Nags Head II

Frank Gentges
Wed, 5 May 1999 13:26:06 +0000 (GMT)

On Wed, 5 May 1999, Andre' Kesteloot wrote:

> Frank Gentges wrote:
> > [...]
> >
> > These VLF signals were close to detectability so they were a good test of the
> > difference of the two receivers.  Essentially signals at the threshold of
> > detectability on the NRD525 in the 200 Hz CW bandwidth were not detectable in
> > the RX320 in the 300 Hz bandwidth.
> Is your conclusion then that the NRD525 is marginally more sensitive than the
> RX320? By the way, what is the price difference?

Yes, the RX320 has just a little bit less detectability than the NRD525 
under these specific conditions.  CW signal sensitivity may be different 
and likely reversed with the RX320 being better.  Cost is a big 
difference as a new RX320 is less than the typical used NRD525.  Of 
course the RX320 needs the AMRAD modification. :-)

> > This may raise the issue if there is a difference between analog and DSP
> > receivers similar to the arguments in the audio field of vinyl record audio
> > vs. digital CD audio.  More work needs to be done to find the differences in
> > some more objective measure.  For now I am convinced it exists.
> meaning ?

More work is needed to better understand this difference.  Keep in mind 
this is a data point of observed data that I feel is genuine but I am 
also puzzled as to why it is and what it means.

> > The RX320 was tried in the car using the automobile 12 volt power in place of
> > the plug-in power supply and the Toshiba notebook on batteries.  A simple
> > cigarette lighter plug cable with the coax power connector on the other end
> > was used. This setup worked well except that more work needs to be done to
> > suppress other automobile interference to make it really usuable.
> but am I to understand that it worked well when the engine was turned off?

Exactly.  I suspect grounding of the receiver setup needs to be made more 
robust so only signals from the antenna go into the receiver.  I am 
thinking about making up a wideband 10 kHz-30MHz active trunk 
mount antenna to go mobile with. 

> Andre'

Frank K0BRA