NEW Symmetricom TrueTime XL-AK w PPO GPS Disciplined TCXO Oscillator 1PPS IRIG-B

NEW OLD STOCK • Tested/Guaranteed • F26 Programmable Pulse Option Installed • TCXO Oscillator • GPSDO • Test Antenna & New Rack Ears Included • 1PPS • IRIG-B

Photos show the actual item for sale

An unused (new old stock, open box, plain packaging) XL-AK GPS Disciplined Clock/Frequency/Pulse Generator with a TCXO oscillator installed. The usual factory supplied accessory pack is included and this includes a short serial cable and a set of rack ears. In addition, this unit reports via F26 that it has the Programmable Pulse Output (PPO) software option installed. I don't see a rear panel jack for the PPO signal so this untested feature may require that to be installed (no additional documentation on this other than the manual is available). This version does not have a keyboard or LCD display so control is via the RS-232 port. This is set to 9600-7-E-1 and needs a Null Modem cable. The output from the console port obtained during testing is copied below. As you can see the unit achieves GPS lock and provides the correct time and date. The internal 3.6V Lithium memory back up battery has just been replaced with a fresh cell and a 1/2 AA cell holder installed to allow easy battery changeover in 7-10 years time when replacement is due. The photos show the actual item for sale. Full product details may be found in the User Manual at https://www.prostudioconnection.net/1311/XL-AK_Manual.pdf. A basic puck antenna is included to allow you to test the unit immediately upon receipt. For a permanent installation and accurate time/frequency generation a professional grade outdoor antenna with a clear view of the sky will be required. I can provide a recommendation if required - the antenna voltage is 5V so almost any professional grade outdoor antenna can be used.

Description

The rack-mount XL-AK GPS receiver provides ultra-precise time and frequency. This configurable instrument provides timing outputs to within 40 nanoseconds rms of UTC/USNO and frequency outputs accurate to less than 1x10-12, even when tracking satellites with Selective Availability (SA) implemented. User-configurable outputs provide significant flexibility in configuring the XL-AK as a central source for IRIG time codes or output pulses.

PPO Feature Description - SERIAL FUNCTION F26 - PROGRAMMABLE PULSE OUTPUT

The Programmable Pulse Output (PPO) is a standard output if the 86-690 “L" board is installed. If the 86-690 “L" board is installed, refer to manual section V for output specifications. Use Serial function F26 to enter or request the parameters for the Programmable Pulse Output, with resolution down to one millisecond.

To set the Programmable Pulse Output parameters, send a string to the Serial port in this format:

F26<SEP><START TIME><SEP><STOP TIME><CR><LF>
where:

F = ASCII character F.
26 = function number.
<SEP> = one or more separator characters: either space, comma or tab.
<START TIME> = time to start the pulse, formatted like:
<DAY>:<HOURS>:<MIN>:<SEC>.<MSEC>
<STOP TIME> = time to stop the pulse, formatted like:
<DAY>:<HOURS>:<MIN>:<SEC>.<MSEC>
<CR> = ASCII Carriage Return character (HEX 0D).
<LF> = ASCII Line Feed character (HEX 0A).
<DAY> = 3-digit day of year.
: = ASCII colon character.
<HOURS> = 2-digit hours, in 24 hour form.
<MIN> = 2-digit minutes.
<SEC> = 2-digit seconds.
. = ASCII decimal point character.
<MSEC> = 3-digit millisecond.

Sending F26 by itself will return the current Programmable Pulse Output time setting.

Sample request: F26<CR>
Response: F26 123:18:33:23.324 124:23:32:43.321<CR><LF>

The user can specify both a Start Time and a Stop Time, in which case the rising edge will occur at the Start Time, and the falling edge will occur at the Stop Time. The times specified are compared with local time, which is UTC adjusted by the local offset. Leading zeros are required.

Sample entry: F26 001:00:00:00.000 002:00:00:00.000<CR>

Response: OK<CR><LF>

This will produce a 1 day pulse on January 1.

Invalid times are rejected with the error message:
ERROR 02 SYNTAX

The user may place an 'X' in any digit position, in which case the Start Time (or Stop Time) will be any time that matches the non-'X' digits. This can be used to produce repetitive pulses from once per year up to 100 per second.
Sample entry: F26 XXX:XX:X0:00.000 XXX:XX:X1:00.000<CR>

Response: OK<CR><LF>

This will emit a 1 minute pulse every 10 minutes, aligned with multiples of 10 minutes. If only the Start Time is specified, a 1 millisecond pulse is generated with the rising edge starting at that time

Sample entry: F26 XXX:XX:30:00.000<CR>
Response: OK<CR><LF>

This will generate a 1 millisecond pulse on the half hour.

Either the Start Time or the Stop Time may be replaced with a semicolon, in which case that item will be unchanged by the command.
Sample entry: F26 ; XXX:XX:10:00.000<CR>
Response: OK<CR><LF>

This will leave the Start Time set to whatever it was before, and will change the Stop Time to 10 minutes after the hour. If both the Start Time and the Stop Time match the current time, then the pulse is turned off.

Sample entry: F26 XXX:XX:XX:XX.2XX XXX:XX:XX:XX.XXX<CR>
Response: OK<CR><LF>
The pulse would normally be turned on every second at 200 milliseconds, but the Stop Time also matches then, so the pulse will stay off.
To clear the output regardless of the time: F26 000:00:00:00.000 XXX:XX:XX:XX.XXX
To set the output regardless of the time: F26 XXX:XX:XX:XX.XXX 000:00:00:00.000
The default power-on Pulse Out setting is: F26 000:00:00:00.00 000:00:00:00.000
Since the day is day 000, the Start and Stop times never match.
When the power is turned off, the current setting is saved in non-volatile memory, to be restored when it is next turned on.

Console Port Output