{"id":22675,"date":"2016-12-06T09:30:21","date_gmt":"2016-12-06T13:30:21","guid":{"rendered":"http:\/\/swling.com\/blog\/?p=22675"},"modified":"2016-12-06T12:18:24","modified_gmt":"2016-12-06T16:18:24","slug":"chris-tracks-down-sources-of-radio-noise","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2016\/12\/chris-tracks-down-sources-of-radio-noise\/","title":{"rendered":"Chris tracks down sources of radio noise"},"content":{"rendered":"

\"spectrum-waterfall-sdr\"<\/a><\/p>\n

Many thanks to SWLing Post contributor, Chris Smolinski, who shares this guest post from his blog, RadioHobbyist.org<\/a>:<\/em><\/p>\n

\n

Yet Another !&*%$! Noise Source<\/h2>\n

by Chris Smolinski<\/a><\/strong><\/p>\n

The past few days, I have noticed higher than usual noise levels, generally on the lower frequencies, and particularly on the longwave band, including the 285-325 kHz DGPS band, where I run nightly SDR recordings, to later process the data and decode and detect DX DGPS stations using my Amalgamated DGPS<\/a> app.<\/p>\n

Thinking back to what new electronics devices have been added to the house, two came to mind, a new cable modem, and a new ethernet switch. The switch is up here in the shack, so it seemed to be a likely candidate. The switch is a D-Link DES-1008E 8-Port 10\/100 Unmanaged Desktop Switch. It uses a mini USB port for power, using either the included AC adapter, or power from a USB port. When I installed it, I decided to not use the AC adapter, but rather a USB port on my UPS, figuring it was better to not add yet another potentially noisy switching power supply to the mix.<\/p>\n

The test was easy, I just unplugged the power to the switch. Sure enough, the noise vanished. Great, the switch is a RFI generator. Or is it? As another test, I plugged it into a port on a USB hub. No noise. Hmm\u2026 so it seems that the noise is indeed from the USB port on the UPS. I did not notice any increase in the noise floor when I got the UPS a few months ago, but It\u2019s something I should look into again, just to be sure. The UPS is a CyberPower CP1350PFCLCD.<\/p>\n

Here\u2019s a waterfall from the SDR, showing the DGPS band, 280-330 kHz. You can see where I changed the power to the switch from the UPS USB port to the USB hub, the bottom part of the waterfall is when the switch was still powered by the UPS (click to enlarge it):<\/p>\n

\"pmuv3bc\"<\/a><\/p>\n

I still have a noise source just above 305 kHz to hunt down.<\/p>\n

Update<\/strong><\/p>\n

I decided to see what I could do to improve things, and reduce the noise floor.<\/p>\n

Here is the baseline, after no longer powering the switch from the UPS:
\n\"qormmpg\"<\/a><\/p>\n

First, I relocated the AFE822 away from the computer and rats nest of assorted cables behind it, powered from an HTC USB charger:
\n\"kljq7ef\"<\/a><\/p>\n

The squiggly noise around 305 kHz vanished!<\/p>\n

I then switched to an Apple USB charger \/ power supply, as their products tend to be a bit better made:
\n\"goyrdt4\"<\/a><\/p>\n

Another improvement, the overall noise floor is a bit less now.<\/p>\n

But can we do better? I then switched to an older USB hub for power to the AFE822, that I thought might be better filtered:
\n\"k0e8eaw\"<\/a><\/p>\n

I then changed to a linear supply plugged directly into the AFE822. I don\u2019t notice any obvious improvement? Maybe it even looks like a little more noise? Difficult to tell. You can see a DGPS station popped up on 304 kHz while I was switching things around, between the last two tests, it was likely Mequon, WI.<\/p>\n

\"ocsavij\"<\/a><\/p>\n

\n

Thank you for sharing this, Chris! I find a wideband spectrum\/waterfall to be such a useful tool for tracking down sources of noise. Not only can you “see” the noise, but you can measure its bandwidth and identify what portions of the dial it affects.<\/em><\/p>\n

