Hope for a GPS alternative

Yes, you are probably correct. I have never looked at the initial output, and have only looked at the module, and the led, once it has already got a satellite fix.

I suspect the problem with running the module from 5v is the USB to serial converter may be expecting higher level serial signals than the GPS modules is sending when its is set to 5v mode.

Edit: I just checked it by powering up the converter first, and then powering up the GPS module. It sends data straight away, and as you say, initially sends all 9's. The green led does not light.

It then starts to get changing figures, but the led still doesn't light. I am guessing its not a minimum number of satellites or something not up to the minimum requirements.

Then the green led starts blinking, at which point I guess it has a satellite fix.

It only seems to behave this way when its started cold. If I power it up again after its been on recently, it seems to get a fix straight away which is probably the onboard cap retaining power to keep satellite information.

I also tried it at 5v, and my setup works fine on 5v too.

Hmmmmm,

well minicom on the laptop with a fix, (after I remembered to set baud rate to 9600) returns a string of this stuff.

$GNVTG,,T,,M,0.884,N,1.637,K,A*3A
$GNGGA,082509.00,3235.38114,S,11538.51213,E,1,08,1.35,2.4,M,-31.2,M,,*7F
$GNGSA,A,3,07,03,16,22,23,30,,,,,,,2.03,1.35,1.52*1D
$GNGSA,A,3,78,79,,,,,,,,,,,2.03,1.35,1.52*1D
$GPGSV,3,1,09,01,00,013,,03,37,058,35,06,42,265,,07,57,329,30*72
$GPGSV,3,2,09,09,61,200,17,16,19,115,24,22,13,051,21,23,44,128,12*7B
$GPGSV,3,3,09,30,28,325,28*47
$GLGSV,3,1,10,66,08,076,19,67,47,116,23,68,42,202,,69,16,090,*6B
$GLGSV,3,2,10,77,48,133,19,78,61,029,28,79,24,354,21,82,02,325,23*6D
$GLGSV,3,3,10,83,18,279,17,84,12,224,*67
$GNGLL,3235.38114,S,11538.51213,E,082509.00,A,A*6E
$GNRMC,082510.00,A,3235.38121,S,11538.51212,E,0.598,,090518,,,A*79
$GNVTG,,T,,M,0.598,N,1.107,K,A*3E
$GNGGA,082510.00,3235.38121,S,11538.51212,E,1,08,1.35,2.5,M,-31.2,M,,*71
$GNGSA,A,3,07,03,16,22,23,30,,,,,,,2.03,1.35,1.52*1D
$GNGSA,A,3,78,79,,,,,,,,,,,2.03,1.35,1.52*1D

So does this look like data of some sort?

I then installed the converter driver and ucenter on laptop windows. I was hoping to download a ubx file to check the geostationary performance. But for some reason, didn't get a com port like I did on this computer, so couldn't get a connection.

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FormulaNova said..
Yeah, that's NMEA data.

Fantastic, something's happening

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You haven't read the spec???

reading specs is an action of last resort, that only happens when things don't work.

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Why couldn't you get a com port on the laptop? Does it require special drivers for the USB to serial converter? I was hoping that they were that common that windows had drivers built in.

Took me by surprise as well, it was only when I read the specs, I found the instruction to install the driver. Both my Ubuntu installations in PC and laptop have the driver in the kernal. Both my windows 7 installs haven't.

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Device Manager should help as the USB adapter will probably show up under 'com and Lpt ports' as a USB serial adapter.

thanks I'll have a look

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Are you comfortable using u-center to change the GPS settings, or does the scripting do that for you?

I've no idea about it, but playing with it yesterday I thought I saw a button that said save ubx data?

I haven't yet worked out how to even see the config settings let alone edit it. I'm even wondering if the ublox chip can receive instructions.

I'll have another play with it on here, and maybe even read the manual

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decrepit said..

Yes, /etc/rc.local is modified as directed.

Since you get NMEA data on Windows, you know that your cables are correct, and that the serial converter works. You do not need to install any drivers for it on the Pi.

The next thing is to verify that you can get the same data on the Pi with minicom. Below are a few things you can do. Step 1 is essential.

1. Undo the modification in /etc/rc.local ,or comment the line in /etc/rc.local out,or(better yet) comment the entire block labeled
#turn HDMI and WiFi off to reduce energy consumption, ignoring any errors
out (add a # at the start of each line).

2. Get a USB hub. Just about any hub would work. But it's quite possible that a mouse would mount at /dev/ttyUSB0/, so plug in the GPS first. If you did not do step 1, that will turn of WiFi and the TV signal.

