// Status=review
=== Standard Exchange
By longstanding tradition, a minimally valid QSO requires the exchange
of callsigns, a signal report or some other information, and
acknowledgments.  _WSJT-X_ is designed to facilitate making such
minimal QSOs using short, structured messages. The process works best
if you use these formats and follow standard operating practices. The
recommended basic QSO goes something like this:

 CQ K1ABC FN42                          #K1ABC calls CQ
                   K1ABC G0XYZ IO91     #G0XYZ answers
 G0XYZ K1ABC –19                        #K1ABC sends report
                   K1ABC G0XYZ R-22     #G0XYZ sends R+report
 G0XYZ K1ABC RRR                        #K1ABC sends RRR
                   K1ABC G0XYZ 73       #G0XYZ sends 73

*Standard messages* consist of two callsigns (or CQ, QRZ, or DE and
one callsign) followed by the transmitting station’s grid locator, a
signal report, R plus a signal report, or the final acknowledgements
RRR or 73.  These messages are compressed and encoded in a highly
efficient and reliable way.  In uncompressed form (as displayed
on-screen) they may contain as many as 22 characters.  Some operators
prefer to send RR73 rather than RRR.  This is workable because RR73 is
encoded as a valid grid locator, one unlikely ever to be occupied by
an amateur station.

*Signal reports* are specified as signal-to-noise ratio (S/N) in dB,
using a standard reference noise bandwidth of 2500 Hz.  Thus, in the
example message above, K1ABC is telling G0XYZ that his
signal is 19 dB below the noise power in bandwidth 2500 Hz.  In the
message at 0004, G0XYZ acknowledges receipt of that report and
responds with a –22 dB signal report.  JT65 reports are constrained to
lie in the range –30 to –1 dB, and values are significantly compressed
above about -10 dB.  JT9 supports the extended range –50 to +49 dB and
assigns more reliable numbers to relatively strong signals.

NOTE: Signals become visible on the waterfall around S/N = –26 dB and
audible (to someone with very good hearing) around –15 dB. Thresholds
for decodability are around -20 dB for FT8, -23 dB for JT4, –25 dB for
JT65, and –27 dB for JT9.

NOTE: Several options are available for circumstances where fast QSOs
are desirable.  Double-click the *Tx1* control under _Now_ or _Next_
to toggle use of the Tx2 message rather than Tx1 to start a QSO.
Similarly, double-click the *Tx4* control to toggle between sending
`RRR` and `RR73` in that message.  The `RR73` message should be used
only if you are reasonably confident that no repetitions will be
required.

=== Free-Text Messages

Users often add some friendly chit-chat at the end of a QSO.
Free-format messages such as "`TNX ROBERT 73`" or "`5W VERT 73 GL`"
are supported, up to a maximum of 13 characters, including spaces.  In
general you should avoid the character / in free-text messages, as the
program may then try to interpret your construction as part of a
compound callsign.  It should be obvious that the JT4, JT9, and JT65
protocols are not designed or well suited for extensive conversations
or rag-chewing.

=== Auto-Sequencing

The T/R cycles of many _WSJT-X_ modes allow only a few seconds to
inspect decoded messages and decide how to reply.  Often this is not
enough time, so for FST4, FT4, FT8, MSK144, and Q65 the program
offers a basic auto-sequencing feature.

Check *Auto Seq* on the main window to enable this feature:

image::auto-seq.png[align="center",alt="AutoSeq"]

When calling CQ you may choose to select *CQ: First* to reply
automatically to the first decoded responder, or *CQ: Max Dist*
to reply to the most distant responder.

NOTE: When *Auto-Seq* is enabled, the program de-activates *Enable Tx*
at the end of each QSO.  It is not intended that _WSJT-X_ should make
fully automated QSOs.  Auto-sequencing is an operator aid, not an
operator replacement.

