NXDN: support full rate (EFR)

EFR vocoder implementation for 4800 S/s rate. DV serial support only

Fixed compilation error

Reverted recent cleanup changes that introduced a compilation error when using serial DV. Fixed the unused variables warning by declaring these variables only if serial DV is used.

HP filter enhancement

HP filter enhancement

Run the high pass filter on the 8 kS/s output from AMBE. It makes it easier to have the -3dB corner at 300 Hz exactly. Moreover it can prevent saturation of the interpolation and LP filter stage in case loud bass audio is present.

NXDN support

NXDN support

Added complete support with voice for NXDN. This has been tested mainly with MMDVM and the 65000 reflector but has also been proved working with some local professional service so it should be fine for all standard NXDN networks.

Debian builds

• dsdcc_1.8.0-1_amd64_xenial.deb Debian package for Intel/AMD 64 bit architecture for Ubuntu 16.04
• dsdcc_1.8.0-1_amd64.deb Debian package for Intel/AMD 64 bit architecture for Ubuntu 18.04

Reverted "Implement DMR negative"

Reverted changes made in v1.7.5 as this breaks normal DMR operation.

Upsampling by 2,3,4,5 with mbelib decoding

Allow upsampling by other integer multiples of 8000 S/s than 6. Thus audio sample rates of 16000, 24000, 32000 and 40000 S/s can be supported in addition of the existing 8000 and 48000 S/s

Implemented DMR negative

v1.7.5

updated Debian changelog

Changed cutoff of audio high pass filter when using mbelib

Changed to a Butterworth filter with 240 Hz @ -3 dB.

Added optional audio high pass filter when using mbelib

Debian builds

• dsdcc_1.7.3-1_amd64.deb Debian package for Intel/AMD 64 bit architecture. Works in Ubuntu 16.04
• dsdcc_1.7.3-1_armhf.deb Debian package for ARM (armv7l) architecture. Intended for Debian Jessie distributions

Activated compiler warnings and made corresponding changes

Activated compiler warnings and made corresponding changes

This might improve stability

Debian builds

• dsdcc_1.7.2-1_amd64.deb Debian package for Intel/AMD 64 bit architecture. Works in Ubuntu 16.04
• dsdcc_1.7.2-1_armhf.deb Debian package for ARM (armv7l) architecture. Intended for Debian Jessie distributions