// Status=review
=== Standard Exchange
By longstanding tradition, a minimal 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:

[width="90%",cols="3,7,12",options="header"]
|=======================================
|UTC|Transmitted Message|Comment
|0001|CQ K1ABC FN42|K1ABC calls CQ
|0002|K1ABC G0XYZ IO91|G0XYZ answers
|0003|G0XYZ K1ABC –19|K1ABC sends report
|0004|K1ABC G0XYZ R–22|G0XYZ sends acknowledgment and report
|0005|G0XYZ K1ABC RRR|K1ABC sends acknowledgment
|0006|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, and in uncompressed form may contain 
as many as 18 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 #0003 above, K1ABC is telling G0XYZ that his signal is
19 dB below the noise power in bandwidth 2500 Hz.  In message #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, while JT9 supports the extended range –50 to +49 dB.

TIP: Signals become visible on the waterfall around S/N = –26 dB and
audible (to someone with very good hearing) around –15 dB. Thresholds
for signal decodability are approximately –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).  It should be obvious that the JT9 and JT65
protocols are not well suited for extensive conversations or rag-chewing.

=== Compound Callsigns

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

.Type 1 Compound-Callsign Messages

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
message word (normally a locator, signal report, RRR, or 73).  Thus,
the following examples are all acceptable *Type 1* messages with
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 a *Type 1* message:

 ZA/K1ABC G0XYZ -22        #These messages will be sent
 G0XYZ K1ABC/4 73          #without the 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 both operators send and receive the full compound
callsign in the first two transmissions.  After that, they 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 short displayable list can be
handled with a *Type 2* message.  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 *Type 2* messages with compound
callsigns:

 CQ W4/G0XYZ FM07
 DE W4/G0XYZ -22
 QRZ K1ABC/VE6 DO33

In each case, the message 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.

TIP: 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 would
receive it.

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

 CQ KP4/K1ABC FK68
                     K1ABC G0XYZ IO91
 G0XYZ K1ABC –19
                     K1ABC G0XYZ R–22
 G0XYZ K1ABC RRR
                     K1ABC G0XYZ 73


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

Each operator sends his own compound callsign in the first (and
possibly also last) transmission, as may be required by licensing
authorities.  Subsequent transmissions may use the standard structured
messages without callsign prefix or suffix.

IMPORTANT: It's up to you, the operator, to ensure that messages with
compound callsigns are composed in the manner described above.
Double-clicking on a line of decoded text may not always produce the
desired result.

=== Pre-QSO Checklist

Before attempting your first QSO with JT9 or JT65, be sure to go
through the <<X15,Basic 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's Split mode selected or not, consistent with your choice 
on *Station* tab of the *Setup | Configuration* window.

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