[[CONTEST_MSGS]]
=== Contest Messages

The FT4, FT8, and MSK144 protocols support special messages optimized
for *NA VHF* and *EU VHF* contests.  FT4 and FT8 also support messages
for *ARRL Field Day*, *FT Roundup*, and the *WW Digi* contest.
The decoders recognize and decode these messages at any time.
Configure the program to automatically generate the required message
types for contest exchanges and carry out suitable auto-sequencing by
selecting a supported operating activity on the *Settings | Advanced*
tab.  Model QSOs then proceed as follows, for each event type:

*NA VHF Contest* and *ARRL International Digital Contest*

 CQ TEST K1ABC FN42
                       K1ABC W9XYZ EN37
 W9XYZ K1ABC R FN42
                       K1ABC W9XYZ RRR
 W9XYZ K1ABC 73

Either callsign (or both) may have /R appended to signify a Rover in a
VHF contest.  You can use RR73 in place of RRR, and the final 73 is
optional.


*EU VHF Contest*

 CQ TEST G4ABC IO91
                                 G4ABC PA9XYZ JO22
 <PA9XYZ> <G4ABC> 570123 IO91NP
                                 <G4ABC> <PA9XYZ> R 580071 JO22DB
 PA9XYZ G4ABC RR73

Either callsign (or both) may have /P appended.

IMPORTANT: Messages conveying signal reports, QSO serial numbers, and
6-character locators have been changed in _WSJT-X v2.2_ and are *not
compatible* with the formats used in earlier program versions.  Be sure
to upgrade _WSJT-X_ if you will use *EU VHF Contest* messages.

*ARRL Field Day*

 CQ FD K1ABC FN42
                       K1ABC W9XYZ 6A WI
 W9XYZ K1ABC R 2B EMA
                       K1ABC W9XYZ RR73

*FT Roundup*

 CQ RU K1ABC FN42
                       K1ABC W9XYZ 579 WI
 W9XYZ K1ABC R 589 MA
                       K1ABC W9XYZ RR73

*WW Digi Contest*

 CQ WW K1ABC FN42
                       K1ABC S52XYZ JN76
 S52XYZ K1ABC R FN42
                       K1ABC S52XYZ RR73


Contest QSOs are generally treated as invalid when they appear in one
station's log and not the supposed QSO partner's.  To avoid Not-in-Log
(NIL) penalties for yourself and others, we recommend the following
guidelines for contest logging with FT4, FT8, and MSK144:

 - Activate and learn to use the *Alternate F1-F6 bindings* selectable
   on the *Settings | General* tab.
 
 - Always log a QSO when you have received RRR, RR73, or 73 from a
   station you are working.

 - Log a QSO when you send RR73 or 73 if you are reasonably confident
  it will be copied. But be sure to watch for any indication that it
  was not copied, and then take appropriate action. For example, if
  you receive the Tx3 message (R plus contest exchange) again, and if
  you have activated the *Alternate F1-F6 bindings*, hit *F4* to
  re-send your RR73.

[[COMP-CALL]] 
=== Nonstandard Callsigns

*Modes with 77-bit message payloads: FST4, FT4, FT8, MSK144, and Q65*

Compound callsigns like PJ4/K1ABC or K1ABC/3 and special event
callsigns like YW18FIFA are supported for normal QSOs but not for 
contest-style messages.  Model QSOs look something like this:

 CQ PJ4/K1ABC
                       <PJ4/K1ABC> W9XYZ
 W9XYZ <PJ4/K1ABC> +03
                       <PJ4/K1ABC> W9XYZ R-08
 <W9XYZ> PJ4/K1ABC RRR
                       PJ4/K1ABC <W9XYZ> 73

The compound or nonstandard callsigns are automatically recognized and
handled using special message formats.  One such callsign and one
standard callsign may appear in most messages, provided that one of
them is enclosed in <  > angle brackets.  If the message includes a
grid locator or numerical signal report, the brackets must enclose the
compound or nonstandard callsign; otherwise the brackets may be around
either call.

Angle brackets imply that the enclosed callsign is not transmitted in
full, but rather as a hash code using a smaller number of bits.
Receiving stations will display the full nonstandard callsign if it
has been received in full in the recent past.  Otherwise it will be
displayed as < . . . >.  These restrictions are honored automatically
by the algorithm that generates default messages for minimal QSOs.
Except for the special cases involving /P or /R used in VHF
contesting, _WSJT-X {VERSION_MAJOR}.{VERSION_MINOR}_ offers no support
for two nonstandard callsigns to work each other.

