Re: [PSES] Tracking down interference at 915 MHz

Fri, 04 Apr 2025 12:10:13 -0700

Hi Ken. I guess I'm not terribly surprised, since this is a Region 2 ISM band from 902-928 MHz. I am making the assumption that this measurement was made in Region 2 🙂😕 

Respectfully,

Brent DeWitt - AB1LF
Milford, MA

On 3/24/2025 1:07 PM, Ken Wyatt wrote:
What really struck me was how busy the 915 MHz ISM band was utilized in an urban environment! See Figure 5 in the article. This was a swept measurement in Max Hold mode over a period of about a minute and you can see the average signal amplitude was 50 dBµV, with strong peaks from the drug store to 70 dBµV. 

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I'm here to help you succeed! Feelfree to call or email with anyquestions related to EMC or EMItroubleshooting - at no obligation. I'malways happy to help! 

Kenneth Wyatt
Wyatt Technical Services LLC
8201 Lighthouse Lane Ct
Windsor, CO 80528
On Mar 23, 2025, at 12:43 PM, Ken Javor <[email protected]> wrote:
My suggestion was not for the original installation, but as a suggested fix after Ken’s troubleshoot appeared to pinpoint the source of the interference. 
--
Ken Javor
Ph: (256) 650-5261
*From:*Ralph McDiarmid <[email protected]>
*Reply-To:****** IEEE emc-pstc List ***** <[email protected]>
*Date:*Sunday, March 23, 2025 at 12:08 PM
*To:*<[email protected]>
*Subject:*Re: [PSES] Tracking down interference at 915 MHz
I agree Ken.  Unfortunately, installation companies don’t have that degree of technical prowess or care, they just go in, do a job as fast as possible, and move on.  The owner of the gas station would be oblivious to the EMC concern. 
Ralph
*From:*Ken Javor <[email protected]>
*Sent:*March 22, 2025 4:51 PM
*To:*[email protected]
*Subject:*Re: [PSES] Tracking down interference at 915 MHz
Nice. Seems as if a simpler fix would be a set of directional antennas for the gas station’s 915 MHz link, yielding higher intentional signal and if the antennas are properly oriented relative to the suspected interference source, diminishing the interference level. 
--
Ken Javor
Ph: (256) 650-5261
*From:*Ken Wyatt <[email protected]>
*Reply-To:****** IEEE emc-pstc List ***** <[email protected]>
*Date:*Saturday, March 22, 2025 at 3:35 PM
*To:*<[email protected]>
*Subject:*[PSES] Tracking down interference at 915 MHz
Hi All,
I thought this interference hunt to a gas station price sign might be of interest to the group. 
https://www.testandmeasurementtips.com/spectrum-measurements-shed-light-on-sign-malfunctions/
Cheers, Ken

_______________________
I'm here to help you succeed! Feel free to call or email with any questions related to EMC or EMI troubleshooting - at no obligation. I'm always happy to help! 

Kenneth Wyatt
Wyatt Technical Services LLC
8201 Lighthouse Lane Ct

Windsor, CO 80528

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