Follow Chris at RadioHobbyist.org.<\/a><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Many thanks to SWLing Post contributor, Chris Smolinski, who shares this guest post from his blog, RadioHobbyist.org: Yet Another !&*%$! Noise Source by Chris Smolinski The past few days, I have noticed higher than usual noise levels, generally on the lower frequencies, and particularly on the longwave band, including the 285-325 kHz DGPS band, where […]<\/p>\n","protected":false},"author":15,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":true,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[545,627,3,196,43],"tags":[5707,2315,4089,2651,453,157,4087],"class_list":["post-22675","post","type-post","status-publish","format-standard","hentry","category-ham-radio","category-how-to","category-news","category-qrm","category-shortwave-radio","tag-amalgamated-dgps-app","tag-chris-smolinski","tag-qrm","tag-radio-frequency-interference","tag-rfi","tag-sdr","tag-software-defined-radio"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pn3uc-5TJ","jetpack-related-posts":[{"id":20804,"url":"https:\/\/swling.com\/blog\/2016\/08\/mysdrplayback-new-version-adds-a-dgps-decoder\/","url_meta":{"origin":22675,"position":0},"title":"mySdrPlayback: new version adds a DGPS decoder","author":"Thomas","date":"August 27, 2016","format":false,"excerpt":"Many thanks to Chris Smolinski, at Black Cat Systems, who recently announced new mySdrPlayback features: I've released a new beta of mySdrPlayback, which is a Mac app that lets you easily go through SDR recording files. It works with recording files produced by SdrDx and SpectraVue, as well as Perseus.\u2026","rel":"","context":"In "News"","block_context":{"text":"News","link":"https:\/\/swling.com\/blog\/category\/news\/"},"img":{"alt_text":"mySdrRecordingWaterfall","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/08\/mySdrRecordingWaterfall-1024x640.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/08\/mySdrRecordingWaterfall-1024x640.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/08\/mySdrRecordingWaterfall-1024x640.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":17965,"url":"https:\/\/swling.com\/blog\/2016\/04\/guest-post-using-the-hackrf-one-for-dgps-beacon-reception\/","url_meta":{"origin":22675,"position":1},"title":"Guest Post: Using the HackRF One for DGPS Beacon Reception","author":"Thomas","date":"April 1, 2016","format":false,"excerpt":"Many thanks to SWLing Post contributor, Mario Filippi (N2HUN) for the following guest post: Receiving \u00a0with a HackRF One, SDR#, and MultiPSK by\u00a0Mario Filippi (N2HUN) The HackRF One is a Software Defined Radio manufactured by Great Scott Gadgets (www.greatscottgadgets.com) and has been on the market for a few years. Having\u2026","rel":"","context":"In "Accessories"","block_context":{"text":"Accessories","link":"https:\/\/swling.com\/blog\/category\/accessories\/"},"img":{"alt_text":"h1-preliminary1-445","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/03\/h1-preliminary1-445.jpeg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":17569,"url":"https:\/\/swling.com\/blog\/2016\/03\/playing-music-with-computer-emitted-interference\/","url_meta":{"origin":22675,"position":2},"title":"Playing music with computer-emitted interference","author":"Thomas","date":"March 6, 2016","format":false,"excerpt":"SWLing Post reader, Chris Smolinski, writes: Here's my Mac Book Pro (2010 model) playing Mary Had A Little Lamb over the radio, by modulating the RFI (Radio Frequency Interference) produced by it and other computers. As picked up on a Sony 7600G receiver. I found the best reception was on\u2026","rel":"","context":"In "Funny"","block_context":{"text":"Funny","link":"https:\/\/swling.com\/blog\/category\/funny\/"},"img":{"alt_text":"RFI-Sony-7600G","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/03\/RFI-Sony-7600G.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/03\/RFI-Sony-7600G.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/03\/RFI-Sony-7600G.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":17683,"url":"https:\/\/swling.com\/blog\/2016\/03\/can-you-help-chris-id-this-station\/","url_meta":{"origin":22675,"position":3},"title":"Can you help Chris ID this station?","author":"Thomas","date":"March 9, 2016","format":false,"excerpt":"SWLing Post\u00a0contributor, Chris Smolinski, would like your help to ID a Spanish language station. Chris notes: \"I record the 6800-7000 kHz band every night with my SDR, looking for pirates, but sometimes I also stumble on other interesting transmissions. The other night (UTC March 8) I picked up a curious\u2026","rel":"","context":"In "News"","block_context":{"text":"News","link":"https:\/\/swling.com\/blog\/category\/news\/"},"img":{"alt_text":"SX-99-Dial","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2014\/05\/SX-99-Dial-1024x192.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2014\/05\/SX-99-Dial-1024x192.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2014\/05\/SX-99-Dial-1024x192.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":17173,"url":"https:\/\/swling.com\/blog\/2016\/01\/chris-has-developed-an-easy-way-to-run-the-rtl-sdr-dongle-on-a-mac\/","url_meta":{"origin":22675,"position":4},"title":"Chris has developed an easy way to run the RTL-SDR dongle on a Mac","author":"Thomas","date":"January 30, 2016","format":false,"excerpt":"Many thanks to Chris Smolinski who writes: I wanted to run SdrDx, and other SDR apps on my Mac with an RTL SDR Dongle. So I wrote this server app, that makes it appear like a networked SDR. No need to install any RTL libraries, or compile any code. Just\u2026","rel":"","context":"In "Apps"","block_context":{"text":"Apps","link":"https:\/\/swling.com\/blog\/category\/apps\/"},"img":{"alt_text":"RTL-SDR-001","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/08\/RTL-SDR-001-1024x649.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/08\/RTL-SDR-001-1024x649.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/08\/RTL-SDR-001-1024x649.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":23060,"url":"https:\/\/swling.com\/blog\/2016\/12\/updates-to-the-morse-pad-app\/","url_meta":{"origin":22675,"position":5},"title":"Updates to the Morse Pad app","author":"Thomas","date":"December 27, 2016","format":false,"excerpt":"Many thanks to Chris Smolinski, who shares the following update: I have a new version of Morse Pad for the iPad\/iPhone\/iPod Touch. This update includes an improved decoder which better handles improper dot \/ dash \/ space timing by the sender (poor fist), automatic speed (WPM) algorithm, and adds AFC\u2026","rel":"","context":"In "Apps"","block_context":{"text":"Apps","link":"https:\/\/swling.com\/blog\/category\/apps\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/12\/MorsePad.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/12\/MorsePad.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/12\/MorsePad.jpg?resize=525%2C300 1.5x"},"classes":[]}],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/22675","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/users\/15"}],"replies":[{"embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/comments?post=22675"}],"version-history":[{"count":0,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/22675\/revisions"}],"wp:attachment":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/media?parent=22675"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/categories?post=22675"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/tags?post=22675"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}