GPS locking using PROGROCK LO synthesisers

[VK2JDS]

Apart from the legendary VK3HZ riglock boards I have been exploring alternate ways of locking the IC910h to a GPS 1pps source.
This week i have been testing a progrock to see if it does what it claims it can. (google progrock)
The 2 i bought do work, one however doesnt like being programmed....but it does respond to 010<enter> and becomes a 10MHz source by reset.
The other one programmed up ok and is now on 30.2MHz which is the frequency of the master oscillator in the ICOM IC910h.
So, lets see if it actually will lock to a 1pps source.
Firstly i tried a garmin gps head (black , model 35) with 1pps enabled, except it produces a one second ttl data burst from the grey wire instead of a nice clean 1pps pulse. The progrock didnt like that.
I hunted around and found a ne555 to use as a one shot to try and clean up the pulse , but struck problems with the old ne555,its not the cmos version. didnt have any. gave up.
Next was the 1pps from the Chinese GPSDO from BG7TBL. These units are really good and work well. search ebay
Mine is still running on the bench now, locking its own internal 10MHz oscillator, and the 1pps is locking the progrock pll as well.
This means you can use a progrock to lock your ICOM IC910h (or other radio with master oscillator within the progrock frequency range like a ft817) and have a 10 MHz source to lock your transverters to as well.
And the combination of the GPSDO and the progrock draws only 350 mA from a 12 volt battery supply, so its perfect for mountaintop field day use on the microwave bands, especially if you are running digital modes.
Getting the BG7TBL GPSDO to run off a 12 volt unregulated battery power source is the subject of another paper i will have to write up.

The point of the exercise is to lock both the radio and the transverters , and this seems to the the most cost effective way.

I listened to the 30.2 MHz signal on the ICOM 746pro as the progrock was locking itself to the 1 pulse per second output of the GPS , and it stepped down in frequency a few hertz at a time until it settled. The process took about half a minute from start to finish. The makers of the progrock claim its faster every time its restarted as the old value is saved.
next job is to check the Phase noise.
73 Dave vk2jds

[VK4ADC]

I did a Google on progrock and got a lot of music results and nothing on synths etc.

The correct web page is at
https://www.qrp-labs.com/progrock.html

"ProgRock - triple GPS-disciplined programmable crystal"

I had envisaged using something similar to frequency lock the IC-7400 shack transceiver plus the IC-706 that I use as a microwave IF but haven't gotten around to it. This article might encourage me to proceed. As a matter of interest, photos of the injection locking idea for the IC-7400 is at http://www.vhfdx.ru/component/option,com...catid,375/ but maybe more generically in this article http://g4hup.com/DFS30/DFS30.html - and make sure you check out G4YTL's article/document.

[VK2JDS]

Hi Doug,
Thanks for finding the link to the correct site.
They seem great and the price is definately right.
I put mine in a small box with plenty of thermal insulating material around it, but a better idea would be to locate a source of 27MHz ocxos and use one of them in the circuit, as it would be less susceptible to fluctuations due to temperature. The thing you dont want is the device to make a frequency increment during a jt65 contact, for example if it was out in the sun on a mountaintop etc.
   

[VK2JDS]

This is a very cheap stand-alone gps module that outputs 1pps. Should be just whats required for the progrock.

<!-- m --><a class="postlink" href="http://www.ebay.com.au/itm/GPS-Module-GPS-Receiver-with-Antenna-SiRF-IV-1PPS-Baud-Rate-4800-/272429645766?hash=item3f6e127fc6:g:TLwAAOSwYHxWOGWy">http://www.ebay.com.au/itm/GPS-Module-G ... SwYHxWOGWy</a><!-- m -->

Will see how it goes whenit arrives.
73 Dave

[VK2JDS]

Further experiments.

Using a Trimble Ace 2 or Ace 3 gps module (cheap from junk sales and ebay, simoco radio pcbs) they have a 1 pulse per second output on pin 6, however this is only 10 microseconds wide , and the progrock wont synch off it. I just tried a few i had here.....
So, a pulse stretcher is required.

The other test was on another garmin head, but it has a 1 pps databurst instead of a clean quartersecond wide pulse. The progrock output frequency was jumping all over the place, like it was electronic music....

