Remote Rig Audio over ip - using Zita-NJbridge - "16 bit" verses "24 bit" audio streaming - test and compare audio stream quality between bit rates

Brief test to see how well the ZITA-NJbridge software would do at streaming high quality, extreme QRQ CW, high speed Morse Code audio tones over the LOCAL AREA NETWORK(LAN)(audio OVER ip).  2 tests were done,  one using a "16 bit" digital audio PCM ZITA-stream and another test using a "24 bit" digital audio PCM ZITA-stream.   The ZITA-PCM 24 bit audio stream won the contest by a wide margin, and preserved perfectly, the pure audio spectrum of the original Morse Code audio Spectrum as observed on an Audio Spectrum Analysis software APP called  Spectralissime.

Here is the SPEC AN READOUT of the Zita-NJbridge in 16 bit PCM audio streaming mode, with the original spectrum on the left and the "streamed" audio after going through the ZITA audio OVER ip TUNNEL - on the RIGHT :

and here are the 24 bit ZITA audio OVER ip streaming results...  LEFT is original,  RIGHT is the 24 bit ZITA-streamed 

As you can see,   the 24 bit stream preserves the original SPECTRUM of the QRQ CW tones the best

here are the two commands used on the TRANSMITTER STATION

16 bit -   "zita-j2n --chan 1 --16bit 5001"

here is the command for 24bit (24 bit is default and you don't have to add any extra commands)

24 bit -   "zita-j2n --chan 1 5001"

NOTE:  FLdigi was set to transmit on its QSK mode - RT channel audio output -  a 1khz square wave tone - continuously sending the letter "S" at 200 wpm(to create the most possible edge noise)...this FLdigi "keying" signal, was then used to KEY a different software CPO called the ZamGate CW KEYER.  The ZamGate CW KEYER has a very pure audio spectrum output when keyed at QRQcw;  as you can see from the original SPEC AN pictures shown above(left side of both pics)

Just to compare how well the ZITA-NJBRIDGE does at preserving the original QRQcw Morse Code Audio Spectrum, here are a couple more examples of tests that were also run...both of the AOIP programs, shown below,  still fall short of the excellence of the 24 bit Zita-njbridge PCM AUDIO Stream

Here are the JACKTRIP test results, a similar program to Zita(streaming raw audio PCM DATA over ip), original Morse Code Audio Spectrum on the LEFT,  and the JACKTRIP audio spectrum on the RIGHT

Here is yet another similar program called Gstreamer(which is using OPUS CODEC compression at 128k bit rate 48k sample rate)....the original on the LEFT,  the Gstreamer(OPUS) SPECTRUM READOUT on the right:

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Comment by Chuck aa0hw on March 3, 2018 at 11:43am

Here are some snapshots of the ZAMGATE software CW KEYER MODULE's spectrum analysis, scope CW waveform view and all 4 of the LV2 plugins that make up the ZamGate software CW KEYER's framework:

THIS is a SCOPE view of the ZamGate software CW KEYER's raised cosine wave shape

Here is the AUDIO SPECTRUM ANALYSIS of the ZamGate CW KEYER's cw notes as shown above

Here is the collection of the LV2 PLUGINS that build the ZamGate software CW KEYER(using INGEN)

Comment by Chuck aa0hw on March 6, 2018 at 3:45pm

Here is a FULL DUPLEX Morse Code "audio OVER ip" example that demo'S the audio excellence that is maintained by Zita-NJbridge at "NEAR ZERO" audio latency/delay... 

Using MORSE CODE AUDIO TONES, a full DUPLEX "audio OVER ip" audio loopback tunnel was created between a remote Linux Laptop(Lubuntu 16.04) and a Raspberry PI 2b(Raspbian Jessie) using a FREE "audio OVER ip" software called: "ZITA-NJbridge"

ZITA's default setting is 24 bit audio using uncompressed PCM...
the ZITA "audio OVER ip" system measured to preserve "perfectly", the original audio spectrum and wave shape of the original Morse Code tones transmitted by FLdigi:

Zita can achieve LOW LATENCY...both the LAPTOP and PI were set to use JACK at 48k and 128 buffer frames and 4 this setting, the latency was not can see on the VIDEO, the GREEN SCOPE waveform is the original FLdigi WAVE...and the RED WAVE below is(slightly delayed) is the FLdigi audio after it goes through 2 sections of the ZITA-njbridge....laptop to PI....and back again ...pi to laptop... on the SCOPE is looks like the round trip latency/delay is only 20 milliseconds, which is considered by the PRO MUSIC INDUSTRY to be "NEAR ZERO LATENCY"

Zita-NJbridge provided LOW LATENCY AUDIO - and - purity of preservation of the original audio fidelity.... 5 STARS *****


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