Hello,
I would like to build a geographically disperse bladeRF network, and I need all of them to be synchronized. I read in another thread that the output signal must be 38.4 MHz, but most GPSDOs are 10 or 100 MHz. The only one I've been able to find is this one:
http://www.leobodnar.com/shop/index.php ... cts_id=234
Is this one compatible? What GPSDO options are available?
GPSDO Availability
-
bglod
- Posts: 201
- Joined: Thu Jun 18, 2015 6:10 pm
Re: GPSDO Availability
Hello,
It has been a while, so I hope you were able to figure our your problem. As of 2016.01-rc1 release (https://www.nuand.com/blog/2016-01-rc1-release/) we added a VCTCXO Tamer module that allows you to hook up a 1.8 V logic 1 PPS or 10 MHz reference to pin J71.1. In software, you can enable the VCTCXO tamer, which will keep the VCTCXO tamed to 38.4 MHz using the 1PPS or 10 MHz as a reference. You can use the Leo Bodnar GPSDO (it's actually what we used). We configured the output to 10 MHz with a drive strength of 16 mA and passed that through a 10 dB attenuator to get the VPP closer to LVCMOS. While the Cylcone IV E is safe up to 3.3 V, we do not recommend this because the bank voltage is only 1.8 V. You'd have to put a Leo Bodnar on each bladeRF, and in doing so, the crystals should be synchronized against the common GPS reference.
I can't speak to how accurate such a solution would be, however. It would require more testing than we've done here in the lab. If you're able to, we'd appreciate any feedback/results you can share with us so we can make any improvements that may be required.
It has been a while, so I hope you were able to figure our your problem. As of 2016.01-rc1 release (https://www.nuand.com/blog/2016-01-rc1-release/) we added a VCTCXO Tamer module that allows you to hook up a 1.8 V logic 1 PPS or 10 MHz reference to pin J71.1. In software, you can enable the VCTCXO tamer, which will keep the VCTCXO tamed to 38.4 MHz using the 1PPS or 10 MHz as a reference. You can use the Leo Bodnar GPSDO (it's actually what we used). We configured the output to 10 MHz with a drive strength of 16 mA and passed that through a 10 dB attenuator to get the VPP closer to LVCMOS. While the Cylcone IV E is safe up to 3.3 V, we do not recommend this because the bank voltage is only 1.8 V. You'd have to put a Leo Bodnar on each bladeRF, and in doing so, the crystals should be synchronized against the common GPS reference.
I can't speak to how accurate such a solution would be, however. It would require more testing than we've done here in the lab. If you're able to, we'd appreciate any feedback/results you can share with us so we can make any improvements that may be required.
Electrical Engineer
Nuand, LLC.
Nuand, LLC.