PSK 31 stands for phase shift keying. The 31 is the bandwidth in Hertz (31.25 Hz to be precise) of the transmitted signal. The mode can be found on all amateur bands but the most popular seems to be on 20 metres at 14.070 Megahertz. An appealing aspect is that high power is not needed or encouraged. I use 40 Watts and a dipole antenna. Here is what is needed to start a digital station:

Have a desktop or laptop computer with at least a 400 MHz Pentium II processor, 256 Megabytes of ram and a sound card. The sound card is probably the most important part because the software you will be using uses the computer's sound card to transmit the necessary tones to send and receive PSK 31 messages.

Find PSK 31 software. There are many freeware programs on the internet. The most popular are DigiPan 2.1; and HamScope. There are payware programs with more modes and features for very little money. For example, there is MixW 2.19 and other software.

Click on a digital mode below to hear a brief sample of the sound these modes make. Hopefully this page will help you identify a mode you've heard (or help me identify ones others have heard!).  Many folks have submitted excellent quality, lengthy files which are no trouble for me to accept, but I do generally drop the sampling rate and length to make them more reasonable to download over a slower line.  The intent here is more for recognition by ear than for signal analysis.  My page focuses on what hams call "Utility" modes or "Utes".  Additional amateur radio mode links are at the bottom of the page.

As used on the BNSF railroad nearly system-wide for vehicle location reporting, detectors, and other statuses.  Also used for the West Texas MesoNet weather sensors on 44.48MHz FM. 9600bd

Heard from a distance, a constant tone.  Last system in North America decommissioned in 2002.  IMTS was the predecessor to the modern cell phone.

This 9600 baud channel is used to tell mobile radios which voice frequency to use. ASTRO is a digital/analog voice trunked radio system.  APCO P25 makes it industry standards compliant for smooth interaction with neighboring systems.

First ROS contact on 500 kHz

On Friday April 30, Graham G0NBD and Gary G4WGT achieved the first contact on 500 kHz using the data mode ROS.
The contact between Graham G0NBD and Gary G4WGT took place on April 30 over a 30 mile path. Initially they used ROS 500/16 mode and then the ROS "eme" mode. During the contact power was reduced from 3 watts output to 30 mW. The antennas were 35ft top loaded whips.
Practical Amateur antennas for this band are very inefficient due to the wavelengths involved. It can require 50+ watts transmitter output just to get 100 mW ERP. Efficient weak signal modes such as ROS can help extend the range that is achieved.
Later in the evening, Jim M0BMU called Graham G0NBD using ROS 500/8 over a distance of 200 miles. they had a 30 minute contact with 100% copy.
Download the latest version of ROS from
http://rosmodem.wordpress.com/

Communication technologies that are specifically designed to improve "live" HF keyboard operation can now be achieved which were previously only theory, too complex, or too costly to implement to be practical. Thanks to the generosity of radio amateurs (hams) with programming knowledge, and to the Internet, new and powerful communications tools are available to all hams. The evolution and wide spread use of the Personal Computer that include a digital sound card for Digital Signal Processing (DSP), is allowing radio amateurs to use these tools to develop new modes of digital communication. The distinguishing features of live HF digital operation today are the use of lower power, compact or indoor antennas and courteous operating techniques. This reverses the trend of several years ago.

 

New ROS modes for 500 kHz band

Two new modes designed for use on the 500 kHz (600m) band have been added to the free ROS Amateur Radio digital data modes software.
In the latest version when you click on "Menu Mode” there are two new ROS MF modes available called: ROS7 MF and ROS1 MF.
The two modes each occupy a bandwidth of just 100 Hz, ROS7 is designed for a "quick" contact whereas ROS1 is a low speed mode for very low power (QRP) working..
Characteristics:
ROS7 MF: 128 characters/minute BW: 100 Hz S/N (2500Hz): -26.7dB
ROS1 MF: 21 characters/minute BW: 100 Hz S/N: (2500Hz): -35.7dB
Download the latest version of ROS from
http://rosmodem.wordpress.com/
To use ROS you just need your radio, a PC and a sound card interface.
Information on sound card Interfacing can be found at
http://www.southgatearc.org/articles/g0ftd/
data_dummy_interface.htm
and
http://www.southgatearc.org/news/september2007/
psk31_soundcard_interface.htm
First ROS contact on 500 kHz
http://www.southgatearc.org/news/may2010/
first_ros_500khz_contact.htm

Craster, the BPSK31 bandwidth is actually 62.5 Hz. the symbol rate is 31.25 baud. This is a common misconception, and was mine when I first used it also. The ITU designation is 63H0G1B.

