[time-nuts] 1900kHz radiolcation testing on east coast US?

[Tom Miller]

They may also be modulating it to spread out the peak energy to meet EMI 
requirements.

Tom

----- Original Message ----- 
From: "Chuck Harris" <cfharris at erols.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Sunday, December 07, 2014 8:41 PM
Subject: Re: [time-nuts] 1900kHz radiolcation testing on east coast US?


> Hi Tim,
>
> Look for a switching power supply that is fairly new, and is
> of the sort that doesn't need to be messed with to cover the full
> 120V to 240V range.
>
> That sort of switcher is also known as a power factor correcting
> switcher.  It has a PWM switched pre-regulator that takes the
> unfiltered ripple straight from a full wave bridge rectifier, and
> PWM's it so that it can charge the filter capacitor, without the
> power line seeing anything but a resistive load.  It also controls
> the inrush current.
>
> PWM pre filters, because they quickly shift the pwm signal at a
> 120Hz rate, are capable of producing lots of broadband 120Hz
> modulated garbage if their shields, or filters are compromised.
>
> -Chuck Harris
>
> Tim Shoppa wrote:
>> Would any time-nuts know of radiolocation-type testing going on, on east
>> coast of US, maybe around Maine? There is a very strong wideband signal 
>> on
>> 1900-1920kHz, with a 120Hz substructure and a 4Hz rep-rate, likely 
>> megawatt
>> power range.
>>
>> Sound sample (recorded with 2400Hz receiver bandwidth, although the whole
>> signal is far far wider bandwidth) at
>> http://www.trailing-edge.com/1910-intruder.wav
>>
>> Pics of the waveform at http://www.trailing-edge.com/1910-intruder-1.png 
>> and
>> zoomed in at http://www.trailing-edge.com/1910-intruder-2.png
>>
>> Tim N3QE
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