Topics

46

General Radio Discussion / Lightsquared returns...

« on: April 14, 2020, 1419 UTC »

About 10 years ago, a company called Lightsquared attempted to obtain approval to offer internet services in L band, using frequencies adjacent to those used for GPS.  There was a huge backlash to this because almost all GPS receivers were not designed to work with strong adjacent signals and would be overloaded.  The combined voices of industry, users, and the DOD managed to kill the proposal.

Lightsquared was renamed Ligado, and is back.  It appears they may get the permission they desired from this administration.

Details are here:

https://www.c4isrnet.com/breaking-news/2020/04/10/fcc-to-approve-spectrum-plan-that-pentagon-claims-will-harm-gps/?

47

Equipment / L band antennas

« on: April 08, 2020, 1329 UTC »

Some good construction info here for L band antennas:

http://www.merseyradar.co.uk/airband-radio/l-band-diy-antennas-for-jaero/

48

General Radio Discussion / What is replacing Short Wave radio?

« on: March 08, 2020, 1238 UTC »

https://www.radioworld.com/columns-and-views/guest-commentaries/what-is-replacing-shortwave

49

SDR - Software Defined Radio / SDR.HU

« on: January 12, 2020, 1705 UTC »

The popular website SDR.HU, used to locate on line SDR receivers, has changed their policies to only allow access by licensed ham radio operators.

Other alternative sites exist for non-hams to find SDR receivers such as https://ve3sun.com/KiwiSDR, http://kiwisdr.com/public and http://rx.linkfanel.net.

50

Longwave Loggings / TDF

« on: January 08, 2020, 0432 UTC »

Hearing TDF France on 162 kHz tonight, well enough to decode the time code information on my KiwiSDR.  TDF is much stronger than DCF77 was a few days ago. 

51

Longwave Loggings / DCF77

« on: January 04, 2020, 0426 UTC »

I was hearing DCF77 on 77.5 kHz tonight, well enough (in Midland, Virginia) that my KiwiSDR was able to decode the time.

52

Equipment / Consumer grade antenna splitters

« on: December 27, 2019, 1443 UTC »

KA7OEI has a good article on the use of consumer antenna splitters for ham/swl purposes.  I wasn’t aware of the problem with using “satellite only” splitters at lower frequencies.

http://ka7oei.blogspot.com/2019/12/using-tv-type-75-ohm-splitters-and-taps.html

53

General Radio Discussion / FT8

« on: December 18, 2019, 1347 UTC »

A pet peeve of mine is when I hear someone claim FT8 operates with signals below the noise floor.  It works well, but there is no magic here.

https://tapr.org/pdf/DCC2018-KC5RUO-TheReal-FT8-JT65-JT9=SNR.pdf

54

Propagation / Updated Prediction for Cycle 25

« on: December 15, 2019, 1258 UTC »

http://cqnewsroom.blogspot.com/2019/12/updated-forecast-for-solar-cycle-25.html

55

General Radio Discussion / E6B

« on: December 14, 2019, 1332 UTC »

https://www.thedrive.com/the-war-zone/31477/heres-why-an-e-6b-doomsday-plane-was-flying-tight-circles-off-the-jersey-shore-today

56

General Radio Discussion / Russian EW

« on: December 08, 2019, 1350 UTC »

The Russians use Icom and AOR receivers?

https://planesandstuff.wordpress.com/2019/09/09/murmansk-bn-hf-ew-complex/

57

General Radio Discussion / FCC approves all digital AM

« on: November 23, 2019, 1109 UTC »

https://radioinsight.com/headlines/181941/fcc-approves-digital-am/

58

Equipment / LF - HF Splitters

« on: November 18, 2019, 1122 UTC »

http://ka7oei.blogspot.com/2019/11/homebrew-construction-of-2-and-4-port.html

I’ve become a fan of KA7OEI’s blog - excellent technical content, concise, and frequently on a topic of interest to me.

59

General Radio Discussion / Garage Door Opener Interference

« on: November 08, 2019, 1152 UTC »

Some residents of Warrenton, VA started to have problems with their garage door openers this month.  The nearby government site denied having any new radio transmitters at first, but activities by the local amateur radio club showed there was a new P25 repeater operating near the frequency used by most of the openers.  The government then issued a statement saying they would suspend operation of the repeater for 30 days in order to give nearby residents a chance to replace their openers (this repeater was in the 380-400 MHz band the DoD uses now for their LMR sysyems).

The residents were not happy but got a lesson in the difference between being a primary user of frequency spectrum and using equipment operating under Part 15 of the rules.

More here:

https://www.fauquiernow.com/fauquier_news/article/fauquier-feds-admit-radios-interfere-with-garage-door-openers-11-5-2019

https://www.fox5dc.com/video/623173

60

Equipment / Copper Clad Steel

« on: November 03, 2019, 1438 UTC »

Owen Duffy points out that Copper Clad Steel (CCS) or Copper Clad Aluminum (CCA)  RG6, RG11, and CAT6 cable are becoming more prevalent.  I’ve also noticed that the only 450 ohm ladder line I can find anywhere is CCS.

Owen says that there are no specs on the thickness of the copper layer, and there are increased losses on these cables at lower frequencies compared to pure copper conductors.  He notes that losses of .03 dB/m at 1 MHz have been seen.  If you have a 100 meter run, this could be significant.

Is this really a problem?  The numbers seem to indicate it is something to pay attention to.

https://owenduffy.net/blog/?p=15974