Search found 53 matches

by UA0LMC
Sat Jan 07, 2023 1:51 pm
Forum: TYT MD-UV380 / UV390 / Retevis RT-3S
Topic: FYI - GPS
Replies: 34
Views: 2556

Re: FYI - GPS

I think the 24 GPS satellites (except the WAAS special purpose ones) fly in all kinds of paths in space and thus no need to orient it toward "north" from the southern hemisphere. It should work globally and thus the namesake. Nope. GPS orbital plane inclination is 55 degrees - so for 40-ish degrees...
by UA0LMC
Mon Jan 02, 2023 5:41 am
Forum: TYT MD-UV380 / UV390 / Retevis RT-3S
Topic: FYI - GPS
Replies: 34
Views: 2556

Re: FYI - GPS

Its a bit of a hack, but if the GPS consumes 8uA, and highest battery voltage is 8.4V when charged, then a 680k from the supply to that pin will give 7.5uA Not sure if the current value is constant enough. But something like 100k+68k divider looks legit. Maybe I'll test it later. The other way is t...
by UA0LMC
Mon Jan 02, 2023 4:05 am
Forum: TYT MD-UV380 / UV390 / Retevis RT-3S
Topic: FYI - GPS
Replies: 34
Views: 2556

Re: FYI - GPS

Which pin is the Backup voltage? I think it would be better if it was possible to fit a small backup battery. Pin 6 (yellow dot on GPSr). And the other yellow dot is +3.3V when the radio is on. I got about 8uA backup current (datasheet claims 10uA typical) - so the same type as CPU RTC backup batte...
by UA0LMC
Sun Jan 01, 2023 11:30 pm
Forum: TYT MD-UV380 / UV390 / Retevis RT-3S
Topic: FYI - GPS
Replies: 34
Views: 2556

Re: FYI - GPS

Now I'm working on the mod to at least keep the almanac until the radio is on. Will write a post about it if/when I finish. There are some PCB design flaws which make it a little harder to do than I thought. DISCLAIMER: this mod requires some fine soldering. I performed this mod and tested it on my...
by UA0LMC
Sun Jan 01, 2023 10:12 pm
Forum: TYT MD-UV380 / UV390 / Retevis RT-3S
Topic: FYI - GPS
Replies: 34
Views: 2556

Re: FYI - GPS

I wonder if it is possible to increase the GPS modem speed a little. Don't know what you're meaning exactly - but the answer is "No". There is no connection between the CPU and GPSr RxD pin - so you can't send any commands to change GPSr settings. Also GPS antenna design is very poor, so I think th...
by UA0LMC
Mon Dec 19, 2022 7:12 pm
Forum: TYT MD-UV380 / UV390 / Retevis RT-3S
Topic: FYI - GPS
Replies: 34
Views: 2556

FYI - GPS

I think the 24 GPS satellites (except the WAAS special purpose ones) fly in all kinds of paths in space and thus no need to orient it toward "north" from the southern hemisphere. It should work globally and thus the namesake. Nope. GPS orbital plane inclination is 55 degrees - so for 40-ish degrees...
by UA0LMC
Mon Dec 19, 2022 6:37 pm
Forum: Off topic
Topic: TYT MD-9600, add GPS later?
Replies: 25
Views: 1498

Re: TYT MD-9600, add GPS later?

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 hav...
by UA0LMC
Fri Dec 16, 2022 11:43 am
Forum: Off topic
Topic: TYT MD-9600, add GPS later?
Replies: 25
Views: 1498

Re: TYT MD-9600, add GPS later?

Thanks Roger for the details. Here are the pin outs on a V2 md9600. Red 3.3V Brown TX from the GPS Black GND Mike As far as I can see, built-in GPS module pin 6 (Vbat) and pin 8 (Vcc) are in parallel with no battery backup - so I expect the problems similar to RT3s, where every GPS on/off cycle cau...
by UA0LMC
Mon Nov 28, 2022 7:06 pm
Forum: TYT MD-UV380 / UV390 / Retevis RT-3S
Topic: ALPHA 2022 11 25
Replies: 11
Views: 1521

Re: ALPHA 2022 11 25

I'm having trouble 😬 testing this facility with the RT3S. On the Bradmeister Network I indicated the Motorola radio, I activated the APRS 60 and GPS, I used the TG GPS: 724999 I activated the TA and SLOT on the Channel I turned on the GPS on the radio and it did not work on the map. Maybe a step-by...
by UA0LMC
Sat Nov 26, 2022 7:59 am
Forum: TYT MD-UV380 / UV390 / Retevis RT-3S
Topic: ALPHA 2022 11 25
Replies: 11
Views: 1521

Re: ALPHA 2022 11 25

That's why I'm asking for a default setting somewhere in the menus, which can be overrided by per-channel setting. Something like DMR ID works now.