3. Plug the TV in before you boot. If the resolution remains too low, Google how to change it. There's a "Settings" or "Preferences" menu, but that won't work if the resolution is really low (the window it opens is too large). There's also the command line to open raspi-config, which should work even with low resolution.

4. The easiest way to control the Pi is by screen sharing through VNC. The current Raspbian version has a VNC server installed, but you need to change the authentication. Also, issues 1. and 3. apply.

5. Look at the scripts to see what they do. They should be easy enough to understand. For example, you'd see that the start_logger script turns WiFi off before starting to log (to increase battery life), and turns it back on when the logging is done (when the dongle is disconnected). It also calls the "logging_done" script, which shuts down the Pi after a 2 minute delay.

Sorry I'm not being clear here. when changing from minicom to ucenter I'm changing operating systems first.
I use ubuntu mate for minicom and windows 7 for ucenter.

And the converter definitely needs a driver, it's manual says so, with instructions how to install it, and once I'd done that I started to get some results with windows. Ubuntu has the driver in the kernal so that's not a problem.

raspberian on pi runs on a different platform to ubuntu on a PC. I doubt the ubuntu driver will work in raspberian, but that may not be the problem.
I think things will become clearer when the dongle arrives, but yes getting a usb hub is probably the next step.

Thanks Pete.
A bit of both, I have a PC and a laptop, both have windows 7 and ubuntu 16.04 separate installations

Initially I was using the PC in here booting between windows and ubuntu. But because of a lack of fix indoors, I used the laptop outside.

Both have identical minicom in ubuntu and ucenter in windows with downloaded converter driver.
Minicom works in both, but only the PC can connect to the converter in windows.

So obviously it would be good to try installing the RXTx libraries in the laptop ubuntu, and see if it will record data. I looked very much like binary to me when I had a fix.

I've now got a usb hub, so I'll have another play with the pi as well

It's a Silicone Labs CP210. I've just found another link telling how to install it with the converter hooked up. I installed it before conecting the converter, so maybe windows doesn't pair them up? So if I get time in the next day or so I'll have another go at the laptop

Pete you were correct Raspbian has the converter drivers in it's kernel.
The USB hub works a treat, so I had everything working with a fix.
Strangely Minicom had vanished, I had to reinstall it. But once that was working I could see NMEA data coming in. but nothing happening in "PiLogger". So I checked your python script and noticed it was looking for " dongle = Path("/dev/ttyACM0")" So I changed to minicom to look for "/dev/ttyACMO" and I got an error message back saying device doesn't exist. So I edited the script, (saving a backup) to USB0 restarted the pi with device plugged in, TV went blank, bit of a worry, no indicators that the Pi is working, except the lights on the converter and GPS module are still on.

So then unplugged the converter, and re-powered the Pi. Zippy Dooo, there's now a .ubx file in PiLogger.

Now I just have to get it into this computer. Thinking if minicom can disappear so can bits of samba, ended up doing a samba purge and reinstall, but I get an error message from the NMB daemon saying it failed to start.

I've installed "vino" on this computer but I can't figure out how to work it yet. There's no sign it's even here, no gui and calling it from the terminal does nothing either, no man files nothing. So I'm back to the mate forum and google.

So I've just checked the Pi, that's using "realvnc", so I tried that here on mate and it's not in the repos.

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decrepit said..
Pete you were correct Raspbian has the converter drivers in it's kernel.
The USB hub works a treat, so I had everything working with a fix.
Strangely Minicom had vanished, I had to reinstall it. But once that was working I could see NMEA data coming in. but nothing happening in "PiLogger". So I checked your python script and noticed it was looking for " dongle = Path("/dev/ttyACM0")" So I changed to minicom to look for "/dev/ttyACMO" and I got an error message back saying device doesn't exist. So I edited the script, (saving a backup) to USB0 restarted the pi with device plugged in, TV went blank, bit of a worry, no indicators that the Pi is working, except the lights on the converter and GPS module are still on.

So then unplugged the converter, and re-powered the Pi. Zippy Dooo, there's now a .ubx file in PiLogger.

Now I just have to get it into this computer. Thinking if minicom can disappear so can bits of samba, ended up doing a samba purge and reinstall, but I get an error message from the NMB daemon saying it failed to start.

I've installed "vino" on this computer but I can't figure out how to work it yet. There's no sign it's even here, no gui and calling it from the terminal does nothing either, no man files nothing. So I'm back to the mate forum and google.

