Nortel GPSTM

Nortel GPSTM
Name	Nortel GPSTM
Zone	Infrastructure
Owner	Nate Bezanson
Make Model	Nortel GPSTM
Part Number	NTBW50AA-11
Date Acquired
Storage Location	Server Rack
Authorization Required	No
Status	Running
Value	$150
IP Address	10.13.0.95
MAC Address	00:01:2e:49:5d:ba
Hostname	harrison.i3detroit.local
Documentation	Manuals ntpsec
Other References

Intro

The Nortel GPSTM is a GPS disciplined, temperature controlled oscillator and time source. The current purpose is for it to provide a high accuracy, high precision time source for the space and provide a 10Mhz reference clock for the E-Room.

ToDo

• Use distribution amplifier to route 10Mhz/PPS to E-Room
• Front panel VFD wiring/software
• Integrate with ntpsec
• Mount antenna
• 48-hour site survey
• Add PPS output from marked via.
• Rackmount case

PPS Discovery

Amelia Meyer and Benjamin Fedorka found inside the unit a PPS output pin, which is exciting because the native output on the unit of PP2S is unsuitable for ntpd.

After some tracing, a more-suitable location near several ground points was located at TP13.

Discussion here: https://www.febo.com/pipermail/time-nuts/2015-May/092151.html

And here's the prior work Ignacio EB4APL refers to, on a different version of the unit (NTGS50AA): https://www.febo.com/pipermail/time-nuts/2014-November/088332.html

Inside of unit, showing a handwritten callout of "PPS" near the oven, pointing to the via upon which the signal was found

Inside of unit, showing handwritten callouts: arrows indicate vias with the PPS signal including the chosen test point TP13; the arc is a pair of ground points

Inside of unit, showing added coax to bring PPS signal out to front panel and power tapped from C22 for the buffer circuit, shown at top

Schematic of the buffer circuit on the PPS signal, to protect the internal circuits

Front side of buffer circuit on the PPS signal, to protect the internal circuits

Back side of buffer circuit on the PPS signal, to protect the internal circuits

Trace of the signal, 1.00Hz with a negative pulse width of 8 μs and a nominal level of 5VDC

Trace of the PPS, PP2S, and 10MHz signals, showing a difference between pulse edges of 226ns and good alignment with the 10MHz signal

Zoomed trace showing the offset between the 1pps and the pp2s signal

Partial schematic of circuit to inject PPS into COM2 (shared with VFD)

Front side of circuit to inject PPS into COM2 (shared with VFD)

Front panel VFD showing example system status

Antenna location

23:10, 12 March 2016 (12-hours, ish): delta of 239.8mm in latlong, 502.9mm alt

Latitude

42.4538034°N

Longitude

83.1138062°W

Altitude

160.73505694 m

13:40, 27 June 2015 (48-hour site survey)

Latitude

42.4538028°N

Longitude

83.1138090°W

Altitude

161.23804233 m

NTP stratum-1 server

Hostname

harrison.i3detroit.local

IP address

10.13.0.95

Services

• NTP on UDP port 123

LCD Front Panel

Noritake CU24063-Y100 Serial VFD cable

Attach FTDI adapter to MAX232 board to VFD CN2 (1x6 0.1" header)

PC Pin	PC Function	VFD Pin	VFD Function
10	5VDC	1	VCC
5	TXD	2	SIN
9	GND	3	GND
6	CTS	4	SBUSY
NC	NC	5	NC
NC	NC	6	/RESET

Example VFD Text

Generated by the following script, depending on psutil, dateutil, and ntpsec

#!/usr/bin/env python
# ~*~ coding: utf-8 ~*~

import socket
from datetime import datetime
import dateutil.tz
import psutil
import os
import ntp.packet
import ntp.util
import ntp.ntpc
import ntp.version
import ntp.control
import ntp.magic

if __name__ == '__main__':
    # Hostname
    output = '%24s'%(socket.getfqdn())

    # ISO8601 in local time
    output +='|%24s'%(datetime.now(dateutil.tz.tzlocal()).strftime('%Y-%m-%d %H:%M:%S%z'))

    # NTP refclock statistics
    session = ntp.packet.ControlSession()
    session.debug=0
    session.logfp=None
    session.openhost('localhost')
    peers = session.readstat()
    gps = []
    pps = []
    for peer in peers:
        stats = session.readvar(peer.associd,raw=True)
        if stats['refid'][0] == 'PPS':
            pps.append(stats['delay'][1][:5])
            pps.append(stats['offset'][1][:5])
            pps.append(stats['jitter'][1][:5])
            pps = tuple(pps)
        if stats['refid'][0] == 'GPS':
            gps.append(stats['delay'][1][:5])
            gps.append(stats['offset'][1][:5])
            gps.append(stats['jitter'][1][:5])
            gps = tuple(gps)

    output +='|GPS:d% 4s o% 4s j% 4s'%gps
    output +='|PPS:d% 4s o% 4s j% 4s'%pps

    # CPU, RAM, and load average
    cpu = psutil.cpu_percent()
    ram = psutil.virtual_memory().percent
    load = os.getloadavg()[0]
    output +='|CPU%3d%% RAM%3d%% Load%3.2f'%(cpu,ram,load)

    # System temperatures
    temps = psutil.sensors_temperatures()
    sys_t = temps['acpitz'][0].current
    c0_t = temps['coretemp'][0].current
    c1_t = temps['coretemp'][1].current
    output +='|C0+%3.1fC C1+%3.1fC SY+%2dC'%(c0_t,c1_t,sys_t)
    print output.replace('|','\n')

h	a	r	r	i	s	o	n	.	i	3	d	e	t	r	o	i	t	.	l	o	c	a	l
2	0	1	7	-	0	7	-	0	4		0	0	:	5	2	:	2	8	-	4	:	0	0
G	P	S	:	r	3	7	7		o	1	6	.	9	7			j	1	.	2	3	4	5
P	P	S	:	r	3	7	7		o	-	4	2	.	1	2		j	1	.	2	3	4	5
C	P	U			7	%		R	A	M		3	7	%		L	o	a	d	0	.	2	3
C	0	+	5	3	.	0	C		C	1	+	5	6	.	0	C		S	Y	+	4	4	C