Internal GPS Mod Tech Support/Q&A

[jonwienke]

https://1drv.ms/f/s!ApJIS-l4xqPtgu9sYWN21iXx9-H1WA

An updated photo gallery showing the GPS install process in a HP-2.

 

[mancow]

What are you using to cut the holes so neatly?

 

[jonwienke]

A drill press with an X-Y table and digital readouts on the X, Y, and Z axes that measure the table position and cut depth to .01mm, and templates that calculate the dimensions and position of all the holes to match the GPS modules and components.

It's pretty much mandatory, given the minimal margin for error fitting the module into the available space.

 

[mancow]

Like a little milling operation. Nice.

 

[jonwienke]

Basically, yes. Not quite as precise as a real mill, but precise enough for the purpose.

 

[jonwienke]

I've run across a possible issue with the default configuration of the RYN25DI modules. The default configuration setting for position fix output is Auto 2D/3D, but instead of reverting to a 2D fix when there aren't enough satellites to calculate a 3D fix, the module doesn't output any fix at all. So in that situation, the indicator LED will say the unit has a fix, but the fix isn't being output.

The solution seems to be to go to the NAV5 section in the U-Center configuration utility, and change the Dynamic Model to Automotive, and the Fix Mode setting to 2D Only. The module will only output 2-D fixes (no altitude), but will do so whenever the indicator LED shows a satellite lock. The calculated position is less precise, (95% within a 100-meter circle instead of 95% within a 10-meter circle), but you at least get get something even when reception is poor.

 

[N9PBD]

I've run across a possible issue with the default configuration of the RYN25DI modules. The default configuration setting for position fix output is Auto 2D/3D, but instead of reverting to a 2D fix when there aren't enough satellites to calculate a 3D fix, the module doesn't output any fix at all. So in that situation, the indicator LED will say the unit has a fix, but the fix isn't being output.

The solution seems to be to go to the NAV5 section in the U-Center configuration utility, and change the Dynamic Model to Automotive, and the Fix Mode setting to 2D Only. The module will only output 2-D fixes (no altitude), but will do so whenever the indicator LED shows a satellite lock. The calculated position is less precise, (95% within a 100-meter circle instead of 95% within a 10-meter circle), but you at least get get something even when reception is poor.

Jon,
How would we be able to determine if we were or were not getting a fix in this case?
Greg

Sent from my SM-G935P using Tapatalk

 

[jonwienke]

If you have the Uniden factory GPS cable, plug the cable into the GPS port on the scanner and the DB9 end into a RS232 serial adapter. When the internal GPS is running you will be able to see the serial data sent from the GPS to the scanner.

Using the u-blox utility, watch the GPS status when it cold starts, and see if there is a time interval between the status light starting to blink and th No Fix indicator in the utility changing to 2D or 3D. If the GPS is showing green signal reception from 3 or more satellites and No Fix for more than a second or two, then you have the issue. Reconfiguring the module to 2D fix only forces it to output a fix even if it doesn't have enough signals to calculate a 3D fix.

https://www.u-blox.com/en/product/u-center-windows
This is the download page for the GPS utility.

 

[N9PBD]

If you have the Uniden factory GPS cable, plug the cable into the GPS port on the scanner and the DB9 end into a RS232 serial adapter. When the internal GPS is running you will be able to see the serial data sent from the GPS to the scanner.

Using the u-blox utility, watch the GPS status when it cold starts, and see if there is a time interval between the status light starting to blink and th No Fix indicator in the utility changing to 2D or 3D. If the GPS is showing green signal reception from 3 or more satellites and No Fix for more than a second or two, then you have the issue. Reconfiguring the module to 2D fix only forces it to output a fix even if it doesn't have enough signals to calculate a 3D fix.

https://www.u-blox.com/en/product/u-center-windows
This is the download page for the GPS utility.

Thanks

Sent from my SM-G935P using Tapatalk

 

[n9mxq]

Quick question. Is this pinout good for the 996p2 also? I have a GPS puck I would like to power from the scanner, but it needs 5v on pin 4. I don't want to let any of the magic smoke out of my scanner trying to hook it all up ;-)

I finally worked up the guts to try this. Since my 996p2 is out of the truck while I figure out where to put in in the new truck.

Breaking 5v to pin 4 worked fine. No ill effects to the scanner, and the GPS puck I have works fine. I'm using a Byonics GPS-2 (no longer available) that I purchased for APRS.. Works great for the scanner and I didn't have to modify the GPS plug.

 

[jonwienke]

Fixing the problem is more difficult, because you have to take the scanner apart to get to the GPS module. You can't send data to an input that is already connected to another output. You'll need to fabricate a plug to connect to the GPS. It's a 6-pin 1.25mm JST female connector, wired as shown:

https://1drv.ms/u/s!ApJIS-l4xqPtgvB5KzPGDvh_fiAiQQ

Red is +3-5V, white is data to GPS, yellow is data from the GPS, black is ground. Connect yellow to the data in on your RS232 adapter, white to the RS232 adapter data out, black to ground, and red to +3-5V power.

You will need a #1 Phillips screwdriver and a tool to unscrew the ring around the SMA connector, either a dedicated tool or a fine-tipped needle-nose pliers.