The 2 old motorola pcbs refuse to output correct timing, so they are going to the bin.
Tests continue, 73 from the bush

[VK4ADC]

Dave

Just been reading through the JF2 Hardware User Guide and discovered :
"By default, the JF2 module communicates using NMEA at 4800 baud, with the periodic output messages limited to the GGA, GSA and RMC messages at once per second and the GSV message once every five seconds."
That may not be important to you but it would provide Lat/Long info to do conversion to grid square by adding a micro to the module's TX line, useful when FDing.

The ebay listing you linked to shows "1PPS, when GPS module get location, it will output 1PPS signal every 1 second. The signal is active high 100ms pulse" so lets hope that it is correct if you need that wider clock pulse.

You could always use the 1PPS out from one of the other rejected units to trigger a 100-500mS monostable (your pulse stretcher) to lengthen the pulse.

I may even grab one or two myself once I see your next report about them.

[VK2JDS]

Over the last few days I have been working on getting some spectrum analyser shots of the transmit carrier from the IC910 comparing the factory optional internal high stability OCXO with the ProgRock board.
On the back panel near the earth screw i added a panelmount SMA socket and a small toggle switch. The switch turns on and off the dc to the internal OCXO. The SMA couples the external 30.2MHz from the ProgRock via a 680 ohm resistor to the junction of R515 and C515. Rex VK7MO came up with this mod and details can be found on the net.
The ProgRock is using a clean 1 Pulse per Second signal from the chinese GPSDO.

   
This shows the IC910h on transmit into a dummy load at full power through a microwave attenuator using the Internal OCXO

   
This shows the same setup with the external ProgRock connected and the internal IC910h OCXO turned off.

I cant see a difference.... (dont worry about the date and time on the speccy clock, i havent got around to setting it)

[VK2JDS]

Here are 2 photos of the close-in spectrum. Again the carrier looks clean.

   
this photo shows the internal OCXO.


   
This shows the external ProgRock PLL fed with 1PPS from chinese GPSDO

I also examined the 30.2 MHz output of the ProgRock on the speccy and it looked very clean.
Note that the marker dot moved on the second shot, that's due to drift of my spectrum analyser as it hadnt been turned on for long.
Next I will have to try the radio that's got the VK3HZ PLL in it and see what its transmit carrier looks like.

The other thing we should think about is that this thread shouldn't just be for the IC910h, as the ProgRock can be used to GPS lock plenty of other rigs too.

73 Dave vk2jds

[VK2JDS]

VK3HZ equipped IC910h this time. first pic is the pll with 10 MHz fed from the chinese GPSDO.
Second one shows the internal OCXO.
Again very similar.

   

   

73 Dave vk2jds

[VK2JDS]

The tiny 13 dollar GPS module has arrived and I have it connected to the progrock. Its working perfectly.
The 2 leds on the GPS pcb indicate data output and 1 pps output. It only outputs 1 pps when its got lock, so perhaps the led could be extended out to the front panel to indictate when its actually sending 1 pps into the pll.
Using BKTtimesync software the data output of the GPS can be used to timesync your laptop, so its worth putting a db9 on the front panel too.
I ran the setup from a couple of LM regulators, 5 volts for the GPS (maximum) and 8 volts for the pll, but 9 volts would be suitable, and it will then run from 11 to 16 volts for portable use.

73 Dave

[VK7KWB]

This is a very cheap stand-alone gps module that outputs 1pps. Should be just whats required for the progrock.

<!-- m --><a class="postlink" href="http://www.ebay.com.au/itm/GPS-Module-GPS-Receiver-with-Antenna-SiRF-IV-1PPS-Baud-Rate-4800-/272429645766?hash=item3f6e127fc6:g:TLwAAOSwYHxWOGWy">http://www.ebay.com.au/itm/GPS-Module-G ... SwYHxWOGWy</a><!-- m -->

Will see how it goes whenit arrives.
73 Dave

Hi Dave 
the Progrock is a bugger to program and to get accurate for use on IC910H  to lock to a 1296 Mhz frequency for stability using WSJTX  digital modes  .
I have tried for ages,  just too drifty . Disciplined oscillators  just dont make it . The oscillators have to be locked to a 10 Mhz GPS signal .
vk7MO had the right combination   you need a 30.2Mhz signal/crystal /oscillator and  GPS 10Mhz signal  through a system of dividers  down to 200Hz and compare both to output the Lock to the  switched out ic910 oscillator input . I have accomplished   this using VK7MO ( borrowed old PLL ) and my Trimble GPS .

VK7KWB