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Re: Topband: SDR Mythbusters - ADC Overload myths debunked

To: "Topband reflector" <topband@contesting.com>
Subject: Re: Topband: SDR Mythbusters - ADC Overload myths debunked
From: "Steve Ireland" <vk6vz@arach.net.au>
Date: Wed, 7 Oct 2015 09:51:43 +0800
List-post: <topband@contesting.com">mailto:topband@contesting.com>
G’day all

As someone who has extensively used a digital down conversion/digital up 
conversion transceiver (original HPSDR) on the Topband, it is good to see this 
myth being debunked publicly as much as possible. Another station who has used 
an HPSDR even more extensively than me on Topband is Greg ZL3IX, who may be 
interested in commenting.

For about 18 months I used the HPSDR transceiver alongside a ‘benchmark’ 
Elecraft K3 in contests and for DXing, alongside keen contester/DXers VK6LW 
(about 3km away) and VK6DXI SK (about 30km away) running full power on Topband 
and the other bands.  I could work equally close (within 500Hz) to Kevin and 
Mirek on the HPSDR as I could on the K3.  

The brick-wall sided constantly variable filtering provided by the fully 
digital HPSDR and its associated OpenHPSDR software and the way this filtering 
handled noise in comparison to the K3’s digital filtering made the HPSDR a 
superior radio for weak signal DXing – simply put, I could read S2/S3 signals 
on the HPSDR in a 50Hz bandwidth that were unreadable on the K3.

The only problem for me is that using computers day in, day out at work, I 
loathe using them for radio and hate spending my evenings fiddling around with 
software, so the HPSDR has finally gone (mind you, so has the K3 – loved the 
radio but hated the audio and went and bought an old Orion 2 which sounds waaay 
better to my ears).  

DDC/DUC radios handle strong signals as well as the best of analogue radios – 
the only question for topbanders is whether you like their ergonomics and the 
whole idea of having a digital radio.

Vy 73

Steve, VK6VZ


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>From Stu, K6TU
 
As with any technological change, there are many myths, past truths or part 
truths that get repeated endlessly and out of context by those frightened or 
challenged by the change.
 
Software defined radios are no exception to this in the world of Ham Radio.
 
Steve Hicks, N5AC and the VP of Engineering at FlexRadio has posted an 
excellent explanation and bust of the ADC overload myth on the FlexRadio 
community.  You don?t need to be registered on the community to read this 
excellent write up:
 
 
https://community.flexradio.com/flexradio/topics/adc-overload-myths-debunked?utm_source=notification&utm_medium=email&utm_campaign=new_topic&utm_content=topic_link
 
 
 

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