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Indoor Noise Conditions in the FM Broadcast Band Steve Johnston Director of Engineering and Operations Wisconsin Public Radio NAB Engineering Conference.

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Presentation on theme: "Indoor Noise Conditions in the FM Broadcast Band Steve Johnston Director of Engineering and Operations Wisconsin Public Radio NAB Engineering Conference."— Presentation transcript:

1 Indoor Noise Conditions in the FM Broadcast Band Steve Johnston Director of Engineering and Operations Wisconsin Public Radio NAB Engineering Conference 2010

2 Introduction Radio hobbyists – Ham radio operators, shortwave listeners, broadcast DXers, and other enthusiasts are usually quite aware of the growing radio noise issues we face… But most people are unaware of this “noise pollution” problem.

3 Observations How many of us have received complaints from listeners, staff, or management regarding reception problems?

4 Observations A significant number of Wisconsin Public Radio analog listeners report deteriorating reception: In the past five years, WPR Audience Services “Listener Logs” show a 37% increase in and telephone complaints related to reception. “I used to get good reception, but not anymore…”

5 Observations FM HD Radio indoor reception is simply not as good as predicted – both at WPR and industry-wide.

6 Hypothesis Growing levels of indoor noise may be masking fringe-area analog signals Could be bothering reception of digital HD Radio and HDTV as well. High indoor noise levels might be contributing to the unexpected HD Radio “building penetration” issues.

7 Measurements Portable spectrum analyzer with home-made loop antenna.

8 Measurements Balun-fed loop antenna 1/4–wavelength in circumference

9 Field Tests Not absolute measurements – instead a comparison of outdoor to indoor reception conditions Study locations Suburban houses Urban apartments Urban offices

10 Field Tests Suburban homes Fitchburg, Wisconsin

11 Outside Suburban Home

12 Inside Suburban Home

13 Field Tests Urban Apartments Quisling Apartments - Madison, Wisconsin.

14 Outside Apartment Building

15 Inside Apartment

16 Field Tests Urban Offices UW Vilas Hall - Madison, Wisconsin

17 Outside Office Building

18 Inside Office Building

19 Typical Noise Sources Switching power supplies Consumer electronics Office equipment

20 Examples of Noise Sources RCA (Thomson) model DRC200N DVD/CD player

21 Examples of Noise Sources Jishisheng Wanji Electric Appliance Model SP80 Battery charger for electric scooter

22 Examples of Noise Sources Voltek (Volgen) model EXU Office equipment power supply

23 Examples of Noise Sources Viewsonic Model LSE9901B1250 Power supply for monitor

24 Examples of Noise Sources Motorola model DCH4-050MV-0301 Cellphone charger

25 Examples of Noise Sources No-Name (IV) (F WHK) type FW7600/05 Cellphone charger

26 Examples of Noise Sources Delta Electronics model ADP-15FB PDA charger

27 Examples of Noise Sources Lite-On Technology model PA Toshiba notebook PC power supply (Toshiba p/n PA3396U-1ACA)

28 Examples of Noise Sources Broksonic Corporation model CTGV-5463TCT Television set “Broke-sonic” - a perfect name for this noisy product!

29 Conclusion Summary of results Increase in noise from outdoor to indoor was dramatic in all cases. In some indoor locations a 20 to 30 dB increase in overall noise.

30 Conclusion Why is this happening? Devices are being made without adequate concern for their incidental RF radiation. Anecdotal reports: prototypes are RFI tested, but actual products are built cheaper and not to tested specs. Switching power supplies from third-parties that have not been tested. Regulatory agencies may have lost control of the situation.

31 Questions? Observations? Thank you… Steve Johnston Director of Engineering and Operations Wisconsin Public Radio


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