Internal GPS Mod Tech Support/Q&A

[jonwienke]

BTW. The 7805 never gets hot and doesn't need any cooling, so I guess all these GPS pucks use very little current.

30-60mA, depending on the module. The Ladybird uses the least, about 30mA, and the U-Blox-based modules draw about 60mA. The Uniden puck draws about 50mA.

 

[jonwienke]

Since the mod business is picking up, I would like to request that the following information be included on a sheet of paper with scanner(s) sent to me to be modded:

Owner name and address

RR username

Email address and/or phone number to contact if any questions or issues arise.

A brief description of work to be done--which GPS module to install, 436 C1 installation, etc. "GMouse GPS install" is fine, it doesn't need to be a paragraph. If multiple scanners are being sent, please itemize the work to be done to each scanner, and reference the serial number (at least the last 3-4 digits), to ensure the desired mod(s) are made to the correct scanner.

 

[jonwienke]

One other note:

If a 436 scanner is missing C1, I will install it for an additional $5 charge, unless instructed otherwise in advance. I will not install C1 on older boards that do not have the pads for C1--if the scanner is sent in to Uniden for the clock or display repair, the board will be replaced with one that will probably have C1 already installed.

 

[nick223]

I don't have a 436 but curious on what a C1 is and what it does?

 

[jonwienke]

It is a tiny capacitor, .01 microfarads. It eliminates the UHF noise from the battery compartment referenced in this thread:

https://forums.radioreference.com/u...-issues-due-noise-battery-compartment-19.html

 

[jonwienke]

Here are two interesting GPS modules:

RYN25DI 10Hz RS232 interface high performance GPS Glonass antenna module battery | eBay
It outputs RS232 instead of TTL, so the extra MAX3232 conversion chip is not required. It also receives the Russian GLONASS navigation system as well as the American GPS.

BDS GPS Dual-mode Module Flight Control Satellite ATGM336H Replacement NEO-M8N S | eBay
The actual module is even smaller than the Ladybird. Since the antenna is not attached to the module, it may fit inside the 436 without cutting open the back of the case. It outputs TTL, so the MAX3232 or some other TTL-to-RS232 converter is still required. This one also claimes to receive GLONASS and GPS.

I have some of both on order for evaluation.

 

[slicerwizard]

A fuse or a separate current-regulated power supply makes sense, as I noted earlier in post #12. A resistor does not, for the simple reason that a resistor with a large enough value to limit short-circuit current to safe levels would also prevent the GPS from operating properly.

+1.0

 

[jonwienke]

The VCC and GND pads on this side of the rear circuit board make routing the power wiring for the 436 internal GPS mod simpler:

 

[jonwienke]

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

The circuit board is 50mm square, and the patch antenna is 35mm square, so it is too large to put in a 436. 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:

https://1drv.ms/v/s!ApJIS-l4xqPtgt5cHVkJvL2zsI-k2g

The safe is in my basement back in a corner of two cinder block walls, and the GPS module is on a metal shelf inside the safe shoved back as far as it will go. I let it sit there a few minutes before shooting the video to give it every chance to lose satellite lock. But other than raising the CEP from 2 meters to 12 meters, it didn't seem to care. I'm very impressed. The only real-world scenario I can imagine where this module would have satellite reception problems is in a vehicle in a long tunnel.

 

[JamesO]

Your safe also looks like it is a "Fire Proof" safe based on the interior volume or lack of it.

But the the other problem is the safe empty!

I may need to modify/hack my Verzion Network Extender and use a different GPS module because it is located in the core of house and the GPS will loose lock from time to time. A better quality module would make the Network Extender more reliable.

 

[jonwienke]

If you need a GPS that receives reliably in crappy conditions, this module is the clear winner so far.

 

[jonwienke]

And this is what I did with the module. The plexiglass cover and standoffs elevate the GPS antenna above the chassis a bit, and make it easy to see the status LEDs. I'm thinking this configuration will work just fine in a vehicle, since the antenna doesn't need to be on the dash to receive the satellites.

