Additional Information

Revision as of 18:24, 23 November 2020 by Sm7iun (talk | contribs) (Networking over internet)
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Using a number server

For contests involving serial numbers you need to secure that the sent number and
the logged serial numbers are the same. In more complex station configurations such as Multi-single with inband, Multi-Multi, and advanced SO2R, QSO can be interleaved and requires a central source source of serial numbers together with a mechanic to protect a used serial number from re-use by another radio.

In DXLog this is achieved using a number server. A number server can be used either by a single instance of DXLog (as in the case of SO2R) or by multiple stations.

The use of a number server involves three elements: Activating the server, forcing DXLog to use it, and making sure serial numbers are correctly reserved.

The number server is enabled in the Options|Configure network panel, described here. Since the server uses a local socket, Options|Networking must be enabled. In the case of multiple stations, UDP broadcast or Client-Server networking must also be enabled. In the case of SO2R, this is however not necessary.

There can only be one number server in a local network and all stations using it must have Options|Networking|Use number server checked.


Networking over internet

When, for instance, activating a special event callsign it is possible to network multiple DXLog stations over the internet.


The most secure way for remote networking is to rely on a VLAN (virtual LAN) software. There are several available such as:


Each VLAN solutions have their own particular set up which is covered in their respective documentations.
With a VLAN solution, all DXLog configurations are the same as when operating in a regular LAN.

One weakness with connections over the internet (a.k.a. WAN), including VLAN solutions, is that they are prone to packet loss.
Packet loss is disastrous to DXLog's (or any logger's) standard UDP networking.

It is therefore absolutely necessary to run ONLY TCP networking over a VLAN.

Hamachi is particularly popular since it is free for up to five computers. Thanks to the communications
architecture of DXLog, this translates into up to five geographical locations.

Since DXLog is able to mix TCP and UDP networking, a distributed station set up should be configured to rely on TCP
for the wide-area network and UDP for the local network at each station location. Below you will find the station
set up for the Swedish HQ station SE9HQ in the 2019 IARU HF Championship. The cluster client was run
on SK3W-A which distributed spots to all stations over the network. inband interlock was used at the SK3W location.


Important to note:

  • For the server as well as the main clients, Server IP should be set to the server's VLAN IP address, not its LAN address.
  • The server should check both "Start networking server" and "UDP network broadcast for multiple stations".
  • The main clients should check both "Connect as network client" and "UDP network broadcast for multiple stations".
  • All other stations should check only "UDP network broadcast for multiple stations".
  • Interlock over VLAN does not work reliably because of packet loss.
Therefore, it is important to configure any interlock to only consider relevant operating positions,
which all must be local. Use the possibility to only consider named stations for the interlock in the software
interlock set up. Options|Networking|Software interlock "Custom station ID(s)"
  • For a large set-up with many stations connecting as clients to a central server you may overload the server if you also
distribute spots via all client-server connections. In this case, check the "No spots via client/server" option
on all stations and use local DX cluster connections via UDP at each location.

Port forwarding

If you are less worried about competitors or government agencies listening in on your contest data,
it is possible to route the traffic directly over the internet using port forwarding at the server.

Important security notice: This solution is not without risk. It offers no security or authentication.
Any DXLog station running the same contest configuration, knowing the URL or IP address and IP port of the
server can connect to the server station. There are no means to disconnect a station by force.

With a port forwarding solution, the following must be observed:

  • Server configuration
  • Only one of the stations should be configured as the server.
  • "Connect as client" should not be checked and "UDP network broadcast" should only be enabled if it is
used to communicate with other stations on the same LAN.
  • The PC acting as server must have a fixed LAN IP address. This is done either by manually configuring the
PC to use a fixed LAN IP address, or by setting up the router in the server's LAN to to always allocate
the same IP address to it.
  • The internet connection used by the server PC must either have a fixed public IP
address or use dynamic DNS. Otherwise clients will not be able to reliable connect over the internet.
  • The server's TCP/IP port (default 9888) must be forwarded to the internet by configuring the router
connecting the server's LAN to internet. Only TCP traffic should be forwarded.
DXLog UDP traffic is not carried well over the internet.

