R< ..................callsign Reads msgs from given callsign
R@ ................callsign Reads msgs with given @BBS Ex: R@ ARRL
RH # # ...........Like R but displays all the R: lines as well (Read Headers)
RP # # ............Like R but doesn't mark msgs as read (Read Preview)
RN # # ............Like R but gives msg text only (Read Noheaders)
RE # # ............Reads the given message numbers in export form (Read Export)
REM ...............Reads all messages to you in export form (Read Export Mine)
#RS ................Reads all messages to SYSOP (Read Sysop)
#RES..............Reads all messages to SYSOP in export form (Read Export Sysop)
#R* ..................Reads held messages showing text
#R+ .................Reads held messages showing why held verbosely
#R- ..................Like R+ but very concise
Typically, after a screefull of lines is displayed on your terminal, you will be asked:
More? [Y]es, No or Continuous
Press just return for next screenfull, N to quit reading this message or category), or C to display all the rest without pausing.
The number of lines per screen is set by the X command.
To list files in subdirectory XXX, put /XXX in the title of a msg to REQDIR.
For information on how to request a file, send a msg to REQFIL and put
REQFIL.HLP in the title.
To request a file, send a private message to REQFIL at this BBS. Put in the
title the name of the file you want. If the file is in a subdirectory,
include the name(s) of the subdirectories. Examples:
SP REQFIL @ WA8BXN
The S command is used to send messages. It several formats:
SP call @ bbscall.haddr Send a private msg Ex: SP K8EIW @ WB8BII.OH.USA.NA
ST zipcode @ NTSst Send traffic msg Ex: ST 44070 @ NTSOH
SB category @ route Send a bulletin Ex: SB NEED @ ALLOH
SR msg# Send reply Ex: SR 12723 or SR 12723.
In SB if call is a user of this system you can omit the @ bbscall.haddr
In ST, NTSst means to replace st with the state its going to: OH for Ohio, etc.
In SR, if you put a period after the msg #, a title will automatically be made
by preceeding the original title with RE:
IMPORTANT: SR tries its best to determine where the reply should go, but
it is not always perfect! The same applies to the REP command.
Never uses SSID's in callsigns (ex: don't use WA8BXN-2, just use WA8BXN)
Hierarchical addresses are of the form state.country.continent. Other parts
may be used by a particular BBS, if you know them, use them.
When sending personal messages to a distant bbs, it is a good idea to put
the destination city and state in the title.
When you are done typing your message, end it with either ^Z (Control-Z) or
Putting * at the beginning of a line makes it a comment.
It also suppresses the next command prompt (but the system will
be waiting for another command). * is useful to answer the SYSOP if you
get a MESSAGE FROM SYSOP ...
Send...........Send a message
The T cmd is used to connect to the sysop's keyboard. This if the sysop is present you may enter into a direct conversation.
If there is no response from the sysop in 60 seconds you will be returned to the BBS. TCP/IP Telnet users note: Server 87
connects directly to the keyboard without going through the bbs.
The U cmd lists the current users of MSYS and what they are doing. The UP command may be used to upload ASCII files.
You must be authorized by the SYSOP to upload files. After you use the UP command you will be asked the file name to
upload. Follow the prompts given by the command.
The V command gives the version of this software.
The What command lists the available files for downloading. The format: W - Lists all files with sizes. A directory name
may be specified to list files names in directories that appear in the list.
W x..............What in x=subdir
The X command can be used to set a variety of options. If no argument is given, X simply toggles and displays the new
Expert status. If a number is given after X, this is the number of lines to display for a command before asking More? To
continue displaying the current message when More? is sent press return. To abort the message, type N and then return. This
facility has been added to prevent a long message from scrolling off your screen faster than you can read it. Experiment with
different values until you find one that pleases you. To not use this facility, set the number of lines to zero. Examples:
X 20 (pause after every 20 lines) X 0 (don't pause ever)
XF Set "fast" mode: BBS will put more than one line per packet
XS Set "slow" mode: BBS will put only one line per packet.
Note: If you have very good path to bbs, use XF. If you have a poor
path to bbs, use XS since short packets make it through easier.
XC............. toggles the automatic display of msg catagories when you connect to the
bbs and are using non-expert mode.
XR toggles the automatic asking if you want to reply to a msg after you read
it. Can be useful if you get a lot of personal mail.
XU toggles the automatic display of Unread mail when you connect.
X #............Lines per page
Yapp...........Down and uploads
YD................Download a file
YU................Upload a file
YW ..............Lists available files for YAPP Download
YD filename Downloads specified file using YAPP protocol
YU filename Uploads specified filename using YAPP protocol
*.....................Comment to sysop
^ZQ or /ex......Return to PBBS
^ZA #...............Invite user on #
^Z gets you this file, as you may already know!
SP REQFIL @ WA8BXN
would get you file NEWFILE.DAT from directory XXX.
