[prev in list] [next in list] [prev in thread] [next in thread] 

List:       gnuradio-discuss
Subject:    Re: [Discuss-gnuradio] AR5000 and downconversion
From:       Joseph DiVerdi <diverdi () xtrsystems ! com>
Date:       2003-05-19 4:56:57
Message-ID: p05210602baee1478a04c () [216 ! 17 ! 160 ! 146]
[Download RAW message or body]

>And the answer is... the 10.7 IF output has two modes.
>
>http://www.aoruk.com/pdf/5000m.pdf
>page 29
>
><quote>
>
>6-18 CONFIG - EXTERNAL I.F. output
>(SDU5000)
>The AR5000 is capable of providing a 10.7 MHz I.F. output
>suitably wide enough to drive the optional SDU5000
>spectrum display unit with a bandwidth of up to =B1 5 MHz.
>The I.F. output is default to OFF so must be activated
>before the SDU5000 (or any other similar peripheral) may
>be used.
>
><snip>
>
>The SUB DIAL is used to select the required parameter from
>those available:
>
>1 I.F. taken from before the selective filtering (least
>selective) and suitable for use with the optional SDU5000
>spectrum display unit. Should this selection not be made,
>the SDU5000 will not display a spectrum trace.
>
>2 I.F. taken from after the selective filtering (most
>selective) and is not suitable for use with the optional
>SDU5000.
>
>OFF I.F. output deactivated (default)
></quote>

Well, it now has been well established that the 10.7MHz output can be=
 configured for a 10MHz (+/-5MHz) state and the concerns raised about the=
 wide band output have been dashed by actual engineering. Now the questions=
 (at least in my mind) are "How?" and "Why?"

I'm guessing that the answer to how is with a pair of filters in tandem, one=
 high pass (5MHz) and one low pass (15MHz) which are always in line and the=
 narrower band pass filters which provide the tens and hundreds of kHz are=
 added downstream.

I'll also venture a guess that the why is because the SDU5000 unit has its=
 own set of narrower band pass filters which it uses or not, as it chooses.
-- 
Joseph A. DiVerdi, Ph.D., M.B.A.          
http://xtrsystems.com/           970.980.5868 (voice) 
PGP Key ID: 0xD50A9E33



[prev in list] [next in list] [prev in thread] [next in thread]