== RTTY FSK ==

=== the FSK connection ===

When transmitting RTTY using FSK, the transceiver generates a Mark frequency or a Space frequency in response to an external signal. Transceivers capable of [[AFSKFSK|FSK]] operation generally provide a [[http://en.wikipedia.org/wiki/Transistor–transistor_logic|TTL]] input (voltage levels +5 VDC, 0 VDC) that controls the frequency generation:

 ||'''Transceiver '''||'''FSK Mode Name'''||'''FSK Input Signal (connector & pin)'''||'''FSK Input Signal Mark Voltage * '''||'''FSK Input Signal Space Voltage *'''||
 ||Elecraft K3||FSK D||FSK IN (ACC pin 1)||0 VDC||+5 VDC||
 ||Icom||RTTY||RTTY (ACC-1 pin 1) *||*||*||
 ||Kenwood TS-590||FSK||RTTY (ACC2 pin 2)||+5 VDC||0 VDC||
 ||Kenwood TS-990||FSK||RTTY (ACC2 pin 2)||+5 VDC||0 VDC||
 ||Kenwood TS-2000||FSK||RTTY (ACC2 pin 2)||+5 VDC||0 VDC||
 ||!TenTec Omni-VII||FSK||MARK/SPACE (ACC 1 pin 5)||+5 VDC||0 VDC||
 ||!TenTec Orion II||FSK||MARK/SPACE (I/O pin 8)||+5 VDC||0 VDC||
 ||Yaesu FT-450||RTTY||FSK IN (DATA pin 4)||+5 VDC||0 VDC||
 ||Yaesu FT-950||RTTY||FSK IN (RTTY/PKT pin 4)||+5 VDC||0 VDC||
 ||Yaesu FT-1000MP MARK-V||RTTY||SHIFT (RTTY pin 1)||+5 VDC||0 VDC||
 ||Yaesu FT-2000||RTTY||SHIFT (RTTY pin 1)||+5 VDC||0 VDC||
 ||Yaesu FTDX-101||RTTY||SHIFT (RTTY/DATA pin 4)||+5 VDC||0 VDC||
 ||Yaesu FTDX-1200||RTTY||FSK IN (RTTY/DATA pin 4)||+5 VDC||0 VDC||
 ||Yaesu FTDX-3000||RTTY||FSK IN (RTTY/PKT pin 4)||+5 VDC||0 VDC||
 ||Yaesu FTDX-5000||RTTY||SHIFT (RTTY pin 1)||+5 VDC||0 VDC||
 ||Yaesu FTDX-9000||RTTY||SHIFT (RTTY pin 4)||+5 VDC||0 VDC||
 
* Notes:

 1. By convention, amateur RTTY uses the lower sideband, with the Mark frequency 170 hz higher than the Space frequency.

 1. Icom transceivers

    a. some Icom transceivers transmit the Mark frequency when the '''FSK Input Signal''' is set +0 VDC, but other models transmit the Space frequency when the '''FSK Input Signal''' is set to 0 VDC

    a. Icom transceivers provide a separate connector for the '''FSK Input Signal'''

    a. the IC-7100, IC-7610, IC-7851, IC-9100 drivers create two virtual serial ports: one virtual port is used for [[ConnectingIcom72007600|transceiver control]], and the other virtual port can convey the FSK signal via a second virtual serial port's '''RTS''' or '''DTR''' signal

       * [[ConnectingIcom72007600|virtual serial ports for transceiver control and FSK generation]] are only created if the transceiver is connected to your computer via a standard USB A-B cable

       * to determine which virtual port is which, see section 3 of Icom's [[https://www.icomjapan.com/support/manual/2574/|Tips for the USB Port Settings]] manual

