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AM Band Scan.

The technical side of broadcasting. Think IBOC is a sham? Talk about it here! How about HDTV? Post DX reports here as well.
k8jd
Posts: 260
Joined: Fri Jun 28, 2013 3:35 pm
Location: Commerce, MI

AM Band Scan.

Post by k8jd » Wed Nov 07, 2018 1:28 pm

I see many band sweeps for FM Band on this forum, BUT here is one for my AM band reception. Run from 17:30 to 18:00 UT today.
I was using a 140 ft closed square loop, hanging in trees at 35 ft above ground, as a standard, I get power line background buzz at a S6 reading today, still hear many signals in the noise but I cut my chart off at S7 strength.
I can hear , clearly, 30 stations on the AM band here in Commerce MI , in mid-West Oakland county .
The Top 7 strongest signals with power, distance to the transmitters and S meter reading. , are;
630 CFCO 10 kW 64 miles S9+15 dB
950 WWJ 50 kW 41.5 miles S9+10
990 WDEO 9.2 kW 23.4 mi S9+15
1030 WUFL 5 kW 29.5 mi S9+10
1200 WMUZ-AM 50 kW 31.1 mi S9+20
1270 WXYT 50 kW 39.6 mi S9+10
1460 WPON 0.67 kW 3.3 mi S9+20

I clearly hear another 23 stations, the most distant is 1390 WLCM at nearly 70 miles reading S7.
Just For FUN !
If you try an AM band scan from your location, your results may vary widely, due to most AM stations using directional antennas !
Try it :D
Anyone interested in my complete list let me know and I will post it.
Last edited by k8jd on Fri Nov 09, 2018 4:50 pm, edited 1 time in total.



Arthur Mometer
Posts: 659
Joined: Wed Oct 22, 2008 9:52 am
Location: Radar Room

Re: AM Band Scan.

Post by Arthur Mometer » Wed Nov 07, 2018 2:34 pm

Where is WJR? Where is WFDF? On 10 kW back up? Still should be there. 910 kHz whistle filter?

http://zipsignal.v-soft.com

Put in 48390.


"I'm meteorologist Arthur Mometer."

"Those of you who think you know everything are very annoying to those of us who do."

"Lies have to be repeated and repeated to be believed. Truth stands on its own merit."

Arthur Mometer
Posts: 659
Joined: Wed Oct 22, 2008 9:52 am
Location: Radar Room

Re: AM Band Scan.

Post by Arthur Mometer » Wed Nov 07, 2018 4:04 pm

The Tecsuns with the digital signal strength meter from 0-99 dB scale seem to be accurate with appropriate fudge factors. I did a bandscan in a place where I had checked previously with a real FI meter. I told the CE of one station that the signal seemed to be inconsistent with FI readings done previously. He told me it sounded about right considering the power had been reduced because of a leaky roof on the TX shack. Now if I could only find my radio after the XYL put it away somewhere.


"I'm meteorologist Arthur Mometer."

"Those of you who think you know everything are very annoying to those of us who do."

"Lies have to be repeated and repeated to be believed. Truth stands on its own merit."

k8jd
Posts: 260
Joined: Fri Jun 28, 2013 3:35 pm
Location: Commerce, MI

Re: AM Band Scan.

Post by k8jd » Thu Nov 08, 2018 1:11 pm

Sorry, WJR and WFDF did not make it on the Strongest Signal list because WJR was only S9 and WFDF was S9+5dB.
I listed only stations with signal strength at S9+10 dB and up. (In case we forget, S9=50 Microvolts at the antenna terminals)
YES TecSun is a great little radio with the Signal strength metering. I have the PL880. BUT with the directional loopstick antenna, I would have to turn it around to find a peak with each signal and the FT990 with the big elevated 40M loop should be pretty nondirectional on the MW band.



Arthur Mometer
Posts: 659
Joined: Wed Oct 22, 2008 9:52 am
Location: Radar Room

Re: AM Band Scan.

Post by Arthur Mometer » Thu Nov 08, 2018 2:23 pm

WFDF is just a few miles further, has a higher IDF toward Commerce, and is on a lower frequency than WMUZ. WJR isn't that far either. WXYT is close also.


"I'm meteorologist Arthur Mometer."

"Those of you who think you know everything are very annoying to those of us who do."

"Lies have to be repeated and repeated to be believed. Truth stands on its own merit."

k8jd
Posts: 260
Joined: Fri Jun 28, 2013 3:35 pm
Location: Commerce, MI

Re: AM Band Scan.