SP REQFIL @ WA8BXN
STUFF.BAS @ K8EIW
would send the file STUFF.BAS back to you at BBS K8EIW, instead of the one
from which you sent the message.
NOTE: YOU CAN REQUEST ONLY ONE FILE PER MESSAGE TO THE SERVER!
NETWORK NODE COMMANDS
BBS............Connect to the PBBS
Connect CALL...Connect to call
C# CALL...C on port # to call
Justheard......Limited output JH
Nodes CALL..Info on node
Routes.........Direct connect nodes
Route CALL..Other node
State Talk...........Page Sysop
Pactor Introduction and Theory
MixW: Pactor Intro and Theory
From the website of RICHARD B. GRIFFIN, NB6Z
PACTOR, specially designed for operation in noisy and fluctuating channels, is an improved half-duplex synchronous ARQ
system combining the reliability of Packet with the fixed AMTOR time frame.
Principal design considerations
PACTOR comprises all important Packet (2-way) characteristics:
fixed timing structure and full synchronism to ensure maximum speed
fast and reliable changeover / break-in
required bandwidth less than 600 Hz
100% ASCII compatible (true binary data transmission)
extremely low probability of undetected errors (16 bit CRC)
independent of shift polarities
no multi-user overhead in a narrow-band channel
inexpensive hardware (Z80 single-board)
high operational comfort (built-in message storage system, etc.)
FEC-mode (CQ-transmissions etc.)
As a novelty in Amateur RTTY, some additional powerful features have been realized:
optimal coherent mode, i. e. system clocks locked to frequency standards (e.g. DCF77, TV deflection signals and
other high precision broadcasts)
online data compression (Huffman coding)
automatic speed change (100/200 baud) without loss of synchronization
fully acknowledged link termination (no QRT-timeout required)
memory ARQ (even noisy packets can be restored)
II. System Details
The basic Pactor transmission frame is very similar to AMTOR; blocks (packets) containing data information are
acknowledged by short control signals sent out by the receiving station.
Shift levels are toggled with every cycle in order to support memory ARQ. Since the shift polarity is clearly definined at
synchronization time, any conventions concerning 'mark/space' become obsolete.
cycle duration : 1.25 sec
packets : 0.96 sec = 192 (96) bits at 200 (100) baud
control signals: 0.12 sec = 12 bits, each 10 msec long
Control Signal-receive gap : 0.29 sec
Change of transmission speed only alters the internal packet structure; all other timing parameters remain constant.
General packet structure:
/header/..20 (8) data bytes at 200 (100) baud../status/CRC/CRC/
header : This byte enables fast synchronization and delivers auxiliary information (memory ARQ, listen mode)
data : arbitrary binary information
status : system control byte (2 bit packet number, tx-mode, break-in request, QRT)
CRC : 16 bit cyclic redundancy check based on CCITT polynomial X^16+x^12+x^5+1, calculated over the entire packet
3. Control signals (CS)
Four CS are used. As a compromise between reliability and fast detection, a CS length of 12 bit was chosen.
CS1: 4D5 CS2: AB2 CS3: 34B CS4: D2C (all hex numbers, LSB right)
The mutual Hamming distance is 8 bit, thus minimizing the chance of receiving a false CS. CS1/2 and CS3/4 form
symmetrical pairs (bitreverse patterns). CS1..3 have the same function as their AMTOR counterparts; CS4 serves as the
speedchange control. In contrast to AMTOR, CS3 is transmitted as head portion of a special changeover packet.
The calling station ('master') sends special synchronization packets: /head (100 bd)/..address (8 bytes, 100 bd)../..address (8
bytes, 200 bd) Normally, the receiver only uses the 100-baud-section to achieve a fast synchronization. The 200-baud-
section supplies additional information about the channel quality: if it is received correctly, the first CS will be CS4,
otherwise CS1 is sent. After in turn having synchronized a CS4 or CS1, the master will continue with sending normal data
packets at 200 or 100 baud, respectively. The first transmitted characters contain the 'system level number' (PACTOR
software-version), followed by the master address (callsign).
4. Changing the transmission direction
Similar to AMTOR, the receiving station (RX) can change the transmission direction whenever it has received a valid
packet. For this purpose a special changeover-packet is transmitted, starting at the CS time frame. The transmitting station
(TX) will switch to RX mode immediately after it has received the CS3 which forms the first section of the changeover-
packet. It then reads in the rest of that packet and transmits a CS (CS1 and CS3 = acknowledge, CS2 = reject) timed at the
last three bytes of the former packet frame.To force a break in, the TX sets the BK-status-bit (this corresponds to AMTOR
Speeddown only being useful in poor conditions or at low data input rates (e. g. manual typing), both directions are treated
The RX may request speeddown after any incorrectly received packet by sending CS4, which immediately forces the TX to
build up 100-baud-packets (any unconfirmed 200 baud information is repeated at low speed).
