Carl Blare

On Sunday the cost of a postage stamp increases by 1-penny.

On another blog someone mentioned “Ramsey” and I realized I hadn’t been over there in awhile so I paid a visit and noticed an interesting product, a power meter for transmitter output from 1mW up to 50W, on a spectrum 10kHz to 450mHz, all for only $110 complete with a 50Watt dummy load.

http://www.ramseyelectronics.com/cgi-bin/commerce.exe?preadd=action&key=PM50

Has anyone tried this meter?

Ever since the dream when I was told to “Promote personal radio stations for every home so that the people would occupy radio,” I have been trying to convince everyone to join the part 15 movement.

Ever since the dream when I was told to “Promote personal radio stations for every home so that the people would occupy radio,” I have been trying to convince everyone to join the part 15 movement.

It’s a free and legal piece of freedom.

So today the “Talking House” name took on new meaning in my thoughts. Of course that is a trademarked name of a part 15 transmitter maker, but they have a great concept built into that name. Of course they intend the name as a real estate sales tool, promoting the use of part 15 radio to allow a “house for sale” to have its own voice on the radio dial.

But applied more broadly, all homes and houses should have a part 15 frequency on the air. TALKING HOME.

“Morning honey, what’s for breakfast?”

“Scrambled eggs and hot cakes.”

“And what’s on our TALKING HOME?”

“I put the New York Times Front Page Podcast followed by a replay of last night’s Mischke from WCCO.”

“Cool.”

This evening after dark I drove around and had my feelings badly hurt by the poor reception from my AM radio transmission which was being entirely swallowed by the entire universe of other babble. “This can’t be right!” I said, and began going through the FCC waste basket from a few years ago.

Way down deep in the waste-can I found a lost rule that had accidentally fallen off the edge of a typist’s desk and never got put in the Part 15 Rules that went to press. Here it is, at long last:

15.222 Nighttime operation in the band 525 – 1705kHz.
To compensate for pretty bad performance after dark other things can be tried just so the damn signal at least matches what you get in the daytime.

Don’t thank me. Just be glad the government puts their wastebaskets into internet databases.

Part 15 people listen to the whole dial, including radio stations, in between stations, and above and below the dial.

Part 15 people listen to the whole dial, including radio stations, in between stations, and above and below the dial.

In the search for a low frequency carrier current spot I often go below the 5kW station at 550 and check 530, which has a history.

Last year there was an Illinois TIS (Traffic Information Service) station at 530, with the transmitter 7-miles away on the other side of the Mississippi River. But reception was from good to poor, but it was there all the time.

Until one day, when it wasn’t there. 530 had gone blank and nothing was detectable.

Around that same time an entirely different frequency had a change of ownership, up at 1430kHz, 5kW, with an unlimited non-directional signal from a farm field in Illinois. Although the programming is automated, the signal was conspicuously beefed up and modulation levels go more “over the bank” than any other station. Without any digital (HD) signal, the splash-over at 1420 and 1440 is major.

And strangest of all, the audio for 1430 AM suddenly comes in at 530kHz, for awhile as a weak signal, but now almost as strong as a full power. Could this licensed station be sending a pirate signal on an un-assigned frequency?

Yesterday I tinkered with increased bit-rate streaming, stepping up from 24kbps all the way to 40kbps, following Artisan Radio’s report that there is a detectable improvement even compared to 32kbps, which I also tried.

The stream sounded better.

Using Hans van Zutphen’s Stereo Tool for processing, I set the bandpass filter to a range of 40 to 20,000 Hz for the following reasons:

Using an article by Dave Moulten from TV Technology titled Thinking About Equalization: The Audio, I set the low end at 40 Hz because Mr. Moulten reports that the 1st octave of the audio spectrum, 20 to 40 Hz, contains little musical content and is not reproduced by most loudspeakers, so I turned it off;

Next the Nyquist Theorem applied (is that right), in which actual frequency response is 50% of the bandwidth. Therefore, at 40kbps the 50% frequency would be 20kHz. True?

The next day I got to thinking about the AM transmission, with bandwidth typically limited to the carrier width, residing on a 10kHz channel. To observe the modulation result using the upper audio band to 20kHz, I tuned to the channel adjacent to 1680kHz, namely 1670kHz, and noted active splash on sibilant sounds and piccolo notes.

SO I set the Stereo Tool bandwidth to a top limit of 5kHz and the modulation spillover at 1670kHz disappeared.

Always the quandry, that means either the stream would best match the situation by tuning down to, say, 16kbs, or…. I guess an outboard component bandpass filter for the transmitter would permit optimizing both types of transmission….

Join us again tomorrow.