Post by k8jd » Fri Nov 09, 2018 4:39 pm

Arthur Mometer wrote:
Thu Nov 08, 2018 2:23 pm
WFDF is just a few miles further, has a higher IDF toward Commerce, and is on a lower frequency than WMUZ. WJR isn't that far either. WXYT is close also.
WJR is 32.4 miles from here, WFDF is 36.6 miles from me and WXYT is 39.6 miles. WMUZ (AM) is only 31.1 miles away.

Sometime soon I will have to rescan the band with my 250 ft dipole but it will have more sensitivity on the high end of the MW band !

Now you can triangulate my pinpoint location and drop the bomb !



Arthur Mometer
Posts: 659
Joined: Wed Oct 22, 2008 9:52 am
Location: Radar Room

Re: AM Band Scan.

Post by Arthur Mometer » Fri Nov 09, 2018 5:19 pm

Arthur Mometer wrote: ↑Thu Nov 08, 2018 3:23 pm
WFDF is just a few miles further, has a higher IDF toward Commerce, and is on a lower frequency than WMUZ. WJR isn't that far either. WXYT is close also.
WJR is 32.4 miles from here, WFDF is 36.6 miles from me and WXYT is 39.6 miles. WMUZ (AM) is only 31.1 miles away.

Sometime soon I will have to rescan the band with my 250 ft dipole but it will have more sensitivity on the high end of the MW band !

Now you can triangulate my pinpoint location and drop the bomb !
Just 4 bytes of information give that away. No triangulation needed.:)


"I'm meteorologist Arthur Mometer."

"Those of you who think you know everything are very annoying to those of us who do."

"Lies have to be repeated and repeated to be believed. Truth stands on its own merit."

Rich
Posts: 48
Joined: Sun Dec 26, 2010 3:28 pm
Location: Illinois
Contact:

Re: AM Band Scan.

Post by Rich » Sat Nov 10, 2018 7:00 am

k8jd wrote:
Thu Nov 08, 2018 1:11 pm
Sorry, WJR and WFDF did not make it on the Strongest Signal list because WJR was only S9 and WFDF was S9+5dB.
I listed only stations with signal strength at S9+10 dB and up. (In case we forget, S9=50 Microvolts at the antenna terminals). ...
According to the V-Soft webpage linked above by Arthur Mometer, the WJR field at 42°34' 31", -83° 29' 19" in Commerce Charter Twsp, MI is 24.18 mV/m, compared to the WWJ daytime field of 20.26 mV/m (nighttime field = 18.7 mV/m). The groundwave fields reported by V-Soft are based on the radiated power, frequency, path length, and earth conductivity along each propagation path.

The path from the WJR radiator to that location is 31.4 miles in length at a bearing of N333.7°T. The path from WWJ to the same geo coordinates in Commerce is 40.4 miles in length at a bearing N341.8°T from the center of their array.

Therefore the daytime field of WJR in Commerce Twsp is about 1.5 dB greater than that of WWJ. So by your instrumentation, if accurate, WJR should show S9 + 11.5 dB, not S9.

Note that to account for this difference in received fields, a receive antenna would need to have a gain change of over 10dB for an azimuth bearing change of 8.1°— which would be unlikely for an antenna oriented to receive the maximum field from either station.



Arthur Mometer
Posts: 659
Joined: Wed Oct 22, 2008 9:52 am
Location: Radar Room

Re: AM Band Scan.

Post by Arthur Mometer » Sat Nov 10, 2018 2:56 pm

Thanks for the analysis, Rich.

The only way that I can see that this could be is if both WJR was operating on Auxiliary facilities and WFDF was on its 10 kW backup transmitter. Maybe on early Monday morning, but still unlikely.


"I'm meteorologist Arthur Mometer."

"Those of you who think you know everything are very annoying to those of us who do."

"Lies have to be repeated and repeated to be believed. Truth stands on its own merit."

Rich
Posts: 48
Joined: Sun Dec 26, 2010 3:28 pm
Location: Illinois
Contact:

Re: AM Band Scan.

Post by Rich » Sat Nov 10, 2018 4:51 pm

Arthur Mometer wrote:
Sat Nov 10, 2018 2:56 pm
...The only way that I can see that this could be is if both WJR was operating on Auxiliary facilities. ...
The reduction in the field of WJR in Commerce, MI with 50 kW applied to a 1/4-wave monopole auxiliary antenna at their tx site is about 87% of what they produce with their 0.54-wavelength main antenna.

The reduced field of WJR in Commerce using its aux antenna would be about 24.18 mV/m x 0.87 = 21.04 mV/m — which is still a bit higher there than the daytime field of WWJ.



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