Replies to This Discussion

Permalink Reply by Paul Mather on June 5, 2011 at 2:37pm

My GCS will listen for GPRMC. You'll get lat, long, speed, heading and date. I assume you only have 1 directional data from the plane to the ground, right? I can't find a lot of information about the PIXY...does it have an auto-pilot?

 

What did they give you to receive the signal from the plane? Is it an X-Bee or something else? It might be possible if you can do 2-way to send a PMTK command using the File, Heartbeats in my GCS to tell the GPS to send more information (Like GPGGA and GPRMC would be great) then you'd have sats, GPS lock, altitude and HDOP which is about everything you can get from a NMEA GPS.

 

I'd start off simple and download my GCS and try it at all the different baud rates from 4800 up to about 38400.... I doublt it's set any higher than that.

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Permalink Reply by Paul Mather on June 5, 2011 at 2:43pm

According to this http://www8.garmin.com/manuals/GPS18x_TechnicalSpecifications.pdf the Garmin 18 PC defaults to 4800 baud.

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Permalink Reply by Paul Mather on June 5, 2011 at 2:53pm

Another thing to consider is it's really inexpensive to add your own GPS unit if you need more information. Altitude is important in my view and is missing from GPRMC. It appears you can add lots of other NMEA messages to the Garmin GPS datastream, but if the drone has an auto-pilot onboard, you probably don't want to send the wrong messages to it....if it doesn't have an autopilot, then you should be able to enable GPGGA....and GPGLL if you want GPS time too...The 5Hz the 18 PC sends at should be plenty fast.

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Permalink Reply by Jakub on June 6, 2011 at 7:51am

Thank you for your informations,

yes, we have only 1 directional data from the plane to the ground, right. We have modul which keep the height. We can see height above the terain in our ground station becouse we use altimetry modul (based on air preasure). We use X-Bee (see the photo) and rx-tx modem Droids (see foto) but I do not know which type of modem it is. The modem is connected to the X-Bee modul. We use this GPS: http://www.sparkfun.com/products/465 but the seller tell me that the modem can transmit only GPRMC sentence. We have not auto-pilot, only "constant flight level" modul. Our ground station works with Google Earth but I would like to use GCS for visualization speed and azimuth. I have not experience with heartbeat. Can you send me a printscreen with settings for GPRMC?

 

Thanks a lot

Jake

Attachments:

• xbee_S5.jpg, 107 KB
• rx_tx_modem.jpg, 131 KB

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Permalink Reply by Paul Mather on June 6, 2011 at 1:56pm

So what do they give you for the ground? or is that what's in the photo?

 

You should be able to connect your X-Bee to your laptop, you'll need to figure out your COM port (but it will be shown as a selection in my GCS). Select 4800 baud and click connect. That should be all you need. It will start parsing the GPRMC messages. You don't need the heartbeat. Once you get that working we can start working on configuring your GPS to sending GPGGA too....

 

http://code.google.com/p/happykillmore-gcs/downloads/list

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Permalink Reply by Jakub on June 6, 2011 at 11:34pm

you're right. devices in the photo are in the ground station. Ground station is in the photo (see below). But I do not know the name of the core of the station. I think that it is some core from the France. I know the COM port and I can connect the ground station to GCS but I see only 1 % and 0 %, and then 1 % and 0 % etc. (see photo below) google earth works fine (see photo). I do not know why.

Attachments:

• ground_station.jpg, 172 KB
• google_earth.jpg, 328 KB
• GCS.jpg, 79 KB

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Permalink Reply by Jakub on June 6, 2011 at 11:35pm

next two photos

Attachments:

• mini_usb.jpg, 106 KB
• xbee_and_txrx_modem.jpg, 116 KB

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Permalink Reply by Jakub on June 7, 2011 at 12:02am

here is a printscreen from the GCS (command line) I do not know what is this.

Attachments:

• command_line.jpg, 86 KB

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Permalink Reply by Jakub on June 7, 2011 at 12:19am

....and serial data tab.

Attachments:

• serial data.jpg, 85 KB

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Permalink Reply by Jakub on June 7, 2011 at 12:48am

I found a new infromation about rx/tx modem. in the ground station and in the model is this device: http://www.droids.it/cmsvb4/content.php?143-990.001-XBee-Simple-Board

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Permalink Reply by Paul Mather on June 7, 2011 at 4:39am

It looks like a baud rate problem. Try changing the baud rates to 9600 or 19200....

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Permalink Reply by Jakub on June 7, 2011 at 5:47am

Great,thank you very much. The first problem is solved. I see GPRMC sentence. I do not know why but correct baud rate is 38400.But I have new problem. I see GPRMC but I do not see latitude and longitude in the right part of the software (see the photo).
Can you help me?

Attachments:

• GPRMC.jpg, 127 KB

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