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Post by cthuskyman on Sept 2, 2018 20:16:04 GMT
Not the best news in the world here, but....heh. I find that Radio Free Connecticut may have to change frequencies. The local TIS station, WPML750, transmits on 1670 AM from about a couple of miles away from me. I think I'm interfering with them....they can be heard at my location with a good amount of strength, so I would guess they're using at least a bit of power. Does anyone know what the average TIS station transmits with? Maybe ten watts or so? BTW, this is a pain in the ass, because I'm not sure if any other X-band frequencies are open around here. May have to look into switching to FM.  |
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mram1500
Junior Member
No Jab -Just Fact
Posts: 67
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Post by mram1500 on Sept 3, 2018 13:01:17 GMT
TIS is limited by both power and field strength.
10 watts max or less if field strength exceeds limit. Also antenna limited to 15 meters in length.
Overall, field strength sets the bar.
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Post by cthuskyman on Sept 4, 2018 22:30:00 GMT
Thanks for the additional info, MRAM. Anywho....an update, as posted on Part15.us.
"And that's the way it is" -- Walter Cronkite
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Post by Boomer on Sept 5, 2018 3:08:51 GMT
I've heard of school stations having to change frequencies when new broadcasters would come on the air. It was a pain because listeners knew where to tune, and the station might have letterhead and promotionals printed for their stations, plus IDs and jingles.
I hear high band TIS with a local strength for about a mile, and after about 3-4 miles they're gone, that's average in my area. The effective radiated power is likely a few hundred milliwatts.
I wonder if a Part-15 station with under a milliwatt ERP could interfere? More likely it would be harder to hear your signal close in to the TIS, and some radios would hear a 10 khz beat tone.
I'd go out and do some testing with radios around the neighborhood. Also, don't count out your old frequency, TIS can come and go, and maybe change frequencies. I used to be able to hear 5 TIS stations, run by the highway department, and now they're all gone.
Boomer
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Post by cthuskyman on Sept 5, 2018 13:55:23 GMT
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Rich
Full Member
RF Systems Engr (retired)
Posts: 112
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Post by Rich on Sept 5, 2018 14:42:17 GMT
... I hear high band TIS with a local strength for about a mile, and after about 3-4 miles they're gone, that's average in my area. The effective radiated power is likely a few hundred milliwatts. I wonder if a Part-15 station with under a milliwatt ERP could interfere? More likely it would be harder to hear your signal close in to the TIS, ... For a TIS station employing a conventional radiating antenna, the FCC-maximum, groundwave field intensity is 2 mV/m at a distance of 1.5 km (0.93 miles) from the radiator.
The graphic below displays groundwave field intensity vs distance from a legal Part 15 AM setup, for the conditions shown there.
Note that the Part 15 station has a groundwave field of about 0.109 mV/m at a horizontal distance of about 1 mile from the radiator. For the same Earth conductivity, a co-channel TIS station has a maximum field intensity at 0.93 miles of about 2 mV/m.
So if these two co-channel stations were separated by two miles, the difference between those two field intensities at the mid-point of that 2-mile path is about 25.3 dB — which would produce a rather low (perhaps tolerable) amount of interference to the TIS station at that mid-path receive location. Of course the Part 15 AM station would be unlistenable there due to interference from the TIS station.
Another concern would be the effect of the TIS station on the operation of the Part 15 AM setup, due to the relatively high field intensity that the Part 15 antenna system would receive from the co-channel TIS station.
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Post by cthuskyman on Sept 18, 2018 0:41:48 GMT
... I hear high band TIS with a local strength for about a mile, and after about 3-4 miles they're gone, that's average in my area. The effective radiated power is likely a few hundred milliwatts. I wonder if a Part-15 station with under a milliwatt ERP could interfere? More likely it would be harder to hear your signal close in to the TIS, ... For a TIS station employing a conventional radiating antenna, the FCC-maximum, groundwave field intensity is 2 mV/m at a distance of 1.5 km (0.93 miles) from the radiator.
The graphic below displays groundwave field intensity vs distance from a legal Part 15 AM setup, for the conditions shown there.
Note that the Part 15 station has a groundwave field of about 0.109 mV/m at a horizontal distance of about 1 mile from the radiator. For the same Earth conductivity, a co-channel TIS station has a maximum field intensity at 0.93 miles of about 2 mV/m.
So if these two co-channel stations were separated by two miles, the difference between those two field intensities at the mid-point of that 2-mile path is about 25.3 dB — which would produce a rather low (perhaps tolerable) amount of interference to the TIS station at that mid-path receive location. Of course the Part 15 AM station would be unlistenable there due to interference from the TIS station.
Another concern would be the effect of the TIS station on the operation of the Part 15 AM setup, due to the relatively high field intensity that the Part 15 antenna system would receive from the co-channel TIS station.
Officially made the change to 1540 AM tonight. Crankin' out the tunes right now! us1.internet-radio.com:8006/listen.pls , control.internet-radio.com:2199/start/fairbol , or streamfinder.com/streaming-radio/radio-free-connecticut/50273/#_ |
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Post by cthuskyman on Sept 18, 2018 0:53:51 GMT
Reception check! I'm being told the station can be heard, at least tonight, up to around 1,500 feet away. That's a good two to three blocks from me....nice!  |
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