[Linrad] Re: Linrad and SRD-IQ Parameter Files

[Leif Asbrink <sm5bsz.com; leif@xxxxxxxxxxxxxxxx>]

Hi Thomas,
 
> Will someone send a set pr parameter files for the SDR-IQ?
> 
> I want to look at a center freq of 20KHz with a bandwidth of 40KHz, or a
> range of 100Hz to 40KHz.
> 
> >From Spectravue,
>   CIC2 rate  8  scale 4
>   CIC5 rate 30  scale 20
>   RCF  rate  5  scale 0
>   RCF Taps 256
> 
>   RF Gain +1-db
>   GN Code 18
>   Preamp Gain 17db
> 
>   6620 IF Gain +24db
> 
>   Filter Bandwidth 50KHz
> 
> FFT Ave 5
> Smoothing 0
> 8192 FFT/BLK Size
> 5db/div
> 
> >From par_sdr14:
>   M_CIC2 [8]
>   M_CIC5 [30]
>   M_RCF [5]
>   OL_RCF [0]
>   Sampl. clk adjust [0]
>   Att [0]
>   Inp.sel [24]
>   Check [2150200]

This will be OK. Sampling rate 55 kHz.

> >From par_cw:
>   First FFT bandwidth (Hz) [6000]
>   First FFT window (power of sin) [2]
This is really extreme. Nothing wrong with it and it will allow
you to catch really fast phenomena because the maximum speed
of the waterfall will be 1700 lines per second. The FFT size would be
64 only. That is the minimum size allowed in Linrad and the bin 
bandwidth will be 1.7 kHz.

I suggest you set First FFT bandwidth (Hz) [12] which
would give an fft size of 8192.

>   First forward FFT version [0]
>   First FFT storage time (s) [1]
>   First FFT amplitude [1000]
>   Main waterfall saturate limit [0]
>   Enable second FFT [1]
As a newcomer you should set this to zero.
 Enable second FFT [0]

As a consequence the following parameters will not be used:
------------------------------------------------
>   First backward FFT version [0]
>   Sellim maxlevel [6000]
>   First backward FFT att. N [2]
>   Second FFT bandwidth factor in powers of 2 [2]
>   Second FFT window (power of sin) [2]
>   Second forward FFT version [0]
>   Second forward FFT att. N [6]
>   Second FFT storage time (s) [5]
-------------------------------------------------

>   Enable AFC/SPUR/DECODE (2=auto spur) [0]
This is fine, wait until you are familiar with normal
operation until you turn this on.

These parameters become unused:
--------------------------------------------------
>   AFC lock range Hz [150]
>   AFC max drift Hz/minute [100]
>   Enable Morse decoding [0]
>   Max no of spurs to cancel [0]
>   Spur timeconstant (0.1sek) [5]
--------------------------------------------------
>   First mixer bandwidth reduction in powers of 2 [4]
>   First mixer no of channels [1]
>   Third FFT window (power of sin) [2]
>   Baseband storage time (s) [5]
>   Output delay margin (ms) [100]
>   Output sampling speed (Hz) [11025]
>   Default output mode [1]
>   Audio expander exponent [3]
>   A/D speed [138888]
This value is not compatible with the sdr parameters
you gave above. Your max waterfall speed would become 
4300 lines per second at a bin resolution of 4.3 kHz.

>   Check [259]
> 
> 
> After I save the parameters I can get a waterfall display, etc.
> 
> The top reads 372500 373000 ... 375000, which I assume is frequency.
> How do I change this to see the part of the spectrum I want?

The general idea is use F1 help. Place the mouse outside any window
and press F1. You will then see where all controls are. Then
place the mouse one one control after the other and press F1 to
read info about each one. You should then find the little
window with four arrows and two numeric fields. The upper
fiels is for setting the center frequency. Enter .025 to set
the center frequency to 25 kHz. To see the full width of the
spectrum and waterfall you may have to use the arrow boxes in
the upper corners of the waterfall window.

It could be a good idea to remove par_userint and select
"newcomer mode" (new in linrad-03.06) by pressing 'N' rather 
than 'S' as the first entry. 

73

Leif


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