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I have been trying to resolve why no packets sent from my circuit built as per documentation could be decoded.
I hooked up an oscilloscope and noticed that the packets being transmitted did not purely consist of the 1.2 & 2.2kHz tones but had a lower frequency tone included at random during the transmission, but with every transmission.

I came across this old reddit post and think it could be related
https://www.reddit.com/r/amateurradio/comments/494467/libaprs_stroller_tracker_how_i_got_it_working/

Once I got the Micromodem schematic and LibAPRS working good with sending packets with the radio I hooked up a Ublox neo-6m GPS module using SoftwareSerial at 9600 baud on port 11 and 12. The GPS worked good and sent serial data that was parsed fine with TinyGPS++. When I hooked in the radio however I could hear the packets sending very slow, like a packet being sent in slow motion over a few seconds in stead of less than a second. They weren’t decoded of course on my other radio. My guess is that there was interference between LibAPRS and SoftwareSerial? I then tried different ports on the Nano without success. After that I tried AltSoftSerial, the difference then was that the sound of the packets was a bit faster but still slow and no packets decoded. In the end I used the hardware serial port RX0 on the Nano and removed SoftwareSerial, now everything works good both GPS and sending packets.

Has anyone else noticed this?

I am using an Arduino Nano clone 328P @ 5V 16MHz

The NMEA conversion routine does not add a leading zero (3 digits always required) if longitude is < 100. This breaks the message and the position will not be decoded by almost all applications, including Yaesu radios, APRSfi and APRSIS.

Hi,

Is there a chance how fix the previous issue with the low rate of aprs? I can not use the HW connection for GPS unit.
Because this problem have to had anyone in past.