       * the transceiver provides a menu item that determines whether the virtual port's '''RTS''' or '''DTR''' signal is used to convey the FSK signal

    a. the IC-7300 and IC-705 drivers create a single virtual serial port for [[ConnectingIcom72007600|transceiver control]] whose '''RTS''' or '''DTR''' signal can be configured to convey the FSK signal via the radio's '''USB Keying (RTTY)''' menu; if this port is being used by Commander for transceiver control, however, its '''RTS''' or '''DTR''' signal cannot be used as the FSK connection '''unless''' you 
       * employ a [[http://www.cedrickjohnson.com/2017/03/icom-ic-7300-usb-for-radio-control-fsk-keying/|serial port splitter]] that creates a virtual port X for transceiver control and a virtual port Y for '''RTS''' or '''DTR''' control, both of which interact with your IC-7300's virtual serial port
       * configure Commander to use virtual serial port X
       * configure !WinWarbler to use virtual serial port Y for FSK control in step 7a in the '''Configuring !WinWarbler for FSK operation''' section below



 1. In most transceivers, the '''FSK Input Signal''' input is connected to a "pull up" resistor connected to +5 VDC. An NPN transistor, opto-isolator, or open-collector logic gate can thus be used to pull the '''FSK Input Signal''' down to 0 VDC, as is shown in the examples below.

 1. Some transceivers provide a menu setting or internal switch that reverses the meaning of the '''FSK Input Signal''' voltage. Alternatively, you can reverse the meaning of the '''FSK Input Signal''' voltage by checking the '''Inv. FSK''' box on the '''EXTFSK''' or '''EXTFSK64''' window (accessible via the Windows Task Bar when !WinWarbler is configured to transmit RTTY via the MMTTY engine in FSK).

!WinWarbler can be configured to generate the '''FSK Input Signal''' on the [[PTTMechanism|PTT serial port's]] TxD pin,  or on the TxD, RTS, or DTR pin of any available serial port. All of these pins employ [[http://en.wikipedia.org/wiki/Rs232|RS-232]] voltage levels (+12 VDC, -12 VDC), so an external level converter is required:

  * a [[http://www.dxlabsuite.com/Wiki/Graphics/WinWarbler/FSK-Opto.jpg|simple opto-isolator circuit]]

  * a [[http://www.dxlabsuite.com/Wiki/Graphics/WinWarbler/FSK-NPN.jpg|simple NPN transistor circuit]]

  * a [[http://www.aa5au.com/fskinterface_ts930.gif|simple PNP transistor circuit]] for the Kenwood TS-930 and TS-940

  * a [[http://www.aa5au.com/fskinterface_omni.gif|series resistor]] for the !TenTec Omni V, VI, and VI+

  * [[https://hamprojects.info/mortty/|MORTTY]] - a CW and RTTY interface

  * a [[http://www.k7sfn.com/projects/signalink.html|modified Signalink USB interface]]

  * a [[http://www.aa5au.com/k5ww/fsk.htm|modified Rigblaster Nomic interface]]

  * a section of a commercial interface ([[Win7VistaHardware|Interfaces known to work with 32-bit and 64-bit flavors of Windows 7 and Vista]]); if your interface is a[[http://usinterface.com|Navigator]]: see the document entitled '''Winwarbler RTTY Setup.pdf ''' in this [[http://groups.yahoo.com/group/NAVIGATOR-Interface/files|Yahoo group Files area]]

  * [[https://www.kkn.net/~n6tv/N6TV_Dayton_2019_Everything_USB.pdf|Everything You Need to Know About USB and Serial Interfaces de N6TV]]

=== Configuring WinWarbler for FSK operation ===

!WinWarbler can be configured to generate the FSK signal on the TxD, RTS, or DTR pins of any available serial port. If you are using a USB-to-serial-port adapter and will be configuring !WinWarbler to generate the FSK signal on the TxD pin, then this USB-to-serial-port adapter must support 5-bit operation at 45 baud, and you must configure the MMTTY engine to transmit characters at a rate that the USB-to-serial-port adapter can handle:

   1. set the '''Main''' window's '''Operating Mode''' panel is set to '''RTTY'''

   1. on the '''Configuration''' window's '''RTTY''' tab,  

      a. check the '''Enabled''' box

      a. in the '''Modulation and transceiver mode''' panel's '''FSK''' sub-panel
         * select ''LSB''
         * set the '''LSB Xcvr Mode''' selector to ''RTTY''
         * set the '''LSB Mark Offset''' to ''-2125''
         * set the '''Optimal Offset''' to ''2210''
         * set the '''FSK Control''' selector to ''ExtFSK'' (if running on a 32-bit flavor of Windows) or ''ExtFSK64'' (if running on a 64-bit flavor of Windows

      a. click the '''MMTTY Setup''' button

   1. on the '''MMTTY Setup''' window's '''Misc''' tab

      a. set the '''Tx port''' panel to '''COM-TxD (FSK)'''

      a. click the '''USB Port''' button

   1. in the '''USB Port Option''' window, select the '''C: Limiting Speed''' option and click the '''OK''' button to close the window

