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||One of EchoLink's strengths is its ability
to link any number of repeaters to each other, or to simplex stations.
Here are some tips for setting up and configuring EchoLink to be used as a link
to a local repeater.
Remote or Hard-Wired?
There are two ways a repeater can be connected to EchoLink.
With the "hard-wired" approach, the PC on which EchoLink
runs is co-located with the repeater controller, and interfaced directly to it,
with no additional RF hardware. This allows positive carrier and PTT
control between the repeater controller and EchoLink, and eliminates extra
"hops" in the audio chain. It also eliminates the need to ID a
link transmitter. One disadvantage of this technique, however, is that it
requires reliable Internet access at the repeater site, which may be in a
With the "remote-link" approach, an FM transceiver is
connected to the EchoLink PC at a convenient location in range of the repeater,
and tuned to the frequency pair of the repeater. In this configuration,
the transceiver behaves very much like an ordinary local repeater user,
transmitting on the repeater's input frequency (on behalf of EchoLink users)
and receiving on the repeater's output frequency. Although this allows
the EchoLink equipment to be placed in a more convenient location, it presents
some challenges with respect to RX control.
With either approach, EchoLink should be configured with a callsign
with a -R suffix, to indicate that the node is a gateway to a repeater,
rather than a simplex frequency. If a remote link is being used, the
software should be configured to identify itself on the air with the host
station's callsign, which is not necessarily the same as the EchoLink callsign
(or the callsign of the repeater). Since the link itself is not a
repeater, a suffix such as /R in the ID is usually not appropriate (for
One of the most important considerations for an EchoLink repeater
node is the method of detecting the presence of a local RF signal.
Although the best approach is usually to wire a COS signal into the COM port of
the PC, it is often necessary (or desirable) to use VOX instead. Several
techniques are described below.
COS from Repeater Receiver: If the node is hard-wired to the
repeater controller, the best source of carrier detect is the COS output from
the repeater receiver itself -- or an equivalent signal from the repeater
controller. This ensures that EchoLink transmits to the Internet only
when a signal is being received on the input. Also, the audio connection
to the sound card should come from the receiver's audio output, rather than the
repeater transmitter's audio path.
COS from Link Transceiver: If the node is remotely located, it
may be desirable to use the COS signal from the link transceiver -- but only if
the repeater's "tail" is extremely short. Otherwise, EchoLink
will keep transmitting to the Internet 5 to 10 seconds after the local user
finishes a transmission, severely interrupting the flow of a QSO. Some
repeater-node operators have successfully incorporated DTMF tones in their
custom Connect and Disconnect announcements to automatically shorten the
repeater's "tail" while an EchoLink station is connected, on
repeaters which support this type of remote command.
VOX: If the node is remotely located, but the repeater's
"tail" cannot be shortened, VOX can be used. When properly
adjusted, EchoLink will detect voice signals coming through the repeater, but
ignore other incidentals such as the "tail", the courtesy tone, and
the squelch crash at the end. This is very important when two
repeaters are linked to each other, to prevent endless ping-ponging of one
repeater bringing up the other. Here are some tips for adjusting the VOX
for use with a repeater:
Set the VOX threshold carefully. (This is the
horizontal slider below the audio-level indicator.) The VOX threshold
should be set just above the audio level of the repeater's dead carrier, so
that it "trips" on voices, but not on the repeater's tail.
Watch the purple SIG annunciator while adjusting the VOX threshold.
If necessary, adjust the VOX delay. The default value
of 1200 ms is appropriate in most situations. (If you decide to change
the value, type it in directly, rather than using the up-down buttons.)
Use the "Smart VOX" feature. This is enabled
by checking the "Squelch Crash Anti-Trip" box on the RX Ctrl
tab. When this feature is enabled, EchoLink's VOX will ignore short noise
bursts, such as the repeater's courtesy tone and the squelch crash when the
repeater's carrier drops. Set the time constant to a value slightly
higher than the longer of these two signals. Typical settings are 250 ms
for a repeater with a (short) courtesy tone, or 80 ms for a repeater with no
courtesy tone. Note that the Smart VOX feature does not necessarily
suppress these signals in the audio path, it merely prevents them from
triggering (or holding open) the VOX.
Anti-Thump: Use the Anti-Thump feature if the squelch
crash, as heard over the repeater when your transceiver stops transmitting,
seems to be triggering the VOX. Start with a low value and move it
gradually higher until the SIG indicator no longer appears when your link stops
When the VOX is properly adjusted, the "acid test" is to
connect the link to the *ECHOTEST* conference server. After hearing the
initial welcome message from the test server, the repeater should drop normally
and then remain idle. If the repeater continues to be keyed up by
responses from the test server, re-check the above settings.
When the settings are correct at both ends of a repeater-to-repeater
link, both repeaters should remain idle except during an actual QSO, or while
either repeater sends its ID.
CTCSS Control: If the node is remotely located, this may be
the best technique of all -- but it requires cooperation from the
repeater. In this set-up, the repeater transmits a CTCSS (a.k.a. PL) tone
only while its receiver's COS is active; that is, only while a station is
transmitting. The EchoLink transceiver is configured to open up only when
this tone is received. The advantage of this system is that EchoLink
triggers only on a true signal, and ignores incidentals such as courtesy tones
and CW IDs. The disadvantage is that most PL-guarded repeaters transmit a
continuous tone, even when no signal is present on the input, so it may require
configuration changes to the repeater itself. (Note that this technique
can be used whether or a not a PL is required to activate the repeater.)