Joe Taylor, K1JT продолжает работать над новой программой WSPR. Перспективы интересные. Кто пробовал, поделитесь впечатлениями. Ниже привожу письмо K1JT c интересными данными. Судя по ним +5dB по сравнению с JT65.
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Subject: [wsjtgroup] WSPR QSO Mode
Date: Fri, 23 May 2008 15:48:16 -0400
From: Joe Taylor <joe@Princeton.EDU>
To: Knightsqrss Knightsqrss <knightsqrss@cnts.be>, wsjtgroup@yahoogroups.com
Dear Friends of WSJT and WSPR,
I write to bring you up to date on continuing evolution of
the WSPR protocol and related software.
As you have already heard, a "QSO mode" for this weak-signal
protocol is in the works. In fact, the first WSPR-mode QSO
was made on May 6: K1JT worked W6CQZ on the 30 m band, using
simple antennas and power levels of 1 W at each end of a
4000 km path.
The WSPR protocol is designed for use with extremely weak
signals. It is suitable for making basic amateur contacts
over any propagation path that provides S/N exceeding -30 dB
in reference bandwidth 2500 Hz, with Doppler spreading less
than about 1 Hz. Such paths should include most LF, MF, and
HF paths of interest to amateurs, as well as the EME path at
VHF.
WSPR messages are structured to permit the efficient packing
of callsigns, grid locators, signal reports,
acknowledgments, and other information commonly exchanged in
minimal QSOs. The protocol includes strong forward error
correction (FEC) using a long-constraint convolutional code
(K=32, rate=1/2). Messages are almost always received
exactly as transmitted, or else the decoder declares "no
result" by remaining silent. False decodes are extremely rare.
WSPR users are already familiar with its beacon-like
messages formatted according to the template
call grid dBm
In QSO mode, WSPR messages have a much richer variety of
formats, as indicated by the templates and examples in the
following list:
Template Example of usage
------------------------------------------------
CQ call grid CQ K1JT FN20
CQ p/call CQ PJ4/K1JT
<call1> call2 <K1JT> W6CQZ
DE call grid DE W6CQZ CM87
DE p/call DE PJ4/K1JT
call1 <call2> rpt W6CQZ <K1JT> S4
QRZ call QRZ K1JT
p/call rpt PJ4/W6CQZ S4
call1 <call2> R rpt K1JT <W6CQZ> R S3
p/call R rpt PJ4/K1JT R S3
<call1> call2 RRR <W6CQZ> K1JT RRR
call1 <call2> RRR W6CQZ <K1JT> RRR
DE p/call RRR DE PJ4/K1JT RRR
73 DE call grid 73 DE W6CQZ CM87
73 DE p/call 73 DE PJ4/K1JT
TNX name 73 GL TNX VICTORIA 73 GL
OP name 73 GL OP HARRY 73 GL
pwr W DIPOLE 5 W DIPOLE
pwr W VERTICAL 10 W VERTICAL
pwr W gain DBD 1 W 0 DBD
pwr W gain DBD 73 GL 1500 W 21 DBD 73 GL
PSE QSY freq kHz PSE QSY 1811 kHz
WX wx temp F/C wind WX SNOW -5 C CALM
freetext CUL JACK
Upper-case letters and numerals are conveyed exactly as
shown in the templates. Lower-case items are replaced by
appropriate information, for example call=K1JT, grid=FN20,
rpt=S1 to S9, name=HARRY, freetext="CUL JACK", etc., as
shown in the examples.
Messages may contain one full callsign and one "hash-coded"
callsign. The transmission of hash codes is indicated by
angle-brackets surrounding the call, as in <K1JT>; the
brackets appear in displays of both transmitted and received
messages. Since hashing is a many-to-one mapping, the
process is not reversible. However, if a full callsign has
been decoded in a previous transmission, the decoder may
assume that a matching hash code usually implies matching
callsigns. With a 15-bit hash code the chances of
mis-identification are very small, especially within the
confines of a particular QSO.
A minimal QSO using WSPR mode might look like the following
sequence of messages:
1. CQ K1JT FN20
2. <K1JT> W6CQZ
3. W6CQZ <K1JT> S4
4. K1JT <W6CQZ> R S3
5. <W6CQZ> K1JT RRR
6. TNX JOE 73 GL
A third-party operator listening to this QSO from the
beginning would copy everything just as the participating
stations do. Even if only one of the QSO partners can be
copied at the third station, both callsigns will be received
in full. If the third-party operator tunes into the middle
of a QSO, so that his decoder cannot yet identify one of the
hashed callsigns, it will produce something like
W6CQZ <...> S4
instead of the full message. He must then stay tuned to
determine the identity of the missing callsign. There will
be no ambiguities at all for the QSO partners themselves.
