CAN-Do Causing RF Frequency Jumps in 70 cm Receiver
John and CAN-Do Team,
I was in the process of checking some configuration files in preparation for my hunt for the 10.7 MHz spur. I initialized the receiver on 435.500, internal reference, and set up the SDR-IQ to display the IF output signal.
Then I clicked the heartbeat button on the Can-Do Net Controller and was about to load the initialization file for external reference. As soon as I clicked the heartbeat button the IF output started jumping. I think it's the three second jumps that I have seen before, but I thought those were caused by a momentary loss of DC input power. In this case the receiver power is coming directly from the bench supply. I killed the CAN-Do module power and the IF jumping stopped. As soon as I applied power to the CAN-Do module again, the jumping returned.
The duration of the jumps is very short and I am unable to capture a carrier - either with the SDR-IQ or using my TS-2000. They sound like clicks over a wide frequency range.
Since the next revision of the receiver will be autonomous, perhaps this won't be an issue for us, but it will for others so it should be understood and documented in my opinion.
73, Juan
Juan,
You say it jumps when you start the heartbeat. Are the jumps at the same frequency as the heartbeat? Are you at a 5Hz poll (for instance) and are the jumps then 5 times a second? This would indicate that something in the configure message is causing the jumps.
You suggest that it might be the 3 Sec. watchdog but that doesn't make sense if the heartbeat is actually running unless the heartbeat is not communicating with your device... The widget watchdog will not fire if a configure message for the widget is heard by the widget within the 3 Sec window.
(I can't tell from your writup what's happening so I'm trying to clarify...)
If you see this happen again you can save the CAN traffic log and send it to me. I might be able to see something in the traffic.
I've been lurking and enjoying reading all of your reports. You've been doing great work.
I'll be glad to help where I can.
Regards, Stephen --
Stephen,
I managed to confuse myself last night so my plan today is to try to retrace my steps and capture the demodulated IF output as a wave file. I'll report back when I have this figured out.
73,
Juan
_____
From: smmoraco@gmail.com [mailto:smmoraco@gmail.com] On Behalf Of Stephen Moraco Sent: Tuesday, July 03, 2007 3:03 AM To: juan-rivera@sbcglobal.net Cc: eagle@amsat.org; Bill Ress; Dave Black (Home); Dave Black (Work); Dave hartzell; David Smith; Don Ferguson; Juan.Rivera (Work); Samsonoff@Mac. Com Subject: Re: [eagle] CAN-Do Causing RF Frequency Jumps in 70 cm Receiver
Juan,
You say it jumps when you start the heartbeat. Are the jumps at the
same frequency as the heartbeat? Are you at a 5Hz poll (for instance)
and are the jumps then 5 times a second? This would indicate that
something in the configure message is causing the jumps.
You suggest that it might be the 3 Sec. watchdog but that doesn't make
sense if the heartbeat is actually running unless the heartbeat is not
communicating with your device... The widget watchdog will not fire if
a configure message for the widget is heard by the widget within the
3 Sec window.
(I can't tell from your writup what's happening so I'm trying to clarify...)
If you see this happen again you can save the CAN traffic log
and send it to me. I might be able to see something in the traffic.
I've been lurking and enjoying reading all of your reports. You've
been doing great work.
I'll be glad to help where I can.
Regards,
Stephen
--
participants (2)
-
Juan Rivera -
Stephen Moraco