department (1/14/2009):

  WTXF's DTV ERP is currently 1,000 kW but directional. We will be changing to 260 kW omni-directional from the top of the tower.

  Since their ERP is only 107 kW in my direction currently, when they up their power after the transition to 260 kW omni-directional, that'll be a 150% increase for me. That should give me much better reception of their channel.

I think that my biggest problem in general is the new transmission standard. As I understand it (and my knowledge may be out of date), digital transmissions use the ATSC standard. This allows 60 fps at 720p, 30 fps at 1080i/p and 60 fields/sec at 1080i. Further, ATSC uses the MPEG-2 spec with 188 byte packets, including error correction. The signals use the same 6 MHz bandwidth as NTSC channels and are modulated using 8VSB for terrestrial broadcasts at a maximum rate of 19.39 Mb/s.

Now, with an NTSC signal, if some kind of interference (buildings, trees, planes, lightning, etc.) causes part of a transmission to be disturbed, the receiver may display ghosting, snow or even "messed up" single or multiple scan lines from time to time. However, if an MPEG packet is distorted by interference beyond the error correction capabilities, the entire packet is "lost", resulting in a block of the picture being "undisplayable" (block size being at least partially dependent on the resolution being transmitted). I believe this is causing the high variability in the signal strength readings I see.

The trees around my house are 60-100 feet tall. I think this may very well also be a significant factor, although why they don't seem to affect reception from the Allentown stations as much, which are farther away than the Philadelphia stations, is beyond me. I have noticed that the worst reception occurs under windy conditions. I noted in an email to the President of WFMZ that "Since the antenna is in my attic, it's not moving. Nor is it obviously affected by icing. I therefore have to conclude that the movement of the trees around my location (and maybe similar objects in my line-of-sight to your tower) are causing packets to be distorted beyond the error correction capabilities of my receiver." He replied that "When the trees are moving, that likely increases the multipath signal the receiver has to deal with. The earlier version chips did not handle mulitipath very well. As time goes on, these chips are getting better and better at handling mulitipath. I can't remember if we are at the 5th or 6th generation chips at this point, but the later the version, the better results you will see."

Maybe the Allentown stations (60, 69) are using antennas in similar tower positions and directivity, and power levels that match what they'll be using after the transition, while many/most of the other stations in the Philadelphia market are not. Also, no station in my list will be transmitting on a frequency higher than channel 49 after the transition (channels 52-69 will be eliminated after the transition - digital TV will be broadcast on channels 2-51). Currently, digital signals for analog channels 6, 10, 12, 17, 39 and 65 are being transmitted on channels in the 54-67 range, so it's possible that reception for these stations will improve after the transition is completed, even if their effective transmitter power levels are not increased.

I really don't want to install a 60+ ft tower! Any comments, corrections and/or suggestions would be appreciated. You can send them to dtv [a] seedship [d] com.

Bob

Last revised: June, 15, 2009