Any valid packet may be confirmed with CS4, forcing a TX speedup. In case the following high-speed-packet is not
acknowledged after a number of tries, the TX will automatically perform a speeddown.
6. Termination of a PACTOR contact
Cutting an ARQ link inevitably leads to the problem that information has to be transmitted without final acknowledgement
(Second WAA theorem). Pactor applies special QRT packets, providing an expensive but rather effective solution. These
packets contain an active QRT status bit and the RX address in byte-reverse order (low speed pattern). If this address is
found during the standby synchronization procedure, the RX responds with a single transmission of the final CS (The timing
relations before stby are stored). This method will always guarantee a well-defined QRT.
7. Data Compression
Character frequency analysis of typical English or German texts shows that the average amount of information per character
does not exceed 4 bits. For that reason, ASCII text transmissions often carry a redundancy of 50%, which could be avoided
by using a vriable length code matched to the character distribution.The most popular example of such a code is the Morse
code; PACTOR data compression mode applies Huffman coding with nearly optimum efficiency, yielding up to 100%
speed gain. Every packet contains a compressed data string; character code lengths vary from 2 to 15 bits.
8. Memory ARQ
In conventional ARQ systems the TX has to repeat a packet until it has been received completely error-free. It is evident that
the probability of receiving a complete packet dramatically decreases with lower S/N ratio. The only way to maintain the
contact in that case is to shorten packet length and/or to apply error correcting codes which in turn will greatly reduce
maximum traffic speed when conditions are good. The method chosen by WAA Research Group is to sum up corresponding
bit samples of subsequent packets and to test if the mean value (reduced to a 0/1-decision) passes the CRC. To keep
quantizing errors small, the samples are taken from the FSK-demodulator low-pass-filter output by means of an 8-bit AD-
converter. Assuming white Gaussian noise, this accumulation method - also known as 'memory ARQ' - will obviously
converge even at a WA4EGT, QRA WA2MFY/SYS1: low S/N ratio. Furthermore, since shift levels are toggled with every
transmission, constant interfering signals within the receiver passband will not affect the resulting mean value. To prevent
accumulation of old request packets, the header is inverted with every new information packet, thus serving as a RQ
indicator (similarity test).
9. Listen Mode (Monitor)
This mode resembles Packet Radio monitoring: the receiver scans for valid packets which are detected by CRC match. This
'brute force' method was chosen in order to ensue maximum flexibility, although it consumes a considerable amount of the
available CPU capacity.
10. FEC Transmissions
CQ and bulletin transmissions are supported by means of a special non- protocol mode. Packets are transmitted with one or
more repetitions; the CS receive gap is omitted. Since the listen mode does not require synchronization, the transmitting
station possesses great freedom of selecting packet repetition rate and speed.
11. Practical Aspects
The first PACTOR programs were running on 'breadboarded' Z80 singleboard- computers. These early experiments led to
the development of a stand-alone 'PACTOR- Controller' with built-in modem and tuning-display.The conventional operating
modes BAUDOT and AMTOR were added in order to maintain compatibility and - what might be more interesting - to
allow easy comparisons. Assuming typical conditions, PACTOR traffic can be expected to run 4 times faster than over an
MixW: Pactor Operation
MixW supports Pactor receive (listen mode) only via the soundcard interface. To transmit Pactor with MixW you must use a
hardware TNC. See the TNC Configuration and Operation topic.
To receive Pactor without a TNC, set the mode for Pactor by selecting Mode | Pactor from the main menu, or by clicking on
the Mode box in the Status Bar and selecting Pactor. Pactor sounds like chirping bursts of packet like transmissions. The
following picture shows the waterfall-tuning window tuned to a Pactor QSO:
As you can see, the width is similar to RTTY and it also utilizes the same two-diamond-with-a-bar indicator used by RTTY,
MFSK, and packet.
PSK Introduction and Theory
MixW: PSK31 Intro and Theory
PSK31 is based on an idea by SP9VRC and developed by Peter Martinez, G3PLX, who also developed AMTOR. Based on
RTTY, PSK is used for live keyboard-to-keyboard QSOs at 50 WPM (31 Baud) and uses "Phase Shift Keying" to signal
mark and space values, instead of changing the frequency.
DSP is used to change the phase by 180 degrees when a switch from mark to space is needed. DSP analysis by the program
instantly detects this "Phase Shift".
PSK works in a very narrow bandwidth, which sharply reduces noise and QRM. This narrow signal also makes it an
excellent QRP (low power) mode, with between 5 and 10 watts producing excellent inter-continental paths in some cases.
The front-end DSP filter and pulse shaping keep the waveform compact, approximately 40 Hz at -3dB and 80 Hz at -40 dB.
Pulse shaping uses a raised cosine to ramp amplitude during phase transitions and leaves the amplitude at full value during
no phase reversals.
PSK31 uses much less bandwidth than traditional digital modes as shown here:
Documents you may be interested
Documents you may be interested