New subject: GSM clock GPS txco help

22 May 2013

Hi Will,

Thank you for the good news. Answering to your question, first please
update your UmTRX firmware and host side UHD:
 1. Update your UHD and umtrx_scripts from the git. Build UHD.
 2. Flash attached ZPU firmware to a UmTRX with the following command:
      ./usrp_n2xx_net_burner.py --addr=192.168.10.2 --fw=usrp2p_txrx_uhd.bin
 3. Power cycle UmTRX

Calibrate with GPS:
 1. Take your UmTRX outside to get GPS lock.
 2. When GPS acquires a lock, use 'umtrx_vcxo.py' utility without
parameters to read current VCTCXO DAC value in a loop.
 3. When the value stabilise (couple minutes after GPS acquires the
lock), write this value to EEPROM:
      ./usrp_burn_mb_eeprom --key tcxo-dac --val <YOUR_VAL>
 4. Now i should pickup the value from EEPROM on boot, so GPS is no
required unless you change ambient temperature considerably.

Note, that you should warm up your UmTRX for a while before
calibration, because it depends on the TCXO temperature.

Let me know if something goes wrong - I wasn't able to test
everything, as I don't have my UmTRX with me at the moment.

On Tue, May 21, 2013 at 9:50 PM, Will Hawkins
&lt;hawkinsw(a)opentechinstitute.org&gt; wrote:
...
  Hey Alexander!

 Yesterday we took our umtrx outside to get the GPS lock for calibrating the
 tcxo voltage. There were some good outcomes and bad outcomes:

 The good:
 If you remember correctly, Dan could not associate to the umtrx with his
 Galaxy Nexus. After getting a GPS signal, Dan's phone could associate! So,
 great news.

 The bad:
 We attempted to record the calibrated tcxo dac values and had no luck. We
 booted the umtrx board connected via serial console to my laptop. I was able
 to see the boot messages and other output so I know the console was working.
 Once the board got a GPS lock, I assumed that I would see some tcxo DAC
 values printed to the console. Based on what you said last week, I was going
 to wait until those values stabilized and then use that output to flash into
 the eeprom. Unfortunately I did not see any output on the serial console.
 Then I thought that we could poll the umtrx (using UHD probe) for its tcxo
 dac values. Unfortunately it showed the default (2048) every time.

 Can you tell me what I'm doing wrong?

 Thanks!
 Will

 PS: CC'ing Dan since he's working this with me. 

-- 
Regards,
Alexander Chemeris.
CEO, Fairwaves LLC / ООО УмРадио
http://fairwaves.ru

Re: GSM clock GPS txco help