[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: "spontaneous" LEILA activation << I hear thepulses here too>> ?? A radar or ranger?? Lband or U band???



I used to operate the radar on the Willy Fudd.  It was a simple 
pulsed magnetron and operated on 3 GHz.  I also flew on the E-2B 
Hawkeye which operates in the 420-450 band and uses a pulse 
compression (chirp) radar.  Both had a slow scan rate.

John WA4WDL

>The US Navy has had, for many years, ships with air search radars in the
>420 to 450 Mhz frequency range which use pulse expansion/pulse
>compression type of modulation.  The technique is somewhat like a cross
>between spread spectrum and FM.  The pulse is generated by sending a
>narrow pulse down an LC type delay line (at a lower IF frequency).  The
>resultant pulse length is something on the order of 200 micro seconds
>long and contains a more or less linear phase (freq) shift from start to
>end.  On the receive end the process is reversed to recover the narrow
>pulse for processing.  This is a very high (average) power radar with a
>beam pattern looking up at the sky.  It could look somewhat like FM to a
>narrow band receiver. There should be a slow antenna rotation rate
>associated with this type of signal.
>
>There are also some airborne radars with actual swept frequency
>modulation methods which I hear often here in the Norfolk, VA area.
>There is a Navy axillary landing field a couple of miles from my QTH and
>when the AEW planes are flying there the interference on 435 is very
>severe.  It is a wideband signal which covers all of my 432 to 437 Mhz
>frequency range.  Fortunately the noise blanker takes them out almost
>completely so they do not cause me a major problem.  These are equivalent
>to the Air Force AWACS planes (the navy used to call them WF ("Willie
>Fudd")  but I don't know what they are named now.  These signals have the
>same type of slow rotation rate associated with them also.
>
>Actually there are many swept frequency type radars in various frequency
>bands in the military inventory that might cause interference on the
>AO-40 uplinks.
>
>73's de Jess - W4MVB
>----
>Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
>To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home