Example configuration for server for networking over internet

Example of port forwarding UI in router

  • All other stations
  • All other PC in the multi-station set up should be set up as TCP clients.
  • Over the internet, "Server IP" is either the public IP address of the server's internet
connection (e.g. or the dynamic DNS address (e.g.
Clients connecting over the internet does not have to enable UDP networking and should not enable a server.
  • A client may connect via UDP if it is on the same LAN as the server or a "master client".
A "master client" is a client that connects to the server using the "connect as client" option in
the networking set up panel. A "master client" can act as a UDP gateway which means that if
several computers on a LAN are part of the same multi station set up but the server is located
elsewhere, only one computer in that LAN needs to connect as a client and the rest can use UDP.
  • Software interlock is UDP-based and can reliably only be used locally. Never over the internet.

Example configuration of client for networking over internet

  • In a multi-station setting it is recommended to enable Options|Networking|Don't allow QSO logging if operator isn't logged
  • Make sure Options|Enable network is checked.

Real time upload to Club Log Live Stream


DXLogStream is a basic Windows utility (which can run minimized) that uses the radio information broadcast over
UDP from DXLog and uploads logged QSO to Club Log for display using its Live Stream feature. Typical use cases
are DXPeditions, IOTA activation, Special event stations, etc.

The utility requires a valid Club Log account with the used station call sign registered.

Networking must be enabled with Options|Enable Network. UDP networking must be enabled and the station ID and
used port must be the same as set in Options|Configure network. Settings are saved by hitting ENTER or clicking
the Save button. If the UDP port is changed, the utility needs to be restarted.

The station callsign entered into the text box is the one used for upload. DXLog does not convey this as
part of the logging information via UDP which means that the corresponding setting in DXLog's contest
configuration is ignored.

The utility can be downloaded here: http://DXLog/sw/#files%2Futilities

Read more about Club Log Live Stream here:


Club Log Gateway

Since the release of the utility above, Michael Wall, G7VJR, the founder of Club Log, has developed a much
more powerful agent for real time uploads. It works with all the three major loggers, DXLog, N1MM Logger+,
and Win-Test.

It is however less user friendly and more demanding to set up. But for a big scale DXpedition, this is the preferred agent.

You can find more information about it here:

Diversity reception

Diversity means receiving the same signal through two different receive chains, including antenna.
With two antennas having different characteristics this can give substantial benefits in receiving
fading and/or weak signals or separating calls in a large pile-up. Particularly on low bands.

DXLog supports diversity operation on a selected number of radio models.

For the supported radios, diversity operation can be toggled on and off using [Ctrl][-] or [Ctrl][Keypad -].

If enabled via the radio's controls, DXLog will automatically detect diversity operation and enable
the necessary mechanics. Diversity operation is indicated by a small DIV icon in the frequency
counter box for the radio's band map.

Yaesu FTDX101D

Yaesu calls this feature "Sync" and it has a dedicated button up and left of the main VFO knob.
Enabling this will make DXLog update both VFO with the same information when grabbing spots.
It will also adjust the sub VFO with the correct amount when RIT is applied to the main VFO.
Since both VFO are kept on the same frequency, split operation is not supported.

ICOM IC-7851 and IC-7610

ICOM calls this feature "Tracking" and it can be enabled either via a menu entry or a long press on the "MAIN/SUB" button.
Enabling this will make DXLog update both VFO with the same information when grabbing spots.
It will also adjust the sub VFO with the correct amount when RIT is applied to the main VFO.
Since both VFO are kept on the same frequency, split operation is not supported.

Elecraft K3/K3S

Elecraft calls this feature by its proper name. It is enabled by a long press on the "Sub" button.
It should be noted that Elecraft's implementation where the main VFO controls both the main and
sub receivers allows for split operation, i.e. transmitting on a different frequency using VFO B.

