The ALPB wishes to thank Part15.org for their continued support!
United We Stand…
Celebrate
July 1st – Happy Canada Day!
It begins here….
As background, I’m the IT guy at the InfoAge Museum in Wall Township, New Jersey USA. I’m helping out the team from the Computer Deconstruction Lab build a podcast studio.
I’ll toss out the social media links in case anyone is interested in taking a look, feel free to ask questions about what we are trying to do.
Computer Deconstruction Lab at InfoAge
- http://www.compdecon.org/
- https://www.facebook.com/groups/compdecon
- Local call-in line: 732-456-5001
- Toll-free call-in line: 833-CDL-LABS
1200 AM BBR
Blue Bucket Radio is back on the air at 1200 kHz with limited range.
Currently the SStran is pumping out heavy metal on 1200 kHz on an indoor antenna due to the unpredictable weather we have here in Kentucky.
Range is of course limited to about 150 to 200 feet around my property, the antenna is a wire that is too long to mount vertically, so it strung up the wall and across the ceiling. It’s limited in range, but it IS on the air.
About the blog post http://www.part15.us/blogs/rock95seven/99-cent-fm-wireless-microphones , I will try harder to make that range test happen some time this Spring. Right now Kentucky weather is all over the place, one warm day followed by snow over night, a couple more cold days and back to warm again.
So hopefully after Winter finally gives up and we have some truly warm Spring days I can do that test and return to this blog with my results.
Until then, Happy Broadcasting
FCC §15.223 – AM Carrier Current Systems (1705 kHz to 10 MHz)
Below is a post I made in another thread here on Pt15us. However the subject of that thread would make it hard to locate for anyone searching for information on this topic. This re-post to my blog should be easier to find.
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Post Audio Clip & Player on Part15us
I think I remember posts here including an audio player console loaded with an audio clip that plays with a single click.
How is that done, please?
From §15.223: The field strength of any emission within the band 1.705-10.0 MHz shall not exceed 100 microvolts/meter at a distance of 30 meters. However, if the bandwidth of the emission is less than 10% of the center frequency, the field strength shall not exceed 15 microvolts/meter or (the bandwidth of the device in kHz) divided by (the center frequency of the device in MHz) microvolts/meter at a distance of 30 meters, whichever is the higher level. For the purposes of this section, bandwidth is determined at the points 6 dB down from the modulated carrier. The emission limits in this paragraph are based on measurement instrumentation employing an average detector. …
The text shown in bolded characters above permits the greatest field strength for a typical, legal AM transmit system permitted by this paragraph — which at a distance of 30 meters is 15 µV/m, not 100 µV/m.
Unfortunately, there are few, if any, consumer-level AM broadcast receivers (or receive locations, for that matter) where a signal strength of 15 µV/m would provide an acceptable/useful signal-to-noise ratio in the audio output of that receiver. Even if receivers could do that, a legal system under §15.223 could not provide a useful coverage area having a radius of a mile or more, unless all or most receivers in that area were located within a 30-meter distance from a radiating conductor of the a-c power lines.
AM broadcast receivers that are powered directly from the a-c line are close enough to it to receive a much higher, legal field strength than 15 µV/m, because they are in the extreme near field of the radiating conductor(s) of the a-c power line they are plugged in to. But that higher field drops very rapidly to below the noise floor when a battery-operated receiver such as a car radio or “Walkman” is located more than several meters away from the nearest radiating conductor of the a-c power lines.