Re: [amsat-bb] APRS signal "W3ADO-1" interfering with Meteor Scatter in England
An FM APRS signal has been received in England on 144.390 MHz. Does anyone know if 144.390 APRS is installed on any current orbiting
satellite...
So sorry, but yes. "Houston, we have a small problem..." I hate to say it, but that beacon was IARU coordinated 15 years ago for operation only when PCSAT is over North America, but after 14 years on orbit, we have lost the ability to turn that backup beacon off.
PCSAT (now 14 years old) had a backup fail-safe beacon on 144.39 that would activate after any unknown spacecraft reset to give us a backup comm link in case the primary 145.825 channel died. Being on the North American APRS frequency with hundreds of IGates there would always be at least one that would hear this "emergency call home" from PCSAT even though the channel is generally saturated. And it worked.
The problem is, that now PCSAT resets on every orbit due to negative power budget and so, on every orbit that beacon comes back on. Even if we did get a command up to reset it, that setting would last only 15 minutes to the next eclipse.
We learned our lesson! That was our FIRST amateur satellite and we sure learned NOT to use a "connected-packet-command link" that needs ACKS and Retries and logon passwords just to LOGON before you can even send a SHUTUP command. All our satellites since, operate without the multiple Send, connect, ACK, retry, ACK, command, ACK overhead.... just to get one command understood. Now, only the receiver on the spacecraft has to be functional to command it to silence in a single packet. But too late for PCSAT.
We are sorry that we have no good answers. But we hope we can mitigate this instance of "friendly fire" collateral damage so that we don't cause an overall black-eye to amateur radio overall friendly operations?
What you may hear will be 2 one-second packets per minute, one at 1200 baud and one at 9600 baud, trying to "call home".
Bob, WB4APR Naval Academy
Thank you for explanation Bob. The MS community in Europe has been suffering this interference for several weeks. I have not seen any notifications on this list that there was a problem with NO-44.
When did you first become aware of the problem ?
We learned our lesson! That was our FIRST amateur satellite and we sure learned NOT to use a "connected-packet-command link"
May I suggest that the lesson to be learned is NOT to use frequencies like 144.390 MHz which have not been agreed Internationally for satellite use across all three IARU Regions.
73 Trevor M5AKA
On Thursday, 30 July 2015, 20:08, Robert Bruninga [email protected] wrote:
An FM APRS signal has been received in England on 144.390 MHz. Does anyone know if 144.390 APRS is installed on any current orbiting
satellite...
So sorry, but yes. "Houston, we have a small problem..." I hate to say it, but that beacon was IARU coordinated 15 years ago for operation only when PCSAT is over North America, but after 14 years on orbit, we have lost the ability to turn that backup beacon off.
PCSAT (now 14 years old) had a backup fail-safe beacon on 144.39 that would activate after any unknown spacecraft reset to give us a backup comm link in case the primary 145.825 channel died. Being on the North American APRS frequency with hundreds of IGates there would always be at least one that would hear this "emergency call home" from PCSAT even though the channel is generally saturated. And it worked.
The problem is, that now PCSAT resets on every orbit due to negative power budget and so, on every orbit that beacon comes back on. Even if we did get a command up to reset it, that setting would last only 15 minutes to the next eclipse.
We learned our lesson! That was our FIRST amateur satellite and we sure learned NOT to use a "connected-packet-command link" that needs ACKS and Retries and logon passwords just to LOGON before you can even send a SHUTUP command. All our satellites since, operate without the multiple Send, connect, ACK, retry, ACK, command, ACK overhead.... just to get one command understood. Now, only the receiver on the spacecraft has to be functional to command it to silence in a single packet. But too late for PCSAT.
We are sorry that we have no good answers. But we hope we can mitigate this instance of "friendly fire" collateral damage so that we don't cause an overall black-eye to amateur radio overall friendly operations?
What you may hear will be 2 one-second packets per minute, one at 1200 baud and one at 9600 baud, trying to "call home".
Bob, WB4APR Naval Academy _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
participants (2)
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M5AKA -
Robert Bruninga