Interference from repeaters
I have for some time wondered what was causing a considerable amount or QRM (S9+60dB) to the ISS downlink on 145.800. It took a while to identify as there is no CW ident etc. but I have now discovered this is a new D-Star repeater on our repeater channel RV63 which is 145.7875 MHz, only a couple of kHz from ISS and inside the doppler shift range. It seems very poor planning to place high this powered high sited repeaters so near to the satellite allocation. Is this becoming a common problem and are repeaters also causing any problems to uplinks? Dick G4BBH
Hi Dick G4BBH
Same problem in Italy ! This will be discussed during the next IARU Region-1 Conference in Sout Africa upon request from Austria.
73" de
i8CVS Domenico
----- Original Message ----- From: "Richard Ferryman" g4bbh@btinternet.com To: amsat-bb@amsat.org Sent: Tuesday, May 24, 2011 1:37 AM Subject: [amsat-bb] Interference from repeaters
I have for some time wondered what was causing a considerable amount or
QRM (S9+60dB) to the ISS downlink on 145.800. It took a while to identify as there is no CW ident etc. but I have now discovered this is a new D-Star repeater on our repeater channel RV63 which is 145.7875 MHz, only a couple of kHz from ISS and inside the doppler shift range. It seems very poor planning to place high this powered high sited repeaters so near to the satellite allocation. Is this becoming a common problem and are repeaters also causing any problems to uplinks?
Dick G4BBH _______________________________________________ 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 Domenico,
Uum not quite - The Austrian conference paper refers only to repeaters that have been established INSIDE the segment of the band allocated to satellite operation ie above 145.800MHz.
The RV63 145.7875MHz operation has come as a result of the adoption of 12.5kHz channel spacing for 2 metre repeaters back in the mid 90's. Before that time the highest repeater output frequency was 145.775MHz - albeit with a higher deviation than now of course.
Here in the UK we have seven FM units and one DSTAR unit on RV63 http://www.ukrepeater.net/channels/rv63.htm
cheers
Graham G3VZV
-----Original Message----- From: i8cvs Sent: Tuesday, May 24, 2011 1:03 AM To: Richard Ferryman ; Amsat - BBs Subject: [amsat-bb] Re: Interference from repeaters
Hi Dick G4BBH
Same problem in Italy ! This will be discussed during the next IARU Region-1 Conference in Sout Africa upon request from Austria.
73" de
i8CVS Domenico
----- Original Message ----- From: "Richard Ferryman" g4bbh@btinternet.com To: amsat-bb@amsat.org Sent: Tuesday, May 24, 2011 1:37 AM Subject: [amsat-bb] Interference from repeaters
I have for some time wondered what was causing a considerable amount or
QRM (S9+60dB) to the ISS downlink on 145.800. It took a while to identify as there is no CW ident etc. but I have now discovered this is a new D-Star repeater on our repeater channel RV63 which is 145.7875 MHz, only a couple of kHz from ISS and inside the doppler shift range. It seems very poor planning to place high this powered high sited repeaters so near to the satellite allocation. Is this becoming a common problem and are repeaters also causing any problems to uplinks?
Dick G4BBH _______________________________________________ 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
_______________________________________________ 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
As I recall IARU Region 1 (Europe&Africa) approved the use of 145.7875 MHz for repeaters over a decade ago.
You're right it's unworkable with the ISS operating on 145.800 MHz +/- 3kHz doppler shift and with 5kHz deviation.
Unfortunately that was what IARU Region 1 decided despite having agreed earlier to 145.800MHz being used for ISS.
That decision means there are a large numnber of FM and D-STAR repeaters using 145.7875MHz. Anyone near to a 145.7875 MHz repeater will suffer considerable interference when listening to the ISS downlink.
73 Trevor M5AKA
--- On Tue, 24/5/11, Richard Ferryman g4bbh@btinternet.com wrote:
I have for some time wondered what was causing a considerable amount or QRM (S9+60dB) to the ISS downlink on 145.800. It took a while to identify as there is no CW ident etc. but I have now discovered this is a new D-Star repeater on our repeater channel RV63 which is 145.7875 MHz, only a couple of kHz from ISS and inside the doppler shift range. It seems very poor planning to place high this powered high sited repeaters so near to the satellite allocation. Is this becoming a common problem and are repeaters also causing any problems to uplinks? Dick G4BBH _______________________________________________ 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 (4)
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g.shirville＠btinternet.com -
i8cvs -
Richard Ferryman -
Trevor .