Unscrew the 6 screws on the back of the scanner, and gently pull the front faceplate off the scanner. Unplug the connector going to the status LED. Unscrew the 4 screws securing the front circuit board to the rear case. You will have to compress the -terminals in the battery compartment to remove the board, and pop the connector loose on the left side near the middle that joins the front and rear circuit boards. Once you have the front board removed, unplug the two connectors from the GPS power switch. Then unscrew the SMA connector retainer ring, and pull the scroll knob off. The rear circuit board can be removed from the rear case. Now you can access the GPS module plug.

Unplug the connector between the GPS and the rear circuit board, and substitute the connector attached to the RS232 adapter. Fire up the GPS power and the U-Blox utility. CTRL + F9 opens the configuration window.

Click on ITFM, and check the box that says "enable Jamming/Interference Monitor". Set Antenna type to 1-Passive and set Broadband Thershold to 3dB and CW Threshold to 15dB. Click the Send button in the bottom left corner to send the settings to the GPS.

Click on NAV5, and change the Dynamic Model to 4-Automotive, and Fix Mode to 1-2D Only. Leave everything else alone. Click the Send button.

Click on CFG, and select the Save Current Configuration option. Make sure all of the Devices are selected, then click Send.

Verify that the fix mode in the Data panel is showing 2D, and that you can see the Satellite Level History. Click the Receiver - Action - Coldstart menu, and watch the module acquire satellites, paying special attention to the blinking red light on the module and the fix indicator. It should show a 2D fix as soon as the red light starts blinking.

Once you've verified everything is working, disconnect the test plug and reassemble the scanner in reverse order of disassembly. You will probably want to use a strip of masking tape to remove any dust particles from the front of the LCD display and the inner surface of the bezel before putting the front case half back on.

Easy, right?

 

[jonwienke]

I finally worked up the guts to try this. Since my 996p2 is out of the truck while I figure out where to put in in the new truck.

Breaking 5v to pin 4 worked fine. No ill effects to the scanner, and the GPS puck I have works fine. I'm using a Byonics GPS-2 (no longer available) that I purchased for APRS.. Works great for the scanner and I didn't have to modify the GPS plug.

As long as pin 4 wasn't connected to anything else in the scanner, you're good. I assume you checked for voltages and connection to ground first.

 

[n9mxq]

As long as pin 4 wasn't connected to anything else in the scanner, you're good. I assume you checked for voltages and connection to ground first.

Yessir..It's sitting here on my bench running happily..

 

[jonwienke]

Going back to the module configuration thing, the modules seem to revert to the default settings if they are powered off long enough to discharge the backup battery. So it's not worth disassembling the scanner to reconfigure the module, when leaving it off for a few days undoes the changes. And the benefit is marginal, the module commonly receives 8-10 satellites, and the issue only applies when exactly 3 satellites are being received.

 

[smason]

I've just finished some torture testing on this GPS/GLONASS module:
RY636AI USB/UART interface High Performance GPS antenna module | eBay

But the reception it gets is INSANE. Cold boot in the house after opening the package from China took about 15 seconds to get a fix. I have been unable to get it to lose satellite fix in any test I've done so far. This test breaks satellite lock on every other GPS receiver I've tested, but not this beast.

First off, nice work on the GPS mods, looks really good. And kudos for so freely sharing all the info.

Thanks for the heads-up on the RY636AI, what a great sensitive unit!
After reading here, I decided to grab a couple, one for my APRS unit (Tinytrak 4)
Finally got them today, and connected one to the Tinytrak. Almost plug and play but wasn't getting a GPS valid on the Tinytrak. Then remembered it wants 4800 baud, so configured the 636 for 4800, and poof, works great!

 

[jonwienke]

Did you need to convert from TTL to RS232? If so, what chip/converter did you use?

 

[smason]

Did you need to convert from TTL to RS232? If so, what chip/converter did you use?

The version of the Tinytrak I have has a set of pads that can be populated with a header jumpers to select between TTL or RS-232 basically bypassing its internal converter (MAX-202)

 

[dave3825]

Oh well, so much for that. Wanted to do a project with my son. Have a 436, a cable that's usb on one end and uniden gps on the other and had a RYN25DI. And just like Jon says, it locks on sats very quickly.

Long story short, unit is dead. (if you want the long story, pm me)

The RYN25DI is nice because it does not need a converter. Are there any other modules that output rs-232 that do not need a converter? I have a trip is 2 weeks away and anything from over seas will take to long.

Thanks

 

[JamesO]

See if Jon has any of the rechargeable external GPS modules on hand or soon to be finished, He ships quick and this will serve your immediate requirement.

 

[jonwienke]

The RYN25DI is nice because it does not need a converter. Are there any other modules that output rs-232 that do not need a converter? I have a trip is 2 weeks away and anything from over seas will take to long.

The weaknesses of the RYN25DI are static electricity and heat. Pretty much any static discharge hitting the antenna will ruin the unit. And I had one customer fry two modules because he hung his 436 in his car from the heater vent, such that the car heater was blowing directly on the GPS module. I've started putting thick tape on the antenna to insulate it from more static than the paint I was using before.

The Uniden puck and its OEM brother (https://www.amazon.com/dp/B00AMAJFUO/) output RS232 natively, and are available with prime 2-day shipping. But for basic modules, Reyax is pretty much the only game in town with decent price/performance combo.