In the US, the surplus equipment market occasionally had GPS-trained oscillators that could provide 10Mhz and 1pps clocking as well as NMEA output. They were parts of CDMA cellphone base stations, each of which had at least two. The one I have was made by HP. I also have one that is a Motorola device that was used to synchronize simulcast transmitters in repeaters.
That is the kind of box (from other manufacturers) that we use as well, attached to a PC with 1PPS and NMEA and to the repeater with 10 MHz. Chrony on the PC keeps the Linux clock within 10us (usually within 1-2us) which we require for the simulcast, and 10 MHz provides the exact transmit frequency reference.
Power... well, maybe it has an oven stabilized crystal oscillator. Or very old digital logic that is a bit too power-hungry. Of course a lowcost uBlox/ SiRF module is easy to get going and provide 1PPS for ntpd.
The LeoNTP box is a plugin-and-forget network clock, of course not the cheapest solution. A Raspberry Pi can be used, I have one in the IPv6 NTP pool at 2a00:f10:103:201:ba27:ebff:fefd:984
Rob
They do indeed. There is an "oven ready" light on the HP's front panel and a large fibreglas-wrapped object taking up much of the space inside the box.
The Motorola device has no NMEA output, but can produce 2.5, 5, 10, 12.5, or 25MHz reference frequencies depending on jumper settings inside the box.
I wish I had a use for them. Right now they're just another piece of the junk piled up in my garage. I use the NTP-syncronized clocks in my computers as my primary time reference because they're on all the time anyway. - Brian
On Tue, Oct 10, 2017 at 11:39:13AM +0200, Rob Janssen wrote:
Power... well, maybe it has an oven stabilized crystal oscillator.
All,
I've added the NTP servers in this email thread to the Services Wiki (I didn't include Bigben since that's not on AMPRNet, let me know if you think I should add it, Brian).
Also, my NTP server is a Stratum 2 that pulls from various military, industrial, government and educational Stratum 1 servers in North America (including AMPRGW).
John, be sure to let us know when you've assigned a 44 IP to your server.
For reference, my NTP Server address is: kb3vwg-001.ampr.org (44.60.44.1)
73,
- Lynwood KB3VWG
I think UCSD would appreciate it if not a lot of external people use Bigben as it's already pretty busy serving thousands of hosts on campus. - Brian
On Tue, Oct 10, 2017 at 10:54:51AM -0400, lleachii--- via 44Net wrote:
I've added the NTP servers in this email thread to the Services Wiki (I didn't include Bigben since that's not on AMPRNet, let me know if you think I should add it, Brian).
On Tuesday, October 10, 2017 2:39:13 AM PDT Rob Janssen wrote:
In the US, the surplus equipment market occasionally had GPS-trained oscillators that could provide 10Mhz and 1pps clocking as well as NMEA output. They were parts of CDMA cellphone base stations, each of which had at least two. The one I have was made by HP. I also have one that is a Motorola device that was used to synchronize simulcast transmitters in repeaters.
That is the kind of box (from other manufacturers) that we use as well, attached to a PC with 1PPS and NMEA and to the repeater with 10 MHz. Chrony on the PC keeps the Linux clock within 10us (usually within 1-2us) which we require for the simulcast, and 10 MHz provides the exact transmit frequency reference.
Power... well, maybe it has an oven stabilized crystal oscillator. Or very old digital logic that is a bit too power-hungry. Of course a lowcost uBlox/ SiRF module is easy to get going and provide 1PPS for ntpd.
The LeoNTP box is a plugin-and-forget network clock, of course not the cheapest solution. A Raspberry Pi can be used, I have one in the IPv6 NTP pool at 2a00:f10:103:201:ba27:ebff:fefd:984
I had one of the surplus CDMA units for my test gear but after many years of service it finally died so I replaced it with one of the Leo Bodnar GPS references. It's nice for test gear and as a reference for my SDR but doesn't have the 1PPS for NTP use.
Recently I picked up one of these: http://www.ebay.com/itm/GPS-Receiver-GPSDO-10MHz-1PPS-GPS-Disciplined-Clock-... There are lots of similar units available on ebay and with 10Mhz and 1PPS outputs they can be used for both purposes. Mine will be feeding one of my Raspberry Pi systems.
-
Brian Kantor -
Ken Koster -
lleachii＠aol.com -
Rob Janssen