// 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.

*Signal reports* are specified as signal-to-noise ratio (S/N) in dB,
using a standard reference noise bandwidth of 2500 Hz.  Thus, in
example message at UTC 0003 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.

IMPORTANT: 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 -23 dB for JT4, –24 dB for
JT65, –26 dB for JT9.

=== 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.

[[COMP-CALL]] 
=== Compound Callsigns

Compound callsigns such as xx/K1ABC or K1ABC/x are handled in
one of two possible ways:

.Messages containing 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-Callsign Messages

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.

IMPORTANT: Remember that during a transmission your transmitted message is
always displayed in the first label on the *Status Bar*, highlighted
in yellow.  It is displayed there exactly as another station will
receive it.  Be sure to check 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. 

IMPORTANT: 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 *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

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

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

IMPORTANT: Remember that JT4, JT9, J65, and WSPR generally do not
require high power. Under most HF propagation conditions, QRP is the
norm.