TIP: Using a nonstandard callsign has definite costs.  It restricts
the types of information that can be included in a message.  It
prevents including your locator in standard messages, which
necessarily impairs the usefulness of tools like PSK Reporter.

*Modes with 72-bit message payloads: JT4, JT9, and JT65*

In the 72-bit modes, compound callsigns are handled in one of two
possible ways:

.Type 1 compound callsigns

A list of about 350 of the most common prefixes and suffixes can be
displayed from the *Help* menu.  A single compound callsign involving
one item from this list can be used in place of the standard third
word of a message (normally a locator, signal report, RRR, or 73).
The following examples are all acceptable messages containing *Type 1*
compound callsigns:

 CQ ZA/K1ABC
 CQ K1ABC/4
 ZA/K1ABC G0XYZ
 G0XYZ K1ABC/4

The following messages are _not_ valid, because a third word is not
permitted in any message containing a *Type 1* compound callsign:

 ZA/K1ABC G0XYZ -22        #These messages are invalid; each would 
 G0XYZ K1ABC/4 73          # be sent without its third "word"

A QSO between two stations using *Type 1* compound-callsign messages
might look like this:

 CQ ZA/K1ABC
                     ZA/K1ABC G0XYZ
 G0XYZ K1ABC –19
                     K1ABC G0XYZ R–22
 G0XYZ K1ABC RRR
                     K1ABC G0XYZ 73

Notice that the full compound callsign is sent and received in the
first two transmissions.  After that, the operators omit the add-on
prefix or suffix and use the standard structured messages.

.Type 2 Compound callsigns

Prefixes and suffixes _not_ found in the displayable short list are
handled by using *Type 2* compound callsigns.  In this case the
compound callsign must be the second word in a two- or three-word
message, and the first word must be CQ, DE, or QRZ.  Prefixes can be 1
to 4 characters, suffixes 1 to 3 characters.  A third word conveying a
locator, report, RRR, or 73 is permitted.  The following are valid 
messages containing *Type 2* compound callsigns:

 CQ W4/G0XYZ FM07
 QRZ K1ABC/VE6 DO33
 DE W4/G0XYZ FM18
 DE W4/G0XYZ -22
 DE W4/G0XYZ R-22
 DE W4/G0XYZ RRR
 DE W4/G0XYZ 73

In each case, the compound callsign is treated as *Type 2* because the
add-on prefix or suffix is _not_ one of those in the fixed list.  Note
that a second callsign is never permissible in these messages.

NOTE: During a transmission your outgoing message is displayed in the
first label on the *Status Bar* and shown exactly as another station
receives it.  You can check to see that you are actually
transmitting the message you wish to send.

QSOs involving *Type 2* compound callsigns might look like either
of the following sequences:

 CQ K1ABC/VE1 FN75
                     K1ABC G0XYZ IO91
 G0XYZ K1ABC –19
                     K1ABC G0XYZ R–22
 G0XYZ K1ABC RRR
                     K1ABC/VE1 73


 CQ K1ABC FN42
                     DE G0XYZ/W4 FM18
 G0XYZ K1ABC –19
                     K1ABC G0XYZ R–22
 G0XYZ K1ABC RRR
                     DE G0XYZ/W4 73

Operators with a compound callsign use its full form when calling CQ
and possibly also in a 73 transmission, as may be required by
licensing authorities.  Other transmissions during a QSO may use the
standard structured messages without callsign prefix or suffix. 

TIP: If you are using a compound callsign, you may want to
experiment with the option *Message generation for type 2 compound
callsign holders* on the *File | Settings | General* tab, so that messages
will be generated that best suit your needs.

=== Pre-QSO Checklist

Before attempting your first QSO with one of the WSJT modes, be sure
to go through the <<TUTORIAL,Basic Operating Tutorial>> above as well
as the following checklist:

- Your callsign and grid locator set to correct values

- PTT and CAT control (if used) properly configured and tested

- Computer clock properly synchronized to UTC within ±1 s

- Audio input and output devices configured for sample rate 48000 Hz,
16 bits

- Radio set to *USB* (upper sideband) mode

- Radio filters centered and set to widest available passband (up to 5 kHz).

TIP: Remember that in many circumstances FT4, FT8, JT4, JT9, JT65, and
WSPR do not require high power. Under most HF propagation conditions,
QRP is the norm.
