I’m not certain how the ranging process works as to what it leaves in the PLL values but it is affected by
the range capacitor (91nF or whatever) as well as board and circuit stray capacitance so that is a possibility.
The purpose of ranging is to align the PLL correctly.
I spent time this weekend doing what Bob did, taking measurements and reviewing the circuits.
Part of the time was using a $29 eBay phase detector I purchased to measure the actual phase out of the transformers.
At the moment no ready to give it a 5 out of 5 and am struggling for a 1. It uses a Analog Devices chip that
apparently goes to 2.8g but the device appeared to struggle at 146mhz and no phase change from input to no input.
I find it difficult to think it is in the code as it’s all load and go but ….
And in the process of moving the board between the work bench and the test stand I banged the LM1117 regulator
and broke a lead at the body.
Digi-Key has one on the way.
I do solemnly swear to never work on this board on a Saturday night. That’s two for two power supply problems
and I know the source for at least one if not the other.
I’ve done my verification work and have a couple ideas to try when the chip arrives (I bought two to quell
the demons).
Jim
Is it possible that this relates to differences in the 91nF capacitors? E.g. that either the caps differ or there is some different capacitance in
in the area on the board or something? I just remember that the ranging seemed to differ some from board to board. Maybe from chip to chip too?
73,
AMSAT(R) Engineering
-- Flight Software
On Mon, May 6, 2024 at 2:44 PM Bob Stricklin via pacsat-dev <[email protected]>
wrote:
I went through a series of test using the instructions provided by Bruns for hanging the frequency.
When i placed 3 of the four AX5043 devices on 145.840 MHz I could mostly only copy signals on Device 2. Occasionally Device 3 would come through also but it is supposed to be set on 145.870 MHz.
Then I placed all four devices on 145.840 and again mostly only Device 2 is copied but occasionally Device 3 would be copied.
Then I moved the frequency setting on device 2 and 3 off of 145.840 to 145.890. At that point occasionally Device 3 would copy the signals.
Using a spectrum analyzer I checked the signal coming into each one of the AX5043 inputs and found the levels to be about the same on all devices.
May need to do more testing by forcing interrupt on the parts not responding if possible. I think I recall Chris indicating he did see interrupts coming back from all four devices.
With the AX5043 devices all set at 145.840 I see different values in the PLL registers. This seems odd to me.
I am attaching logs for my testing this morning.
I plan to spend some time looking over the layout for each AX5043 to make sure they all match except for Device 2.
When I first started this morning the frequency for one of the devices was 145.860 MHz. I did change the values in config.h file and I had issues an "init new proc" and a "pre flight init" yesterday trying to get the config.h frequencies in place.
There are some minor issues which may be addressed later but not a problem on debug. There may be a bug in the AX5043 code however.
Bob
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