I was getting ready for a pass today and heard a very disturbing signal in the 70 cm satellite band (435.84MHz). The signal was very strong. The signal was at least 500KHz wide (max range on spectrum scope). The the spectrum looked like FM but the recording was made with the receiver set to usb mode. I checked the signal on two different receivers (IC-7000 and IC-7600 with a 70cm converter) to make sure it was not a internal birdie of some sort. During the pass it wiped out the sat when it was on. Fortunately it went away after about an hour. I am fairly sure it was terrestrial as the signal level did not change over the hour. Since it was on for only very short periods of time it was impossible to point the beam at it.
Any help identifying the signal type would be appreciated.
http://www.tomdoyle.org/RX-8-12-2012-435.84MHz%20-%20USB.WAV
tnx & 73 W9KE Tom Doyle
Military radar. It's a common occurrence here on the gulf coast.
73, Drew KO4MA
Sent from my iPhone
On Aug 12, 2012, at 6:29 PM, Thomas Doyle tomdoyle1948@gmail.com wrote:
I was getting ready for a pass today and heard a very disturbing signal in the 70 cm satellite band (435.84MHz). The signal was very strong. The signal was at least 500KHz wide (max range on spectrum scope). The the spectrum looked like FM but the recording was made with the receiver set to usb mode. I checked the signal on two different receivers (IC-7000 and IC-7600 with a 70cm converter) to make sure it was not a internal birdie of some sort. During the pass it wiped out the sat when it was on. Fortunately it went away after about an hour. I am fairly sure it was terrestrial as the signal level did not change over the hour. Since it was on for only very short periods of time it was impossible to point the beam at it.
Any help identifying the signal type would be appreciated.
http://www.tomdoyle.org/RX-8-12-2012-435.84MHz%20-%20USB.WAV
tnx & 73 W9KE Tom Doyle _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Hi Tom, W9KE
It was a RADAR signal with a prf (pulse repetition frequency ) of about 400 Hz
http://www.tomdoyle.org/RX-8-12-2012-435.84MHz%20-%20USB.WAV
It is very common to hear those signals in my QTH close to the see here in the bay of Naples.
The only cure to eliminate completely this type of interference was to use a very efficient Noise Blanker like the circuit used into the old nice receiver DRAKE R-4C with in front of it a VHF or UHF downconverter.
I tryed many other novadays receivers with their Noise Blankers built in but the only one capable to cut off completely the interference was the optional solid state Noise Blanker for the old HF receiver DRAKE R-4C
73" de
i8CVS Domenico
----- Original Message ----- From: "Thomas Doyle" tomdoyle1948@gmail.com To: AMSAT-BB@amsat.org Sent: Monday, August 13, 2012 12:29 AM Subject: [amsat-bb] Can anyone help identify this signal
I was getting ready for a pass today and heard a very disturbing signal in the 70 cm satellite band (435.84MHz). The signal was very strong. The signal was at least 500KHz wide (max range on spectrum scope). The the spectrum looked like FM but the recording was made with the receiver set to usb mode. I checked the signal on two different receivers (IC-7000 and IC-7600 with a 70cm converter) to make sure it was not a internal birdie of some sort. During the pass it wiped out the sat when it was on. Fortunately it went away after about an hour. I am fairly sure it was terrestrial as the signal level did not change over the hour. Since it was on for only very short periods of time it was impossible to point the beam at it.
Any help identifying the signal type would be appreciated.
http://www.tomdoyle.org/RX-8-12-2012-435.84MHz%20-%20USB.WAV
tnx & 73 W9KE Tom Doyle _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (3)
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Andrew Glasbrenner -
i8cvs -
Thomas Doyle