Small DIY GPS powered by BCD-436HP -- make it yourself!

[ShyFlyer]

I'd be interested perhaps. Not sure on the value though.

 

[ResQguy]

I have a question:

Would there be any interest in a scanner modding service to install a GPS in scanners for those who are not highly skilled with a soldering iron?

If so, any thoughts on the value of such a service?

Yes. I'd be much more likely to pay for this than a provoice upgrade that's for sure.

 

[KC2EIP]

I would be very interested in an internal GPS installation service, and would likely pay anything within reason to someone who could do it quickly and cleanly.

 

[milcom_chaser]

I would be very interested in an internal GPS installation service, and would likely pay anything within reason to someone who could do it quickly and cleanly.

And where on the PC Board do you propose to install it?


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[milcom_chaser]

Here you go:

https://www.adafruit.com/product/79...FGfJF5C9yIcmXmYIkhFrsHJgWXJVAWAyP2RoCAuzw_wcB

-Draws 25ma of current
-9600 baud

You just need a heat gun to tack it on to the PC board. That is, if there is room...

 

[jonwienke]

It doesn't attach directly to the scanner circuit boards. The pads for the power and serial data connections aren't even on the same circuit boards. There's also a second module needed to convert from TTL to RS-232 signal format. There's space in the rear of the scanner case where the GPS module and converter chip can be installed such that the GPS patch antenna is not obstructed by the circuit boards and shielding inside the scanner. Wires need to be run from that location to the pads on the circuit boards for power, ground and serial data.

 

[jonwienke]

This module gets better reception, but requires a cutout in the rear of the scanner case for the antenna, as shown in my avatar. It also draws slightly more power (approximately 30mA vs 20mA for the Ladybird).

https://www.amazon.com/gp/product/B015R62YHI/

 

[milcom_chaser]

It doesn't attach directly to the scanner circuit boards. The pads for the power and serial data connections aren't even on the same circuit boards. There's also a second module needed to convert from TTL to RS-232 signal format. There's space in the rear of the scanner case where the GPS module and converter chip can be installed such that the GPS patch antenna is not obstructed by the circuit boards and shielding inside the scanner. Wires need to be run from that location to the pads on the circuit boards for power, ground and serial data.

You may not need a converter since the voltage swings won't go past 5 volts. That is assuming those solder pads are just straight TTL. RS-232 standard can swing up to 12volts.


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[jonwienke]

TTL and RS-232 use opposite voltage polarity to indicate 1s and 0s, so the converter is necessary. The pad on the board connects to the jack for external RS-232 GPS data.

 

[jonwienke]

And where on the PC Board do you propose to install it?

There are photos in posts 12, 35, and 45 of this thread.

 

[Fidpal]

Would something like this be small enough to fit in the case and have enough db gain to get a good lock inside a truck?

https://www.adafruit.com/product/746

I am not really sure what db gain is good enough for this type of application or what that value really means, something to do with how well it can get a signal?

If that is too big will this stripped down package work?

https://www.adafruit.com/product/790

All i should need to wire up is +3.7v, GND, and RX pad correct?

 

[jonwienke]

The first one is the worst of all worlds--small less sensitive antenna, extra-large circuit board, and twice as expensive as elsewhere.

The second one has the same antenna, but is small enough to install without making a cutout in the case for the antenna. It is available on ebay for about half the price.

All of the commonly-available GPS modules have TTL output, and require a TTL-to-RS232 converter between the GPS and the scanner, such as the MAX3232 module. There are some wiring tricks needed to prevent the MAX3232 from drawing excessive power and frying itself. Read my previous posts in this thread for details.

 

[jonwienke]

RCmall VK16E Gmouse GPS Module SIRF3 Chip Ceramic Antenna TTL Level 9600bps | eBay
Larger antenna, better reception, requires cutout in rear of case for antenna.

GTOP LadyBird 1 GPS Module - PA6H | eBay
The same ultra-compact module sold by Adafruit for twice the money.

http://www.ebay.com/itm/112305146124
RS-232 converter module.

You may be able to find US sellers and get faster shipping at a somewhat higher price.

 

[mancow]

The first one is the worst of all worlds--small less sensitive antenna, extra-large circuit board, and twice as expensive as elsewhere.

The second one has the same antenna, but is small enough to install without making a cutout in the case for the antenna. It is available on ebay for about half the price.

All of the commonly-available GPS modules have TTL output, and require a TTL-to-RS232 converter between the GPS and the scanner, such as the MAX3232 module. There are some wiring tricks needed to prevent the MAX3232 from drawing excessive power and frying itself. Read my previous posts in this thread for details.

Been there, done that.

 

[jonwienke]

Post #93 is the key.

 

[mancow]

Post #93 is the key.

Thanks

 

[blantonl]

I just finished a nice dry run with my Bluetooth GPS setup, and it worked flawlessly. Drove from San Antonio to Georgetown TX back and forth today.

My drive to Montana from San Antonio on Wed is going to be fun with the 436 and no bundle of cables and trying to manage the puck. I'll simply put the GPS puck and bluetooth transmitter in the back of the SUV, and have the 436 in the front with me connected to an external antenna.

What a time to be alive

 

[jonwienke]

Definitely agree with that.

 

[mancow]

Yes, it really does make the whole experience much more enjoyable. Having nothing but the HP, power and antenna as it should be was nice. I drove from KS to FL and KS to OH and back with zero issues. The GPS indicator never varied from steady green.

 

[jonwienke]

I have been playing with my GPS-modded scanner and so far the only way I have been able to break satellite lock is to take it in the basement and put the scanner GPS antenna facing down between two large metal cabinets. Even then, it would only lose lock intermittently--locked for a few seconds, then acquiring for a few seconds, etc.

I haven't been able to break satellite lock in a vehicle yet. But I haven't driven in a skyscraper (or natural) canyon yet. It is possible to disrupt satellite lock, but it doesn't seem like it is possible under anything resembling "normal" scanner usage conditions.

These cheap GPS modules are really quite remarkable technology.