FMQB HD Article

[mgpt6]

Makes the 5 tube AM Radios from the 50s and 60s great. Had better sound 45 years ago on AM.

 

[Play Freebird]

Jason you are one of the few who gets good reception at DX ;D distance, it's probably partially because Texas is so flat, enjoy iy while you can it ain't going to be around for much longer.

The flat terrain certainly helps, but also keep in mind most of the Houston stations are nearly maximum Class C facilities, whereas the most powerful Philadelphia stations are Class B (and most are short-spaced to New York stations.) The difference between C and B, taking antenna height into account, is about 16 dB or 40 times the power. Of course, the difference between C and A is even greater -- about 28 dB.

This is why anecdotal reports like "I can receive HD 40 miles away, so there's nothing wrong with the system" don't tell the whole story.

For example, consider WPPZ, a Class A which transmits from the highest antenna in the Philadelphia Roxborough tower farm, yet I lose their HD reception only 4 miles northwest of the site along I-76 (between the Conshohocken curve and I-476) due to shadowing. WPPZ's predicted field strength along that stretch of highway ranges from 85 to 80 dBu, yet the digital signal still won't decode.

 

[R.F. Burns]

Jason you are one of the few who gets good reception at DX ;D distance, it's probably partially because Texas is so flat, enjoy iy while you can it ain't going to be around for much longer.

The flat terrain certainly helps, but also keep in mind most of the Houston stations are nearly maximum Class C facilities, whereas the most powerful Philadelphia stations are Class B (and most are short-spaced to New York stations.) The difference between C and B, taking antenna height into account, is about 16 dB or 40 times the power. Of course, the difference between C and A is even greater -- about 28 dB.

This is why anecdotal reports like "I can receive HD 40 miles away, so there's nothing wrong with the system" don't tell the whole story.

For example, consider WPPZ, a Class A which transmits from the highest antenna in the Philadelphia Roxborough tower farm, yet I lose their HD reception only 4 miles northwest of the site along I-76 (between the Conshohocken curve and I-476) due to shadowing. WPPZ's predicted field strength along that stretch of highway ranges from 85 to 80 dBu, yet the digital signal still won't decode.

So how do you explain that I can receive WAWZ, Zaraphath from a location 25 miles north of Manhattan. This is with a Receptor and a dipole. Of course the reception is much easier using my HDT-1X. That puts me about 60 miles or so north of WAWZ.

 

[Play Freebird]

So how do you explain that I can receive WAWZ, Zaraphath from a location 25 miles north of Manhattan. This is with a Receptor and a dipole. Of course the reception is much easier using my HDT-1X. That puts me about 60 miles or so north of WAWZ.

You probably have a favorable path between their transmitter and your location.

If you want to check the terrain profile, there's a great online resource at www.heywhatsthat.com

I've plotted a shadow map from the WAWZ site here:

http://www.heywhatsthat.com/?view=T38OL3N7

Click on "Visibility Cloak" to see line-of-sight areas, and "Show Profile" to see the terrain between the WAWZ antenna and other spots on the map. Even if the path appears to be blocked, a prominent obstacle (like a sharp ridge) would provide knife-edge diffraction.

Actually, I can copy WAWZ in digital with about 95% reliability on my Accurian, using a 9-element yagi turned just the right way to reject WUSL's signal. The respective bearings are about 40 degrees apart, so if I position the main lobe a bit north of WAWZ, it puts WUSL in a null. Although I don't have line of sight, nearby terrain works in my favor, as I have a fairly clear path as far as Doylestown, PA but some blockage towards Roxborough. But I'm a "DX-er", not a typical listener!

I've tried listening to WAWZ on the JVC HD radio in my truck while driving local roads, but there's no trace (even in analog) due to WUSL digital hash.

 

[rbrucecarter5]

The flat terrain certainly helps, but also keep in mind most of the Houston stations are nearly maximum Class C facilities, whereas the most powerful Philadelphia stations are Class B (and most are short-

I've got 50 miles with a dipole in the Dallas area, one tower for some rim shots is 50 miles from my house. It is also up nearly 2000 feet and the stations 100 kW.

This underscores the fallacy of asking for a power increase for FM. Dropouts are logarithmic power drops over several decades of power, more power will not stop dropouts in the car nor alleviate dead zones in rough terrain.