I’ve tried for fun ,to record with a cheap USB Sound Card, a Radxa Rock Board with a custom kernel (added some audio and USB modules) running Ubuntu Server and the Explorer E202 , some stations in the VLF band. We usually monitor them in Turin observatory for SID correlations (http://sidmonitor.rf.gd/gallery/station.html ) The VLF receiver […]
I’ve tested the server into two different environments: LAN and WAN. I confirm the relatively small capacity of the Soekris to support 200-300 units connected to it for NTP UDP as ideal load without alter performances.Of course the major limits comes with Ethernet , T1 and line speed. We could never get nanoseconds over there […]
All is mounted inside my old 2850 rack case, ready to launch The software it’is basically a shell script that resides in FreeBSD sources , and usually you can find it as nanobsd.sh under the folder /usr/src/tools/tools/nanobsd/ . It creates a very little version of FreeBSD that fit into a common 512 MB Compact Flash card. […]
First operative test of the RB Stratum 1 Server Following Poul-Henning Kamp project to modify a 4501 router to build a Stratum 1 NTP server , I’ve decided to build my own using instead a Rubidium Frequency standard source of 10 MHz to clock the Elan processor inside the Soekris. It requires some hardware changes […]
I Recently found a couple of Lucent RFTG at less than 200$, always on eBay ,from a stock in California. These Redundant Frequency and Time Generator, or RFTG were used in big Cell stations to provide high frequency standards. it’s also available the “yellow tuna” type, the RFG-RB, that is of course more expensive and […]
The Raspberry Pi B 512 MB connected to my “old” Aspire One with a crossover cable If you need precise and accurate time for your projects while sampling a digital record or doing something that need precise timestamps you can use a Raspberry Pi with the Adafruit Breakout GPS module to build a stratum 1 NTP […]
What are we talking about? Today I’ll talk about this magnificent little device found on eBay : the Efratom M-100.First of all, what is a Rubidium Frequency Standard? It’s an atomic clock.Just in the 80-90 they were such an expansive units! The working mechanism is fascinating. It uses the hyperfine transition of electrons in rubidium-87 atoms […]
During these days i was searching for something modular and scalable that can gives me a clear PPS ( http://en.wikipedia.org/wiki/Pulse_per_second ) from a GPS satellite with some datas like UTC times.I’ve tested the Arduino UNO board with the Adafruit GPS module. It’s very easy to use them on a little breadboard. The Adafruit GPS is […]
So now we should have our little Unix server running into the WandBoard with SSH running and SFTP of course. Let’s have fun installing NTP client ! First of all we should want have a precise clock. FreeBSD is capable to use NTP protocol as server or client. The protocol is a UDP so it […]
In the previous post I did a quick overview of what I think are two valid alternatives to the common development boards as Raspberry or BeagleBoard. Radxa and Wandboard. Since i would like to use the Wandboard as a little backup server I’ve decided to put inside it FreeBSD 10.1 . So this guide will […]
Delta² 