TYT MD-9600, add GPS later?

UA0LMC
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Re: TYT MD-9600, add GPS later?

Post by UA0LMC » Mon Dec 19, 2022 6:37 pm

VK3KYY wrote:
Mon Dec 19, 2022 8:29 am
I had not previously come across 10V RS232.

I have seen 20V RS232 using native voltages, but that was a long time ago..

The problem with the 10V signals from the module I bought was that the signal is inverted as well as being higher voltage.

If it wasn't inverted a simple voltage divider would have fixed the problem.

However 3.3V or 5V signals down a couple of meters of wire seems to be OK
IIRC, RS-232 standard allows logical "1" to be anywhere between -3 and -15...-20 volts, and logical "0" from +3 to +15...+20 volts.

Inverted signal is not a big deal - use a small BJT or MOSFET to invert it once again. One extra part compared to a divider.
Or if you have access to GPSr PCB - you may just remove or bypass the TTL-RS232 level converter. Most likely it's max3232 or similar IC.

ve2wkr
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Location: Silverthorne, Colorado, USA

Re: TYT MD-9600, add GPS later?

Post by ve2wkr » Wed Jan 25, 2023 12:49 am

hi!
So I ordered a GPS Module Ebyte E108-GN02D for about US$6. It has a built-in antenna, and a backup battery all in a 2cm square package.
I installed it in the front of my MD-9600 that had no GPS. I used double-sided installation tape to stick it to the plastic case on the left side of the radio
The antenna is pointing forward toward the display PCB. There is a gap of approximately 5mm between the antenna and the display PCB.
I figured that I would try this installation first and see if it worked.
To my surprise, this setup works 10 times better than the TYT built in GPS!
It acquires from cold start in about 2 minutes. After that it is pretty much instantaneous, as by the time I get into the GPS menu, after power up, it already has a position lock.
It appears to update the position at a higher rate then the H210 GPS module used by TYT. It always maintains 12 satellites lock and reports a position error or 0 m. ( maybe there is a rounding error in the software, and the error is less than 1m )
The installation took 30mins and the wiring is according to the picture in this thread.
To make it clear: the GPS module in internal to the radio and not visible.
Thanks for giving me this idea!
73's
Luca

VK3KYY
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Location: Melbourne, Australia

Re: TYT MD-9600, add GPS later?

Post by VK3KYY » Wed Jan 25, 2023 2:05 am

Thanks

That sounds like a good solution.

Unfortunately, I still have not had time to test the latest external GPS module I ordered from AliExpress ;-( But the previous modules I ordered worked well after I modified them to output the correct voltage signals.

Potentially the module you found may also fit in the UV380/RT-3S, and would work better than the one supplied with the GPS version of the radio

VK3KYY
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Re: TYT MD-9600, add GPS later?

Post by VK3KYY » Wed Feb 08, 2023 10:26 pm

I've now received and tested that eByte branded Chinses GPS module and initially it was very slow to acquire satellites

Very much like the GPS module in my RT3S.

I waited 10 minutes and it had not found any satellites, so I left it powered all night and this morning it had acquired 6 satellites. Then after a few minutes it could only receive 2 satellites.

I'm using it indoors, with the unit next to the window, so it would probably work better if it was outside, but I'd say that it is not as good as come other / larger modules.

However, it is better than the GPS in the RT3S because it has a backup battery on the PCB, so it always does a "warm start" meaning it already has data from the last time it was running and hence will acquire much more quickly.

BTW. The data sheet for the eByte module I bought is here.

https://www.ebyte.com/en/downpdf.aspx?id=1125


I'm not sure if there is room inside the GD-77 case, as this module could potentially be a way to add GPS to the GD-77, albeit, I'm not sure if the MCU/CPU chip has any spare pins which can be used for Serial data

VK3KYY
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Location: Melbourne, Australia

Re: TYT MD-9600, add GPS later?

Post by VK3KYY » Thu Feb 09, 2023 5:18 am

ve7mdt wrote:
Thu Feb 09, 2023 5:12 am
Very nice work, Rogers and others, on this.

Right now the only OpenGD77 compatible radios I have that also has a built in GPSr is the RT3s, but I haven't tested the GPSr function yet as I have been busy lately. (But I will, even knowing that it is rather weak.)

Just ordered a new MD-9600 on Aliexpress w/o GPSr built in. Will see if I will add an external one in the future, depending on the use case.

My other radios have GPSr (non OpenGD77 ones), and I sometimes use it for APRS etc: Anytone 878, 578, all the Motorola ones (talking about that, there is something interesting about Motorola ones: their factory whip antennas have several models, some are labelled as GPS compatible, some aren't. It might mean that Motorola uses the whip antenna to get signal for the GPSr inside (for the HT models, not mobiles, as that use a real ext ant.).

I have some older GPSr units that can output data of NMEA 0183 format in RS-232, that I can always use for this testing, before I buy a newer, smaller device for them.
The firmware has the option to output NMEA to Serial, but you have to remember this, as the CPS wont talk to the radio if its being bombarded with NMEA data

VK3KYY
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Re: TYT MD-9600, add GPS later?

Post by VK3KYY » Sat Feb 11, 2023 10:51 am

I've now tested the "TTL" output, self contained GPS receiver module, which I ordered from Aliexpress

https://www.aliexpress.com/item/1005004470010643.html
GPS_Module.jpg
GPS_Module.jpg (22.47 KiB) Viewed 5118 times
And it works well with my MD9600

One thing to note is that this module is not really waterproof and is at best water resistant

If anyone needs to leave this outdoors permanently, then they would need to peel off the sticky pad under the module, unscrew the 4 screws, remove the base of the module and re-seal it with silicon sealant, before reassembling

I also think its unlikely that the sticky pad on the base of the GPS is actually made by 3D despite having 3M written on it.

None of my 3 x MD9600 radios have internal GPS, and I think even for anyone who does own a MD-9600 which came with GPS fitted... For mobile opertion would be better to disconnect the internal module and fit the cable so that an external module like this one can be used.


Basically any GPS module that outputs NMEA at 9600 baud, at 3.3V TTL levels will work

However a word of warning. The modules I intially bought, were sold as RS232 and had a DB-9 connector on the end of the cables.

These did not work becasue the serial data signal was inverted, and also at a higher voltage than 3.3V (I can't remember the voltage, it may have been 12V or more)

I won't link to the modules that did not work, as this would cause confusion.

So be sure to buy a module that says its TTL output

DF1OG
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Joined: Thu Mar 17, 2022 8:44 am

Re: TYT MD-9600, add GPS later?

Post by DF1OG » Wed Dec 20, 2023 11:58 am

Hi.

I have fitted a E108-GN02D GPS module from EBYTE in my MD-9600. I used JST 1.25mm Connectors to get the opportunity for testing out different modules. The connector is fixed with a drop of epoxy glue. The module was fixed with hot glue. The module works fine and delivers very quick position data. Therefore there really is no need to change the module.

73 de Ingo, DF1OG
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