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Messages - ThElectriCat

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106
General Radio Discussion / Re: Broadcasting in SSB many advanategs a few disadvantages
« on: February 02, 2018, 2035 UTC »
I would tend to agree that transmitting in SSB brings benefit, especially for low power broadcasters such as part 15 and pirate broadcasts, and although SSB has a lower fidelity than AM by traditional standards, that is because of a bandwidth restriction, rather than the inherent limitations of the mode itself.  If one were to use a 10 or 15 KHz audio signal to drive an SSB transmitter(without a narrowband filter of its own), the audio quality would be equal to or greater than an AM transmitter. the only 2 problems with this are as follows;
1. the average SSB receiver has a narrowband filter, which will limit the audio quality regardless of the transmitter.
2. the signal must remain very well tuned for the receiver to demodulate the audio properly.

In the modern age, with fancy SDR receivers and PLL or DDS transmitters than can be locked to an accurate frequency reference (WWV/GPS/OCXO/RubidiumTO) these problems are easily dealt with, and the savings of 66% of your power not used for the carrier, and another 17 not used for the other sideband, it may be the right choice in SOME situations.

(P.S. I love AM as much as the next guy, just saying its not the only right way)

107
Equipment / Re: Grounding systems
« on: February 02, 2018, 1911 UTC »
This article is the best one I have ever read on radio station lightning protection/grounding
 http://www.nautel.com/wp-content/uploads/2011/04/Lightning-Protection-Radio-Stations-Oct-1998.pdf
It is probably a bit overkill for a pirate/amateur/SWL station, but all of the rules and principles still apply.
It is probably also worth noting that some of the FM broadcast stations I maintain can withstand a direct lightning strike to the tower and stay on the air.

Of course the grounding dosen't only apply to lightning protection, but the same techniques will help reduce RFI and noise as well.

108
The RF Workbench / Re: Power Supply for TX
« on: February 02, 2018, 1648 UTC »
Its funny you should mention that, the only thing wrong with mine is that the indicator light in the switch has failed.

109
The RF Workbench / Re: Power Supply for TX
« on: February 02, 2018, 0034 UTC »
If you want a used one,  I agree with the eBay/ hamfest idea, but also advise you to acquire a linear power supply rather than switchmode.

if you want to buy a new one, I wholeheartedly recommend Astron power supplies, I have one rated for 20 amps at 12 volts, and it will gladly provide its maximum power with almost no ripple day in and day out

110
General Radio Discussion / FCC licences
« on: November 17, 2017, 1900 UTC »
I work in the broadcast industry by day, and I found this search tool on the FCC website to be most useful, hopefully it hasn't been posted before, but I didnt find it.

http://wireless2.fcc.gov/UlsApp/UlsSearch/searchLicense.jsp

if you click on "advanced search" you can search by discrete frequency or frequency ranges.  This may not be helpful for pirates, but plenty of unusual transmissions are actually legal.  Pretty much any united states licensed transmission should show up here.

P.S this search can return huge numbers of results, especially as frequency gets higher, so be as specific as possible

111
SDR - Software Defined Radio / Re: SDR design and architecture
« on: June 01, 2017, 0233 UTC »
 Dont mean to be just talking to myself here, but over 100 views tells me its not a waste,
 Has anyone thought of tuning the sample rate of the ADC in an sdr? Kind of like the LO in a receiver, That way one could move receiver images and aliases around, and determine that your heard signal was actually the desired one?

112
22 Meter Band HiFER Beacons / Re: PVC loop aerial experiments.
« on: May 29, 2017, 2157 UTC »
 I have been listening to the area right around the PVC center frequency with my HP8594E, and any ability to hear it has been obscured by a loud signal centered on 13560.15 Kilocycles, it is pulse width modulated with pulses occurring every 23 ms or so, and it has very wide ( the better part of 1 Mc) sidebands, have any other listeners encountered this signal while trying to receive PVC? or is it just a local noise source?

I have a 27 meter long wire antenna, and live in humboldt county, CA

113
SDR - Software Defined Radio / SDR design and architecture
« on: May 29, 2017, 2014 UTC »
Maybe this is scary technical, but is anyone out there designing or building their own software defined radio?
 I think this is a project that is getting more attainable with the myriad of phenomenal parts from Analog devices, Maxim, TI and others. 
If anyone has any Ideas they have been thinking of lately, let me know, especially anyone who has ideas but feels like building an SDR is a big stumbling block.
            My hope if for this thread to be a source of input and feedback for people with ideas so those ideas can be further developed.

so far my main interests in sdr are;
   effecient undersampling to realize higher frequencies with a direct sampling front end
   use of homodyne and weaver architectures in the digital realm to reduce the dependence on processor power for demodulation

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