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Author Topic: Entry-level wireless mic for exercise instruction: Shure BLX, PGDX, or...?  (Read 930 times)

Matt Staroscik

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Thank you for the links. If I am reading Seattle market table correctly, physical channels 15 & 17 in K-band are unused. Physical channels 26-29, all of D-band, are all in use though most transmitters are distant. So, K looks like the better choice.
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Mac Kerr

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Thank you for the links. If I am reading Seattle market table correctly, physical channels 15 & 17 in K-band are unused. Physical channels 26-29, all of D-band, are all in use though most transmitters are distant. So, K looks like the better choice.

At least one of those 2 channels may be used by public service land mobile radios, like police fire and other emergency uses. If so, it is out of bounds.

Mac
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Russell Ault

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At least one of those 2 channels may be used by public service land mobile radios, like police fire and other emergency uses. If so, it is out of bounds.

Maybe I'm looking at the wrong regulations (47 CFR 90.303, right?), but I'm not seeing Seattle as a listed urbanized area.

-Russ
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Matt Staroscik

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If any of the slots that look free are in use by the government, where can I look that up?

As to "urbanized" Seattle, I am in the Seattle TV market... but I live 20+ miles away in unincorporated county land, 98072. The mic will live in the suburbs, nowhere near Seattle itself, or any other metro area.

Edit to add: I do have a variety of radio gear... a couple of scanners, and a SDR radio dongle. I guess I could scan my environment, though that would not tell me about a licensed gov't station that was not in use at the time of the scan. (e.g. https://dbbaudio.com/2016/inexpensive-rf-spectrum-analyzers/)
« Last Edit: May 23, 2020, 05:54:36 pm by Matt Staroscik »
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Jason Glass

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If any of the slots that look free are in use by the government, where can I look that up?

As to "urbanized" Seattle, I am in the Seattle TV market... but I live 20+ miles away in unincorporated county land, 98072. The mic will live in the suburbs, nowhere near Seattle itself, or any other metro area.

https://d24z4d3zypmncx.cloudfront.net/KnowledgeBaseFiles/cjrhnq22f0w4q0189as3rhlwv/UHF_20Spectrum_20After_20DTV_20Transition.pdf

If you're using Shure Wireless Workbench to coordinate your frequencies, as you should be, it automatically excludes Public Safety T-Band when you do a proper TV stations search.

Seattle does not currently have protected Public Safety T-Band and you don't need to worry about it as long as you are operating locally.

Matt Staroscik

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If you're using Shure Wireless Workbench to coordinate your frequencies, as you should be, it automatically excludes Public Safety T-Band when you do a proper TV stations search.

Seattle does not currently have protected Public Safety T-Band and you don't need to worry about it as long as you are operating locally.

Thanks much for the reference. Glad to know there is no public safety issue in Seattle. I also looked up a list of frequencies in use by my county and there is no K-band conflict.

I will take a another look at Shure Wireless Workbench. When I looked at it a few days ago the site made it look like it was only for users of Shure hardware. I mean, it looked like it required a Shure receiver to do anything. I didn't realize it was a general reference tool.

For fun I dug out my old DVB-T receiver and set up RTLSDR Scanner. These plots are with dwell 1 sec, gain 14 db, FFT 512 samples, which is advice from the article I link I posted earlier. I am using a generic garbage antenna but this is the best I can do with what I had on hand. K seems more congested than D in these plots, but I really don't know if this test is meaningful at all.

D Band


K Band


« Last Edit: May 23, 2020, 08:33:13 pm by Matt Staroscik »
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Matt Staroscik

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Now, this I don't understand. I rescanned the bands this morning and got different results. However it still seems like I should order a K-band mic as there are more clear areas. If anyone can make a case for D please speak up. :)

D Band
Missing the wide and strong TV station peaks? Do stations not broadcast constantly?


K Band
This plot is similar to the original, though the noise floor and hash on the right side look different now. However, I did move the antenna.


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Scott Helmke

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A TV station would look like a block, 6MHz wide.  The first channel starts at 470MHz, so that ripple starting at 482-488 could be a distant station.
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Matt Staroscik

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A TV station would look like a block, 6MHz wide.  The first channel starts at 470MHz, so that ripple starting at 482-488 could be a distant station.

Makes sense.

Thanks everyone for the help, I think I am all set.
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Matt Staroscik

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Last update: the Airline 88x, K-band, arrived today and so far my "client" loves it. No RF issues so far, and it fits her well. Thanks again for the suggestion @Jason Raboin.
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