Several weeks ago, we posted a message seeking information about time sources. There were many helpful and educational responses. An excerpt from one of the responses is included below. We have been following up with regard to how SDR capabilities might be used for obtaining time using SDR dongles as well as using the time source product referenced in that response.
Our SDR investigation has yielded many sources of information, but not a source dedicated to CentOS support for SDR products. Is there a CentOS subgroup and mail list directly involved with SDR device or system support?
The SDR information resulting from our search has many references to ADS-B and the P3. It is almost like one absolutely must have a P3 to make use of SDR products.
One thing that we did not find was any reference at all to SDR products and software for monitoring the frequencies used by recreational Remote Controlled Aircraft.
Thanks again for all the helpful system time responses.
Chris Olson wrote:
Several weeks ago, we posted a message seeking information about time sources. There were many helpful and educational responses. An excerpt from one of the responses is included below. We have been following up with regard to how SDR capabilities might be used for obtaining time using SDR dongles as well as using the time source product referenced in that response.
<snip> I missed that one, so a clarification, please: is that software-defined-radio, or the SDR that ipmitool offers info on, or....
mark
Software Defined Radio
On Wednesday, July 19, 2017 8:40 AM, "m.roth@5-cent.us" m.roth@5-cent.us wrote:
Chris Olson wrote:
Several weeks ago, we posted a message seeking information about time sources. There were many helpful and educational responses. An excerpt from one of the responses is included below. We have been following up with regard to how SDR capabilities might be used for obtaining time using SDR dongles as well as using the time source product referenced in that response.
<snip> I missed that one, so a clarification, please: is that software-defined-radio, or the SDR that ipmitool offers info on, or....
mark
On 7/19/2017 11:41 AM, Chris Olson wrote:
Software Defined Radio
I wouldn't want to use SDR as a simple time source.... SDR uses a /lot/ of CPU to make up for the lack of radio hardware. It would make far more sense to get a dedicated WWV or GPS reciever to use as a time reference, unless you're going to dedicate a server just to be a software radio.
On Wed, July 19, 2017 1:57 pm, John R Pierce wrote:
On 7/19/2017 11:41 AM, Chris Olson wrote:
Software Defined Radio
I wouldn't want to use SDR as a simple time source.... SDR uses a /lot/ of CPU to make up for the lack of radio hardware. It would make far more sense to get a dedicated WWV or GPS reciever to use as a time reference, unless you're going to dedicate a server just to be a software radio.
I would second that and also would add that SDR adds latency to what gets on its output, the last grossly depends on system load, and is affected by system scheduler etc, hence, IMHO SDR is poor device to time synchronization in general.
Valeri
-- john r pierce, recycling bits in santa cruz
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++++++++++++++++++++++++++++++++++++++++ Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ++++++++++++++++++++++++++++++++++++++++
On 07/19/2017 11:02 AM, Chris Olson wrote:
We have been following up with regard to how SDR capabilities might be used for obtaining time using SDR dongles as well as using the time source product referenced in that response.
...
One thing that we did not find was any reference at all to SDR products and software for monitoring the frequencies used by recreational Remote Controlled Aircraft.
GNUradio works well on CentOS 7, but it is a bit of an adventure to get it built. Marcus Leech's build-gnuradio.sh script works fine, and I've used it several times to build GNUradio on C7, both on x86_64 and on aarch64 (although I haven't performed that build on any of my ODROID C2s in some time and it really was a pain due to EPEL not being available for aarch64 at the time). I tried the PyBOMBS build, but it wasn't successful for me, so I reverted to the build-gnuradio.sh script.
GNUradio supports a number of SDR dongles, including the RTL-SDR.
An old version of GNUradio used to be in EPEL, but it's no there as of today.
For general-purpose SDR work GNUradio is fine, but if you need deterministic latency you may be disappointed.
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Chris Olson -
John R Pierce -
Lamar Owen -
m.roth＠5-cent.us -
Valeri Galtsev