Programming frequencies in a Open Source GPSDO - Page 1
Forum section: electronics / general

author: dcbrown73
author_rank: Regular Contributor
timestamp: April 23, 2024, 05:44:37 pm
content: Hi,I have several instruments that can take a 10mhz reference, so I decided to pick up one of the cheap eBay references based on open source design. (Found here =>http://sq1gu.tobis.com.pl/pl/index.php?option=com_content&view=article&id=44:generator%20-si5351a&catid=12&Itemid=107)This is an image of it:Mine is the push button encoder version rather than the three button version. The instructions for programming it are basically an image here:I'm having an issue as it does not seem to save as I try to program it. I'm not sure if I'm in error, or the device is malfunctioning and won't safe. It has two outputs (A & B) and you can program 10 frequencies in 10 different banks for each output. Output A already has 10Mhz programmed into it, but Output B does not.'When I try to program it, it does not seem to save it in the specified bank. It will change the frequency, it's not that simple. You can only change a "step" and all the banks in output B are not multiples of any step, so I have to save it at a multiple and then change it again with a different step. (does that make sense?)Basically, I want 10Mhz, but a freq is 192khz. I set the step to 1khz and walk it up to 200khz. Then save it and change the step to 100khz and then I can easily change it 100khz at a time till it reaches the expected 10Mhz. Then save it again.What happens is, I set the 1khz step and change it to 200khz. The output shows (display and actual output) 200khz. I'm unclear as to why it wont save as when I navigate back to change the step to 100khz which goes fine, but when I switch back to edit the 200khz to 10mhz, it immediately switches back to 192khz and the 100khz step is not useless.So, I'm basically asking. Is there some step I'm missing to actually get it to save the frequency setting in the bank rather than just temporarily change it?Just so it's clear. Pushing the encoder moves to the next option in the menu. I figure when I use the encoder and then press the encoder button, it saves it as it moves to the next. That doesn't appear to be what's happening when saving the frequency, though it works fine when changing the "step" or the setting the timezone or even selecting what memory bank I want to use.As noted, the frequency doesn't change (even after I push the encoder button) until I switch back to it and then it immediately switches back to the previous frequency that was in that bank.Blah!Dave

author: dcbrown73
author_rank: Regular Contributor
timestamp: April 25, 2024, 09:30:13 pm
content: Just an update in case someone else picks up one of these devices.I figured out what was wrong. When you set the frequency, you have to go back to the main (first that tells how many SATs it's hearing) screen using the encoder. It will then save the frequency. Then you can go back to the A or B channel and the frequency will be what you set it to and even after you cycle the power.

author: SCSKITS
author_rank: Regular Contributor
timestamp: August 16, 2024, 01:02:26 pm
content: This is meant to be a signal generator, not a reference for other equipment.The SI-5351 does not have the low pass PLL loop filter required to remove the low frequency clock jitter from a GPS module.Look at a unit such as the BODNAR GPS that has the SI-5328 which has a low frequency PLL filter.ed