End of  amateur radio digital mode ROS

It would appear that the latest version of the amateur radio digital mode software ROS may also prove to be its last.
Writing on his website, the software's author Jose Alberto says:
ROS 1.0 (the last)
11 July, 2010 by José Alberto Nieto Ros

Our thanks to Phillip ZL2TZE for spotting the above item

In spite of the author, ROS Modem appears gain in popularity.

ROS mode development definitely continues

It appears that the author of the new amateur radio digital mode software ROS has had a change of heart, and has reversed his earlier decision to discontinue devlopment work on the project.
The GB2RS website reports:

GB2RS are delighted to confirm that the author of ROS has definitely decided to continue development work.
The software's author, Jose Alberto Nieto Ros, told GB2RS that he will be implementing new modes and enhanced facilities.
The most recent development is an auto reporting system linked into the PSK-Reporter system at http://pskreporter.info/pskmap.html.
The latest version of ROS is available for download at http://rosmodem.wordpress.com.

Dear ALL

There is a new hope for you guys in the US !
2 officially us hams have been given permission to operate on a temp. basis on this fascinating mode, in the last couple of weeks. The last one is WF9XJE David Weinshenker - granted 18 Jan 2012

Worth a listen.
I am practically on the air everyday on 30m band ROS mode between 1700 to 2200hrs GMT

