Q15X25
Encyclopedia
Q15X25 is a communications protocol for sending data over a radio link. It was designed by amateur radio
operator Pawel Jalocha, SP9VRC, to be an open communications standard. Like all amateur radio communications modes, this protocol uses open transmissions which can be received and decoded by anyone with similar equipment. Q15X25 is a form of packet radio
. Anyone can design or adapt the open-source software
to develop their own Q15X25 system.
Q15X25 is a digital signal processor
-intensive mode
designed to pass AX.25
packets on HF with speed and reliability much greater than traditional HF ARQ
modems. It uses 15 QPSK modulated carriers separated by 125 hertz, each modulated at 83.333 baud. Q15X25 uses forward error correction
(FEC), and like MT63
, uses time- and frequency-interleaving in order to avoid most error sources. The raw transmission data rate is typically 2500 bit/s.
Typically the DSP based receiver and transmitter modulator or codec is implemented as PC software that uses a sound card to connect directly to an SSB transceiver. Linux implementations are usually called "newpsk" or "newqpsk". MixW ( http://www.mixw.net/ ), a multipurpose communications control and digital modes package on Windows can implement Kiss and/or "TCP/IP over X.25" on either traditional 300 baud, 1200 baud and 2400 baud FSK packet "modems" implemented as DSP via sound card or over Q15X25. The "FlexNet" Windows packet software also has a newqpsk / Q15X25 option.
Anyone can listen/decode Q15X25 transmissions, but a license is required for transmission. It can be used by Radio Amateurs (Hams or in Ireland "Wireless Experimenters") to interconnect local VHF AX.25 packet networks over transcontinental distances.
Frequencies (all USB) in use are:
80 m 3585 kHz
40 m 7035 kHz
20 m 14109 kHz(MixW center about 1350 Hz higher)
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
operator Pawel Jalocha, SP9VRC, to be an open communications standard. Like all amateur radio communications modes, this protocol uses open transmissions which can be received and decoded by anyone with similar equipment. Q15X25 is a form of packet radio
Packet radio
Packet radio is a form of packet switching technology used to transmit digital data via radio or wireless communications links. It uses the same concepts of data transmission via Datagram that are fundamental to communications via the Internet, as opposed to the older techniques used by dedicated...
. Anyone can design or adapt the open-source software
Open-source software
Open-source software is computer software that is available in source code form: the source code and certain other rights normally reserved for copyright holders are provided under a software license that permits users to study, change, improve and at times also to distribute the software.Open...
to develop their own Q15X25 system.
Q15X25 is a digital signal processor
Digital signal processor
A digital signal processor is a specialized microprocessor with an architecture optimized for the fast operational needs of digital signal processing.-Typical characteristics:...
-intensive mode
designed to pass AX.25
AX.25
AX.25 is a data link layer protocol derived from the X.25 protocol suite and designed for use by amateur radio operators. It is used extensively on amateur packet radio networks....
packets on HF with speed and reliability much greater than traditional HF ARQ
ARQ
Automatic Repeat reQuest , also known as Automatic Repeat Query, is an error-control method for data transmission that uses acknowledgements and timeouts to achieve reliable data...
modems. It uses 15 QPSK modulated carriers separated by 125 hertz, each modulated at 83.333 baud. Q15X25 uses forward error correction
Forward error correction
In telecommunication, information theory, and coding theory, forward error correction or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels....
(FEC), and like MT63
MT63
MT63 is a digital radio modulation mode for transmission in high-noise situations developed by Pawel Jalocha SP9VRC. MT63 is designed for keyboard-to-keyboard conversation modes, on HF HAM bands.- Features and Attributes :...
, uses time- and frequency-interleaving in order to avoid most error sources. The raw transmission data rate is typically 2500 bit/s.
Typically the DSP based receiver and transmitter modulator or codec is implemented as PC software that uses a sound card to connect directly to an SSB transceiver. Linux implementations are usually called "newpsk" or "newqpsk". MixW ( http://www.mixw.net/ ), a multipurpose communications control and digital modes package on Windows can implement Kiss and/or "TCP/IP over X.25" on either traditional 300 baud, 1200 baud and 2400 baud FSK packet "modems" implemented as DSP via sound card or over Q15X25. The "FlexNet" Windows packet software also has a newqpsk / Q15X25 option.
Anyone can listen/decode Q15X25 transmissions, but a license is required for transmission. It can be used by Radio Amateurs (Hams or in Ireland "Wireless Experimenters") to interconnect local VHF AX.25 packet networks over transcontinental distances.
Frequencies (all USB) in use are:
80 m 3585 kHz
40 m 7035 kHz
20 m 14109 kHz(MixW center about 1350 Hz higher)
See also
- radioteletypeRadioteletypeRadioteletype is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations, later superseded by personal computers running software to emulate teleprinters, connected by radio rather than a wired link.The term radioteletype is used to...
- shortwaveShortwaveShortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...
- ARRL description of Q15X25
- Description of Q15X25 from Murray Greenman