Q15X25

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Q15X25
Q15X25 2400.jpg
Frequencies 3.585 MHz,7.035 MHz,14.109 MHz
Frequency Range 3.585 MHz - 14.109 MHz
Mode USB
Modulation PSK,OFDM
ACF
Bandwidth 1.95 kHz,2.35 kHz
Location Worldwide
Short Description Q15X25, also known as NEWQPSK, is an experimental amateur radio packet modem developed by Pawel Jalocha SP9VRC. Q15X25 is a OFDM QPSK implementation of the AX.25 Packet protocol used in PACKET.
I/Q Raw Recording
Audio Sample

Q15X25, also known as NEWQPSK, is an experimental amateur radio packet modem developed by Pawel Jalocha SP9VRC. Q15X25 is an OFDMOrthogonal Frequency-Division Multiplexing QPSKQuadrature Phase-Shift Keying (2 bits per symbol) implementation of the AX.25 Packet protocol used in PACKET. Q15X25 uses ARQAutomatic Repeat reQuestAutomatic Repeat Query and FECForward Error Correction and performs just like a packet radio terminal.


Characteristics[edit]

Q15X25 uses 15 QPSKQuadrature Phase-Shift Keying (2 bits per symbol) subcarriers to transmit AX.25 data packets at between 1000 bpsBits per second (bps) to 5000 bpsBits per second (bps). The original mode is set for 2500 bpsBits per second (bps) with an additional mode for 3000 bpsBits per second (bps).


Q15X25
Original 8000 Sample Rate Mode Modified 9600 Sample Rate Mode
Data Rate: 2500 bpsBits per second (bps) Data Rate: 3000 bpsBits per second (bps)
Carrier Spacing: 125 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). Carrier Spacing: 150 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
83.33 BaudBaud (unit symbol Bd) is the unit for symbol rate or modulation rate in symbols per second. 100 BaudBaud (unit symbol Bd) is the unit for symbol rate or modulation rate in symbols per second.
~1950 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). Bandwidth ~2350 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). Bandwidth


Q15X25 is adjusted by five configuration parameters: bpsBits per second (bps), interleaving depth, FECForward Error Correction level, tune length, and sync length.

4 FECForward Error Correction modes are supported with Q15X25:

Original 2500 bpsBits per second (bps) | Modified 3000 bpsBits per second (bps)

  • no FECForward Error Correction: 2500 bpsBits per second (bps) | 3000 bpsBits per second (bps) User Data Rate
  • Simple (11/15) FECForward Error Correction: 1833.3 bpsBits per second (bps) | 2200 bpsBits per second (bps) User Data Rate
  • BCH (7/15) FECForward Error Correction: 1166.7 bpsBits per second (bps) | 1400 bpsBits per second (bps) User Data Rate
  • Walsh (5/15) FECForward Error Correction: 833.3 bpsBits per second (bps) | 1000 bpsBits per second (bps) User Data Rate

Samples[edit]

2500 bpsBits per second (bps) 3000 bpsBits per second (bps)
Q15X25 2400.jpg
Q15X25 3000.jpg

Frequencies[edit]

  • 80m: 3585 kHzKiloHertz (kHz) 10^3 Hz
  • 40m: 7035 kHzKiloHertz (kHz) 10^3 Hz
  • 20m: 14109 kHzKiloHertz (kHz) 10^3 Hz

Decoding Software[edit]

Hobby Level Software


Video Examples[edit]

Additional Links[edit]


Additional Images[edit]