UDP broadcast

For interaction with other applications, DXLog can broadcast useful information as
XML datagrams over UDP.

There are five types of broadcast messages:

  • QSO information. Sent when logging.
  • Radio information. Sent at changes as well as periodically.
  • Antenna direction information. Sent when rotor control is invoked.
  • Callsign look-up information
  • Spots

In addition, DXLog also recognizes Waterfall Bandmap-style QSY commands via UDP.

The broadcasting is enabled using the Options|Broadcast and Options|DX Cluster|Send spots to SmartSDR submenus.


UDP broadcast parameters are configured in the Options|Network configuration panel.
Please note that up to three ports can be specified for each broadcast, thereby supporting
multiple receivers of the information.


If you are writing a C# application to make use of these datagrams, there is a very nice online tool
for creating an object from a sample XML datagram here

In C# parsing is easily done using Linq. One example of XML parsing and deserialization using Linq
can be found here

QSO information

Keyword Meaning
logger The name and version of the logging program
qsoid A unique string for this QSO. If this QSO is edited another contactinfo message will be sent with the same qsoid.
Note that the qsoid is only unique within one instance of DXLog. If the computer is networked to others running
DXLog the different computers may have a different qsoid for the same QSO.
contestname The name of the contest as it would be written to a Cabrillo file.
timestamp The UTC date and time of the QSO.
mycall The callsign of this station.
band The band on which the QSO was made.
txfreq The frequency on which the QSO was made.
operator The callsign of the operator if the OPON command was used to set it, otherwise blank.
mode The mode used for the QSO.
call The callsign of the station worked.
countryprefix The DXCC country of the station worked.
wpxprefix The WPX prefix of the station worked.
snt The RST sent. This is always included whether or not the contest exchange contains an RST.
rcv The RST received. This is always included whether or not the contest exchange contains an RST.
nr The number sent if the exchange uses a serial number, otherwise the QSO number from this station.
exch1 The first element in the contest exchange if any.
exch2 The second element in the contest exchange if any.
exch3 The third element in the contest exchange if any.
exch4 The fourth element in the contest exchange if any.
xqso True if this QSO should not be counted towards the score.
invalid True if this QSO is invalid, for example a DX QSO in a domestic contest.
duplicate True if this QSO is a dupe (the station has previously been worked).
rule10broken True if this QSO breaks the 10 minute or similar rule. Note that a QSO may not break the 10 minute
rule when it is logged but may later if another QSO is edited. This may not cause a broadcast.
azimuth The approximate direction of the station worked, in degrees.
distance The approximate distance of the station worked, in kilometers.
stationid The station ID of the station which made the QSO.
stationqso A unique QSO ID generated by the logging station. The combination of
stationid and stationqso forms a unique identifier for the QSO.
stationtype The type of station - R for run, R1 for run 1 etc.
local True if this broadcast is due to this QSO being logged or edited on this computer.
mult1 The name of the multiplier if this station is a new multipllier, blank otherwise.
mult2 The name of the multiplier if this station is a new multiplier, blank otherwise.
mult3 The name of the multiplier if this station is a new multiplier, blank otherwise.
points The logged points for the QSO.
period The number of the operating period.

Example message:

<?xml version="1.0" encoding="utf-8"?>
    <logger>DXLog v2.4.13</logger>
    <timestamp>2020-01-13 18:28:07</timestamp>

Radio information

Keyword Meaning
logger The name and version of the logging program.
Station The ID of the station.
RadioNr The radio being described.
Freq The receiving frequency
TXFreq The transmitting frequency
InactiveFreq The frequency of the VFO not receiving.
Mode The radio's mode
OpCall The callsign of the operator if the OPON command was used to set it, otherwise blank.
IsRunning "True" if the station is running, "False" if search and pounce.
FocusEntry The Windows handle for the focused entry window
Antenna Antenna number.
Rotors Rotators used by selected antenna (not currently used by DXLog).
FocusRadioNr The radio which has keyboard focus.
IsStereo True if headphones are listening to two radios.
ActiveRadioNr The radio which is transmitting, if any.
Technique SO1R, SO2R, SO2R_ADV, or SO2V
isTransmitting True if a radio is transmitting. This is only true if DXLog is transmitting.
Otherwise it may be false if a radio is transmitting due to PTT or VOX.

