[USRP-users] error message from GPSDO

Nowlan, Sean Sean.Nowlan at gtri.gatech.edu
Fri Feb 24 17:52:49 EST 2012


Sorry to resurrect such an old post, but I was recently playing around with the GPSDO and again encountered this error: "no $GPGSA message found".

Looking through the Firefly-1A manual (http://www.jackson-labs.com/assets/uploads/main/firefly_1A_manual.pdf), it doesn't appear that GPGSA is a valid option, so I'm not sure why it was even build into UHD in the first place. Here are the possible queries (p.14/44 of the PDF, labeled p.8):

GPS:SATellite:TRAcking:COUNt?
GPS:SATellite:VISible:COUNt?
GPS:GPGGA <int> [0,255]
GPS:GGASTat <int> [0,255]
GPS:GPRMC <int> [0,255]
GPS:XYZSPeed <int> [0,255]
GPS:POSition?
GPS:RESET ONCE

I also noticed in uhd/host/lib/usrp/gps_ctrl.cpp that you set GPS:GGAST to 0. What's the rationale behind this?

Thanks,
Sean

-----Original Message-----
From: Nick Foster [mailto:nick at ettus.com] 
Sent: Thursday, December 15, 2011 11:43 AM
To: anastas at umich.edu
Cc: Nowlan, Sean; usrp-users at lists.ettus.com
Subject: Re: [USRP-users] error message from GPSDO

That warning is fine, it should just return "false" when GPGGA isn't found. When the device is first started, before it acquires lock, it won't output GPGGA. After lock, it will output GPGGA with a positive lock status, and if it subsequently loses lock it will continue to output GPGGA but with a negative lock status.

It does look like GPGSA isn't being output. I'll look into that.

--n

On Thu, Dec 15, 2011 at 7:43 AM, Achilleas Anastasopoulos <anastas at umich.edu> wrote:
> same here: all other sensors work.
>
> BTW, another point is that every now and then when quering the 
> "gps_locked" sensor and when it is not yet locked I get a warning of 
> the form:
>
> UHD Warning:
>    locked: ValueError: get_nmea(): no $GPGGA message found
>
> Achilleas
>
>
>
> On Wed, Dec 14, 2011 at 3:16 PM, Nowlan, Sean 
> <Sean.Nowlan at gtri.gatech.edu> wrote:
>> Yes,  I could query for GPGGA and GPRMC successfully.
>>
>> Sean
>>
>> -----Original Message-----
>> From: Nick Foster [mailto:nick at ettus.com]
>> Sent: Wednesday, December 14, 2011 2:57 PM
>> To: Nowlan, Sean
>> Cc: anastas at umich.edu; usrp-users at lists.ettus.com
>> Subject: Re: [USRP-users] error message from GPSDO
>>
>> Hmm, I'm enabling GPGSA during init, so it should be output once per second. Are the other GPS sensors working for you?
>>
>> --n
>>
>> On Wed, Dec 14, 2011 at 10:44 AM, Nowlan, Sean <Sean.Nowlan at gtri.gatech.edu> wrote:
>>> I also saw that error message when using a locked GPSDO. Is it a bug in the Jackson Labs chip?
>>>
>>> Sean
>>>
>>> -----Original Message-----
>>> From: usrp-users-bounces at lists.ettus.com
>>> [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of Achilleas 
>>> Anastasopoulos
>>> Sent: Wednesday, December 14, 2011 1:42 PM
>>> To: usrp-users at lists.ettus.com
>>> Subject: [USRP-users] error message from GPSDO
>>>
>>> I am testing the GPSDO on a N200 with the following program using an active GPS antenna.
>>> I successfully lock to the GPS signal as evidenced by the program output.
>>> However I have never gotten a valid gps_gpgsa sensor reading.
>>> (always getting the error message: Error: ValueError: get_nmea(): no $GPGSA message found).
>>>
>>> Is this a GPS issue or a uhd issue?
>>>
>>> thanks
>>> Achilleas
>>>
>>>
>>> ========================================
>>> [anastas at jefe gnuradio_examples]$ ./a.out linux; GNU C++ version 
>>> 4.6.1
>>> 20110908 (Red Hat 4.6.1-9); Boost_104600;
>>> UHD_003.004.000-b433c25
>>>
>>>
>>> Creating the usrp device with: ...
>>>
>>> -- Opening a USRP2/N-Series device...
>>> -- Current recv frame size: 1472 bytes
>>> -- Current send frame size: 1472 bytes
>>> -- Found a Jackson Labs GPS
>>> -- Setting references to the internal GPSDO
>>> -- Initializing time to the internal GPSDO
>>>
>>> Using Device: Single USRP:
>>>  Device: USRP2 / N-Series Device
>>>  Mboard 0: USRP-N200
>>>  RX Channel: 0
>>>    RX DSP: 0
>>>    RX Dboard: A
>>>    RX Subdev: WBX RX v2 + Simple GDB
>>>  TX Channel: 0
>>>    TX DSP: 0
>>>    TX Dboard: A
>>>    TX Subdev: WBX TX v2 + Simple GDB
>>>
>>>
>>> GPS lock status: locked   time ellapsed: 0(sec)
>>>
>>>
>>> GPS lock status: locked
>>>
>>>
>>> UTC time: 2011-Dec-14 18:34:48
>>>
>>>
>>> Local time: 2011-Dec-14 13:34:48
>>>
>>>
>>>  PS_GPGGA:
>>> $GPGGA,183451.00,4217.5059,N,8342.8721,W,1,06,2.5,339.5,M,-34.7,M,,*
>>> 6C
>>>
>>>
>>>  PS_GPRMC:
>>> $GPRMC,183454.00,A,4217.5063,N,8342.8711,W,0.4,72.0,141211,,*2B
>>>
>>> Error: ValueError: get_nmea(): no $GPGSA message found
>>>
>>> _______________________________________________
>>> USRP-users mailing list
>>> USRP-users at lists.ettus.com
>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com




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