[time-nuts] lawnmower robots may be the end of VLF timekeeping

[Mark Spencer]

In practice it seems to be hard to fight interference issues at lower frequencies.   A local 50,000 watt AM (medium wave) broadcaster, put up a FM (VHF) transmitter several years ago.   One of the reasons they gave for going to FM were the interference issues on the AM band.   I noticed the newer electric trolly busses were significant sources of interference on my drive home from work. 

I've largely stopped using my HF amateur radios in the city, and even at VHF the noise floor is noticeably lower in the country side.    
    
Reception for my WWVB clock is also rather hit or miss from south western Canada but it does work on occasion.    I was however pleased that my 1.2 Ghz amateur radio activities don't seem to disrupt my own GPS reception despite less 15 feet of antenna separation. 

Sent from my iPad

On 2015-05-09, at 12:48 PM, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
> 
> The real questions:
> 
> 1) Are they breaking any laws with their pollution? 
> 
> 2) Is there a regulatory body that is charged with enforcing those laws?
> 
> 3) Is the cost (hours / dollars / hassle) of taking action prohibitive? 
> 
> Often it’s a combination of more than one that gets you …
> 
> This is fundamentally no different than the boys setting up their system right next to
> GPS. The main difference is that they had to go through the licensing process and not
> all these devices do that. I do know that when every radio clock within 1/2 Km goes dead,
> there are towns that will have a lot of people scratching their heads ….
> 
> Bob
> 
>> On May 9, 2015, at 2:15 PM, Björn <bg at lysator.liu.se> wrote:
>> 
>> The same has been observed by the lightning listeners at blitzortnung.org
>> 
>> --  
>> 
>>     Björn
>> 
>> <div>-------- Originalmeddelande --------</div><div>Från: Poul-Henning Kamp <phk at phk.freebsd.dk> </div><div>Datum:2015-05-09  14:15  (GMT+01:00) </div><div>Till: time-nuts at febo.com </div><div>Rubrik: [time-nuts] lawnmower robots may be the end of VLF timekeeping </div><div>
>> </div>I spent some time capturing some data today.
>> 
>> The measurements is from my $20 loop-antenna in the attic, which is
>> something like 8 meters up and 10 meters besides the lawn-mower loop:
>> 
>> http://phk.freebsd.dk/time/20150509.html
>> 
>> -- 
>> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
>> phk at FreeBSD.ORG         | TCP/IP since RFC 956
>> FreeBSD committer       | BSD since 4.3-tahoe
>> Never attribute to malice what can adequately be explained by incompetence.
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