Example message:

<?xml version="1.0" encoding="utf-8"?>
    <logger>DXLog v2.4.13</logger>

Antenna direction

Keyword Meaning
logger The name and version of the logging program.
station The ID of the station.
radio The radio associated with the rotator.
go True if the rotator should be turned.
stop True if the rotator should be stopped if it is turning.
azimuth The direction to turn the rotator if go is True.
frequency The transmit frequency of the specified radio.

Example message:

<?xml version="1.0" encoding="utf-8"?>
    <logger>DXLog v2.4.13</logger>

Callsign lookup

Sent either when callsign in entry row is changed or when space or tab is pressed.

Keyword Meaning
logger The name and version of the logging program.
contestname The name of the contest.
mycall Station's call
band Current band
txfreq Transmitter frequency
operator The call sign of the logged in operator
mode Operating mode
call Call entered in the logging field
countryprefix DXCC entity prefix
wpxprefix WPX prefix
azimuth Short path antenna direction
distance Distance in km
stationid The ID of the station sending the datagram
stationtype The role of the station sending the datagram; R, R1, R2, M, or R+
period Contest period
reason Reason for transmission; SpaceOrTab or CallChanged

Example message:

<?xml version = "1.0"?>
	<logger>DXLog v2.4.20</logger>

Broadcast listener

DXLog also listens for commands over UDP.

Currently only one command is implemented, <radio_setfrequency>, which is a QSY command.

Keyword Meaning
app Application sending the command
radionr The radio to be changed. In SO2V radio 2 means VFO B.
frequency Requested frequency. NB. Uses period as decimal separator.
mousebutton Which mouse button was used to create message, if any.

Example message:

<?xml version="1.0" encoding="utf-8"?>

SDR integration

HDSDR, OmniRig, and microHAM

Contributed by Ingo SM5AJV/SE5E

Until DXLog offers SDR integration there are still ways to get a waterfall/spectrum display with DXLog.

I have integrated the free SDR software HDSDR with DXLog using Microham Device Router,
OmniRig and AutoHotkey.

As illustrated below I place the HDSDR window at the very top of the desktop with DXLog right below.

I share my transceiver's (an Elecraft K3) antenna with the SDR. The receiver antenna signal from my
K3's RX-ANT OUT is connected to the input of a 3dB power splitter. The two outputs from the splitter
are connected RX-ANT IN on the K3 and the SDR Receiver antenna input, respectively. On a K3 you
need to enable the RX-antenna input to make this to work. An additional benefit with this method
is that the SDR is protected during transmission. It is a widely used method and is e.g. described
by Bob N6TV in this presentation.

Screenshot of my desktop:


Since both DXLog and HDSDR need to communicate with the radio, you need to "split"
the CAT communication. microHAM's USB Device Router provides a second, independent,
CAT port that can be used via HDSDR's omniRig interface.

"PORT" Tab on microHamRouter:


OmniRig settings in HDSDR:


With this set up, the radio, DxLog, and HDSDR will be fully synchronized. For instance, you can
click in the waterfall to make the radio QSY, and it is easy to quickly find a clean frequency.

To make the integration even better I use a small AutoHotkey script. The script pulls entry focus
back to DxLog after clicking on the HDSDR waterfall and in DXLog it allows you to use hotkeys to
control HDSDR. [Ctrl][Alt]+ and [Ctrl][Alt]- zooms the waterfall/spectrum
in and out, and [Ctrl][Alt]C centers it.