 

[jonwienke]

One other nice thing about u-blox GPS modules (which includes the one above)--there is a full-featured testing, diagnostic, and configuration app that you can download for free:

https://www.u-blox.com/en/product/u-center-windows

You can see EVERYTHING the module is doing, including which satellites are being tracked, a history of the computed location and altitude, power management settings, and much more.

 

[tumegpc]

And this is what I did with the module. The plexiglass cover and standoffs elevate the GPS antenna above the chassis a bit, and make it easy to see the status LEDs. I'm thinking this configuration will work just fine in a vehicle, since the antenna doesn't need to be on the dash to receive the satellites.

Looks pretty darn cool ! Nice work

 

[jonwienke]

Thank you. I'm thinking this is going to be the default/recommended GPS mod for base/mobile scanners with metal cases going forward. The GPS reception is good enough that it will keep satellite lock in pretty much any base or mobile installation, there is no external wiring, and it looks cool. And wiring it up is pretty simple, too--no extra connections for indicator lights.

 

[frazpo]

Port for external module.

Would there be a problem with creating an external GPS module in an enclosure that obtained power from the scanner and data to the scanner through a two pin plug. I realize this defeats the "no cables" approach but that I don't mind, especially if it is just a single cable between the scanner and the module. I am sure they are probably ok but I am still a little hesitant to install this setup internally with such a small time frame of testing so far. This would make it much easier to upgrade and test other modules.

 

[jonwienke]

Which scanner?

You need a minimum 3-pin connection for the GPS: power, ground, and data. I've done what you are describing 2 different ways with the mobile scanners:

1. Connect +5V power to pin 9 of the DB-9 connector on the back of the scanner, then put a DB-9 connector on a Uniden or similar puck, so the puck connects directly to the scanner without the extra wiring going to the 12V plug. (Posts 2-3) This can be done with any GPS module with a RS-232 output, housing and cable, such as https://www.amazon.com/GlobalSat-BR-355S4-GPS-Receiver-Black/dp/B00AMAJFUO or you can construct your own housing and put a module of your choice in it. There are dozens of options on Amazon and eBay for modules and housings if you want to DIY to that level. If you want to be able to easily swap modules for testing purposes, this is definitely the way to go.

2. Get a module with 4 mounting holes, and mount it to the scanner case similar to what I did in post 32. If you get a module with status LEDs on the same side of the circuit board as the antenna, you can eliminate the need for wiring separate status LEDs.

Modding a 436 to accept an external GPS powered by the scanner is possible, but not really practical. The GPS connector is buried under a metal shield soldered to the front board in several places, and removing it without specialized desoldering tools is not advisable. The GPS connector pins are also very closely spaced, and soldering one without bridging multiple pins together with solder would be very difficult.

 

[frazpo]

Which scanner?

Modding a 436 to accept an external GPS powered by the scanner is possible, but not really practical. The GPS connector is buried under a metal shield soldered to the front board in several places, and removing it without specialized desoldering tools is not advisable. The GPS connector pins are also very closely spaced, and soldering one without bridging multiple pins together with solder would be very difficult.

Yes I would be modding the 436.

My thought was building an external case with one of the many GPS modules you mentioned and installing another port in the scanner for the GND, power and data. That way you could simply plug the external home made module setup to the scanner where it would get GND, power and supply data to the scanner.

I did not mean utilizing the existing GPS port. make sense?

 

[jonwienke]

I'd suggest using this connector then:

https://www.amazon.com/Micro-Connector-150mm-Cable-Female/dp/B01DUC1PW6/

I'm not sure where the best egress point would be if you don't use the existing GPS connector.

 

[frazpo]

I would basically just bring the points you tap for the internal setup to the female plug mounted to the case frame. The same setup as your installing internally but just making it into an external module without a need for an external power supply.

thanks for the link to those plugs