Full callsigns are always decoded (or already available, in
the case of one’s own call) before their hash codes are needed.
Signal report S1 corresponds to "-30 dB" on the WSJT scale,
S2=-27 dB, S3=-24 dB, etc., up to S9=-6 dB. On this scale,
the threshold for signal audibility is around S5 to S6. The
placeholder "p/" stands for an add-on prefix or suffix in
compound callsigns like ZB2/DF2ZC or DH7FB/P. Information
conveying the add-on prefix or suffix replaces the
information that would otherwise convey a grid locator or
hashed callsign.
Items "pwr", "gain", "freq", and "temp" stand for numbers.
A 2m EME station might send
1500 W 21 DBD 73 GL
to inform his QSO partner about his equipment, at the end of
a QSO. Similarly, a QRP HF station might send
1 W 0 DBD
or
5 W DIPOLE
If he finishes a QSO on 80 m and wants to try 160 m next, an
operator might send
PSE QSY 1811 kHz
Names may contain up to 9 letters, and "freetext" may
contain any combination of 8 or fewer letters, numerals,
spaces, and the punctuation marks + . / ?.
Space has been reserved in the WSPR protocol for many more
"canned" or "partially canned" messages like those in the
final group of templates. I hereby solicit suggestions for
messages that might be included in this group. Note that
the variable information to be inserted in a given message
type should be no more than one, two, or possibly three
numbers or words. Please help me to populate the list
of message types in the most useful way.
In addition to the QSO-mode messages described above, a new
format will be provided so that true beacon stations can
transmit solar/geomagnetic/ionospheric data (K-index, MUF,
events in progress, events expected) in a compact and useful
form.
Although the first WSPR-mode QSO was made with a special
version of the WSPR program, future evolution will most
likely follow a different path. It seems best to keep the
WSPR program relatively simple and intended for automatic,
quasi-beacon-like transmission and reception of
propagation-probing signals. The next released version of
WSPR will be capable of decoding all of the new messages,
however. For use in making WSPR QSOs, support for the full
WSPR protocol will be added to a future version of WSJT.
This seems desirable because WSJT already has all of the
necessary amenities for setting up messages, controlling the
Tx/Rx sequences, etc.
How will WSPR compare in sensitivity with other weak signal
communication modes? Under the assumption of additive white
gaussian noise, no QSB, and negligible Doppler spreading,
the following table applies:
Mode Threshold Comments
S/N
----------------------------------------------------
CW -18 dB Best human operators
JT65B -24 KV decoder
JT65B -27 Avg of 3 transmissions, KV decoder
JT65B -28 Deep Search
WSPR -29
WSPR -32 Avg of 3 transmissions
It should be noted that JT65 uses 1-minute T/R sequences
while WSPR uses 2-minute sequences. The occupied bandwidth
of a WSPR signal is about 6 Hz, about 60 times smaller than
the JT65B bandwidth.
Technical Details
-----------------------------------------------------------------------
For those with technical interest in the WSPR protocol, here
are a few additional details. The WSPR message "payload" is
50 information bits per transmission. Most of the message
formats use 28 bits for a standard callsign and 15 bits for
a hash-coded callsign or grid locator. The remaining 7 bits
convey signal reports, acknowledgments, power levels, and
special message types. Special messages may use the first
43 bits for any dedicated purpose.
The WSPR protocol uses continuous-phase 4-tone FSK with tone
spacing and keying rate both equal to 12000/8192 = 1.46 Hz.
Each transmission contains (50+K-1)*2 = 162 channel
symbols, and each symbol conveys a data bit (MSB) and a
time-and-frequency synchronizing bit (LSB). Transmissions
last for 162*8192/12000 = 110.6 s. The occupied bandwidth
of a WSPR signal is about 6 Hz.
Open Source
------------------------------------------------------------------------
You probably already know that WSJT, WSPR, and MAP65 are
open-source programs licensed under the GNU General Public
License. Source code is stored in a public repository at
developer.berlios.de/projects/wsjt/. If you are interested
in contributing to the development of these programs, please
send me email. We also solicit your comments and
suggestions on the plans outlined above!
With best wishes,
-- 73, Joe, K1JT
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