AutoHotkey script:

 SetTitleMatchMode, 2
 #IfWinActive, HDSDR
 F4:: return ; disable F4
 ~LButton Up::
   sleep, 1
   Winactivate, DXLog
 #IfWinActive, DXLog
 ^!+:: ControlSend ,, ^{+}, HDSDR
 ^!-:: ControlSend ,, ^{-}, HDSDR
 ^!c:: ControlSend ,, {c}, HDSDR

The script can be downloaded here.

If you start two instances of HDSDR with two different SDR you can even have two waterfalls
running at the same time.

I have not yet found a way to display cluster spots in the HDSDR spectrum panel.
But I still find it very useful to check band activity and it allows me to easily find
a new Run frequency on a crowded band.

Waterfall Bandmap

The free waterfall/spot display utility "Waterfall Bandmap" by Steve N2IC is supported by DXLog.

Waterfall Bandmap supports almost any SDR that produce I/Q output either via ExtIO.DLL or a
sound card; SDRPlay, FunCubeProPlus, HackRF, SDR-IQ, RTLSDR, SoftRock, etc.

A zip file with an executable binary and a Microsoft word document with installation and
configuration instructions can be found here:

If you are not a member of the support forum group, you need to apply for membership to download.
Membership is free.


The SDR can be connected either to a separate receive antenna, an external receiver output on
your transceiver or to an IF output, should your transceiver have one. If connected to an antenna,
keep in mind that you may need protection from the transmitter such as a T/R relay or a passive level limiter.

Please refer to Waterfall Bandmap's documentation for setting it up with your SDR.

Waterfall Bandmap needs two information feeds over UDP: Radio information and spot information.
Both are provided as UDP broadcast by DXLog.

The default port for both is 13063 and this needs to be set in DXLog's Network configuration panel.
If Waterfall Bandmap runs on the same computer as DXLog, the broadcast address can be left at the default


Clicking on the waterfall display can set the frequency of DXLog. (Left click sets VFO A, right click sets VFO B.)
To enable this functionality, check the option Options|Broadcast|Receive Broadcasts
Also make sure "UDP broadcast listener" includes port 13064 in the network settings panel.

The radio information feed needs to be enabled by checking the Options|Broadcast|Radio information option


and the spot feed needs to be enabled by checking the Options|DX Cluster|Send spots to SmartSDR option.


Time synchronization

In a multi-station setting, the time needs to be accurately synchronized across all networked PC.

Windows' built in time synchronization is very crude and for a PC with poor clock stability the
inaccuracy of the clock may be up to a minute. Which of course is not acceptable for contesting.

DXLog has built in support for time synchronization as described in the Configure network section.

Due to Windows' security system, this however requires all except the PC running as time server to
run DXLog with elevated permissions. There is unfortunately no way around this inconvenience.

An equally accurate and less intrusive method is to use a standalone time synchronization application on each networked PC.
This will keep each PC's clock accurate within a fraction of a second.

Contrary to a solution built into a logger it also has the great benefit of being an "install and forget" solution.

A popular application is Dimension 4 by Thinking Man Software. It is free for personal use and
can be downloaded here:

It runs in the background and only shows up as a tiny icon in your system tray.
You hover the mouse above the icon to check status and right-click to open and change settings.


After installation a brief configuration is required.

First of all, allow the application to disable Windows' time service and to modify your system clock.

For maximum accuracy, select a time server geographically close to your location.
When in doubt, you can always add the global server "" to the list and use that.

There are also national and continental pools of time servers. You can find them here


Make sure the check boxes "Load Dimension 4 at startup", "Start minimized", "Hide when minimized",
and "Display icon in tray" are all checked.


Click the Advanced button and also make sure the option "Use the selected server" is selected.

Make sure the application reports a successful connection to the selected time server.
From here on, you can basically forget the application.
It will silently start with your PC and always keep its time accurate.

