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RE: [linrad] Linrad Questions


    Thanks for the reply.   Slowly but surely I am making progress.


At 03:05 PM 10/8/02 +0200, you wrote:
>Hi Terry,
> >      A few questions.   I currently have Linrad running under RedHat 7.3
> > using a very old SB16 sound card and taking the receive audio from a
> > Kenwood TS-850SAT.
> >
> >     Could some one give me some good starting values to use in setting up
> > Linrad?   I really don't know which ones to play with.
>It depends on what you want to do.

Fair question.   Should have put that in the original message.   My main 
interest in Linrad is for use on 432 MHz EME.

> >     I am thinking of building a KK7B direct conversion binaural I-Q 
> receiver
> > but don't know how much difference it might make.    Is it worth the 
> effort
> > to go to a direct conversion radio with IQ output?   With two kids in
> > university and another going next year ham radio funds are very limited 
> here.
>The component cost for a direct conversion receiver is close to nothing
>if you make 74HC4052 or 74HC5053 mixers and skip the anti-alias filters.
>Performance will be good enough for many purposes.
>If it is worth the time/money to go to a larger bandwidth depends
>entirely on what you want to do. Is noise blanking important or not?
>The blanker improves with larger bandwidth but otherwise bandwidth
>will not affect sensitivity for weak signals. Do you have strong
>signals from nearby amateurs? If that is the case you need a
>sophisticated IQ receiver that has adequate dynamic range. In a good
>location the simplest solution will be good enough.

Noise blanking is not a huge need here.  Since moving up to 432 MHz EME 
noise is no longer an issue.   A bigger problem is all the birdies.   The 
lower 20 KHz is almost un useable due to all the garbage.   The ability to 
"see" the bottow 20 KHz or so of the the band to spot stations on the air 
would be great.   I don't have any active stations near me on 432.   There 
are one or two in town but they never seem to be active.