So I've just checked the Pi, that's using "realvnc", so I tried that here on mate and it's not in the repos.

Glad you got to see NMEA data on the Pi, and figured out how to change the script for your converter.

It's theoretically possible that the unreadable .ubx file is due to baud rate issues, although I think it's unlikely. My guess is that the file got damaged when you "transferred" it by email. For example, if one of the programs involved treated it as a text file, that would damage it. I've seen this happen before. If you have not already done so, try compressing the file first, and emailing the compressed file. Gzip or Zip should work.

As for the TV going blank, check the script you edited. There are two lines that turn off the WiFi and the HDMI output to reduce battery use. Just comment them out, battery use is irrelevant right now.

Also, once you disconnected the dongle, wait 3 minutes - the Pi should shut down after 2 minutes (if you commented out the two lines as suggested, you should be able to see the shutdown on the TV screen). If you get SAMBA working again, then you should be able to copy the .ubx file in these two minutes .

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boardsurfr said..
My guess is that the file got damaged when you "transferred" it by email. For example, if one of the programs involved treated it as a text file, that would damage it. I've seen this happen before. If you have not already done so, try compressing the file first, and emailing the compressed file. Gzip or Zip should work.

As for the TV going blank, check the script you edited. There are two lines that turn off the WiFi and the HDMI output to reduce battery use. Just comment them out, battery use is irrelevant right now.

Also, once you disconnected the dongle, wait 3 minutes - the Pi should shut down after 2 minutes (if you commented out the two lines as suggested, you should be able to see the shutdown on the TV screen). If you get SAMBA working again, then you should be able to copy the .ubx file in these two minutes .

Thanks Pete, I hadn't considered that emailing could corrupt, I'll give Gzip a go.
I've had some good help from the Pi forum, but haven't got around to trying the latest advice.

My next question was going to be, is it safe to comment out the WIFI HDMI off script.

Should have further developments tomorrow.

And great work with the display, but I'll be a while before I get there.

A bit of a surprise yesterday: I got some first data with my u-blox 8 + Bluetooth + Android from a test drive, and the data did look quite bad. SDoP much higher, fewer sats, obvious "bad areas" in the speed over multiple seconds. It does seem to be a genuine ublox, I was able to upgrade the firmware to 3.0.1 (and it cost $30), although that's not definitive.

Thinking it might be the bluetooth, I hooked it up over USB and compared it to a ublox7 with a same-sized (25 mm) antenna. The older chip got more satellites, and had lower SDoPs. Strange. Maybe it's a fake ublox chip, after all. The company lists "Weak sensitivity and overall performance" as one of the possible problems with Chinese rip-offs.

Hmmm, now you've got me thinking.

It's not going to be a simple process to approve DIY devices as a group, if some could have bad chips.
It's going to have to be an individual thing.
I hope mine's OK.

I have just updated the firmware in my module to at least check that that was possible and it worked.

I used the instructions at www.rei-labs.net/how-to-update-neo-m8n-firmware/

I guess that doesn't mean its not a knock-off though, as it could just be a better knock-off with flash instead of rom.

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decrepit said..
Just tried zipping and re-emailing, no luck, file still unreadable.

I've just commented out the wifi and monitor shutdown.
watching the file in pilogger it starts as expected, but stops as soon as the GPS starts seeing satellites, just a bit before it gets a fix.

Can I manually start the logger, after the fix?

Now I can see the Pi shutdown after gps disconnection, but it did take longer than I expected. I'll have to remember that when there's no monitor.

Do you know what baud rate the scripting expects? Are there any entries in there that look like a baudrate, i.e. 9600, 38400, or 115200?

Its possible that the USB dongle speed is set differently, and you might need to initially set the baud rate of the GPS module. I would suggest 115200 as its the fastest most common baudrate. You can set that in u-centre by going to the configuration view, and then selecting ports. By default it will have 9600 there, you just change it to 115200 and then hit the 'send' button/icon. It should stop responding as it is now at the wrong baudrate, until you go back into the Receiver/Baudrate menu and then set that to 115200 also.

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decrepit said..
Pete's software is meant to set the baud rate to 9600, which seems to work with minicom.
I haven't got u-center to work yet. windows and I just don't get on.

Really? 9600 is fine for 1hz updates but it won't be anywhere near fast enough for 10hz UBX updates. I wouldn't be surprised if it uses a higher baudrate as 9600 won't be enough.

You can't get u-center to work? Its a piece of cake. As long as you have your serial driver working, it will work fine.