regards to all
George
9H1AA

WF9XJD Experimental Station Operating Schedule

The experimental station WF9XJD will be active Thursday, Feb 2 using HF Spread Spectrum and radio amateurs are requested to participate as monitoring stations using the free ROS soundcard software.
Schedule for HF spread spectrum transmisssions:
Note - Dial frequencies.
Date: 02 Feb 2012
Time: 0000Z - 0155Z
Frequencies(MHz): 10.132(primary ), 10.133 (alt #1), and 10.134MHz (alt #3)
Modes: ROS16/500, ROS8/500, ROS4/500
Bandwidth: 0.5 KHz
ROS Version: 6.9.0
Transceiver: Flex 5000A
Transmitter Power: 0.5 to 25 Watts
Date: 02 Feb 2012
Time: 0200Z - 0355Z
Frequencies(MHz): 7055(Primary), 7.039(alt #1), 7044(alt #2), 7115(alt #3)
Modes: ROS 16/500, ROS 8/500, ROS 8/500, ROS16/2000, ROS8/2000, ROS4/2000
Bandwidth: <=2.5 KHz
ROS Version: 6.9.0
Transceiver: Flex 5000A
Transmitter Power: 0.5 to 25 Watts
Date: 02 Feb 2012
Time: 0400Z - 0600Z
Frequencies(MHz): 3.583(Primary), 3.585, 3.595
Modes: ROS16/2000, ROS8/2000, ROS4/2000
Bandwidth: <=2.5 KHz
ROS Version: 6.9.0
Transceiver: Flex 5000A
Transmitter Power: 0.5 to 25 Watts
Activities Planned:
(1) Check frequency occupancy by other services. If occupied, move to alternate #1 frequency. If alternate #1 is occupied move to the alternate #2. Terminate operations if all planned frequencies are occupied.
(2) Test of CW functions - station identification/announcement.
(3) Test of announcement messages via ROS along with CW identification.
(4) Transmissions at incremental power levels. Monitoring stations providing reports. Determine minimum power levels to maintain error free copy.
(5) As time permits, exchange of messages with other stations operating under a Part 5 STA and stations outside US .
Description of WF9XJD’s Operation
The station is operating under an STA granted by the FCC Experimental License Service to experiment with spread spectrum on the HF and VHF bands assign to the Amateur Radio Service(ARS). The control operator of the station is Phil Williams, KA1GMN. The goal of this experiment is to determine if spread spectrum can co-exist with other emission types authorized in the ARS.
The ROS MODEM is one of the spread spectrum modes that will be transmitted during the operation of the station. Depending on the operating frequency, the bandwidth of the ROS MODEM can range from .500 to 2.5KHz. The signal is transmitted much like any other digital mode using a SSB transceiver that is operating upper single sideband (USB). Two model of radios have been authorized:
Flex-Radio Flex 5000A
Yaesu FT-857D
Interference from WF9XJD
One of the stipulations of the the Special Temporary Authorization (STA), is that the station is on the amateur radio frequencies strictly on a secondary basis. This experimental station cannot interfere with any other service. If I am notified of interference, I must cease operations immediately. If you suspect that I am causing interference, please contact me immediately. The first thing I will do is stop transmitting. Please help me mitigate the interference issue by providing date, times, and frequencies of the interference.
You don’t have to gather up these details when you initially suspect that I am causing interference, that can be gathered up later.
Contact Information:
WF9XJD
Phil Williams
ka1gmn@gmail.com
cell: 469.682.5393
How to participate in WF9XJD’s Experimental Operation
Monitoring stations play an important role in this experiment by providing signal reports to the experimental stations. We are looking for a many monitoring station to participate as possible. Monitoring stations will decode and send decode data transmission using the ROS MODEM application. You can download the ROS application here:
http://rosmodem.wordpress.com/
The ROS MODEM application will decode the ROS transmissions and provide detailed signal reports. An example of the decoded text is shown below:
RX8: 18:01 @ 0.0 Hz: CQ CQ de WF9XJD WF9XJD <CRC-OK> -9 dB WF9XJD WF9XJD miles @ 043 14.101 MHz
RX8 - Baud rate used.
18:00 - Time of when signal received and start of decoding.
@ 0.0 Hz - Center frequency error
<CRC-OK> - Signal decode with no errors.
-9 dB - Signal to Noise ratio of decoded signal
@ 43 - Bearing of transmitting station.
14.101 MHz - Dial frequency
The are two methods of forwarding the signal reports to WF9XJD. The first method is to manually send the signal reports to:
wf9xjd@gmail.com
Signal reports can simply be copied from the receive window of the ROS application and e-mailed to wf9xjd@gmail.com . Please ensure that you send the completely decoded transmission:
Correct - RX8: 18:01 @ 0.0 Hz: CQ CQ de WF9XJD WF9XJD <CRC-OK> -9 dB WF9XJD WF9XJD miles @ 043 14.101 Mhz
No so correct - CQ CQ de WF9XJD WF9XJD <CRC-OK>
You may also decode ROS transmissions with errors <BAD-CRC>. These reports are equally important:
RX8: 15:01 @ -23.4 Hz: Cqt | de hIomQCN de IZ2QCN in JN45oq kca
<BAD-CRC> -18 dB 5324 miles @ 043 21.110 Mhz
The second option is to enable automatic forwarding of signal reports to wf9xjd@gmail.com. This feature requires configuration of the ROS application. Details on how to configure this feature is described later is this message under the title, “ROS Automated Signal Reporting”.
Your contribution of signal report will help determine what power levels are necessary for successful decoding the spread spectrum signal.
Thank you for taking the time to participate in this experiment. You contributions are greatly appreciate. Please feel free to send me questions about the operation of WF9XJD that you may have.
73 from Texas,
Phil Williams
Control Operator, WF9XJD
ka1gmn@gmai.com

You can download the ROS v6.9.5 software from
http://rosmodem.wordpress.com/
ROS joins USA experimental spread spectrum tests
http://www.southgatearc.org/news/january2012/
ros_%20joins_usa_experimental_spread_spectrum_tests.htm