Disabling USB power management

In the interest of saving energy, Windows habitually power down USB interfaces
when it believes there is inactivity. Some USB-to-serial and USB audio devices
respond poorly to being suspended or powered down so as a rule this "feature" should
be disabled when used in a ham radio environment.

There are two places where this functionality needs to be disabled; the device driver
and Windows' energy management.

To disable it for each USB interface and device, open Windows settings. (Click the Windows
icon in the lower left corner and then chose the cogwheel.) Type device manager and select the result.


This opens up a new window, Windows' Device Manager.


For every USB interface component (there may be many), COM-port, and audio device,
and uncheck the option Allow the computer to turn this device off to save power.

The devices you are looking for are in the categories: Ports (COM & LPT),
Sound, video and game controllers, Universal serial bus controllers,

Note that some devices may not have a Power Management tab.


The next step is to disable Windows Selective suspend feature for USB interfaces.

Go back to Windows Settings and type edit power, click the appearing Edit power plan menu entry.


This should open the window below, the plan editing panel.


Click Change advanced power settings. Scroll down to USB settings and make
sure USB selective suspend setting is disabled for all situations.


Reboot your computer to make sure all settings are recognized by Windows.

Interlock and inband operation

In contest station terminology, the term Interlock refers to a technical solution preventing
more than one station from using a shared resource, typically an antenna, at the same time.

The most common use for interlock is for inband operation. Inband operation means to have multiple
transmitters on a single band, interleaving their transmissions. Sometimes on a split-second basis.

As long as you never have more than one transmitter active at any time, the majority of contests allow
an unlimited number of transmitters and receivers on a single band for multi-operator categories.
This fact is used by most big contest stations.

For an inband solution to be effective, each station must be able to receive while the
other station transmits. This means it requires a separate, high performance receive antenna
with very good isolation from the transmitter antenna. The most common way to
achieve this is physical separation and geographic orientation to minimize the situations
when they will radiate/listen in the direction of the other antenna.

For a station operating in the M/M, M/S, or M/2 category, inband operation can boost the points
per hour performance significantly. It is also a lot more fun.

However, as with everything else, it comes at a cost. An efficient inband solution has:

  • A high performance receive antenna for each operated band(s) with very good isolation from the transmitter antenna.
  • A fail-safe antenna switching hardware.
  • Interlock-capable keyers and/or station controllers.
  • An interlock-capable contest logging software

A typical inband configuration can be seen in the illustration below.


DXLog offers a software-based interlock which can be configured in a variety of ways, e.g. based on frequency
band, operating mode, or station role. It supports an unlimited number of stations interlocking each other
using a great variety of strategies.

The interlock relies on UDP networking and is overlaid on the communication for multi-station logging.
UDP networking has the benefit of speed and low latency but is, unlike TCP, susceptible to packet loss.
This means that a wired LAN is strongly recommended for any station set up using interlock.
For the same reason, it is also not recommended to run interlock over e.g. VLAN/VPN link for
geographically distributed stations.

A software interlock is not 100% reliable. Computer or software malfunction, networking issues such as packet
loss, etc. can cause interlock to fail, even if only momentarily.

For this reason it is necessary to also accompany a software interlock with a fail-safe hardware interlock.
Without hardware supported interlock you run the risk of not only violating contest rules but also cause serious equipment damage.
Some contests, such as CQ WW, explicitly requires hardware interlock when using multiple stations on the same band.

There are many designs and even commercial products available for hardware interlock.
One example of a simple but effective two station hardware interlock which also supports
power amplifier sharing can be found HERE.

The purpose of this section is to describe steps of setting up a basic two station in-band solution with
DXLog and microHAM keyers. The microHAM keyers are not mandatory but offers a much better user experience
and removes the need for additional hardware.


Open the networking configuration panel with Options|Configure network and make sure each
station has a unique name and that only UDP networking is enabled.

Make sure the two stations use the same broadcast IP address and that it is in line with your LAN's
configuration. Pressing the Default button is a good way to ensure this.