   1. close the '''MMTTY Setup''' window by click the '''OK''' button in its lower-right corner

   1. Set the  '''Main''' window's '''Operating Mode''' panel to '''RTTY''' with the '''Enabled''' box checked on the '''Configuration''' window's '''RTTY''' tab;  an '''EXTFSK''' icon will appear in the '''Windows Task Bar''' along the bottom of your monitor (it may be included in the RTTY icon already present there, in which case you must click the RTTY icon to gain access to the EXTFSK icon). 

   1. Click the '''EXTFSK''' icon in the '''Windows Task Bar''' to open the '''EXTFSK''' window; in this window,

     a. set the '''Port''' selector to the desired serial port

     a. set the '''FSK output''' panel to ''TxD'', ''RTS'', or ''DTR'' - whichever is being used to control Mark/Space frequency switching (if using a USB-to-serial-port adaptor that doesn't support 5-bit operation at 45 baud, choose ''RTS'' or ''DTR'')

The '''EXTFSK''' icon will appear in the '''Windows Task Bar''' whenever you operate in soundcard RTTY mode, but it will remember the settings you've established, so subsequently opening the '''ESTFSK''' window is unnecessary.

To use the [[PTTMechanism|PTT serial port's]] TxD pin to control Mark/Space frequency switching, open the '''Configuration''' window's '''PTT''' tab and note the serial port selected in the '''PTT''' panel's '''Port''' tab. Select the Configuration window's '''RTTY''' tab, and in the '''Modulation and transceiver mode''' panel's '''FSK''' section, 

 * click the '''LSB''' button

 * set the '''FSK Control''' selector to the same serial port selected in '''Port''' panel on the '''Configuration''' window's '''PTT''' tab

If necessary, you can [[ChangeAdaptorCOMPort| change the COM port number that Windows assigns to a USB-to-serial-port adaptor]].


=== Debugging ===

When a transceiver is configured to transmit RTTY via FSK, its transmitter sends either '''Mark''' or '''Space''' tone as dictated by the voltage level of a single input, variously named '''FSK IN''' or '''RTTY''' or '''MARK/SPACE''' or '''SHIFT'''. Directing !WinWarbler to switch from receiving to transmitting without specifying any characters to be transmitted will result in the transmission of a continuous sequence of '''diddle''' characters - each composed of a single start bit ('''Space''' tone) followed by 5 data bits, all of which are '''Mark''' tone; audibly, the result is a recognizable warbling between the '''Mark''' and '''Space''' tones.

If instead of '''diddles''', you hear a single tone, that means your transceiver's '''FSK IN''' or '''RTTY''' or '''MARK/SPACE''' or '''SHIFT''' input signal is not being correctly driven. To determine why, work backwards from that input signal:

 1. the cable between the input signal and the interface that generates the signal is broken in the middle, or one of its two connectors is damaged

 1. the interface that generates the signal is not working, either because it's not powered, or is defective

 1. the interface the generates the signal is working, but is not receiving appropriate directives from the application that controls it because

   a. the cable between the interface and computer is broken in the middle, or one of its two connectors is damaged

   a. !WinWarbler is not properly configured, e.g. wrong serial port, or wrong modem control signal

If !WinWarbler is configured as described in the section above but you're still hearing a single tone when transmitting RTTY FSK, then focus on items 1 through 3a. An oscilloscope will enable you to trace the signals backward from the transceiver input; since FSK signaling occurs at 45.45 baud, even an old oscilloscope whose fastest sweep rate is 50 KHz will be useful.

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[[WinWarblerTinyFSK|Transmitting RTTY FSK with TinyFSK]]

[[Multimode_Setup|Setting up CW, Phone, PSK, and RTTY Operation]]

[[Operation|Getting Started with CW, Phone, PSK, and RTTY Operation]]

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