Make sure the menu option Options|Enable network has a checkmark.


DXLog Interlock configuration

First of all, make sure that the Options|Interface specific options|Prevent TX if another radio is on same band
is not enabled. This option completely prevents transmission if more than one networked station is set to the same band
and the whole idea with inband is to have exactly that.

Next, activate software interlock on both stations using the menu option Options|Networking|Software interlock
or by typing the commmand ILOCKON.


There are multiple options for configuring the interlock. In a simple set up with only two stations, the topmost
option Same band from status list is a good choice. This option will prevent more than one station transmitting
on the same band, regardless of mode.

In an environment with many stations (such as a multi-operator-multi-transmitter station) it is
recommended to use the bottom option to only interlock with one or several named stations.
This will reduce both LAN traffic and inband operation latency. This is particularly important when
running parts of the DXLog network over high latency links such as VLAN/VPN or if some stations (albeit not
part of the interlock cluster) are connected via Wi-Fi.

For more advanced scenarios you can also use interlock based on mode or station type (e.g. Run 1, Run 2, Mult, etc.).

The "status list" listing the networked DXLog stations is displayed in the Status Window which is opened
with Windows|Status window or [Alt][J].


DXLog also offers great flexibility when it comes to interlock strategy. The most straightforward and
most commonly used is First one wins. This is also typically the behavior of "unintelligent"
hardware solutions when not assisted by software. With this strategy, the station starting to transmit
first can not be interrupted and always gets to finish its transmission.


With a Last one wins strategy, the transmitting station can be interrupted. A carte blanche permission
to interrupt all transmissions by the other station may however be counterproductive in a real contest situation.

For this reason, DXLog offers additional control of which transmit actions can be interrupted and which can not.
This is a powerful tool but requires both operators to be aware of it and may require
practice before fully effective.

NB. "Silent messages" such as setting S&P PLUS to only "$CR", may cause interlock deadlocks since there is
no PTT deassertion to release the interlock. With ESM this is typically not a problem since you log when you send your
exchange in S&P. Without ESM the options are to either remap [+] to [Ctrl][+] or just to always log with [Ctrl][+].
To avoid unintentional mistakes it is a good practice to change the standard S&P PLUS message to "TU $CR".


F1 through F7, PLUS and INS refers to DXLog's standard messages. KEYB means a free text transmission
from the keyboard using the [Alt][K] function and MAN means manual transmission using either paddle
break-in or a footswitch.

Since DXLog recognizes a footswitch connected to a microHAM device, this is the recommended approach.
It is also possible to connect a footswitch to the DSR pin (pin 6) on a physical COM-port on the PC, but today
few PC have such a port and it also requires additional circuitry. Details on how to do this is available HERE.

microHAM configuration

Open the microHAM device configuration panel with Options|microHAM device configuration.


Check the option Enable TX lock/unlock. This will do two things; it will enable DXLog to prevent
transmission and and it will make DXLog aware of the microHAM device's PTT status. The latter is particularly
important since it means DXLog will recognize PTT assertion not only by a footswitch connected to the
microHAM device but also by the built-in Winkeyer (requires microHAM USB Device Router version 9.3.0 or later)
Paddle-based break-in in an inband solution is currently unique for microHAM with DXLog.

Check the option Dual radio device if you are using a u2R, MK2R, or MK2R+, otherwise, leave this unchecked.

Check the option Device without CAT interface if the device lacks a CAT interface (like the u2R)
or if its CAT interface is not connected to the radio. This option will make sure the e.g. keying and
audio routing is always set correctly in line with the operating mode (Voice, CW, or RTTY).


Inband operation requires a fair amount of training and it is a good idea to define and agree
on general rules for operation, such as hand signals for challenging QSO, beforehand.

There are more than enough YouTube videos of inband operators yelling at each other.

The operating tactics may have to be adjusted during the contest. If Run is slow,
doing S&P on the inband station can increase the points per minute significantly.
However, if Run is strong, an overly active inband operator doing S&P, but not working
multipliers, may actually reduce the station's points per minute significantly.

Real-time interlock status is shown in the Radio status window, which is opened with
Windows|Radio status.

Inbandblocking.png Inbandblocked.png

For Phone contesting, you typically rely on footswitches for PTT and the option
Options|Networking|Show QSO status when blocking makes the blocking
station send a more helpful blocking cause than MAN.

With this option enabled, the blocking station will instead send CQ, QSO, or EXCHANGE
as blocking cause, determined by cursor location and entry field content at the locking station.

Further reading can be found in the microHAM device configuration and Networking sections.

Connecting a footswitch

To free up both hands in Phone contesting, a footswitch PTT is a great help.

Also, to use interlock in Phone contesting, a footswitch is mandatory.

There are two basic ways to interface a footswitch with DXLog; via a microHAM device (which is the recommended solution)
or directly connected to a physical serial port on the PC (which very few PC have today).

The connection of a footswitch to a microHAM device is very straightforward and by checking the Enable TX lock/unlock
in the microHAM device configuration panel, it is recognized by DXLog.

Lacking a microHAM device, it is also possible to use the computer's DB9 RS-232 serial port connector, providing it has one.

The required steps to do this are:

  • Connect a 10k resistor between DB9 pin 6 and pin 7.
  • In the port's settings (Options|Configure interfaces) set DTR (pin 4) to Always On and RTS (pin 7) to Always Off for the port.
  • Connect the footswitch between DB9 pins 4 and pin 6. NB. Neither pole on the footswitch must be connected to ground.
  • In the radio's configuration panel, check use CAT PTT command on Phone and set Foot switch (pin 6) to PTT

Special support for AR Cluster 6

With the advent of skimmers, the traffic on the DX Cluster has risen dramatically.
Even though CW skimmers are generally quite reliable, the absolute number of busted spots can be quite high during a busy contest.

Jose CT1BOH has developed an algorithm for evaluating spot quality which is included in version 6 of AR Cluster.
Today many cluster nodes runs this version and thereby offer this mechanic. A complete list can be found here: AR Cluster nodes

To enable the functionality on a cluster node running AR Cluster 6, the command SET DX EXTENSION SKIMMERQUALITY needs to be issued to the cluster node.
The easiest way to do this in DXLog is via [Alt][T].

The quality of the spots is indicated by a character ("tag") in the last column of the comment field and in some cases a corrected callsign within parenthesis.
This syntax is recognized by DXLog and can greatly reduce the number of bad spots in your bandmap.

The CT1BOH skimmer quality algoritm is based on three parts:

When a callsign is first spotted, it is tagged with "?" in the last column of the spot's comment field.
If the callsign of an unverified spot closely resembles an already verified one, the verified callsign is provided within parenthesis in the spot's comment field.
When two or more skimmers agree on the spot, it is considered verified and the tag becomes "V".
When a verified spot appears on a new frequency, this spot is first marked "Q" for QSY.
Once verified, this becomes the new verified frequency and is tagged "V".
The algorithm checks uncertain spots for resemblance with already verified spots and spots at or near the same frequency.
If the resemblance is high enough, the spot is considered busted "B" and the corrected callsign is provided within parenthesis in the spot's comment field.

Below you can see an example of the spot flow from W9PA-4 with skimmer quality enabled.
The flow contains one unverified and one busted spot.


DXLog's policy for spots with CT1BOH skimmer quality tags is the following:

V - Accept spot.
Q - Accept spot.
? - Accept spot. Use corrected call when provided.
B - Accept spot if corrected call provided. Else ignore.

This basic policy can be modified by using additional filters at the cluster node end. Some examples are:

SET DX FILTER NOT SKIMBUSTED - Do not send busted spots at all
SET DX FILTER SKIMVALID - Only send verified spots

You can also compose more complex filters such as:


This filter will provide only validated and human spots except if they are from outside the US and EU.